Aortitis is inflammation of the aortic wall, which can be caused by infectious agents, large-vessel vasculitides (such as giant cell arteritis or Takayasu arteritis), or autoimmune conditions, potentially leading to aneurysm formation, stenosis, or aortic valve insufficiency.

Exam domain	One-glance essentials
Definition / diagnosis	Inflammation of the aortic wall from immune-mediated or infectious causes ^[1] It can cause aneurysm, stenosis, regurgitation or rupture ^[1]
Epidemiology / risks	Giant-cell arteritis, Takayasu arteritis and IgG4 disease are key inflammatory causes ^[1] Bacteraemia and syphilis are infectious considerations ^[1]
Core mechanism	Transmural inflammation damages elastic media and remodels the wall ^[1] Branch-vessel inflammation produces ischaemia and pulse deficits ^[1]
Clinical picture	Constitutional pain, limb claudication or vascular bruits ^[1] Aortic regurgitation, unequal pulses or aneurysm may be the first sign ^[1]
Investigations	Inflammatory markers plus CT/MR angiography define extent ^[2] PET can assess activity; obtain cultures/serology before immunosuppression when infection is possible ^[2]
Management	Immunosuppression treats non-infectious large-vessel vasculitis ^[3] Infectious aortitis needs urgent antibiotics and surgical/endovascular source control ^[3]
Complications	Aneurysm, dissection, rupture and branch-vessel ischaemia ^[4] Steroid toxicity and relapse require long-term monitoring ^[4]
Prevention / follow-up	Treat infection sources and cardiovascular risk factors ^[3] Serial whole-aorta imaging detects silent progression ^[3]
Exam traps	*Never give immunosuppression before considering infectious aortitis* ^[2] Normal inflammatory markers do not reliably exclude smouldering large-vessel disease ^[3]

References

^[1] Lecture slides: GC 199. Pulsating abdominal mass aortic aneurysm.pdf (p4)

^[2] Senior notes: Ryan Ho Cardiology.pdf (p160, p220–222)

^[3] Senior notes: Maksim Medicine Notes.pdf (p15)

^[4] Lecture slides: GC 199. Pulsating abdominal mass aortic aneurysm.pdf (p3, p13, p15, p22)

Aortitis

Aortitis literally means inflammation of the aorta ("aort-" = aorta, "-itis" = inflammation). It is a histopathological and clinical entity characterised by inflammatory cell infiltration of one or more layers of the aortic wall (intima, media, adventitia), leading to wall weakening, aneurysm formation, stenosis, dissection, or aortic valve dysfunction.

Think of it this way: the aorta is the largest artery in the body, and when its wall becomes inflamed, the structural integrity of its elastic lamellae and smooth muscle is compromised. The downstream consequences depend on which layer is primarily affected and how much destruction occurs.

Aortitis is not a single disease — it is a manifestation of many different underlying conditions (infectious, autoimmune, autoinflammatory). The clinical importance lies in two facts:

It can be clinically silent until a catastrophic complication occurs (rupture, dissection).
It may be the first presentation of a systemic vasculitis or infection.

Key Concept

Aortitis is inflammation of the aortic wall. It is a pathological process, not a single diagnosis. Always think: "What is causing this aortitis?" — the answer determines management.

2. Epidemiology

True population prevalence is difficult to determine because many cases are subclinical or discovered incidentally on surgical/autopsy specimens.
In large surgical series, clinically isolated aortitis (inflammation found on histology of resected aortic aneurysm specimens without prior diagnosis of systemic disease) is found in 4–8% of thoracic aortic surgical specimens ^[1]^[2].
Giant cell arteritis (GCA) is the commonest cause of aortitis in Western populations, with an incidence of ~20/100,000/year in those > 50 years old ^[3].
Takayasu arteritis is more prevalent in Asian populations (incidence ~1–2/million/year globally, but higher in Japan, India, and Southeast Asia) and is the more relevant large-vessel vasculitis in younger Hong Kong patients ^[3]^[4].

Feature	GCA-related aortitis	Takayasu-related aortitis	Infectious aortitis
Age	> 50 years (avg 70y)	< 50 years (10–40y)	Any age
Sex	F:M = 2:1	F:M = 8–9:1	M > F
Ethnicity	More common in Northern Europeans; less common in Asians	More common in Asians	Universal

Takayasu arteritis is relatively more important in Hong Kong/Asian populations compared to Western settings ^[4].
Infectious aortitis — particularly mycotic aneurysms from non-typhoid Salmonella — is a well-recognised entity in Hong Kong and Southeast Asia, especially in immunocompromised or elderly patients ^[1]^[5].
Syphilitic aortitis, once a classic cause, is now rare but still seen occasionally, particularly in high-risk populations (MSM, HIV co-infection). Hong Kong has seen a resurgence of syphilis cases in recent years, so this should remain on the differential ^[2].
IgG4-related aortitis is increasingly recognised in Asian populations.

3. Anatomy and Function of the Aorta (Relevant to Understanding Aortitis)

The aorta is divided into:

Aortic root: Contains the sinuses of Valsalva, from which the coronary arteries arise. The aortic valve sits here.
Ascending aorta: From the sinotubular junction to the brachiocephalic trunk origin.
Aortic arch: Gives off brachiocephalic trunk, left common carotid, left subclavian.
Descending thoracic aorta: From the left subclavian to the diaphragm.
Abdominal aorta: From the diaphragm to the bifurcation at L4. Gives off coeliac trunk, SMA, renal arteries, IMA, and others.

Why does anatomy matter for aortitis?

Different diseases preferentially affect different segments:
- GCA: thoracic aorta (ascending > arch > descending)
- Takayasu: aortic arch and abdominal aorta
- Syphilis: ascending aorta (especially the vasa vasorum-rich proximal portion)
- Atherosclerotic/infectious: infrarenal abdominal aorta (where vasa vasorum are sparse and atherosclerosis is most severe)

Layer	Components	Function	Relevance to Aortitis
Intima	Endothelium + subendothelial connective tissue	Barrier, anti-thrombotic surface	Site of atherosclerotic plaque; PAU starts here
Media	Concentric elastic lamellae + smooth muscle cells + collagen	Provides tensile strength and elasticity (Windkessel function)	Main target in GCA and Takayasu; destruction → aneurysm/dissection
Adventitia	Collagen, vasa vasorum, nervi vasorum, lymphatics	Nutrition of outer media; structural support	IgG4-related disease often involves adventitia; syphilitic aortitis targets vasa vasorum here

The vasa vasorum ("vessels of vessels") are small arteries that supply the outer two-thirds of the aortic media and adventitia. They are most dense in the:

Ascending aorta and aortic arch
Descending thoracic aorta

They are sparse or absent in the infrarenal abdominal aorta (which relies on diffusion from the lumen).

Why is this important?

Syphilitic aortitis classically involves the ascending aorta because Treponema pallidum causes obliterative endarteritis of the vasa vasorum → ischaemic necrosis of the media → scarring, weakening, aneurysm formation ^[2].
Infectious agents can seed the aortic wall via the vasa vasorum.
Intramural haematoma (IMH): rupture of vasa vasorum within the medial layer without intimal injury ^[2].

The aorta serves two main functions:

Conduit: Delivers oxygenated blood from the LV to the systemic circulation.
Windkessel function: The elastic recoil of the aortic wall during diastole converts pulsatile flow into more continuous flow, maintaining diastolic perfusion pressure (especially important for coronary perfusion).

When aortitis destroys elastic fibres → the wall loses compliance → aneurysmal dilatation → risk of rupture/dissection.

4. Etiology (with Focus on Hong Kong)

The causes of aortitis can be broadly divided into non-infectious (autoimmune/inflammatory) and infectious.

4.1 Non-Infectious Aortitis

A. Giant Cell Arteritis (GCA)

The most common cause of aortitis overall ^[3].
Granulomatous arteritis of the aorta and its major branches.
Typically affects individuals > 50 years old, F:M = 2:1, more common in Northern Europeans but occurs in all ethnicities ^[3].
Aortic involvement (large vessel GCA) is present in 40–80% of GCA patients on imaging (PET-CT), even when clinically silent.
Often co-exists with polymyalgia rheumatica (PMR): 40–50% GCA has PMR, 10% PMR has GCA ^[3].
Can cause thoracic aortic aneurysm (especially ascending), aortic dissection, aortic stenosis of branch vessels.
Risk of thoracic aortic aneurysm is 17× higher than age-matched controls.

B. Takayasu Arteritis

Granulomatous inflammation affecting aortic arch and abdominal aorta, a.k.a. "pulseless disease" ^[4].
Usually affects females < 50 years old ^[4].
More common in Asians — especially relevant in Hong Kong ^[4].
Also known as: pulseless disease, aortic arch syndrome, occlusive thromboaortopathy ^[4].
Histology: granulomatous inflammation, most commonly affecting aortic arch and abdominal aorta ^[4].
Epidemiology: uncommon, usually affects F (80–90%) of reproductive age (10–40y) especially in Asians ^[4].

GCA vs. Takayasu — How to Tell Them Apart

Both are granulomatous large vessel vasculitides. The key distinguishing factor is age: GCA > 50 years, Takayasu < 50 years. Histologically, they can look identical. Some experts consider them a spectrum of the same disease.

In Hong Kong, Takayasu is relatively more common than in Western populations.

C. Behçet Disease

Systemic vasculitis of unknown aetiology ^[3].
More common along ancient Silk Road (Turkey, Middle East, China) ^[3].
Vascular disease: remarkably affects A/Vs of all sizes ^[3].
Can cause aortitis, aortic aneurysms (often saccular), and arterial/venous thrombosis.
Strongly associated with HLA-B51 in Asians ^[3].

D. ANCA-associated Vasculitis

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) can rarely involve the aorta.
Eosinophilic granulomatosis with polyangiitis (EGPA) has occasional aortic involvement reported.
These are primarily small vessel vasculitides — aortic involvement is uncommon.

E. Relapsing Polychondritis

Autoimmune destruction of cartilage; 10–15% develop aortitis (ascending aorta) with aortic regurgitation.

F. Spondyloarthropathies (SpA)

Ankylosing spondylitis (AS) is associated with aortitis, AI (aortic insufficiency), conduction defects ^[3].
The aortitis in AS characteristically involves the aortic root → causes fibrosis at the base of the aortic valve cusps → aortic regurgitation.
Reactive arthritis (ReA) can also rarely cause aortitis with AI, conduction defects ^[3].

G. IgG4-Related Disease (IgG4-RD)

Increasingly recognised cause of aortitis, especially in Asian populations.
Characterised by dense lymphoplasmacytic infiltration rich in IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis.
Typically affects the infrarenal abdominal aorta → inflammatory abdominal aortic aneurysm (perianeurysmal fibrosis).
Distinguished from ordinary atherosclerotic AAA by the thick, shiny, white retroperitoneal fibrosis encasing the aorta and ureters.
Responds to corticosteroids (unlike atherosclerotic aneurysm).
Elevated serum IgG4 (though not always).

H. Sarcoidosis

Rare cause of granulomatous aortitis.

I. Clinically Isolated Aortitis (CIA)

Found incidentally on histology after aortic surgery for aneurysm.
No identifiable systemic disease at time of diagnosis.
May represent limited or early GCA/Takayasu — these patients need long-term follow-up as some develop systemic vasculitis later.
Found in 4–8% of thoracic aortic surgical specimens.

4.2 Infectious Aortitis

A. Mycotic Aneurysm / Infected Aortic Aneurysm

The term "mycotic" is a historical misnomer (coined by Osler) — it does not mean fungal. It refers to any infected aneurysm.

Relevant organisms (especially in Hong Kong): ^[1]^[5]

Non-typhoid Salmonella (most common cause of mycotic aortic aneurysm in Asia/Hong Kong) — seeds atherosclerotic plaques, especially in elderly/immunocompromised.
Staphylococcus aureus — haematogenous seeding, often acute/fulminant.
Streptococcus species
Gram-negative organisms (E. coli, Klebsiella)
Syphilis (Treponema pallidum) — tertiary syphilis ^[2].

Feature	Non-typhoid Salmonella	Staphylococcus	Syphilis
Setting	Elderly, atherosclerotic, DM, immunosuppressed	IV drug use, bacteraemia	Untreated tertiary syphilis
Location	Infrarenal aorta (atherosclerotic)	Any segment	Ascending aorta
Course	Subacute–acute	Acute, fulminant	Chronic (years–decades)
Aneurysm type	Saccular, often with rapid expansion	Pseudoaneurysm	Fusiform or saccular ascending

B. Syphilitic Aortitis (in more detail)

Occurs in tertiary syphilis (10–30 years after primary infection).
Treponema pallidum causes obliterative endarteritis of the vasa vasorum in the ascending aorta.
This leads to:
- Ischaemic destruction of the media (loss of elastic fibres and smooth muscle)
- "Tree-barking" appearance of the intima (wrinkling due to medial scarring)
- Aneurysm of the ascending aorta (saccular or fusiform)
- Aortic root dilatation → aortic regurgitation (supravalvular) ^[2]
- Coronary ostial stenosis (from intimal thickening at the aortic root → angina)
Now rare in developed countries but still encountered.

Mycobacterium tuberculosis: TB aortitis is rare but reported, especially in endemic regions.
Can cause mycotic aneurysms, usually from contiguous spread from adjacent infected lymph nodes or vertebral bodies.

True fungal aortitis (Aspergillus, Candida) is very rare, almost exclusively in severely immunocompromised patients (post-transplant, prolonged neutropenia).

HIV, CMV, HBV, HCV — may contribute to aortitis/arteritis indirectly via immune mechanisms.

Radiation aortitis: Following thoracic radiation (e.g., for lymphoma, breast cancer). Causes intimal and medial fibrosis → stenosis or aneurysm, typically 10–20 years after exposure.
Drug-induced: Rare. Fluoroquinolones (ciprofloxacin, levofloxacin) are associated with aortic aneurysm and dissection — the mechanism may involve MMP upregulation in the aortic wall.
Cogan syndrome: Interstitial keratitis + vestibuloauditory dysfunction + aortitis (resembles Takayasu in a Western patient).

5. Pathophysiology

Regardless of the cause, aortitis follows a common pathological pathway:

5.2 Pathophysiology by Disease Category

Initiation: Unknown antigen (possibly elastin or another aortic wall component) is presented to dendritic cells in the adventitia via the vasa vasorum.
T-cell activation: CD4+ T-helper cells infiltrate the adventitia and media → produce IFN-γ and IL-17.
Macrophage activation: IFN-γ activates macrophages → form multinucleated giant cells → produce MMPs (matrix metalloproteinases) and reactive oxygen species → digest elastic lamellae.
Intimal hyperplasia: PDGF and VEGF from activated macrophages drive smooth muscle cell migration and proliferation into the intima → concentric intimal thickening → stenosis (especially in Takayasu).
Medial destruction: Loss of elastic fibres → wall weakens → aneurysm (especially in GCA).
Neovascularisation: VEGF promotes new vessel formation in the media (normally avascular) → further inflammatory cell infiltration.

Key distinction: Takayasu tends to cause more stenosis (especially in younger, thicker-walled arteries with more fibroproliferative response), while GCA tends to cause more aneurysmal disease (in older, already degenerating arteries).

Pathology: subacute granulomatous inflammation of large/medium sized arteries with lymphocyte, plasma cell, neutrophil and giant cell infiltration ^[3].

T. pallidum spirochetes colonise the vasa vasorum of the ascending aorta during secondary/early latent syphilis.
Obliterative endarteritis of the vasa vasorum → endothelial swelling and perivascular inflammation → luminal narrowing.
Ischaemic injury to the outer media (which depends on vasa vasorum for oxygen) → necrosis and loss of elastic fibres and smooth muscle.
Replacement by scar tissue → patchy medial scarring.
Intimal wrinkling over scarred media → characteristic "tree-bark" appearance grossly.
Wall weakening → aneurysm of the ascending aorta (the area richest in vasa vasorum).
Aortic root dilatation → aortic valve cusps are pulled apart (the cusps themselves are normal, but the annulus is dilated) → aortic regurgitation.
Intimal fibrosis around coronary ostia → coronary ostial stenosis → angina (classically exertional).

Organisms reach the aortic wall via:
- Haematogenous seeding (most common): bacteraemia → organisms lodge in pre-existing atherosclerotic plaque or intimal damage.
- Contiguous spread: from adjacent infection (e.g., vertebral osteomyelitis, para-aortic abscess).
- Direct inoculation: trauma, iatrogenic (post-catheterisation, post-graft).
Bacterial invasion of the arterial wall → acute/subacute neutrophilic inflammation.
Rapid destruction of media and adventitia → weakened wall → pseudoaneurysm or saccular aneurysm with high rupture risk.
Classically Salmonella has tropism for atherosclerotic endothelium → seeds on pre-existing plaques in the infrarenal aorta → rapid expansion.

Enhancement of proteolytic activity (elevated Matrix metalloproteinases [MMP]) is a key mechanism in both atherosclerotic and inflammatory aneurysm formation ^[1].

Unknown trigger → activation of T-follicular helper cells and cytotoxic CD4+ T cells.
IgG4-positive plasma cells and lymphocytes infiltrate the adventitia predominantly.
Storiform fibrosis (matted, whorled pattern) develops.
Obliterative phlebitis (inflammation and obliteration of small veins within the wall).
Dense periaortic fibrosis → often encases ureters → hydronephrosis.
Responds dramatically to corticosteroids (unlike most other aneurysms).

Chronic inflammation at the aortic root (near the insertion of the aortic valve cusps).
Fibrosis extends from the base of the cusps into the membranous interventricular septum.
Aortic valve cusps become thickened and retracted → aortic regurgitation.
Fibrosis extending into the conduction system → AV block (first degree, progressing to complete).
This pattern is characteristic: aortitis, AI (aortic insufficiency), conduction defects ^[3].

6. Classification

Category	Examples
Large vessel vasculitis	GCA, Takayasu
Medium/small vessel vasculitis with aortic involvement	Behçet, PAN (rare), ANCA vasculitis (rare)
Spondyloarthropathy-associated	AS, ReA
Other autoimmune/inflammatory	IgG4-RD, sarcoidosis, relapsing polychondritis, Cogan syndrome
Infectious	Salmonella, Staph, Streptococcus, Syphilis, TB, fungal
Clinically isolated aortitis	No identifiable systemic disease
Other	Radiation, drug-induced

Location	Common causes
Ascending aorta / aortic root	GCA, syphilis, AS/SpA, relapsing polychondritis
Aortic arch	Takayasu, GCA
Descending thoracic	GCA, Takayasu
Abdominal aorta	IgG4-RD, Takayasu, infectious (Salmonella), atherosclerotic inflammatory

Pattern	Diseases
Granulomatous	GCA, Takayasu, sarcoidosis, TB
Lymphoplasmacytic	IgG4-RD, syphilis
Neutrophilic/suppurative	Bacterial mycotic aneurysm
Mixed	Behçet, PAN
Giant cell-rich	GCA, Takayasu

High Yield Classification Point

When you see "granulomatous aortitis" on a pathology report after aortic surgery, the main differential is GCA vs. Takayasu vs. isolated aortitis vs. sarcoidosis vs. infection (TB, syphilis). Age is the most important distinguishing factor.

7. Clinical Features

7.1 Symptoms

The clinical features of aortitis are often non-specific and may be silent until complications develop. The symptoms can be divided into:

Fever, malaise, weight loss, night sweats, fatigue
- Why? Aortitis is an inflammatory process → production of pro-inflammatory cytokines (IL-1, IL-6, TNF-α) → systemic inflammatory response → fever, anorexia, weight loss.
- Constitutional symptoms (40%) are noted in Takayasu arteritis ^[4].
- Fever (50%, usually low grade), fatigue, weight loss in GCA ^[3].
- In infectious aortitis, fever can be high-grade and spiking (bacteraemia).

Chest pain, back pain, abdominal pain
- Why? Inflammation of the aortic wall stretches pain-sensitive nerve fibres in the adventitia (nervi vasorum). Rapid expansion of an inflammatory aneurysm distends the wall → pain.
- Chest pain (ascending/arch aortitis), interscapular pain (descending thoracic), abdominal/back pain (abdominal aortitis).
- Pain may be vague and indolent in chronic aortitis, or sudden and severe if dissection/impending rupture occurs.
- Abdominal / back / loin / groin pain: due to compression on nerves and organs in AAA ^[1].

Limb claudication (70%) in Takayasu ^[4].
- Why? Inflammatory intimal thickening → stenosis of aortic branch vessels → reduced blood flow to limbs → intermittent ischaemic pain on exertion (claudication), typically upper limb (subclavian involvement) in Takayasu vs. lower limb in PAD.
Jaw claudication in GCA.
- Why? Ischaemia of the masseter muscle due to inflammation/stenosis of branches of the external carotid artery.
- Jaw claudication (1/2) (due to ischaemia of masseter muscle) ^[3].
- Pathognomonic! ^[3].
Angina — from coronary ostial stenosis (syphilitic aortitis, Takayasu) or from aortic regurgitation (reduced diastolic BP → reduced coronary perfusion).
Mesenteric angina (postprandial abdominal pain, food fear, weight loss) — from stenosis of coeliac trunk or SMA (Takayasu, GCA).
Visual symptoms:
- Amaurosis fugax (transient), can progress into permanent visual loss (15–20%) ^[3].
- Due to arteritic acute ischaemic optic neuropathy (AAION) ^[3].
- This is specific to GCA (ophthalmic/posterior ciliary artery involvement), not typical of aortitis alone.
Neurological symptoms: TIA, stroke (carotid/vertebral stenosis), syncope.
Renovascular hypertension: renal artery stenosis → activation of RAAS → secondary hypertension.
- HTN ( > 50%) due to renal artery stenosis in Takayasu ^[4].
Subclavian steal syndrome in Takayasu ^[4] — stenosis of proximal subclavian artery → retrograde flow down the ipsilateral vertebral artery → vertebrobasilar insufficiency on arm exercise (dizziness, syncope).

Palpitations, awareness of heartbeat (compensated phase — due to increased stroke volume).
Progressive dyspnoea on exertion, orthopnoea, PND (decompensated phase — LV failure).
Angina: due to reduced diastolic BP and increased ventricular demand ^[2].
Aortic root dilatation (supravalvular): hypertension, infection (syphilitic aortitis), inflammatory (AS), CT disease (Marfan's, EDS) as causes of AR ^[2].

Often asymptomatic until rupture or dissection.
Compressive symptoms:
- Hoarseness (recurrent laryngeal nerve compression — thoracic aortic aneurysm)
- Dysphagia (oesophageal compression — "dysphagia aortica")
- Stridor/cough (tracheal/bronchial compression)
- SVC syndrome (rare)

GCA: new-onset headache (temporal), scalp tenderness, PMR symptoms (shoulder/pelvic girdle pain and stiffness).
Takayasu: upper limb fatigue, Raynaud's phenomenon, arthralgias.
Behçet: oral ulcers, urogenital ulcers, ocular inflammation, skin lesions ^[3].
AS/SpA: inflammatory back pain, morning stiffness, enthesitis.
IgG4-RD: symptoms from other organ involvement (autoimmune pancreatitis, lacrimal/salivary gland enlargement, retroperitoneal fibrosis with flank pain/hydronephrosis).
Syphilis: history of primary chancre, secondary rash (usually decades prior).

7.2 Signs

Asymmetric BP (50%) in Takayasu ^[4].
- Why? Stenosis of one subclavian artery → lower BP reading in the affected arm. A difference of > 10 mmHg systolic between arms is significant; > 20 mmHg is very concerning.
Absent/weak pulses (60%): most commonly radial, often asymmetric in Takayasu ^[4].
- Why? Inflammatory stenosis or occlusion of subclavian, axillary, or brachial arteries. This is why Takayasu is called "pulseless disease" ^[4].
Bruits (80%): usually audible over subclavian, brachial, carotid, abdominal vessels in Takayasu ^[4].
- Why? Turbulent blood flow through a stenosed artery generates audible vibrations (bruits).
Hypertension: secondary to renal artery stenosis (RAAS activation) or aortic coarctation-like stenosis.
Early diastolic murmur (EDM) if aortic regurgitation develops ^[2].
- Best heard at left sternal edge with patient sitting up, leaning forward, at end-expiration.
- Ejection systolic murmur also common (↑SV) if significant AR present ^[2].
- Austin Flint murmur: mid-diastolic low-pitched murmur (regurgitant jet impinging on anterior mitral leaflet → functional MS) ^[2].
Signs of wide pulse pressure (in AR):
- Collapsing (water-hammer) pulse
- Displaced, thrusting apex (LV dilatation)
- Duroziez sign, Quincke's pulse, Traube's sign, De Musset's sign ^[2].
Pulsatile abdominal mass: if inflammatory AAA (typically epigastric, expansile).
- Physical examination: pulsatile and expansile mass (usually in epigastrium) ^[1].

Temporal artery: prominent, tender, non-pulsatile ^[3].
Scalp tenderness ^[3].
Fundus: chalky white, swollen optic disc with haemorrhage (NAION as d/dx) ^[3].

Signs of rupture: haemodynamic instability (hypotension, tachycardia), peritonism, Grey Turner/Cullen sign (retroperitoneal haemorrhage).
Signs of dissection: asymmetric BP and pulse between arms (e.g., radial-radial delay for Type A, radial-femoral delay for Type B) ^[2].
Signs of distal embolisation: blue toes, livedo reticularis, absent distal pulses.

Disease	Specific Signs
GCA	Tender, thickened, non-pulsatile temporal artery; scalp tenderness
Takayasu	Absent radial pulses, BP discrepancy, subclavian/carotid bruits
Behçet	Oral aphthous ulcers, genital ulcers, pathergy test positive, hypopyon
AS	Loss of lumbar lordosis, reduced chest expansion, question mark posture
IgG4-RD	Parotid/lacrimal gland enlargement, orbital pseudotumour
Syphilis	Argyll Robertson pupils, Charcot joints, tabes dorsalis (tertiary)
Infectious	Fever, leucocytosis, septic emboli (splinter haemorrhages, Janeway lesions)

Clinical Pearl — Aortitis Presenting as FUO

Aortitis (especially GCA or Takayasu) is an important cause of fever of unknown origin (FUO) in the elderly. If an elderly patient has fever, raised ESR/CRP, and weight loss without an obvious source, think about large vessel vasculitis. PET-CT showing aortic uptake clinches the diagnosis.

Clinical Pearl — When to Suspect Aortitis

Think of aortitis when you see:

Inflammatory back/chest/abdominal pain + raised inflammatory markers
New-onset aortic regurgitation in a younger patient without traditional risk factors
Aortic aneurysm in an unusual location (ascending, arch) or an unusual patient (young woman)
Asymmetric pulses/BP with constitutional symptoms
FUO in the elderly with high ESR/CRP

Feature	GCA	Takayasu	Syphilitic	Infectious (mycotic)	IgG4-RD	SpA-associated
Age	> 50	< 50	Any (tertiary)	Any (elderly)	Middle-aged	Young adults
Sex	F > M	F >> M	M > F	M > F	M > F	M > F
Aortic segment	Thoracic (ascending)	Arch + abdominal	Ascending	Infrarenal	Infrarenal	Root
Main pathology	Granulomatous, medial destruction	Granulomatous, intimal thickening/stenosis	Vasa vasorum endarteritis	Suppurative, rapid wall destruction	Lymphoplasmacytic, storiform fibrosis	Root fibrosis
Main complication	Aneurysm, dissection, AR	Stenosis, aneurysm, HTN	AR, ascending aneurysm, coronary ostial stenosis	Pseudoaneurysm, rupture, sepsis	Inflammatory AAA, hydronephrosis	AR, conduction block
Key investigation	PET-CT, temporal artery Bx	CTA/MRA	Treponemal serology	Blood cultures, CT	Serum IgG4, biopsy	HLA-B27, imaging
Treatment	Steroids ± tocilizumab	Steroids + MTX/AZA	Penicillin	Surgery + antibiotics	Steroids ± rituximab	Biologics for SpA

High Yield Summary

Definition: Aortitis = inflammation of the aortic wall; a pathological process with many causes.

Key Causes (Hong Kong focus):

Non-infectious: GCA (> 50y, commonest overall), Takayasu (< 50y, more common in Asians), Behçet, IgG4-RD, spondyloarthropathies
Infectious: Non-typhoid Salmonella (most common mycotic aneurysm in Asia), Syphilis (ascending aorta), Staph aureus, TB

Pathophysiology: Inflammatory cell infiltration → medial destruction (elastic fibres/SMC) → aneurysm ± stenosis ± AR ± dissection/rupture.

Clinical Features:

Constitutional: fever, weight loss, fatigue
Pain: chest/back/abdominal (adventitial inflammation, aneurysm expansion)
Vascular: asymmetric pulses/BP, bruits, claudication (stenosis)
Cardiac: AR (root dilatation), conduction defects (SpA)
End-organ ischaemia: stroke, mesenteric ischaemia, renovascular HTN, visual loss

Must-know distinctions:

GCA vs. Takayasu: Age ( > 50 vs. < 50)
GCA: temporal headache, jaw claudication, AAION, PMR
Takayasu: pulseless disease, BP asymmetry, bruits, young Asian female
Syphilitic: ascending aorta, tree-bark intima, AR, coronary ostial stenosis
Mycotic (Salmonella): infrarenal, rapid expansion, saccular, high rupture risk
IgG4-RD: infrarenal inflammatory AAA, periaortic fibrosis, steroid-responsive

Active Recall - Aortitis

^[1] Lecture slides: GC 199. Pulsating abdominal mass aortic aneurysm.pdf (p4) ^[2] Senior notes: Ryan Ho Cardiology.pdf (p160, p221–222) ^[3] Senior notes: Ryan Ho Rheumatology.pdf (p58, p95–96, p98) ^[4] Senior notes: Maksim Medicine Notes.pdf (p332); Ryan Ho Rheumatology.pdf (p96) ^[5] Senior notes: Maksim Surgery Notes.pdf (p161)

Differential Diagnosis of Aortitis

When you encounter a patient in whom you suspect aortitis — whether the presentation is unexplained aortic aneurysm, new aortic regurgitation, constitutional symptoms with raised inflammatory markers, or asymmetric pulses — the differential diagnosis must be approached systematically. The challenge is twofold: (1) distinguishing aortitis from non-inflammatory aortic pathology, and (2) identifying the specific cause of the aortitis itself.

Let me walk you through this the way you'd think at the bedside.

The differential depends entirely on how the patient presents. Aortitis rarely declares itself with a sign saying "I am aortitis." Instead, you encounter one of several clinical scenarios, and aortitis sits within a broader differential for each:

B. Differential Diagnosis by Clinical Scenario

This is perhaps the most common way aortitis comes to attention — an aneurysm is discovered (often incidentally), and the question is whether it is "ordinary" degenerative/atherosclerotic or something else.

Differential	Key Features	Why it's on the differential
Degenerative / atherosclerotic aneurysm (commonest)	Elderly male, smoking history, 95% associated with atherosclerosis ^[1]^[5], 97% infrarenal ^[2], often asymptomatic, pulsatile and expansile mass ^[5]	By far the most common cause of AAA. Typically infrarenal, fusiform, in an elderly man with cardiovascular risk factors.
Connective tissue disease	Younger patient, Marfanoid habitus (tall, arachnodactyly, pectus), joint hypermobility (EDS), family history. Marfan's, Ehlers-Danlos IV ^[1]	These conditions cause structural weakness of the aortic wall (fibrillin-1 deficiency in Marfan, collagen III deficiency in EDS IV) → aneurysm at a younger age, often involving the ascending aorta/root.
GCA-related aortitis	Age > 50, F > M, temporal headache, jaw claudication, PMR symptoms, ESR > 50, temporal artery tenderness/decreased pulsation ^[4]	GCA causes thoracic aortic aneurysm (ascending > arch). Risk is 17× higher than age-matched controls. May present silently.
Takayasu arteritis	Females < 50 years, especially Asians, absent/weak pulses (60%), bruits (80%), asymmetric BP (50%) ^[3]^[6]	Can cause aneurysmal dilatation (especially of the aortic arch/descending aorta) in addition to stenosis.
IgG4-related aortitis	Middle-aged male, storiform fibrosis, lymphoplasmacytic infiltrate of mainly IgG4+ plasma cells ^[7], thick periaortic fibrosis on CT, may have other IgG4-RD features (AIP, sclerosing cholangitis, sialadenitis). Group 2 phenotype: retroperitoneal fibrosis ± aortitis ^[7]	Presents as inflammatory AAA. The aneurysm is surrounded by a thick rind of soft tissue (unlike simple atherosclerotic AAA). Responds to steroids.
Infectious (mycotic) aortitis	Fever, leucocytosis, positive blood cultures, saccular aneurysm with rapid expansion, air/gas in aortic wall on CT. Non-typhoid Salmonella, Staphylococcus, Syphilis ^[5]	Organisms seed atherosclerotic plaque or the wall via vasa vasorum. Saccular morphology, unusual location, or rapid growth should raise suspicion.
Syphilitic aortitis	Ascending aorta involvement, AR, coronary ostial stenosis, "tree-bark" intima. Syphilitic aortitis as a cause of aortic root dilatation (supravalvular) ^[2]^[8]	Tertiary syphilis. Obliterative endarteritis of vasa vasorum → ascending aortic aneurysm. Now rare but still seen.
Behçet disease	Oral ulcers, urogenital ulcers, ocular inflammation, HLA-B51, young male along Silk Road (Turkey, Middle East, China) ^[3]	Behçet can cause saccular aortic aneurysms with high rupture risk. Arterial involvement is less common than venous but carries worse prognosis.

Red Flags for Non-Atherosclerotic Aneurysm

Suspect an inflammatory or infectious cause when the aneurysm is:

In an unusual location (ascending aorta, arch, suprarenal)
In a young patient without typical atherosclerotic risk factors
Saccular rather than fusiform
Rapidly expanding on serial imaging
Surrounded by periaortic soft tissue thickening on CT (IgG4-RD, infectious)
Associated with constitutional symptoms (fever, weight loss, raised ESR/CRP)

The question here is whether the AR is due to valve cusp disease or aortic root/ascending aortic dilatation — the latter being the domain of aortitis.

Aetiology of AR ^[2]^[8]:

Category	Causes	Mechanism
Cusp disease	Degenerative (MC), RHD, congenital (bicuspid AV), IE, aortic dissection ^[8]	Primary damage to the valve leaflets themselves
Aortic root dilatation (supravalvular)	Hypertension, syphilitic aortitis, inflammatory (AS/SpA), CT disease (Marfan's, EDS) ^[8]	The annulus dilates → cusps are pulled apart → coaptation failure → regurgitation. The cusps themselves may be structurally normal.

For aortitis-related AR, think:

Syphilitic aortitis: ascending aortic aneurysm → root dilatation → AR. Also causes coronary ostial stenosis → angina.
Spondyloarthropathy (AS, ReA): aortitis, AI, conduction defects ^[9]. The mechanism is a sclerosing inflammatory process involving aortic root, AV cusps and IV septum ^[9]. Fibrosis thickens and retracts the cusps + may extend into the conduction system → heart block.
GCA: ascending aortic aneurysm/dilatation → AR.
Relapsing polychondritis: aortic root inflammation → AR (10–15% of cases).
Behçet disease: aortic root involvement (less common).

This is the "stenotic/occlusive" presentation of large vessel vasculitis. The differential here includes:

Differential	Key Features
Takayasu arteritis	Pulseless disease, females < 50, Asians, bruits (80%), absent/weak pulses (60%), limb claudication (70%), asymmetric BP (50%) ^[3]^[6]
GCA (large vessel)	> 50 years, may have temporal headache/PMR, bruits over subclavian/axillary, upper limb claudication
Atherosclerosis	Older patient with CV risk factors, Leriche syndrome (gradual occlusion of terminal aorta → absent femoral pulses, intermittent claudication, gluteal pain, impotence) ^[5]. Lower limb predominant.
Aortic coarctation	Young patient, upper limb hypertension with weak femoral pulses, rib notching on CXR. Congenital.
Fibromuscular dysplasia (FMD)	Young to middle-aged women, "string of beads" on angiography, most commonly renal arteries → renovascular HTN
Mid-aortic syndrome	Narrowing of the abdominal aorta ± renal arteries in children/young adults. May be due to Takayasu, FMD, NF1, Williams syndrome, or idiopathic.

Aortitis (especially large vessel vasculitis) is an important and often under-recognised cause of fever of unknown origin (FUO) in the elderly. The differential is broad:

Category	Examples
Infection	IE, TB, occult abscess, osteomyelitis, mycotic aneurysm
Malignancy	Lymphoma, solid organ tumour
Connective tissue disease	SLE, RA, adult-onset Still's disease
Large vessel vasculitis	GCA (commonest form of primary vasculitis ^[3]), Takayasu
Medium/small vessel vasculitis	PAN (systemic necrotizing ANCA-negative vasculitis affecting medium-sized arteries ^[3]), ANCA vasculitis
Other inflammatory	IgG4-RD, sarcoidosis

Common to all vasculitides: unexplained systemic illness with constitutional symptoms, with no evidence of malignancy / infection / drug-induced / other CTD ^[4].

Exam Pearl — FUO in the Elderly

In an elderly patient with FUO + very high ESR (often > 100), always consider GCA even without classic temporal headache. PET-CT showing diffuse FDG uptake in the aorta and great vessels can clinch the diagnosis. Up to 20% of GCA patients present with FUO as the dominant feature.

When a patient presents with acute severe chest/back pain and imaging shows an acute aortic pathology, the differential includes:

Entity	Mechanism
Aortic dissection	Intimal tear → blood enters media → false lumen
Intramural haematoma (IMH)	Rupture of vasa vasorum → haematoma within media without intimal tear
Penetrating atherosclerotic ulcer (PAU)	Atherosclerotic plaque ulcerates through intima → haematoma in media
Ruptured aortic aneurysm	Classical triad: severe abdominal/back pain, pulsatile mass, hypotension ^[1]^[5]
Inflammatory aortitis with acute complication	Any aortitis causing dissection or rupture (GCA, Takayasu, Behçet, infectious)

The key point is that pre-existing aortitis is a risk factor for dissection. Vasculitis, e.g. Takayasu arteritis is listed as a risk factor for aortic dissection ^[2].

Once you've established that the aortic pathology is inflammatory (i.e., true aortitis), the next step is differentiating among the causes. This is the core differential diagnosis question.

Key Distinguishing Features

Feature	GCA	Takayasu	Syphilitic	Mycotic	IgG4-RD	SpA
Age	> 50 (avg 70)	< 50 (10–40)	Any (decades after infection)	Any (often elderly)	Middle-aged	Young adult
Sex	F > M	F >> M	M > F	M > F	M > F	M > F
Ethnicity	N. Europeans > Asians	Asians ^[3]^[6]	Universal	Universal	Asians	Universal
Aorta location	Ascending/thoracic	Arch + abdominal	Ascending	Infrarenal	Infrarenal	Root only
Dominant pathology	Aneurysm	Stenosis > aneurysm	Aneurysm + AR	Pseudoaneurysm, saccular	Inflammatory AAA	AR + conduction block
Pathology	Granulomatous	Granulomatous	Lymphoplasmacytic, vasa vasorum endarteritis	Suppurative	Storiform fibrosis, IgG4+ plasma cells ^[7]	Root fibrosis
Key Ix	Temporal artery Bx, PET-CT	CTA/MRA	Treponemal serology (RPR, TPHA, FTA-Abs)	Blood cultures, CT	Serum IgG4, tissue Bx	HLA-B27, MRI SIJ
Other features	Headache, jaw claudication, PMR, AAION ^[4]^[10]	Absent pulses, bruits, asymmetric BP, claudication ^[3]^[6]	Argyll Robertson pupils, tabes dorsalis	Fever, sepsis, rapid aneurysm growth	AIP, sialadenitis, RPF ^[7]	IBP, sacroiliitis, enthesitis, uveitis ^[9]

Mimic	Why it mimics aortitis	How to distinguish
Atherosclerotic AAA with periaortic inflammation	Can have perianeurysmal soft tissue on CT, raised ESR/CRP	Usually thin rim of reaction around thrombus, not the thick rind of IgG4-RD. No other IgG4-RD features.
Aortic intramural haematoma	Aortic wall thickening on CT	Crescentic high-density within the wall on non-contrast CT, no enhancement. Not inflammatory.
Erdheim-Chester disease	Histiocytic disorder causing periaortic infiltration ("coated aorta")	Non-Langerhans histiocytosis. BRAF V600E mutation in 50%. Bone pain, long bone sclerosis on X-ray.
Retroperitoneal fibrosis (idiopathic)	Encasement of aorta and ureters	May actually be IgG4-RD in many cases. If not IgG4-RD, consider drug-induced (methysergide, ergotamine) or malignancy-associated.
Periaortic lymphadenopathy (lymphoma, metastatic disease)	Can encase aorta on CT	Discrete nodes rather than diffuse soft tissue. Biopsy distinguishes.

Common Exam Mistake

Students often forget that clinically isolated aortitis exists — this is granulomatous aortitis found incidentally on histology of resected aortic aneurysm, with no systemic disease at the time. It accounts for 4–8% of thoracic aortic surgical specimens. These patients need follow-up because some later develop full-blown GCA or Takayasu.

When you suspect aortitis, the clinical reasoning flows like this:

Is this really inflammatory?
- Constitutional symptoms? Raised ESR/CRP? Periaortic soft tissue on imaging? PET-CT showing FDG uptake?
- If no → likely degenerative/atherosclerotic.
Is it infectious?
- Fever with positive blood cultures? Recent bacteraemia? Saccular aneurysm with rapid expansion? Gas in the aortic wall?
- If yes → mycotic aneurysm (Salmonella, Staph). Check syphilis serology as well.
If non-infectious, what is the age?
- > 50: GCA (check for headache, jaw claudication, PMR, visual symptoms, temporal artery). IgG4-RD (check for other organ involvement). Clinically isolated aortitis (diagnosis of exclusion on histology).
- < 50: Takayasu (check for absent pulses, bruits, asymmetric BP, limb claudication). Behçet (check for oral/genital ulcers, uveitis, pathergy). SpA (check for inflammatory back pain, sacroiliitis, enthesitis, uveitis).
What aortic segment is involved?
- Ascending → syphilis, GCA, SpA, relapsing polychondritis
- Arch → Takayasu, GCA
- Infrarenal → IgG4-RD, infectious, atherosclerotic (with inflammatory component)
What is the dominant aortic pathology?
- Aneurysm → GCA, syphilitic, mycotic, IgG4-RD
- Stenosis → Takayasu (predominantly), GCA
- AR → syphilitic, SpA, GCA, Takayasu

High Yield Summary — Differential Diagnosis of Aortitis

By presentation:

Aortic aneurysm → atherosclerotic (commonest), CTD (Marfan, EDS), GCA, Takayasu, IgG4-RD, mycotic, syphilitic, Behçet
Aortic regurgitation → cusp disease (degenerative, RHD, bicuspid, IE) vs. root dilatation (syphilitic, SpA, GCA, Marfan)
Asymmetric pulses / stenosis → Takayasu, GCA, atherosclerosis, coarctation, FMD
FUO + high ESR → GCA (think "aortitis without a temporal headache"), Takayasu, PAN, infection

By age:

50 years → GCA, IgG4-RD, syphilitic (late), clinically isolated aortitis
< 50 years → Takayasu, Behçet, SpA-associated, infectious

Must-know mimics: Atherosclerotic AAA, IMH, Erdheim-Chester, RPF, periaortic lymphadenopathy

Hong Kong relevance: Takayasu (Asian predilection), non-typhoid Salmonella mycotic aneurysm, IgG4-RD (increasingly recognised in Asians)

Active Recall - Differential Diagnosis of Aortitis

References

^[1] Lecture slides: GC 199. Pulsating abdominal mass aortic aneurysm.pdf (p4, p20) ^[2] Senior notes: Ryan Ho Cardiology.pdf (p160, p222) ^[3] Senior notes: Ryan Ho Rheumatology.pdf (p94–96, p98, p159) ^[4] Senior notes: Maksim Medicine Notes.pdf (p311, p332) ^[5] Senior notes: Maksim Surgery Notes.pdf (p161, p163, p166) ^[6] Senior notes: Ryan Ho Rheumatology.pdf (p96) ^[7] Senior notes: Maksim Medicine Notes.pdf (p335) ^[8] Senior notes: Maksim Medicine Notes.pdf (p35) ^[9] Senior notes: Ryan Ho Rheumatology.pdf (p57–58, p60) ^[10] Senior notes: Ryan Ho Neurology.pdf (p65)

Aortitis presents a unique diagnostic challenge because there is no single unified diagnostic criterion for "aortitis" as a whole. Unlike conditions such as rheumatoid arthritis or SLE, where a single classification system exists, the diagnosis of aortitis requires two steps: (1) confirming that the aortic wall is inflamed, and (2) identifying the underlying cause. Each underlying cause has its own diagnostic criteria or approach.

Let me walk you through this logically.

The reason is simple: aortitis is a pathological process, not a disease. It is like saying "hepatitis" — you need to specify what kind (viral, autoimmune, drug-induced, etc.). The diagnostic approach therefore involves:

Suspecting aortitis (clinical features + imaging)
Confirming aortic wall inflammation (imaging ± histology)
Determining the underlying cause (applying disease-specific criteria)

B. Disease-Specific Diagnostic Criteria

ACR Classification Criteria (1990) — "BATHE" mnemonic (≥ 3/5) ^[4]:

Criterion	Detail	Rationale
B — Biopsy evidence	Necrotizing arteritis with predominant mononuclear cells / multinucleated giant cells (granuloma)	Histological confirmation of granulomatous vasculitis — the gold standard
A — Age ≥ 50y	Onset of disease at age 50 or older	GCA is exceedingly rare below 50; this criterion separates it from Takayasu
T — Tenderness / decreased pulsation of temporal artery	New tenderness or decreased pulsation of temporal artery, unrelated to atherosclerosis of cervical arteries	Temporal artery is superficially accessible and commonly involved in GCA
H — new onset localised Headache	New type of headache or localised pain in the head	Reflects inflammation of cranial arteries and stimulation of nociceptive neurones
E — ESR > 50	Elevated ESR > 50 mm/h (Westergren method)	Systemic inflammatory response; GCA characteristically causes very high ESR (often > 100)

Critical Exam Point

For visual S/S, do NOT wait for biopsy result → start empirical steroids ^[4]. Treatment must not be delayed — the risk of permanent blindness from AAION far outweighs any benefit of waiting for histological confirmation. Biopsy remains positive for up to 2 weeks after starting steroids.

2022 ACR/EULAR Updated Classification Criteria for GCA (point-based system):

These newer criteria incorporate vascular imaging (temporal artery ultrasound showing halo sign, or cross-sectional/PET imaging showing large vessel involvement) alongside traditional clinical and laboratory features.
They distinguish cranial GCA (headache, jaw claudication, visual symptoms, temporal artery abnormality) from large-vessel GCA (limb claudication, asymmetric BP, aortic involvement).
A score ≥ 6 classifies as GCA (applied to patients aged ≥ 50 with new-onset signs/symptoms not better explained by another diagnosis).

ACR Classification Criteria (1990) (≥ 3/6):

Criterion	Detail
1. Age at disease onset ≤ 40 years	Younger age distinguishes from GCA
2. Claudication of extremities	Development of fatigue and discomfort in muscles of ≥ 1 extremity during use, especially upper limbs
3. Decreased brachial artery pulse	Decreased pulsation of one or both brachial arteries
4. BP difference > 10 mmHg	Difference of > 10 mmHg systolic between arms
5. Bruit over subclavian artery or aorta	Bruit audible on auscultation over one or both subclavian arteries or abdominal aorta
6. Arteriogram abnormality	Arteriographic narrowing or occlusion of the entire aorta, its primary branches, or large arteries in proximal upper or lower extremities, not due to atherosclerosis, FMD, or similar causes

Investigations: ESR/CRP↑, angiogram (CTA/MRA) ^[4]^[6].

Dx based on clinical finding + vascular imaging ^[6].

Limitation of ACR Criteria

The 1990 ACR criteria were designed for classification (for research purposes), not for diagnosis in clinical practice. They have reasonable sensitivity (~90%) but imperfect specificity. In practice, the diagnosis of Takayasu relies on clinical suspicion + characteristic vascular imaging findings + exclusion of alternatives.

International Study Group (ISG) Criteria (1990) ^[3]:

Mandatory: Recurrent oral ulceration (≥ 3 episodes in 12 months)
Plus ≥ 2 of:
- Recurrent genital ulceration
- Eye lesions (uveitis, retinal vasculitis)
- Skin lesions (erythema nodosum, pseudofolliculitis, papulopustular lesions, acneiform nodules)
- Positive pathergy test

Diagnostic approach ^[7]:

Serum IgG4 (elevated in ~60–70%, but not required for diagnosis — can be normal)
Tissue biopsy with immunostaining: > 10 IgG4+ plasma cells per HPF, elevated IgG4:IgG ratio ( > 40%)
Hallmark histological features: lymphoplasmacytic tissue infiltrate of mainly IgG4+ plasma cells, "storiform" pattern of fibrosis, obliterative phlebitis ^[7]

The 2019 ACR/EULAR IgG4-RD Classification Criteria use an inclusion/exclusion approach followed by a weighted scoring system across clinical, serological, and histopathological domains. A total score ≥ 36 classifies as IgG4-RD.

No specific criteria for the aortitis itself. The diagnosis rests on establishing the SpA diagnosis and finding aortic involvement on imaging/echocardiography:

Modified New York criteria for AS (1984): radiological sacroiliitis + ≥ 1 clinical criterion ^[9]
ASAS criteria for axSpA: imaging arm (sacroiliitis on MRI/XR + ≥ 1 SpA feature) or clinical arm (HLA-B27 + ≥ 2 SpA features) ^[4]
Extra-articular manifestations of AS — "4As" mnemonic: Apical fibrosis, Anterior uveitis, Aortic regurgitation, Achilles tendinitis ^[9]
The aortitis in SpA probably represents a sclerosing inflammatory process involving aortic root, AV cusps and IV septum ^[9]

No formal diagnostic criteria. Diagnosis is clinical + microbiological + imaging:

Positive blood cultures (Salmonella, Staphylococcus, etc.)
Imaging showing saccular aneurysm, periaortic gas, rapid expansion
Syphilitic aortitis: treponemal serology (RPR/VDRL for screening, TPHA/FTA-Abs for confirmation)

Diagnosis of exclusion: granulomatous or lymphoplasmacytic aortitis found on histology of resected aortic specimen, with no identifiable systemic disease after thorough workup.
These patients require long-term follow-up (some develop systemic vasculitis years later).

Here is a practical approach to diagnosing aortitis, moving from clinical suspicion to confirmed aetiology:

D. Investigation Modalities — Detailed Breakdown

Test	Expected Findings in Aortitis	Interpretation / Why
CBC	NcNc anaemia, thrombocytosis ^[10], leucocytosis (infection)	Anaemia of chronic disease (IL-6 suppresses erythropoiesis, sequesters iron). Thrombocytosis = reactive (IL-6 stimulates megakaryopoiesis). Leucocytosis with neutrophilia in bacterial aortitis.
ESR	Characteristically very high (reaching 100 mm/h) in GCA ^[3]; elevated in Takayasu and most inflammatory causes	ESR measures the rate at which RBCs settle in a tube — elevated when acute-phase proteins (fibrinogen, immunoglobulins) increase and cause RBC rouleaux formation. Non-specific but very sensitive for systemic inflammation.
CRP	Elevated in all active aortitis	CRP is synthesised by hepatocytes in response to IL-6. More specific and rapid marker than ESR. Rises within hours and falls quickly with treatment — useful for monitoring.
Serum IgG4	Elevated in IgG4-RD (but normal in ~30–40%)	Screening test for IgG4-RD. Elevated levels ( > 135 mg/dL) are suggestive but not diagnostic — false positives occur in other inflammatory conditions, and false negatives in up to 30%.
ANCA	Usually negative in large vessel vasculitis. Positive in ANCA vasculitis (rare cause of aortitis). p-ANCA = anti-MPO, c-ANCA = anti-PR3 ^[4]	Helps exclude ANCA vasculitis as a cause. If positive, consider GPA/MPA with aortic involvement.
ANA, anti-dsDNA, complement	Relevant if SLE-related aortitis suspected	SLE can rarely cause aortitis.
HLA-B27	Present in 80–90% of AS ^[9]	Supports diagnosis of axSpA if clinical features present. Not diagnostic on its own but increases confidence.
Blood cultures	Positive in infectious aortitis (Salmonella, Staph, Strep)	Essential in any patient with fever + aortic pathology. At least 3 sets from different sites before antibiotics.
Syphilis serology	RPR/VDRL (screening, non-treponemal), TPHA/FTA-Abs (confirmatory, treponemal)	Syphilitic aortitis is tertiary — RPR may be non-reactive in late syphilis (prozone phenomenon or seroreversion), so always send treponemal tests. FTA-Abs remains positive for life.
ALP	↑ALP in GCA ^[10] and severe AS ^[9]	Mechanism not entirely clear in GCA — may relate to hepatic inflammation or as an acute-phase reactant. In AS, reflects active bone metabolism.
Procalcitonin	Elevated in bacterial infection, usually normal in autoimmune inflammation	Helps differentiate infectious from non-infectious aortitis. Procalcitonin is released by C-cells of the thyroid and neuroendocrine cells in response to bacterial endotoxin, NOT in sterile inflammation.

ESR vs CRP in Aortitis

Both are elevated in active aortitis. ESR is slow to rise and slow to fall — it reflects disease burden over weeks. CRP rises within 6 hours and falls within days — better for monitoring acute flares and treatment response. In GCA, the ESR is classically very high ( > 100), but normal ESR does not exclude GCA (up to 5% have normal ESR at presentation).

D2. Imaging — The Cornerstone of Aortitis Diagnosis

CT angiography: use of rapid injection of a large intravenous bolus of contrast to opacify vessels for CT imaging ^[11].

Applications include: aneurysms and dissection ^[11].

Feature	Findings in Aortitis	Interpretation
Wall thickening	Circumferential or eccentric thickening of the aortic wall ( > 2–3 mm)	Inflammatory infiltration and oedema of the wall. The single most important imaging sign of aortitis on CTA.
Mural enhancement	Enhancement of the thickened wall on contrast-enhanced CT (especially delayed phase)	Active inflammation with increased vascularity/permeability of the wall. Double-ring sign: enhancing inner and outer rings with lower-density middle layer (inflamed intima/adventitia surrounding oedematous media).
Aneurysm	Dilatation of the aortic lumen ( > 50% of normal diameter)	Loss of wall integrity due to medial destruction → outward expansion.
Stenosis	Narrowing or occlusion of the aorta or branch vessels	Intimal thickening → luminal compromise. More common in Takayasu.
Periaortic soft tissue	Thick rind of soft tissue surrounding the aorta, especially infrarenal	IgG4-RD: thick, homogeneous periaortic fibrosis. Infectious: irregular soft tissue ± gas.
Calcification	Linear calcification in the aortic wall	Long-standing/burnt-out disease. Also seen in atherosclerosis.
Saccular aneurysm with gas	Saccular outpouching with air within or around the wall	Strongly suggests mycotic aneurysm (gas-forming organisms or communication with bowel).
Dissection	Intimal flap, true and false lumen. True lumen is compressed by false lumen ^[2]	Aortitis-related dissection.

For AAA specifically: USG abdomen: confirm diagnosis and surveillance of AAA size (surgery if ≥ 5.5 cm); CT abdomen + pelvis with contrast: preoperative assessment of anatomy for suitability for EVAR ^[5].

MRA has the advantage of no ionizing radiation and excellent soft tissue contrast. It is particularly useful for:

Application	Advantage
Detecting wall oedema	T2-weighted images with fat suppression show oedema (bright signal) in the inflamed wall — sensitive marker of active inflammation
Wall thickening and enhancement	Post-gadolinium T1-weighted images show wall enhancement (similar to CTA but without radiation)
Stenosis assessment	Time-of-flight or contrast-enhanced MRA shows stenosis and occlusion of branches
Serial follow-up	No radiation → ideal for repeated imaging in young patients (e.g., Takayasu)
Aortic dissection	Highly sensitive and specific (almost 100%) ^[2]. Identifies intimal flaps, great vessel anatomy.

Limitations: time-consuming, need to disconnect monitoring devices, gadolinium contraindicated in severe renal impairment, less available in emergency settings.

This is increasingly the investigation of choice for diagnosing large vessel vasculitis and monitoring treatment response. Let me explain why from first principles:

Principle: FDG is a glucose analogue that is taken up by metabolically active cells. Activated inflammatory cells (macrophages, lymphocytes) in the aortic wall have very high glucose metabolism → they take up FDG avidly.
Result: Diffuse increased FDG uptake in the aortic wall and/or its major branches indicates active vascular inflammation.
Grading: Visual grading against liver uptake — Grade 0 (no uptake), Grade 1 (< liver), Grade 2 (= liver), Grade 3 ( > liver). Grade ≥ 2 is considered positive for vasculitis.

Strength	Limitation
Detects inflammation before structural damage occurs (earlier than CTA/MRA)	Cannot reliably detect inflammation in vessels < 4 mm diameter (limited spatial resolution)
Whole-body assessment — identifies aortitis + branch involvement simultaneously	FDG uptake can be seen in atherosclerosis (usually focal/patchy vs. diffuse/smooth in vasculitis)
Useful for monitoring treatment response (uptake decreases with successful therapy)	Must be performed before starting steroids (or within the first 3 days) — steroids rapidly suppress macrophage FDG uptake
Most useful for GCA (large vessel GCA) and Takayasu	Expensive, involves radiation, limited availability

High Yield — PET-CT Timing

PET-CT should ideally be performed before starting glucocorticoids or within the first 72 hours. After this window, steroid-induced suppression of inflammatory cell metabolism dramatically reduces sensitivity. However, in GCA with visual symptoms, never delay steroids for the sake of imaging — vision takes priority.

Temporal Artery Ultrasound (for GCA):

Temporal artery ultrasound (halo sign) ^[4]:

The "halo sign" is a dark (hypoechoic) rim around the temporal artery lumen on colour Doppler ultrasound.
Why does this happen? The halo represents oedematous, inflamed vessel wall surrounding the narrowed lumen.
Sensitivity: ~77% and specificity: ~96% for GCA (in experienced hands).
Increasingly used as first-line investigation in the 2022 ACR/EULAR pathway — may replace temporal artery biopsy in some settings if performed by an experienced sonographer.

Abdominal Aorta Ultrasound (for AAA):

First-line for measuring aortic diameter and surveillance of known AAA.
Cannot reliably detect wall inflammation (unlike CTA/MRA/PET).
USG abdomen: confirm diagnosis and surveillance of AAA size ^[5].

Colour Doppler USG of head, neck, and lower limb vessels:

Used in GCA to assess temporal, axillary, subclavian arteries for halo sign, stenosis, or occlusion ^[3].

The historical gold standard for Takayasu arteritis — shows stenoses, occlusions, and aneurysms.
Now largely replaced by CTA/MRA for diagnosis (less invasive) ^[11].
Still used when interventional treatment is planned (angioplasty, stenting).
Angiogram (CTA/MRA) for Takayasu ^[4].
Limitation: shows only the lumen, not the wall. Cannot detect early inflammation without luminal changes.

D3. Histopathology — The Definitive Investigation (When Available)

Investigations: biopsy if tissue accessible, angiography if tissue inaccessible ^[4].

Temporal artery biopsy: diagnostic features ^[10]:

Must order urgently (< 24–48h) or else risk permanent visual impairment ^[10]
May be falsely negative due to patchy inflammation ^[10] — this is called "skip lesions" (segments of normal artery interspersed with inflamed segments). To minimise false negatives, a specimen ≥ 1 cm in length is recommended.
Consult NS for biopsy (1 side, 1 cm long) ^[4].

Histological Finding	Significance
Granulomatous inflammation in the media	Hallmark of GCA — giant cells destroying the internal elastic lamina
Giant cells at the intima-media junction	Multinucleated cells engulfing fragments of the internal elastic lamina
Fragmentation of the internal elastic lamina	Confirmed on elastic stain (Verhoeff-van Gieson) — specific feature
Lymphoplasmacytic infiltrate	CD4+ T cells and macrophages predominantly
Intimal hyperplasia	Contributes to luminal stenosis → ischaemic symptoms

Important: A negative biopsy does NOT exclude GCA (sensitivity ~85–90% with adequate specimen length). If clinical suspicion is high and biopsy is negative, consider:

Contralateral temporal artery biopsy
Imaging (PET-CT, temporal artery USG)
Treating empirically and observing response

When the aorta is resected for aneurysm repair, the specimen should always be sent for histopathology. This is how clinically isolated aortitis and unsuspected GCA/Takayasu are often diagnosed.

Pattern	Suggests
Granulomatous with giant cells	GCA, Takayasu, sarcoidosis
Lymphoplasmacytic with storiform fibrosis	IgG4-RD — storiform fibrosis, IgG4+ plasma cells ^[7]
Neutrophilic / suppurative	Bacterial mycotic aneurysm
Caseous granulomas	Tuberculosis
Obliterative endarteritis of vasa vasorum	Syphilis
Non-specific chronic inflammation	Non-specific; consider clinically isolated aortitis

Applied to aortic wall tissue or other biopsied tissue (salivary gland, pancreas, etc.)
> 10 IgG4+ plasma cells per HPF, ↑ IgG4:IgG ratio ^[7]
Combined with storiform fibrosis and obliterative phlebitis → diagnostic triad of IgG4-RD

Investigation	When to Order	What You're Looking For
Echocardiography (TTE/TEE)	Suspected aortic regurgitation, aortic root dilatation	ECHO & CT thorax (mid-portion of ascending aorta difficult to be visualised by ECHO) ^[8]. TTE: aortic valve morphology, AR severity, LV dimensions. TEE: better for ascending aorta/root detail.
ECG	Suspected conduction defects (SpA-associated aortitis), MI from coronary ostial stenosis	ECG: LVH +/- strain ^[8] in chronic AR. First-degree AV block → complete heart block in SpA. ST changes if coronary ostial stenosis (syphilitic).
CXR	All patients	CXR: cardiomegaly ^[8] (if AR → LV dilatation). Widened mediastinum (thoracic aortic aneurysm/dissection). Calcification of ascending aorta (syphilitic — "eggshell" calcification).
Syphilis serology	All aortitis patients (especially ascending aorta involvement)	RPR/VDRL (non-treponemal — screens for active disease). TPHA/FTA-Abs (treponemal — confirmatory, remains positive for life).
Tuberculin skin test / IGRA	If TB aortitis suspected	TB aortitis is rare but must be excluded in endemic areas.
HLA-B27	If SpA suspected	Present in 80–90% of AS ^[9]. Supports diagnosis but not diagnostic alone.
Pathergy test	If Behçet suspected	Skin prick with 20G needle → +ve if pustule-like lesion/papules after 48h ^[3]

Suspected Cause	First-Line Ix	Second-Line / Confirmatory Ix	Key Diagnostic Finding
GCA	ESR/CRP, CBC, temporal artery USG	Temporal artery Bx (urgent!), PET-CT for large vessel GCA	ESR > 50, halo sign on USG, granulomatous arteritis on Bx ^[4]^[10]
Takayasu	ESR/CRP, CTA or MRA of aorta and branches	Conventional angiography (if intervention planned)	Concentric wall thickening with stenosis/occlusion of aortic branches on CTA/MRA
IgG4-RD	Serum IgG4, CTA (periaortic soft tissue)	Tissue biopsy with IgG4 immunostaining	> 10 IgG4+ plasma cells/HPF, storiform fibrosis, obliterative phlebitis ^[7]
Infectious	Blood cultures (×3), CRP, procalcitonin, syphilis serology, CTA	Surgical specimen culture/Gram stain/histology	Positive cultures, saccular aneurysm ± gas on CTA
SpA-associated	HLA-B27, ESR/CRP, MRI SIJ, echocardiography	Clinical assessment for SpA features	Sacroiliitis on imaging + SpA features + AR/conduction defect ^[9]
Behçet	Clinical assessment (ISG criteria), pathergy test, CTA	Angiography, tissue biopsy if needed	Recurrent oral ulcers + ≥ 2 other criteria ^[3]

High Yield Summary — Diagnosis of Aortitis

No unified diagnostic criteria exist for "aortitis" — diagnosis requires confirming aortic wall inflammation + identifying the cause.

Key Imaging Modalities:

CTA: First-line for structural assessment (wall thickening, aneurysm, stenosis, periaortic changes)
MRA: Excellent for wall oedema (T2), no radiation, ideal for young patients and serial follow-up
PET-CT: Best for detecting active inflammation (before structural changes), must be done before or within 72h of starting steroids
Temporal artery USG: Halo sign — increasingly first-line for GCA

Key Blood Tests:

ESR/CRP (all), blood cultures (infectious), syphilis serology (all ascending aorta), IgG4 (suspected IgG4-RD), ANCA (exclude ANCA vasculitis), HLA-B27 (SpA)

Key Histological Patterns:

Granulomatous + giant cells → GCA/Takayasu
Lymphoplasmacytic + storiform fibrosis → IgG4-RD
Suppurative/neutrophilic → bacterial
Vasa vasorum endarteritis → syphilis

GCA-specific:

ACR criteria "BATHE" (≥ 3/5): Biopsy, Age ≥ 50, Temporal artery, Headache, ESR > 50
Temporal artery Bx: urgent, ≥ 1 cm, skip lesions cause false negatives
Never delay steroids for biopsy if visual symptoms present

Active Recall - Diagnosis of Aortitis

^[2] Senior notes: Ryan Ho Cardiology.pdf (p160, p220–222) ^[3] Senior notes: Ryan Ho Rheumatology.pdf (p95–96, p98) ^[4] Senior notes: Maksim Medicine Notes.pdf (p311, p323, p332–333) ^[5] Senior notes: Maksim Surgery Notes.pdf (p161) ^[6] Senior notes: Ryan Ho Rheumatology.pdf (p96) ^[7] Senior notes: Maksim Medicine Notes.pdf (p335) ^[8] Senior notes: Maksim Medicine Notes.pdf (p35) ^[9] Senior notes: Ryan Ho Rheumatology.pdf (p58, p60) ^[10] Senior notes: Ryan Ho Neurology.pdf (p65) ^[11] Senior notes: Ryan Ho Diagnostic Radiology.pdf (p43)

The management of aortitis is fundamentally driven by two parallel goals: (1) treat the underlying cause of the inflammation, and (2) manage the structural complications that the inflammation has produced (aneurysm, stenosis, aortic regurgitation, dissection). Think of it as putting out the fire and repairing the building at the same time.

Let me organise this systematically.

Before diving into specifics, let me lay out the key principles:

Treat the inflammation first — in most non-infectious aortitis, immunosuppression is the cornerstone. Operating on an actively inflamed aorta is associated with higher complication rates (anastomotic aneurysm, graft dehiscence) because inflamed tissue holds sutures poorly.
Surgical intervention for structural complications — aneurysm repair, valve replacement, revascularisation. The timing depends on urgency (emergency for rupture/dissection, elective for stable aneurysm reaching size threshold).
Treat the infection before (or simultaneously with) surgery in infectious aortitis — antibiotics alone are rarely sufficient; the infected aortic wall must be excised.
Long-term surveillance — aortitis can recur, and structural complications can develop years after initial treatment. Serial imaging is mandatory.
Cardiovascular risk factor modification — applies to all patients with aortic disease.

C. Management by Aetiology

C1. Giant Cell Arteritis (GCA)

GCA-related aortitis management is centred on glucocorticoids, with the critical imperative of preventing irreversible visual loss.

Urgent high-dose systemic corticosteroids: prednisolone 1–2 mg/kg/d → slowly tapered 1–2y ^[3].

High-dose prednisolone 1 mg/kg/day: save vision of other eye and prevent brainstem stroke ^[4].

Scenario	Regimen	Rationale
GCA without visual/neurological complications	Prednisolone 1 mg/kg/d (usually 40–60 mg/d) PO	Suppresses granulomatous inflammation; most patients respond dramatically within 48–72h
GCA with visual symptoms (AAION, amaurosis fugax)	IV methylprednisolone 250–1000 mg/d for 3 days → then switch to oral 1 mg/kg/d	Higher bioavailability and faster onset with IV pulse therapy; aim to rescue any remaining viable retinal ganglion cells before irreversible ischaemic damage
GCA with stroke/neurological complications	IV methylprednisolone pulse → oral high-dose	Same principle as visual loss

Tx started upon presumed clinical dx even despite –ve initial Ix ^[3].

For visual S/S, do NOT wait for biopsy result → start empirical steroids ^[4].

Why steroids work in GCA: The granulomatous inflammation is driven by T-cell and macrophage activation producing IFN-γ, IL-6, and MMPs. Glucocorticoids suppress transcription of these pro-inflammatory cytokines by binding to the glucocorticoid receptor → translocating to the nucleus → inhibiting NF-κB and AP-1. They also induce apoptosis of inflammatory cells. The result is rapid suppression of vessel wall inflammation.

Tapering: This is the art:

Maintain initial dose for 2–4 weeks until symptoms resolve and ESR/CRP normalise.
Then reduce by ~10 mg every 2 weeks down to 20 mg/d.
Below 20 mg/d, reduce by 2.5 mg every 2–4 weeks.
Below 10 mg/d, reduce by 1 mg every 1–2 months.
Total duration: slowly tapered 1–2y ^[3]. Many patients need 18–24 months; some need longer.
Monitor ESR/CRP at each dose reduction — if flare, increase dose back up.

Prognosis: usually a/w dramatic response to steroid (complete resolution of S/S ≤ 48–72h of Tx) ^[3].

Steroid Side Effects — Must Be Addressed

Long-term steroid use causes: osteoporosis (give calcium + vitamin D + bisphosphonate), hyperglycaemia (monitor glucose), hypertension, cataracts, adrenal suppression, weight gain, skin thinning, increased infection risk, and mood disturbance. These are especially problematic in the elderly GCA population. This is why steroid-sparing agents are essential.

Steroid-sparing agents: tocilizumab (anti-IL6), methotrexate upon relapsing disease ^[3].

Agent	Mechanism	Indication	Evidence
Tocilizumab (anti-IL-6 receptor mAb)	Blocks IL-6 signalling → IL-6 is the master cytokine driving systemic inflammation in GCA (causes fever, raised ESR/CRP, acute-phase response). By blocking IL-6R, you cut off the inflammatory cascade at its most important node.	First-line steroid-sparing agent for GCA (2024 ACR/EULAR guidelines). Recommended for all GCA patients at diagnosis to reduce steroid exposure.	GiACTA trial: tocilizumab + steroid taper achieved sustained remission at 52 weeks in ~56% vs ~14% with steroid taper alone.
Methotrexate	Folate antagonist → inhibits purine synthesis → suppresses rapidly dividing inflammatory cells (lymphocytes). Also has anti-inflammatory effects via adenosine release.	Second-line steroid-sparing agent. Consider if tocilizumab unavailable, contraindicated, or patient has relapsing disease.	Modest benefit in meta-analyses; reduces relapse rate and cumulative steroid dose.

Tocilizumab dosing: 162 mg SC weekly or IV 8 mg/kg Q4w.

Important caveat with tocilizumab: It normalises CRP and ESR even during active disease (because it blocks the very cytokine that drives CRP production). This means you cannot rely on ESR/CRP to monitor disease activity while the patient is on tocilizumab — use clinical assessment and imaging instead.

Low-dose aspirin (75–100 mg/d) is sometimes recommended in GCA to reduce the risk of ischaemic complications (visual loss, stroke) — the rationale is that GCA causes intimal hyperplasia and thrombosis. However, evidence is mixed, and recent guidelines are less emphatic about universal aspirin.

Thoracic aortic aneurysm: Repair if ascending aorta > 55 mm (or > 50 mm in the context of active aortitis/rapid growth). Elective repair should ideally be performed after controlling inflammation with steroids.
Aortic root disease: dilated ascending aorta > 50 mm is an indication for surgery even if asymptomatic ^[8].
Aortic regurgitation: Valvular replacement if symptomatic or if LVEF < 50% or LV dilation: End-systolic diameter > 55 mm or end-diastolic diameter > 75 mm ^[8].

C2. Takayasu Arteritis

The management of Takayasu follows a similar immunosuppressive approach but with more emphasis on revascularisation for stenotic disease and longer-term need for disease-modifying therapy in a younger population.

High dose steroids + steroid-sparing agents (MTX/AZA) ^[4].

High-dose corticosteroids: 1 mg/kg/d up to 2–4w then taper ^[6].

Prednisolone 1 mg/kg/d (max 60 mg/d) for 2–4 weeks, then gradual taper over 6–12 months.
~60% of patients achieve remission with steroids alone, but ~50% relapse during taper.

Steroid-sparing agents: usually methotrexate or azathioprine ^[6].

Agent	Dose	Notes
Methotrexate	15–25 mg PO/SC weekly	First choice; good evidence for maintaining remission and reducing steroid dose. Give with folic acid to reduce side effects.
Azathioprine	2–2.5 mg/kg/d	Alternative if MTX not tolerated. Check TPMT/NUDT15 before starting (pharmacogenomics — deficiency leads to severe myelosuppression).
Mycophenolate mofetil	2–3 g/d	Used if MTX and AZA fail.

Agent	Mechanism	Indication
Tocilizumab (anti-IL-6R)	Same as in GCA — blocks IL-6	Refractory/relapsing Takayasu. TAKT trial showed superiority over placebo in maintaining remission.
Anti-TNF agents (infliximab, adalimumab)	Block TNF-α → reduce granulomatous inflammation	Used in refractory disease; open-label data suggest efficacy in ~50–60%.

Because Takayasu is predominantly a stenotic disease (unlike GCA, which is predominantly aneurysmal), revascularisation procedures are often needed:

Modality	Indication	Considerations
Percutaneous transluminal balloon angioplasty (PTA) ± stenting ^[12]	Short-segment stenosis (e.g., subclavian, renal artery)	Less invasive; preferred for focal lesions. High restenosis rate in Takayasu (30–50%) — the inflamed arterial wall tends to re-stenose.
Surgical bypass	Long-segment stenosis, failed angioplasty, critical ischaemia	Preferred for complex, multi-vessel disease. Autologous vein grafts preferred over synthetic (lower infection risk in immunosuppressed patients).
Aortic aneurysm repair	Aneurysm reaching surgical threshold (similar principles to atherosclerotic aneurysm)	Open repair or EVAR depending on anatomy and fitness.

Critical principle: Revascularisation should ideally be performed during disease quiescence (inactive phase) — operating on actively inflamed vessels leads to higher rates of anastomotic failure, restenosis, and graft thrombosis. Control inflammation first with immunosuppression, then operate electively.

Glucocorticoids as first-line treatment e.g. prednisolone 0.6 mg/kg/day ^[7].

± other immunosuppressants: rituximab preferred over AZA/MTX/MMF ^[7].

Step	Treatment	Detail
Induction	Prednisolone 0.6 mg/kg/d (usually 30–40 mg/d) for 2–4 weeks	IgG4-RD is characteristically steroid-responsive — dramatic improvement in symptoms, imaging findings, and serum IgG4 levels.
Taper	Reduce by 5 mg every 1–2 weeks to 5–10 mg/d maintenance	Relapse is common on discontinuation (~30–50%), hence maintenance needed.
Maintenance / Relapse	Rituximab (anti-CD20 monoclonal antibody)	Preferred steroid-sparing agent. Depletes B cells → reduces IgG4-producing plasma cell precursors. Effective for both induction and maintenance. Dose: 1 g IV × 2 doses 2 weeks apart, then Q6 months for maintenance.
Alternatives	AZA, MTX, MMF	If rituximab unavailable or contraindicated. Less preferred.

Why rituximab is preferred over conventional immunosuppressants: IgG4-RD is a B-cell driven disease (IgG4-positive plasma cells are the effector cells). Rituximab targets CD20 on B cells, depleting the precursors of these pathogenic plasma cells. It is more targeted and effective than non-specific immunosuppressants like AZA or MTX.

Surgical management: If the aneurysm is large enough to warrant repair, the same surgical principles apply as for atherosclerotic AAA. However, many IgG4-related inflammatory aneurysms shrink with steroid therapy — so a trial of medical treatment before committing to surgery is reasonable if the aneurysm is not at imminent risk of rupture. Also, if there is ureteric obstruction from retroperitoneal fibrosis, ureteric stenting may be needed.

C4. Spondyloarthropathy-Associated Aortitis

The aortitis in SpA is managed through treatment of the underlying SpA plus specific management of cardiac complications.

NSAIDs or COX-2 inhibitor as first line ^[9].

Anti-TNF or anti-IL-17A as second line ^[9].

Step	Agent	Notes
1st line	NSAIDs (e.g., naproxen 500 mg BD, ibuprofen 800 mg TDS, celecoxib 200 mg BD) ^[9]	~70–80% report substantial relief. Have modest disease-modifying effect with continuous use.
2nd line	Biologics: TNF-α inhibitor (etanercept, infliximab, adalimumab) or anti-IL-17A (secukinumab) ^[9]	Indicated if persistent high disease activity (BASDAI ≥ 4) despite adequate trial of NSAIDs involving 2–3 NSAIDs with ≥ 2 months each ^[9]. C/I: active infection, latent TB, demyelinating disease, heart failure, malignancy ^[9].

Aortic regurgitation: Medical management with vasodilators (ACEI/ARB/CCB) to reduce afterload ^[8]. Valvular replacement when symptomatic or when LV dysfunction develops ^[8].
Conduction defects: Monitor ECG. Permanent pacemaker if symptomatic high-degree AV block.
The aortitis itself in SpA does not typically respond to conventional DMARDs (sulphasalazine, MTX) — it is the biologics (anti-TNF) that may slow progression.

Aortitis and arterial aneurysms in Behçet carry a high mortality and are among the most dangerous vascular complications.

Component	Treatment
Immunosuppression	High-dose corticosteroids (prednisolone 1 mg/kg/d) + cyclophosphamide or azathioprine for arterial aneurysms
Biologics	Anti-TNF (infliximab/adalimumab) for refractory vascular disease
Surgery	Aneurysm repair if needed, BUT surgery in active Behçet is fraught with complications (pseudoaneurysm at anastomosis, wound dehiscence). Immunosuppression must be optimised before and after surgery.
Anticoagulation	Controversial — VTE is common in Behçet, but arterial aneurysms can rupture with anticoagulation. Individualised decision.

Behçet — Surgery is High Risk

Behçet vascular disease is notoriously difficult to manage surgically. The inflamed vessel wall holds sutures poorly, and pseudoaneurysms at anastomotic sites are common. Endovascular approaches (stent grafts) may reduce this risk compared to open surgery, but data are limited. Always ensure adequate immunosuppression perioperatively.

C6. Infectious Aortitis (Mycotic Aneurysm)

Infectious aortitis is a surgical emergency — antibiotics alone are almost never curative because the infected, necrotic aortic wall cannot heal.

Scenario	Empirical Regimen	Duration
Pending cultures	Broad-spectrum: IV vancomycin + piperacillin-tazobactam (or meropenem)	Until culture and sensitivity available
Non-typhoid Salmonella	IV ceftriaxone 2 g/d (or ciprofloxacin if susceptible)	Minimum 6 weeks IV; some advocate lifelong oral suppressive therapy
Staphylococcus aureus	IV flucloxacillin (MSSA) or vancomycin (MRSA)	Minimum 6 weeks IV
Syphilitic aortitis	IV benzylpenicillin G 3–4 MU Q4h for 10–14 days (or IM benzathine penicillin if non-neurosyphilis)	Per syphilis treatment guidelines. Note: treating the syphilis will not reverse existing structural damage (aneurysm, AR), but will halt further progression.

Why prolonged antibiotics are needed: The aortic wall is relatively avascular (especially the media), and biofilm on prosthetic grafts or thrombus makes organisms difficult to eradicate. Short courses lead to recurrence.

Graft excision with extra-anatomical bypass ^[5] is the classical approach for infected aortic aneurysms.

Step	Detail	Rationale
1. Debridement	Excise all infected aortic tissue with wide margins	Remove the nidus of infection — necrotic, pus-filled wall will not heal
2. Reconstruction	Option A: Extra-anatomical bypass (e.g., axillofemoral bypass) + aortic stump ligation	Routes the graft through clean tissue planes, away from the infected field. Lower risk of graft infection but poorer long-term patency.
	Option B: In-situ reconstruction with antibiotic-soaked graft or cryopreserved allograft	Graft placed in the same anatomical position. Better haemodynamics and patency. Risk of re-infection, but reduced with antibiotic-impregnated grafts (rifampicin-soaked Dacron).
	Option C: EVAR (endovascular stent graft) as bridge or definitive in high-risk patients	Less invasive; may be used as temporising measure in septic, haemodynamically unstable patients. Long-term durability in infected field is uncertain.
3. Prolonged antibiotics	Minimum 6 weeks IV post-surgery, often lifelong oral suppression	Sterilise the operative field and prevent recurrent infection

Discovered incidentally on histology after aortic aneurysm repair.
No systemic disease identified.
Management:
1. Thorough workup to exclude systemic vasculitis (ESR/CRP, ANCA, IgG4, syphilis serology, autoantibodies).
2. If all negative → observation with serial imaging (CTA or MRA at 3–6 months, then annually).
3. Some experts advocate a short course of glucocorticoids, but this is controversial.
4. Long-term follow-up is essential — ~15–20% may develop overt GCA or Takayasu over subsequent years.

D. Management of Structural Complications (Regardless of Aetiology)

Surgical management indications ^[5]:

Criterion	Threshold
AAA ≥ 5.5 cm (UK Small Aneurysm Trial) / 5 cm (local HK consensus) ^[5]	Size-based threshold
Rapidly expanding AAA (> 1 cm/year or > 0.5 cm/6 months) ^[5]	Growth rate
Symptomatic AAA e.g. pain, distal embolisation ^[5]	Symptoms indicate impending rupture
Thoracic aortic aneurysm > 55 mm (or > 50 mm in connective tissue disease/aortitis)	Lower threshold for inflammatory aneurysms

Conservative management for sub-threshold aneurysm ^[5]:

CV risk factor modification: smoking cessation, BP control, statin, aspirin, weight loss, exercise ^[5]
USG monitoring: yearly for 3.0–3.9 cm, Q6m for 4.0–5.4 cm ^[5]

Open repair vs EVAR ^[5]:

EVAR: less 30-day morbidity and mortality, shorter hospitalisation, rapid return of QoL ^[5]
Open: lower risk of rupture / re-intervention in the long run ^[5]
No significant difference in long-term morbidity and mortality ^[5]

For inflammatory aneurysms (IgG4-RD, GCA), medical therapy may reduce aneurysm size, so a trial of immunosuppression is warranted before committing to surgery in non-urgent cases.

Management of aortic dissection ^[2]^[13]:

Component	Detail
Supportive	NPO, complete bed rest, O2, cardiac monitor, analgesia ^[2]
Monitoring	Book CCU / ICU bed for intensive monitoring of BP/P, ECG, I/O ^[2]
Anti-impulse therapy	Target SBP 100–120 (MAP 60–75), HR 60–70 ^[2]
1st line	IV labetalol (α1 blocker + non-selective β blocker ^[2]) or esmolol; alternative: diltiazem/verapamil (non-DHP CCB) if BB contraindicated ^[13]
2nd line	IV sodium nitroprusside (with labetalol pre-Tx) ^[13] — must give beta-blocker first to prevent reflex tachycardia
Surgery — Type A	ALL Type A → usually open repair ^[13]. Bentall procedure if AV, root, ascending aorta replaced ^[13].
Surgery — Type B	If complicated (organ ischaemia, aneurysm, rupture, retrograde dissection, Marfan's) → endovascular stent-grafting vs open ^[13]
Long-term	Lifelong antihypertensive therapy to aim target BP < 120/80 mmHg ^[13]. Serial imaging (MRA/CTA at 3, 6, 12 mo) ^[13].

Hydralazine is C/I in aortic dissection ^[2] — it causes reflex tachycardia which increases aortic wall shear stress (dP/dt), promoting further dissection.

Management of AR ^[8]:

Component	Detail
Medical	Diuretics; Vasodilators for HT: ACEI/ARB/CCB ^[8] — reduce afterload → decrease regurgitant volume → delay LV decompensation
Valvular replacement	When symptomatic (HF, angina), or if asymptomatic with LVEF < 50%, or LV dilation (ESD > 55 mm or EDD > 75 mm), or dilated ascending aorta > 50 mm ^[8]
Acute severe AR	Surgical emergency (e.g., IE) ^[8] → valve replacement

PTA ± stenting for focal stenosis ^[12].
Bypass surgery for long-segment or failed endovascular treatment.
Endarterectomy at specific sites (e.g., carotid, femoral bifurcation) ^[5].
Always control underlying inflammation before elective revascularisation.

Component	Detail
Disease activity	Serial ESR/CRP (except on tocilizumab — use clinical + imaging). For IgG4-RD: serum IgG4 levels.
Imaging surveillance	CTA or MRA at 3, 6, 12 months after diagnosis, then annually. More frequent if aneurysm present. PET-CT to assess treatment response if needed.
Steroid side effects	Bone densitometry (DEXA) at baseline; calcium + vitamin D + bisphosphonate if indicated. Monitor glucose, BP, weight, eyes (cataracts/glaucoma).
Immunosuppressant monitoring	MTX: CBC + LFT Q2–4 weeks initially, then Q3 months. AZA: CBC + LFT similarly. Rituximab: immunoglobulin levels, hepatitis B screening before starting.
Cardiovascular risk	BP control, lipid management, smoking cessation, antiplatelet therapy as appropriate.
Screening for new complications	Annual echocardiography if aortic root disease. ECG for conduction defects (SpA). Ophthalmological review (GCA).

Aetiology	First-Line	Steroid-Sparing	Surgery	Special Considerations
GCA	Prednisolone 1 mg/kg/d	Tocilizumab (preferred), MTX	Aneurysm repair, AVR if needed	Never delay steroids for visual symptoms
Takayasu	Prednisolone 1 mg/kg/d	MTX, AZA; tocilizumab/anti-TNF if refractory	PTA ± stenting, bypass for stenosis; aneurysm repair	Revascularise in quiescent phase
IgG4-RD	Prednisolone 0.6 mg/kg/d	Rituximab (preferred)	Aneurysm repair if needed; ureteric stenting for RPF	Trial of steroids may shrink aneurysm
SpA	NSAIDs	Anti-TNF, anti-IL-17A	AVR, pacemaker for heart block	Oral steroids risk psoriasis flare in PsA
Behçet	Prednisolone + CYC/AZA	Anti-TNF (infliximab)	Aneurysm repair (high complication risk)	Immunosuppression perioperatively is critical
Mycotic	IV antibiotics (ceftriaxone for Salmonella, flucloxacillin/vancomycin for Staph)	N/A	Excision + extra-anatomical bypass or in-situ graft	Lifelong suppressive antibiotics may be needed
Syphilitic	IV benzylpenicillin	N/A	AVR for AR, aneurysm repair	Structural damage is irreversible; treatment halts progression

High Yield Summary — Management of Aortitis

Core Principle: Treat the inflammation AND the structural complications.

GCA: High-dose prednisolone immediately (never delay for visual symptoms). Tocilizumab as first-line steroid-sparing. Taper over 1–2 years. Dramatic response expected within 48–72h.

Takayasu: Prednisolone + MTX/AZA. Biologics for refractory disease. Revascularise during quiescent phase — operating on actively inflamed vessels leads to failure.

IgG4-RD: Prednisolone 0.6 mg/kg/d → rituximab if relapse. Aneurysm may shrink with medical therapy.

SpA-associated: NSAIDs first, then anti-TNF/anti-IL-17A. AVR for significant AR. Pacemaker for heart block.

Infectious: IV antibiotics (prolonged) + surgical excision of infected aorta ± extra-anatomical bypass. Syphilitic: IV penicillin (halts progression but does not reverse structural damage).

Aortic dissection: Anti-impulse therapy (labetalol), SBP 100–120, HR < 60. Type A = ALL go to surgery. Type B = surgery only if complicated.

AR management: Vasodilators (ACEI/ARB/CCB). Valve replacement if symptomatic, LVEF < 50%, LV dilated, or ascending aorta > 50 mm.

Long-term: Serial imaging, steroid side-effect monitoring, CV risk factor modification.

Active Recall - Management of Aortitis

^[2] Senior notes: Maksim Medicine Notes.pdf (p15) ^[3] Senior notes: Ryan Ho Rheumatology.pdf (p95) ^[4] Senior notes: Maksim Medicine Notes.pdf (p311, p332) ^[5] Senior notes: Maksim Surgery Notes.pdf (p162) ^[6] Senior notes: Ryan Ho Rheumatology.pdf (p96) ^[7] Senior notes: Maksim Medicine Notes.pdf (p335) ^[8] Senior notes: Maksim Medicine Notes.pdf (p35) ^[9] Senior notes: Ryan Ho Rheumatology.pdf (p58, p60, p62) ^[12] Senior notes: Ryan Ho Diagnostic Radiology.pdf (p84–85) ^[13] Senior notes: Ryan Ho Cardiology.pdf (p221)

Aortitis can produce a devastating cascade of complications. The key to understanding them is to remember the fundamental pathophysiology: inflammation weakens or thickens the aortic wall. Weakening leads to aneurysm, dissection, and rupture. Thickening leads to stenosis and ischaemia. Both processes can coexist. And then there are complications of the treatment itself — long-term immunosuppression carries its own toll.

Let me systematically walk through every important complication, explaining the mechanism from first principles.

A. Structural/Vascular Complications of Aortitis

Mechanism: Inflammatory infiltration of the media → destruction of elastic lamellae and smooth muscle by MMPs and reactive oxygen species → loss of wall tensile strength → progressive dilatation under arterial pressure → aneurysm.

GCA: thoracic aortic aneurysm risk is 17× higher than age-matched controls. Predominantly ascending aorta.
Takayasu: both thoracic and abdominal aortic aneurysms.
Syphilitic: classically ascending aortic aneurysm (vasa vasorum endarteritis → medial necrosis).
Infectious/mycotic: saccular, rapidly expanding aneurysm (most dangerous — highest rupture risk).
IgG4-RD: inflammatory infrarenal AAA with characteristic thick periaortic fibrosis.

Complications of aneurysms ^[1]:

Rupture
Thrombosis
Embolism
Infection
Pressure effects

This is the most feared complication and is often fatal.

Mechanism: The wall weakens progressively as inflammation destroys the media. Once wall stress (governed by Laplace's law: wall stress = pressure × radius / 2 × wall thickness) exceeds the residual wall strength, the aorta ruptures.

Ruptured AAA ^[1]:

Only 1 in 3 reaches hospital
Surgical emergency
Immediate diagnosis → operation
Operative mortality > 50%
Overall mortality > 80%

Clinical triad of rupture: pain (abdomen/back), mass (pulsatile), shock (transient/profound) ^[1].

Why aortitis-related aneurysms have particularly high rupture risk: Unlike atherosclerotic aneurysms where the wall degenerates slowly over decades with compensatory fibrosis, inflammatory aneurysms have active ongoing destruction. Mycotic aneurysms are especially dangerous — the suppurative inflammation can destroy the wall in days to weeks, and the aneurysm may rupture at relatively small diameters.

Specific complications of ruptured AAA ^[1]:

Cardiac (perioperative MI)
Respiratory (ARDS)
Renal failure (shock)
Bleeding tendency (massive transfusion)
Paralytic ileus (retroperitoneal haematoma)
Jaundice (bleeding + transfusion)

Mechanism: Inflammation weakens the media → an intimal tear allows blood under high pressure to enter the medial layer → creates a false lumen that propagates along the aorta → can occlude branch vessels, rupture externally, or rupture into the pericardium.

Vasculitis, e.g. Takayasu arteritis is a recognised risk factor for aortic dissection ^[2].

Aortic arch syndrome: aneurysm, dissection, stenosis of aorta and its major branches as a complication of GCA ^[4].

Complications of dissection ^[2]:

Ischaemia: MI, ischaemic stroke, mesenteric ischaemia, AKI, limb ischaemia
Rupture: aortic rupture, cardiac tamponade, acute aortic regurgitation (→ APO)

The clinical features of aortic dissection complicating aortitis are identical to dissection from any other cause:

Chest pain: sudden onset, tearing, radiate to back ^[2]
Asymmetric BP and pulse between arms ^[2]

Symptoms due to occlusion of aortic branches ^[13]:

Coronaries → MI
Carotids → syncope, CVA
Spinal → paraplegia
Coeliac or SMA → mesenteric infarct with acute abdomen
Renal → renal failure
External iliac → acute ischaemic limb

Aortic root dilatation (supravalvular): hypertension, infection (syphilitic aortitis), inflammatory (AS), CT disease (Marfan's, EDS) ^[8].

Mechanism: Aortitis involving the aortic root → dilatation of the aortic annulus → the valve cusps are pulled apart → loss of coaptation → regurgitation. In SpA, the mechanism is different: sclerosing inflammatory process involving aortic root, AV cusps and IV septum ^[9] → cusps become thickened, fibrosed, and retracted.

Consequences of chronic AR ^[14]:

↑LV EDV → compensatory LV dilatation → ↑SV 2–3× → characteristic widened pulse pressure
Gradual decompensation → ↑LV EDP → ↓CO → SOB + HF
Angina due to ↓diastolic BP and ↑ventricular demand ^[14]

Acute AR (e.g., from sudden aortic dissection tearing into the root):

LV does not dilate → acute pulmonary oedema (emergency!) ^[14]
This is a surgical emergency requiring immediate valve replacement.

Mechanism: Inflammatory intimal hyperplasia → concentric thickening → progressive luminal narrowing → stenosis/occlusion.

This is the dominant pathology in Takayasu arteritis and contributes to:

Vessel Affected	Complication	Mechanism
Subclavian artery	Limb claudication, absent/weak pulses, asymmetric BP ^[6]	Upper limb ischaemia
Carotid artery	Stroke, TIA, syncope	Cerebral ischaemia
Vertebral artery	Vertebrobasilar insufficiency	Posterior circulation ischaemia
Coronary ostia	Angina, MI	Especially in syphilitic aortitis — intimal fibrosis around coronary ostia
Renal artery	HTN ( > 50%) due to renal artery stenosis ^[6], renal failure	RAAS activation → secondary hypertension
Coeliac / SMA	Mesenteric ischaemia (postprandial angina, weight loss)	Gut ischaemia
Subclavian proximal	Subclavian steal syndrome ^[4]	Retrograde vertebral flow on arm exercise → dizziness/syncope

Mechanism: Inflamed, damaged endothelium activates the coagulation cascade (loss of the normal anti-thrombotic endothelial surface, exposure of subendothelial collagen and tissue factor). Additionally, stagnant blood flow within aneurysmal sacs promotes mural thrombus formation.

Complications of aneurysms: thrombosis and embolism ^[1]^[15].

Mural thrombus within aneurysms can embolise distally:
- Limb ischaemia (e.g., blue toe syndrome, trash foot): due to distal embolisation of mural thrombus ^[5]
- Due to distal embolization → acute ischaemic limb or blue toe syndrome ^[15]
In Behçet disease, there is a particular propensity for venous thrombosis (VTE occurs in up to 53% of patients) as well as arterial thrombosis.

Complication: Trash Foot ^[1] — distal microembolisation of thrombus/atheromatous debris to digital arteries → ischaemia/gangrene of toes despite palpable pedal pulses. The hallmark is painful, cyanotic/necrotic toes with a palpable dorsalis pedis pulse.

B. Organ-Specific Ischaemic Complications

Anterior ischaemic optic neuropathy (AION): sudden painless blindness (vasculitis of posterior ciliary arteries) — may be preceded by amaurosis fugax, 15–20% permanent visual loss ^[4].

AAION: presenting as amaurosis fugax, may progress into permanent visual loss (15–20%) ^[3].

Mechanism: Granulomatous inflammation of the posterior ciliary arteries (which supply the optic nerve head) → thrombosis → infarction of the optic nerve head → permanent, irreversible visual loss. The optic nerve head is an end-organ — there is no collateral supply.

Thrombosis due to vessel wall thickening: Ophthalmic artery → amaurosis fugax; Basilar artery → posterior circulation infarct ^[10].

This is the ophthalmological emergency in GCA:

Once one eye is affected, the risk of involvement of the contralateral eye is very high (up to 50% within days if untreated).
For visual S/S, do NOT wait for biopsy result → start empirical steroids ^[4].
Urgent Tx prevents blindness and brainstem stroke ^[10].

Stroke (ischaemic): from carotid/vertebral stenosis (Takayasu) or thromboembolism (GCA involving cranial arteries).
- Basilar artery → posterior circulation infarct ^[10].
- Neurological S/S: stroke, hearing loss, myelopathy, neuropathy ^[10].
Paraplegia: from spinal artery occlusion (dissection involving intercostal arteries/artery of Adamkiewicz, or thromboembolism).
Hearing loss: from labyrinthine artery involvement in GCA.

Myocardial infarction: from coronary artery involvement.
- In Takayasu: coronary ostial stenosis from intimal inflammation.
- In syphilitic aortitis: coronary ostial stenosis from intimal fibrosis at the aortic root.
- In aortic dissection: retrograde dissection extending into the coronary ostia (usually right coronary → inferior STEMI).
Heart failure: from chronic aortic regurgitation → progressive LV volume overload → eventual decompensation.
- Decompensated stage: signs of LV failure, angina, syncope ^[14].
Conduction defects: specifically in SpA-associated aortitis.
- CAD, aortitis, AI, conduction defects as extra-articular features of AS ^[9].
- First-degree AV block → may progress to complete heart block → may require permanent pacemaker.
- Mechanism: sclerosing inflammatory process extending from the aortic root into the membranous interventricular septum, which houses the bundle of His ^[9].
Cardiac tamponade: from aortic dissection rupturing into the pericardial space.
- Aortic dissection can extend proximally leading to rupturing into pericardium giving rise to tamponade ^[13].

Renovascular hypertension: renal artery stenosis (Takayasu, GCA involving renal arteries) → activation of RAAS → secondary hypertension → can be resistant to conventional antihypertensives.
Renal infarction: from thromboembolism.
Renal failure: from prolonged hypoperfusion, contrast-induced nephropathy (during investigations), or perioperative ischaemia.

Mesenteric ischaemia: from stenosis of the coeliac trunk or SMA (Takayasu, GCA) → postprandial abdominal pain (mesenteric angina), food fear, weight loss.
Bowel infarction: acute mesenteric occlusion → surgical emergency.
Aortoenteric fistula: communication between the aorta and adjacent bowel (usually duodenum D3/D4).
- Aortoenteric fistula (massive GIB) ^[5].
- Can occur as a primary complication of infectious aortitis (erosion through bowel wall) or as a late complication of aortic surgery (graft-enteric fistula).

Clinical features of aneurysm: compression, e.g. RLN compression by thoracic aortic aneurysm ^[15].

Structure Compressed	Clinical Result	Location
Recurrent laryngeal nerve	Hoarseness (Ortner syndrome)	Aortic arch/descending thoracic
Oesophagus	Dysphagia (dysphagia aortica)	Descending thoracic
Trachea/left main bronchus	Stridor, cough, respiratory distress	Aortic arch
SVC	SVC obstruction (facial swelling, dilated veins)	Ascending/arch. Non-malignant causes of SVCO include syphilitic aortitis, aortic aneurysm ^[16]
Vertebral bodies	Erosion, back pain	Descending thoracic/abdominal
Ureter	Hydronephrosis	IgG4-RD with retroperitoneal fibrosis

C. Complications of Surgical Treatment

AAA: Operative Complications: Early ^[1]:

General Complications: Cardiac (clamp/declamp), Respiratory ^[1].

Specific Complications ^[1]:

Haemorrhage
Bowel ischaemia — from ligation or injury to the IMA or SMA. Bowel ischaemia: due to ligation of mesenteric vessels. More commonly affect colon (IMA) > small bowel (SMA) ^[15].
Impotence — damage to retroperitoneal autonomic nerves (hypogastric plexus).
Renal failure — embolism, clamp time, reduced renal artery perfusion. More commonly occur with suprarenal AAA repair ^[15].
Distal embolism — Trash foot ^[1]: atheromatous/thrombotic debris embolises to pedal arteries during clamping/manipulation.
Paraplegia — from ligation of spinal segmental arteries, especially the artery of Adamkiewicz (T9-L2). More common in thoracic AA repair ^[15].

Why does clamping/declamping cause cardiac complications? Clamping the aorta acutely increases afterload → the LV must pump against higher resistance → can precipitate MI or LV failure, especially in patients with pre-existing coronary disease. Declamping causes sudden drop in afterload + release of ischaemic metabolites (lactate, potassium) → hypotension, arrhythmias.

AAA: Operative Complications: Late ^[1]:

Graft infection
Anastomotic aneurysm (pseudoaneurysm at suture lines — particularly problematic in aortitis because the inflamed native aortic wall holds sutures poorly)
Graft-duodenal fistula — the graft erodes into the adjacent duodenum (D3/D4) → presents as massive GI bleeding, often months to years after repair. Aortoenteric fistula (mostly D3/4 — can occur years after repair) ^[5].

Why Aortitis Makes Surgery Riskier

Inflamed aortic tissue is friable, oedematous, and holds sutures poorly. This leads to higher rates of:

Anastomotic pseudoaneurysm (sutures cut through the inflamed wall)
Graft dehiscence
Postoperative haemorrhage This is why immunosuppressive control of inflammation BEFORE elective surgery is so important.

Endograft complications ^[15]:

Endoleak (30%): persistent blood flow into the aneurysm sac after EVAR.
- Type I: inadequate seal at attachment sites (high-pressure — needs repair)
- Type II: backflow from visceral vessels (most common, usually benign)
- Type III: flow from mechanical disruption of endograft (needs repair)
- Type IV: flow through porous graft (self-limiting)
Graft migration
Graft infection / thrombosis
Limb kinking and occlusion

Systemic complications of EVAR ^[15]:

Cardiac (1.8–5.3%): MI
Contrast complications: contrast-induced nephropathy (0.7–2%), allergy
Ischaemic complications: renal, intestinal, lower limb, pelvic, spinal ischaemia
Post-implantation syndrome (13–60%): transient flu-like inflammatory syndrome in first 7–10 days, mechanism unknown, no treatment required.

D. Complications of Immunosuppressive Treatment

Since most non-infectious aortitis requires prolonged immunosuppression, treatment-related complications are a major source of morbidity:

System	Complication	Mechanism
Bone	Osteoporosis → fractures	Inhibits osteoblasts, increases osteoclast activity, decreases calcium absorption
Metabolic	Hyperglycaemia / steroid-induced DM	Increases hepatic gluconeogenesis, induces insulin resistance
Cardiovascular	Hypertension	Mineralocorticoid effect → Na+/water retention
Immune	Infection susceptibility	Suppresses innate and adaptive immunity
GI	Peptic ulcer disease	Inhibits prostaglandin synthesis → reduced mucosal protection
Eyes	Posterior subcapsular cataract, glaucoma	Altered lens protein metabolism; increased aqueous outflow resistance
Adrenal	Adrenal suppression/crisis on withdrawal	Chronic exogenous steroid → HPA axis suppression → atrophied adrenals
Skin	Thin skin, easy bruising, poor wound healing	Inhibits collagen synthesis
Psychiatric	Insomnia, mood disturbance, psychosis	Central effects of glucocorticoids
Musculoskeletal	Steroid myopathy (proximal weakness), AVN of hip	Muscle catabolism; altered lipid metabolism in bone

These are particularly problematic in the elderly GCA population who are already at high risk of osteoporosis, DM, and infection.

Agent	Key Side Effects
Tocilizumab	Infection (masking of CRP/fever), GI perforation (especially in diverticular disease), hepatotoxicity, hyperlipidaemia, neutropaenia
Methotrexate	Hepatotoxicity, myelosuppression, pneumonitis, mucositis, teratogenicity
Azathioprine	Myelosuppression (especially in TPMT/NUDT15 deficiency), hepatotoxicity, increased lymphoma risk
Rituximab	Infusion reactions, hypogammaglobulinaemia (→ recurrent infections), hepatitis B reactivation, PML (rare)
Cyclophosphamide	Myelosuppression, haemorrhagic cystitis (prevented by mesna), infertility, secondary malignancy (bladder cancer, leukaemia)

E. Disease-Specific Complications

Complication	Frequency	Mechanism
Permanent visual loss (AAION)	15–20% ^[3]^[4]	Posterior ciliary artery thrombosis → optic nerve infarction
Thoracic aortic aneurysm	17× risk	Medial destruction
Aortic dissection	Increased risk	Weakened wall
Stroke	~3–4%	Carotid/vertebral involvement
Scalp necrosis	Rare	Temporal/occipital artery occlusion

Complication	Mechanism
Renovascular hypertension	Renal artery stenosis → RAAS activation
Ischaemic stroke	Carotid/vertebral stenosis
Limb ischaemia	Subclavian/iliac stenosis
Aortic aneurysm and AR	Medial destruction
Retinopathy	Chronic ocular hypoperfusion → hypotensive retinopathy
Pulmonary artery involvement	Takayasu can involve pulmonary arteries (10–40%) → pulmonary HTN

Prognosis: chronic, relapsing/remitting course in majority, 80–90% 5-year survival ^[6].

Complication	Mechanism
Ascending aortic aneurysm	Vasa vasorum endarteritis → medial necrosis
Aortic regurgitation	Aortic root dilatation → cusp separation
Coronary ostial stenosis → angina	Intimal fibrosis at the ostia
"Tree-bark" aorta	Intimal wrinkling over scarred media

Complication	Mechanism
Rapid aneurysm expansion and rupture	Fulminant wall destruction (especially Staph, Salmonella)
Sepsis / septic shock	Uncontrolled bacteraemia
Aortoenteric fistula	Infected aneurysm erodes into adjacent bowel
Vertebral osteomyelitis	Contiguous spread from infected aortic wall

Complication	Mechanism
Ureteric obstruction → hydronephrosis	Retroperitoneal fibrosis encases ureters
Multi-organ fibrosis	Pancreas (AIP), biliary (sclerosing cholangitis), salivary glands, orbits
Inflammatory AAA rupture	Though less common than atherosclerotic AAA rupture

Aetiology	5-Year Survival	Major Causes of Mortality
GCA	> 90% (with treatment)	Cardiovascular events, aneurysm rupture, treatment complications
Takayasu	80–90% ^[6]	Heart failure, stroke, renal failure, aneurysm rupture
Syphilitic	Depends on stage at diagnosis	Aortic rupture, heart failure from AR
Mycotic	Variable (poor without surgery)	Sepsis, rupture
IgG4-RD	> 90% (steroid-responsive)	Multi-organ fibrosis, treatment complications
Behçet	~80–85%	Arterial aneurysm rupture, pulmonary artery aneurysm, CNS disease

High Yield Summary — Complications of Aortitis

Structural:

Aneurysm (all types; risk of rupture — highest with mycotic)
Dissection (weakened media; especially GCA, Takayasu; Takayasu is a known risk factor)
Rupture (most feared; overall mortality > 80% for ruptured AAA)
AR (root dilatation in syphilis/GCA; root fibrosis in SpA)
Stenosis/occlusion (dominant in Takayasu → limb claudication, renovascular HTN, stroke)

Organ-specific ischaemia:

Visual loss (GCA: AAION, 15–20% permanent if untreated — emergency)
Stroke (carotid/vertebral stenosis)
MI (coronary ostial stenosis in syphilis; dissection flap occluding coronary)
Mesenteric ischaemia
Renal failure

Cardiac:

Heart failure from chronic AR
Conduction defects in SpA
Cardiac tamponade from dissection into pericardium

Surgical complications:

Early open repair: haemorrhage, bowel ischaemia, renal failure, trash foot, paraplegia
Late open repair: graft infection, anastomotic aneurysm, aortoenteric fistula
EVAR: endoleak (30%), graft migration, post-implantation syndrome

Treatment complications:

Steroids: osteoporosis, DM, infection, adrenal suppression
Immunosuppressants: myelosuppression, hepatotoxicity, infection risk
Anastomotic failure higher in inflamed aortic tissue

Active Recall - Complications of Aortitis

^[1] Lecture slides: GC 199. Pulsating abdominal mass aortic aneurysm.pdf (p3, p13, p15, p22) ^[2] Senior notes: Maksim Medicine Notes.pdf (p15) ^[3] Senior notes: Ryan Ho Rheumatology.pdf (p95) ^[4] Senior notes: Maksim Medicine Notes.pdf (p311) ^[5] Senior notes: Maksim Surgery Notes.pdf (p162) ^[6] Senior notes: Ryan Ho Rheumatology.pdf (p96) ^[8] Senior notes: Maksim Medicine Notes.pdf (p35) ^[9] Senior notes: Ryan Ho Rheumatology.pdf (p58, p60) ^[10] Senior notes: Ryan Ho Neurology.pdf (p65) ^[13] Senior notes: Ryan Ho Cardiology.pdf (p220–221) ^[14] Senior notes: Ryan Ho Cardiology.pdf (p160) ^[15] Senior notes: Ryan Ho Cardiology.pdf (p222, p225–226) ^[16] Senior notes: Maksim Medicine Notes.pdf (p45)

Aortitis

References

Aortitis

1. Definition

2. Epidemiology

2.1 Overall Prevalence

2.2 Demographics

2.3 Hong Kong Context

3. Anatomy and Function of the Aorta (Relevant to Understanding Aortitis)

3.1 Gross Anatomy

3.2 Histological Layers

3.3 Vasa Vasorum

3.4 Function

4. Etiology (with Focus on Hong Kong)

4.1 Non-Infectious Aortitis

4.1.1 Large Vessel Vasculitis

4.1.2 Other Vasculitides

4.1.3 Non-Vasculitic Inflammatory Aortitis

4.2 Infectious Aortitis

4.2.1 Bacterial

4.2.2 Mycobacterial

4.2.3 Fungal

4.2.4 Viral

4.3 Other / Rare Causes

5. Pathophysiology

5.1 General Pathophysiological Framework

5.2 Pathophysiology by Disease Category

5.2.1 Granulomatous Aortitis (GCA / Takayasu)

5.2.2 Syphilitic Aortitis

5.2.3 Infectious/Mycotic Aortitis

5.2.4 IgG4-Related Aortitis

5.2.5 Spondyloarthropathy-Associated Aortitis

6. Classification

6.1 By Etiology

6.2 By Anatomical Location

6.3 By Histopathological Pattern

7. Clinical Features

7.1 Symptoms

7.1.1 Constitutional / Systemic Symptoms

7.1.2 Pain

7.1.3 Symptoms from Vascular Stenosis / Occlusion

7.1.4 Symptoms from Aortic Regurgitation

7.1.5 Symptoms from Aneurysm

7.1.6 Symptoms Specific to the Underlying Disease

7.2 Signs

7.2.1 Cardiovascular Signs

7.2.2 Signs Specific to GCA

7.2.3 Signs of Aortic Aneurysm Complications

7.2.4 Signs Specific to Underlying Disease

8. Summary Table: Quick Comparison of Major Causes of Aortitis

Active Recall - Aortitis

References

Differential Diagnosis of Aortitis

A. Framework for Approaching the Differential Diagnosis

B. Differential Diagnosis by Clinical Scenario

Scenario 1: Patient Found to Have an Aortic Aneurysm

Scenario 2: Patient Presents with Aortic Regurgitation

Scenario 3: Patient Presents with Asymmetric Pulses, Bruits, or Limb Claudication

Scenario 4: Patient Presents with FUO / Constitutional Symptoms + Raised Inflammatory Markers

Scenario 5: Acute Aortic Syndrome

C. Differential Diagnosis of Aortitis by Cause — Distinguishing Among the Aetiologies

Key Distinguishing Features

D. Important Mimics — Conditions That Can Look Like Aortitis But Aren't

E. Practical Approach — How to Work Through the DDx at the Bedside

Active Recall - Differential Diagnosis of Aortitis

References

Diagnostic Criteria, Algorithm, and Investigations for Aortitis

A. Why There Are No Universal "Aortitis Diagnostic Criteria"

B. Disease-Specific Diagnostic Criteria

B1. Giant Cell Arteritis (GCA)

B2. Takayasu Arteritis

B3. Behçet Disease

B4. IgG4-Related Disease

B5. Spondyloarthropathy-Associated Aortitis

B6. Infectious Aortitis

B7. Clinically Isolated Aortitis (CIA)

C. Diagnostic Algorithm

D. Investigation Modalities — Detailed Breakdown

D1. Blood Tests (First-Line)

D2. Imaging — The Cornerstone of Aortitis Diagnosis