Cor pulmonale is right ventricular enlargement and dysfunction resulting from pulmonary hypertension caused by diseases of the lung parenchyma, pulmonary vasculature, or chest wall.

Exam domain	One-glance essentials
Definition / diagnosis	*Cor pulmonale = RV hypertrophy/dilatation/failure due to pulmonary hypertension caused by lung parenchymal, pulmonary vascular, or chest wall disease — explicitly EXCLUDES left heart disease* ^[1]^[2] Gold standard haemodynamic definition: mPAP > 20 mmHg, PAWP ≤ 15 mmHg (pre-capillary PH), PVR ≥ 3 WU on right heart catheterisation ^[3]^[4] Acute cor pulmonale (e.g. massive PE) = sudden RV dilatation without hypertrophy → haemodynamic collapse; chronic = progressive RV hypertrophy → eventual failure ^[5]^[6]
Epidemiology / risks	*COPD is the most common cause (>50% of cases); "blue bloaters" (chronic bronchitis) develop cor pulmonale more readily than "pink puffers" due to greater hypoxia/hypercapnia ^[2]^[1] In HK, key underlying causes: COPD (smoking), pneumoconiosis (construction workers), post-TB bronchiectasis, and OSA/obesity hypoventilation syndrome* ^[7]^[8] Other causes: ILD, CTEPH, kyphoscoliosis, neuromuscular disease, Group 1 PAH (young women, connective tissue disease esp. SSc/MCTD) ^[9]^[5]
Core mechanism	Lung disease → chronic alveolar hypoxia → hypoxic pulmonary vasoconstriction (HPV) + vascular bed destruction + remodelling → ↑PVR → pulmonary hypertension → RV pressure overload ^[1]^[5] RV pressure overload → RV hypertrophy → eventual RV dilatation and failure; secondary polycythaemia (Hct >56%) from chronic hypoxia further ↑viscosity → ↑PVR in vicious cycle ^[10]^[1] *HPV is partially reversible* — this is the pathophysiological rationale for LTOT in COPD to reduce PVR and slow cor pulmonale progression ^[11]^[5]
Clinical picture	Symptoms: exertional dyspnoea (most common), fatigue, exertional chest pain, syncope, peripheral oedema, abdominal distension — always on background of underlying lung disease ^[1]^[5] *Pulmonary hypertension signs: loud P2, parasternal (RV) heave, narrow splitting of S2; RHF signs: raised JVP, hepatomegaly, peripheral oedema, ascites, TR murmur, cyanosis ^[12]^[1] Key discriminator from LHF*: lungs are typically clear (no pulmonary oedema) despite peripheral congestion; orthopnoea/PND less prominent ^[5]^[13]
Investigations	*ECG: P pulmonale (tall P >2.5 mm in II, III, aVF), RAD, RVH, RV strain ± RBBB* — insensitive but specific; in acute PE: S1Q3T3 + sinus tachycardia ^[14]^[15] *Echocardiography is the KEY non-invasive test: RV dilatation/hypertrophy, ↑RVSP, TR, normal LV function — may be limited in COPD due to hyperinflation ^[14]^[16] ABG: hypoxaemia ± hypercapnia (driver of HPV); CBC: secondary polycythaemia; BNP/NT-proBNP: mildly elevated in RV strain vs markedly elevated in LHF ^[17]^[13] Spirometry mandatory for COPD (post-BD FEV₁/FVC <0.7)*; CXR shows prominent hilar vessels with peripheral pruning + RV enlargement; CTPA if PE suspected ^[17]^[18]
Management	*Treat underlying lung disease first: COPD → smoking cessation + bronchodilators + pulmonary rehab; CTEPH → anticoagulation ± pulmonary endarterectomy; OSA → CPAP ^[2]^[19] LTOT improves survival in stable hypoxaemic COPD: assess by ABG; offer if PaO₂ ≤ 7.3 kPa, or 7.3–8.0 kPa with polycythaemia, oedema or pulmonary hypertension; use ≥ 15 h/day* ^[20] *Diuretics + salt and fluid restriction for RHF* — use cautiously as RV is preload-dependent; venesection if Hct >56%; digoxin ONLY for atrial tachyarrhythmias ^[2]^[1] *PAH-specific drugs are for Group 1 PAH ONLY — NOT for Group 3 PH (COPD/ILD)*; lung transplantation is the definitive treatment for end-stage disease ^[5]^[19]
Complications	*Progressive RHF is the defining complication* — once oedema develops in COPD, 5-year survival is ~30% ^[10]^[1] *Arrhythmias: AF (most common sustained), MAT (classic for severe lung disease), VT/VF (sudden death risk) — first-line: correct hypoxia and electrolytes ^[1]^[8] Thromboembolism: in situ PA thrombosis, DVT/PE, paradoxical embolism via PFO; driven by polycythaemia, stasis, immobility ^[10]^[21] Congestive hepatopathy* → cardiac cirrhosis (AST > ALT pattern); cardiorenal syndrome; massive haemoptysis from hypertrophied bronchial arteries ^[22]^[1]
Prevention / follow-up	Primary prevention: smoking cessation is the single most important measure to prevent COPD-related cor pulmonale; occupational dust control prevents pneumoconiosis ^[2]^[7] *LTOT ≥15 h/day prevents progression of pulmonary hypertension* and improves 3-year survival by ~50% in qualifying COPD patients; must confirm ABG on two occasions ≥3–4 weeks apart while stable ^[11]^[23] Monitoring: serial echocardiography for RV function; regular ABGs and Hct to detect worsening hypoxaemia or polycythaemia; pulmonary rehabilitation for functional capacity ^[14]^[10]
Exam traps	*Must exclude LEFT heart failure before diagnosing cor pulmonale* — use echo (normal LV) and BNP (only mildly elevated); PAWP ≤15 mmHg on RHC is the definitive discriminator ^[13]^[3] *Do NOT use HFrEF "4 pillars" (ACEi, BB, MRA, SGLT2i) for isolated cor pulmonale* — evidence base is for LV failure; non-selective beta-blockers and excessive diuresis are harmful ^[24]^[19] *Echo may be falsely reassuring in COPD* — hyperinflation creates poor acoustic windows; a "normal" echo does not exclude cor pulmonale; consider RHC if clinical suspicion is high ^[16]^[5] *PAH-specific vasodilators (e.g. sildenafil, bosentan) worsen V/Q mismatch in Group 3 PH (COPD/ILD)* — only indicated for Group 1 PAH ^[25]^[19]

References

^[1] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39) ^[2] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (Complications of COPD p.9; COPD management principles — cor pulmonale: diuretics, salt and fluid restriction p.25) ^[3] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39; PH classification, p.137–138) ^[4] Senior notes: Block A - Three Cases of Dyspnea .pdf (PAH classification and catheterisation, p.4) ^[5] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39; PH classification, p.137–138; COPD section, p.107–108) ^[6] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (p.21–22) ^[7] Lecture slides: GC 083. Shortness of breath in a construction site worker.pdf ^[8] Senior notes: Maksim Medicine Notes.pdf (COPD section, p.298–300) ^[9] Senior notes: Ryan Ho Rheumatology.pdf (MCTD section, p.86–87; SSc section, p.83) ^[10] Senior notes: Maksim Medicine Notes.pdf (COPD complications p.298–300; LTOT p.300–302; bronchiectasis complications p.302–304; IPF causes of death p.304–306) ^[11] Lecture slides: Handbook of Internal Medicine 2024.pdf (LTOT indications including cor pulmonale, p.415) ^[12] Lecture slides: General clerkship Teaching Clinic - Haemoptysis_Prof MSM Ip_25 October 2024.pdf (Physical signs, p.48) ^[13] Senior notes: Block A - Shortness of breath on exertion_ heart failure.pdf (BNP utility, p.7–11) ^[14] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (COPD investigations including ECG ± echo for cor pulmonale, p.11) ^[15] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (COPD CXR/ECG for cor pulmonale, p.222; chest pain DDx, p.399) ^[16] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (Echocardiography, p.366) ^[17] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (COPD Investigations, p.11) ^[18] Senior notes: Block A - Chest Pain - Department of Radiology.pdf (CTPA, V/Q scan, p.1) ^[19] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale management, p.39; ILD management, p.121–122) ^[20] Guideline: NICE NG115. Chronic obstructive pulmonary disease in over 16s — long-term oxygen therapy ^[21] Senior notes: Ryan Ho Haemtology.pdf (VTE section, p.131) ^[22] Senior notes: Block A - Introduction to GI_Hepatology investigations (LFT, Endoscopy).pdf (AST > ALT pattern in CHF, p.5) ^[23] Lecture slides: Handbook of Internal Medicine 2024.pdf (LTOT indications, p.415) ^[24] Senior notes: Maksim Medicine Notes.pdf (Heart failure section, p.16–18) ^[25] Senior notes: Ryan Ho Respiratory.pdf (Pulmonary Hypertension section, p.137–138; COPD section, p.107–108)

Cor Pulmonale

Cor pulmonale is defined as right ventricular (RV) structural and/or functional alteration (hypertrophy, dilatation, or both) that results from pulmonary hypertension (pHTN) caused by diseases affecting the lung parenchyma, pulmonary vasculature, or ventilatory mechanics ^[1]^[2]. Critically, cor pulmonale excludes RV dysfunction secondary to left heart disease (e.g., left-sided valvular disease, LV failure, congenital heart disease with left-to-right shunts). The Latin roots tell you the condition: "cor" = heart, "pulmonale" = of the lung — literally, a lung-driven heart problem.

The sequence is always: lung/pulmonary vascular disease → pulmonary hypertension → RV pressure overload → RV hypertrophy ± dilatation ± RV failure.

Cor pulmonale = Right heart failure secondary to pulmonary hypertension caused by primary respiratory/pulmonary vascular disease. Left heart disease is excluded by definition. ^[1]^[2]

Key Conceptual Point

Cor pulmonale is NOT simply "right heart failure." It is right heart failure specifically due to lung or pulmonary vascular pathology causing pulmonary hypertension. If the RV fails because of mitral stenosis or LV failure causing back-pressure, that is NOT cor pulmonale — that is RV failure secondary to left heart disease.

Prevalence: Cor pulmonale accounts for approximately 6–7% of all types of adult heart disease in Western countries. In regions with high smoking prevalence (such as Hong Kong), COPD-related cor pulmonale is particularly significant.
COPD is the most common cause: COPD accounts for >50% of all cases of cor pulmonale ^[1]^[2]. Among COPD patients, up to 40% eventually develop some degree of pulmonary hypertension, and cor pulmonale develops in approximately 25% of those with moderate–severe COPD.
Demographics: M > F (reflecting the higher prevalence of COPD and smoking in males, though this gap is narrowing). Age typically > 50 years when related to COPD/ILD.
Hong Kong context: COPD is highly prevalent in HK due to historical smoking rates and indoor biomass/cooking fume exposure (particularly in elderly women). Occupational lung diseases (e.g., silicosis in construction workers, asbestosis) are also locally relevant causes ^[3]^[4].
Mortality: Cor pulmonale carries a poor prognosis — 5-year survival ~30% once peripheral oedema develops in COPD patients with cor pulmonale. Development of cor pulmonale in COPD is an independent predictor of mortality.

The risk factors for cor pulmonale mirror the risk factors for chronic lung disease and pulmonary hypertension:

Category	Risk Factors
Smoking	Most important modifiable risk factor — causes COPD (the #1 cause of cor pulmonale) ^[1]^[5]
Occupational exposure	Silica (construction workers), asbestos, coal dust → pneumoconiosis/ILD ^[3]
Indoor air pollution	Cooking fumes, biomass fuel — relevant in HK elderly women ^[4]
Chronic lung disease	COPD, ILD (IPF, pneumoconiosis), bronchiectasis, cystic fibrosis
Obesity	Obesity hypoventilation syndrome (Pickwickian syndrome) → chronic hypoxia
Obstructive sleep apnoea	Intermittent hypoxia → pulmonary vasoconstriction
Residing at high altitude	Chronic hypoxia → chronic pulmonary vasoconstriction
Chronic thromboembolic disease	Recurrent PE → CTEPH (Group 4 PH)
Thoracic cage deformities	Kyphoscoliosis → restrictive ventilatory defect → chronic hypoxia
Neuromuscular disease	Muscular dystrophy, MND → hypoventilation
Connective tissue disease	SSc, MCTD → pulmonary fibrosis and/or pulmonary vascular disease ^[6]

Anatomy and Functional Considerations

To understand cor pulmonale, you must understand the RV:

The RV is a thin-walled, crescent-shaped chamber (wall thickness ~3–5 mm vs LV ~10–15 mm) designed as a volume pump operating in a low-pressure, low-resistance pulmonary circuit.
Normal mean pulmonary artery pressure (mPAP) = 14 ± 3 mmHg (cf. systemic MAP ~90 mmHg). The pulmonary circulation is a high-flow, low-resistance system.
The RV is highly compliant — it can accommodate large increases in preload (volume) but is very poorly tolerant of acute increases in afterload (pressure). A sudden doubling of pulmonary artery pressure can cause acute RV failure, whereas the LV can easily handle this in the systemic circulation.

Pulmonary arteries are thin-walled and highly distensible with much less smooth muscle than systemic arteries.
The low resistance comes from the large total cross-sectional area and high compliance of the pulmonary vascular bed.
Hypoxic pulmonary vasoconstriction (HPV) is a unique homeostatic mechanism: when alveolar PO₂ falls, the local pulmonary arterioles constrict to divert blood away from poorly ventilated alveoli and towards better-ventilated ones. This optimises V/Q matching. However, when hypoxia is global (e.g., diffuse lung disease, high altitude), HPV causes generalised pulmonary vasoconstriction → ↑PVR → pulmonary hypertension.

When the RV faces chronically elevated afterload:

RV hypertrophy (compensatory phase): increased wall thickness to normalise wall stress (Laplace's law: wall stress = pressure × radius / 2 × wall thickness)
RV dilatation (decompensated phase): when the RV can no longer cope, it dilates → ↑wall stress → ↓contractility → RV failure
Tricuspid regurgitation: RV dilatation pulls the tricuspid annulus apart → functional TR → further volume overload → vicious cycle
Ventricular interdependence: the dilated RV pushes the interventricular septum leftward (especially in diastole) → impairs LV filling → ↓LV output → systemic hypotension

The causes of cor pulmonale are best understood through the WHO classification of pulmonary hypertension, specifically Groups 3, 4, and 5 (Groups 1 and 2 are excluded or represent special circumstances):

Important Classification Point

Cor pulmonale relates primarily to WHO Group 3 (lung diseases/hypoxia) and Group 4 (pulmonary artery obstruction) pulmonary hypertension. Group 2 (left heart disease) is excluded by definition. Group 1 (PAH) can cause RV failure but is typically classified separately as "PAH with RV failure" rather than "cor pulmonale" — though in practice the terms overlap ^[2]^[7].

Aetiological Classification

A. Diseases of the Lung Parenchyma (Most Common — WHO Group 3)

Cause	Mechanism	HK Relevance
COPD	Hypoxic vasoconstriction + destruction of pulmonary vascular bed + polycythaemia → ↑PVR	Most common cause overall; very common in HK due to smoking ^[1]^[5]
Interstitial lung diseases (IPF, pneumoconiosis, sarcoidosis)	Fibrosis obliterates pulmonary capillaries + hypoxia	Silicosis in HK construction workers ^[3]
Bronchiectasis	Chronic infection/inflammation → vascular destruction + hypoxia	Common in HK (post-TB, childhood infections)
Cystic fibrosis	Mucus plugging → V/Q mismatch + chronic infection → vascular changes	Less common in Asians

B. Disorders of Pulmonary Vasculature (WHO Group 4 and some Group 1)

Cause	Mechanism
Chronic thromboembolic pulmonary hypertension (CTEPH)	Organised thrombi → mechanical obstruction + secondary vasculopathy ^[7]
Primary pulmonary arterial hypertension (PAH)	Idiopathic intimal proliferation + medial hypertrophy → ↑PVR ^[7]
Pulmonary vasculitis (e.g., in SLE, SSc, MCTD)	Inflammatory destruction of pulmonary vessels ^[6]
Sickle cell disease	In situ thrombosis + chronic haemolysis → pulmonary vasculopathy

C. Disorders of Ventilatory Mechanics (Inadequate Ventilation → Chronic Hypoxia)

Cause	Mechanism
Obesity hypoventilation syndrome	Central hypoventilation + chest wall restriction → global hypoxia
Obstructive sleep apnoea	Intermittent severe hypoxia → pulmonary vasoconstriction
Kyphoscoliosis	Restrictive ventilatory defect → ↓alveolar ventilation
Neuromuscular disease (MND, Duchenne, myasthenia gravis)	Respiratory muscle weakness → hypoventilation
Central hypoventilation syndromes	↓Respiratory drive → global hypoxia

D. High Altitude (Chronic Hypoxic Exposure)

Chronic residence at high altitude → sustained hypoxic pulmonary vasoconstriction → chronic pHTN

In Hong Kong, the most important causes of cor pulmonale are: (1) COPD (smoking), (2) pneumoconiosis/ILD (occupational), (3) bronchiectasis (post-TB), and (4) OSA/obesity hypoventilation (rising prevalence).

Pathophysiology

The pathophysiology of cor pulmonale follows a logical chain. Let's break it down step by step:

Step 1: Pulmonary Hypertension Develops

Pulmonary hypertension is defined as mPAP > 20 mmHg at right heart catheterisation ^[7]. The mechanisms by which lung disease causes pHTN include:

Normal physiology: Local alveolar hypoxia triggers local arteriolar constriction (HPV) to redirect blood to better-ventilated areas → optimises V/Q matching.
In diffuse lung disease: Hypoxia is global → HPV becomes generalised → ↑PVR throughout the pulmonary vascular bed → pHTN.
Mechanism of HPV: Alveolar hypoxia → inhibition of voltage-gated K⁺ channels in pulmonary vascular smooth muscle cells → membrane depolarisation → opening of voltage-gated Ca²⁺ channels → ↑intracellular Ca²⁺ → smooth muscle contraction → vasoconstriction.
Hypercapnia and acidosis potentiate HPV (both common in COPD/T2RF).
This component is partially reversible with oxygen therapy — which is why long-term oxygen therapy (LTOT) is a key treatment.

Chronic hypoxia → structural changes in pulmonary arterioles:
- Medial smooth muscle hypertrophy
- Intimal fibrosis and proliferation
- Adventitial thickening
- Neomuscularisation of previously non-muscular small arterioles
These changes are largely irreversible → fixed ↑PVR.
Endothelial dysfunction → ↓NO and prostacyclin (vasodilators), ↑endothelin-1 and thromboxane A₂ (vasoconstrictors).

In emphysema: destruction of alveolar walls → destruction of the associated pulmonary capillaries → ↓total cross-sectional area of pulmonary vascular bed → ↑PVR.
In ILD/fibrosis: fibrotic obliteration of pulmonary capillaries.
Significant pHTN usually does not develop until >50–60% of the pulmonary vascular bed is lost.

Chronic hypoxia → ↑EPO secretion from kidneys → secondary polycythaemia → ↑blood viscosity → ↑PVR ^[1]^[2].
This further worsens pulmonary hypertension (viscous blood is harder to push through the pulmonary circuit).

Hyperinflation (in COPD): hyperinflated lungs compress alveolar vessels → ↑PVR (especially during exercise).
Acidosis: potentiates hypoxic vasoconstriction.
Mechanical obstruction: in CTEPH, organised thrombi physically obstruct pulmonary arteries.

↑PVR → ↑RV afterload → the RV must generate higher pressures to maintain CO through the pulmonary circuit.
Initially, the RV compensates with concentric hypertrophy (↑wall thickness, preserved cavity size) — this is "compensated cor pulmonale."

Eventually, the RV cannot sustain the elevated afterload → RV dilatation → ↑wall stress (Laplace's law) → ↓contractility.
Tricuspid annular dilatation → functional tricuspid regurgitation → further RV volume overload → vicious cycle.
↓RV output → ↓pulmonary venous return to LA → ↓LV preload → ↓cardiac output → systemic hypotension + organ hypoperfusion.
Ventricular interdependence ("septal bowing"): dilated RV pushes the interventricular septum towards the LV → impairs LV diastolic filling → further ↓CO.
↑RV filling pressure → transmitted backwards:
- ↑RA pressure → ↑JVP (raised JVP)
- ↑systemic venous pressure → hepatic congestion (hepatomegaly, congestive hepatopathy), peripheral oedema, ascites

Feature	Acute Cor Pulmonale	Chronic Cor Pulmonale
Onset	Sudden	Gradual (months–years)
Common cause	Massive pulmonary embolism, severe acute asthma, tension pneumothorax, ARDS	COPD, ILD, CTEPH, OSA
RV response	Acute dilatation (no time for hypertrophy)	Hypertrophy → eventual dilatation
Prognosis	Medical emergency, can be rapidly fatal	Chronic progressive, poor long-term prognosis

Acute Cor Pulmonale — Massive PE

A massive PE can acutely obstruct > 50% of the pulmonary vascular bed → acute RV failure → cardiogenic shock → death within minutes to hours. The thin-walled RV cannot generate systolic pressures > 50–60 mmHg acutely (it has no time to hypertrophy). ECG may show S1Q3T3, RV strain pattern, RBBB, sinus tachycardia ^[8]^[9].

Classification

Acute cor pulmonale: massive PE, severe acute asthma, tension pneumothorax
Subacute cor pulmonale: repeated small PE, primary PAH
Chronic cor pulmonale: COPD, ILD, CTEPH, OSA — most common clinical scenario

Compensated cor pulmonale: RV hypertrophy with preserved function; patient may be asymptomatic at rest
Decompensated cor pulmonale: RV failure with signs of systemic venous congestion (peripheral oedema, hepatomegaly, raised JVP)

WHO Group	Mechanism	Examples
Group 1 (PAH)	Pulmonary arterial vasculopathy	Idiopathic PAH, CTD-associated PAH, drug-induced
Group 3 (Lung disease/hypoxia)	Hypoxia + vascular bed destruction	COPD, ILD, OSA ^[7]
Group 4 (Pulmonary artery obstruction)	Thromboembolic/mechanical obstruction	CTEPH ^[7]
Group 5 (Multifactorial)	Various	MPN, sarcoidosis, glycogen storage disease ^[7]

Clinical Features

The clinical features of cor pulmonale are a combination of:

The underlying lung disease symptoms
Pulmonary hypertension symptoms
Right heart failure symptoms

Symptom	Pathophysiological Basis
Exertional dyspnoea (most common and often earliest symptom)	Multifactorial: (1) underlying lung disease limits gas exchange; (2) ↑PVR → RV cannot adequately ↑CO on exercise → inadequate O₂ delivery; (3) ↓LV filling due to ventricular interdependence → ↓systemic output ^[2]^[7]
Fatigue and exercise intolerance	Inability to increase CO during exercise → inadequate O₂ delivery to skeletal muscles ^[7]
Exertional chest pain / angina	Subendocardial ischaemia of the hypertrophied RV: ↑RV wall stress + ↑myocardial O₂ demand in the setting of ↓coronary perfusion pressure (RV coronary perfusion occurs in both systole and diastole, but ↑RV systolic pressure compresses intramural coronary vessels) ^[7]
Exertional syncope / pre-syncope	Fixed or ↑PVR → RV cannot increase CO on exercise → ↓cerebral perfusion → syncope. Also may be due to arrhythmias ^[7]
Peripheral oedema (ankle swelling)	↑RV filling pressure → ↑RA pressure → ↑systemic venous pressure → ↑capillary hydrostatic pressure → transudation of fluid into interstitium
Abdominal distension and discomfort / RUQ pain	Hepatic congestion: ↑RA pressure → ↑hepatic venous pressure → hepatomegaly with capsular stretching → pain. Ascites from hepatic congestion + ↑portal venous pressure
Anorexia, nausea	Gut congestion from elevated systemic venous pressure → intestinal mucosal oedema → ↓absorption + ↓appetite
Cough, sputum production, wheeze	From underlying lung disease (e.g., COPD, bronchiectasis) ^[1]^[5]
Haemoptysis	(1) Underlying lung disease (e.g., bronchiectasis, lung Ca); (2) rupture of hypertrophied bronchial arteries in severe pHTN; (3) pulmonary infarction in PE/CTEPH
Hoarseness (Ortner syndrome)	Compression of left recurrent laryngeal nerve by dilated pulmonary artery — rare but classic

Clinical Pearl — Blue Bloaters vs Pink Puffers

In COPD, "blue bloaters" (chronic bronchitis predominant) are MORE prone to developing cor pulmonale than "pink puffers" (emphysema predominant) ^[1]^[2]. Why? Blue bloaters have more V/Q mismatch, more hypoxia, more hypercapnia → more hypoxic pulmonary vasoconstriction → more pulmonary hypertension. Pink puffers maintain their drive to breathe and are less hypoxic — though they eventually develop cor pulmonale too if disease progresses.

B. Signs

Sign	Condition
Barrel chest, hyperinflation, pursed-lip breathing, use of accessory muscles, prolonged expiration, wheeze	COPD ^[1]^[5]
Fine late-inspiratory crackles (Velcro crackles), finger clubbing	ILD/IPF
Coarse crackles, clubbing	Bronchiectasis
Thoracic deformity	Kyphoscoliosis
Obesity, short thick neck	OSA / OHS

Sign	Pathophysiological Basis
Loud P2 (loud pulmonary component of S2)	↑pressure in the pulmonary artery → forceful closure of the pulmonary valve → louder P2 (best heard at LUSB). Normally P2 < A2; when P2 is palpable or louder than A2 at the apex, this suggests significant pHTN ^[2]
Narrow splitting or single S2	↑PVR → delayed RV ejection → P2 moves closer to A2
Palpable P2	Very high PA pressure → palpable closure of pulmonary valve at LUSB
Right ventricular heave (parasternal heave / lift)	RV hypertrophy → the hypertrophied RV pushes the anterior chest wall forward during systole — felt as a sustained lift at the left parasternal edge ^[2]
Pulmonary ejection click	Dilated pulmonary artery → forceful opening of the pulmonary valve
ECG: P pulmonale (tall peaked P waves > 2.5mm in lead II), RAD, RVH, RV strain pattern	P pulmonale = RA enlargement (from RV back-pressure); RAD + RVH from chronic RV pressure overload; RV strain = ST depression + T-wave inversion in right precordial leads (V1–V3) and inferior leads ^[1]^[2]

Sign	Pathophysiological Basis
Raised JVP with prominent 'a' wave (if in sinus rhythm) or 'v' wave (if TR present)	↑RA pressure → distension of internal jugular veins; 'a' wave = forceful RA contraction against stiff RV; large 'v' wave = regurgitant wave from TR ^[2]
Kussmaul's sign (JVP rises with inspiration)	Normally, JVP falls on inspiration (↓intrathoracic pressure → ↑venous return → empties RA). In RV failure, the stiff/dilated RV cannot accommodate the increased venous return → JVP paradoxically rises
Hepatomegaly (tender, pulsatile if TR)	↑RA pressure → transmitted to hepatic veins → hepatic congestion → liver enlargement. If TR is present, regurgitant flow causes systolic hepatic pulsation
Hepatojugular reflux	Pressing on the congested liver displaces blood into the already distended jugular veins → sustained ↑JVP
Peripheral pitting oedema	↑systemic venous pressure → ↑capillary hydrostatic pressure → fluid transudation into interstitial space. Gravity-dependent (ankles when upright, sacral when supine)
Ascites	Hepatic congestion → ↑hepatic sinusoidal pressure + ↑portal pressure → transudation into peritoneal cavity
Tricuspid regurgitation murmur	PSM at LLSB, louder on inspiration (Carvallo's sign) — due to RV dilatation stretching the tricuspid annulus. The ↑venous return during inspiration increases RV volume → louder murmur
Right ventricular S3 gallop	Rapid ventricular filling into a volume-overloaded, failing RV → low-pitched sound in early diastole, best heard at LLSB, louder on inspiration
Cyanosis (central ± peripheral)	(1) Central cyanosis from underlying lung disease (V/Q mismatch, shunt, hypoventilation → ↓SaO₂); (2) Peripheral cyanosis from ↓CO → ↑O₂ extraction peripherally ^[1]
Tachycardia	Compensatory sympathetic activation to maintain CO in the setting of ↓stroke volume
Hypotension (in severe/acute cases)	↓LV preload (due to ↓RV output + ventricular interdependence) → ↓CO → ↓BP

Distinguishing Right Heart Failure Signs from Left Heart Failure

Students commonly confuse the signs of LHF and RHF:

LHF: pulmonary congestion → bilateral basal crepitations, S3 at apex, orthopnoea, PND, pulmonary oedema
RHF (as in cor pulmonale): systemic venous congestion → raised JVP, hepatomegaly, peripheral oedema, ascites, TR murmur

In cor pulmonale, the lungs are usually clear of pulmonary oedema (because the problem is BEFORE the lungs, not after). The crackles you hear are from the underlying lung disease (e.g., COPD, ILD), NOT from pulmonary oedema. If you hear bilateral crepitations + raised JVP + peripheral oedema, think about whether there is COEXISTING LHF.

Stage	Features
Underlying lung disease only	Dyspnoea, cough, sputum, wheeze, crackles — no RV signs
Compensated cor pulmonale	Loud P2, RV heave, ECG changes (P pulmonale, RAD, RVH); may be asymptomatic at rest
Decompensated cor pulmonale	All the above PLUS raised JVP, hepatomegaly, peripheral oedema, ascites, TR, cyanosis, ↓CO
Acute cor pulmonale (e.g., massive PE)	Sudden dyspnoea, chest pain, syncope, shock, tachycardia, raised JVP, RV S3 ± cardiac arrest ^[8]^[9]

ECG is an important but insensitive tool for detecting cor pulmonale ^[1]^[2]. Findings include:

ECG Finding	Explanation
P pulmonale (P wave > 2.5 mm in lead II)	Right atrial enlargement → taller P wave
Right axis deviation (RAD)	RV hypertrophy shifts the cardiac axis rightward (axis > +90°)
RV hypertrophy (RVH)	Dominant R wave in V1 (R > S), deep S wave in V5/V6
RV strain pattern	ST depression + T-wave inversion in V1–V3 and inferior leads (II, III, aVF)
RBBB	RV conduction delay from RV hypertrophy/dilatation
Low voltage QRS	Hyperinflated lungs (in COPD) → ↑air insulation → ↓QRS amplitude
S1Q3T3 pattern	Classic (but not specific) for acute RV strain, especially massive PE ^[8]^[9]
Right atrial rhythm / multifocal atrial tachycardia	Seen with severe lung disease and hypoxia

ECG features of cor pulmonale: P pulmonale, RAD, RVH, RV strain pattern. In acute PE, look for S1Q3T3, sinus tachycardia, RBBB, RV strain. ^[1]^[2]^[8]

CXR Finding	Explanation
Enlarged right descending pulmonary artery ( > 16 mm)	Dilated from pulmonary hypertension
Prominent hilar vessels with peripheral pruning	Central vessels dilated, peripheral vessels narrowed/obliterated
Cardiomegaly with RV enlargement	RV filling the retrosternal space on lateral CXR; overall heart shadow may enlarge
Signs of underlying lung disease	Hyperinflation + flat diaphragm (COPD), reticular opacities (ILD), bilateral hilar lymphadenopathy (sarcoidosis)
Oligaemic lung fields	In massive PE — reduced peripheral pulmonary vascularity (Westermark sign)

Since COPD is the most common cause of cor pulmonale ^[1]^[5], it deserves special mention:

COPD patients develop cor pulmonale through multiple mechanisms ^[1]^[2]:

Hypoxic pulmonary vasoconstriction (the dominant mechanism — and partially reversible with O₂)
Destruction of pulmonary vascular bed (emphysema destroys alveolar walls and their capillaries)
Polycythaemia secondary to chronic hypoxia → ↑blood viscosity → ↑PVR
Hyperinflation → alveolar vessel compression
Hypercapnia and respiratory acidosis → potentiate pulmonary vasoconstriction
Pulmonary vascular remodelling from chronic inflammation

Clinical clue: COPD patient who develops peripheral oedema — think cor pulmonale until proven otherwise. However, remember that peripheral oedema in COPD is not ALWAYS cor pulmonale; hypercapnia itself can cause peripheral vasodilation and fluid retention via renal mechanisms.

Mechanisms of respiratory failure in COPD include: (1) V/Q mismatch (most common), (2) alveolar hypoventilation, (3) shunting (if complicated by pneumonia/CHF) ^[1].

COPD complications include: (1) Polycythaemia (secondary to hypoxaemia), (2) Cor pulmonale (secondary to pulmonary vasoconstriction), (3) Pneumothorax (secondary to rupture of emphysematous bullae) ^[1]

High Yield Summary

Cor pulmonale = RV hypertrophy/dilatation/failure due to pulmonary hypertension caused by lung or pulmonary vascular disease (NOT left heart disease)
COPD is the most common cause (> 50% of cases) — through hypoxic pulmonary vasoconstriction, vascular bed destruction, polycythaemia, and remodelling
"Blue bloaters" (chronic bronchitis) develop cor pulmonale more readily than "pink puffers" (emphysema) due to greater hypoxia/hypercapnia
Key pathophysiology: Lung disease → global hypoxia → generalised HPV + vascular remodelling → ↑PVR → pHTN → RV pressure overload → RV hypertrophy → eventual RV failure
Symptoms: Exertional dyspnoea (most common), fatigue, exertional chest pain, syncope, peripheral oedema, abdominal distension — on a background of underlying lung disease symptoms
Signs: (a) pHTN signs — loud P2, RV heave, narrow split S2; (b) RHF signs — raised JVP, hepatomegaly, peripheral oedema, ascites, TR murmur, cyanosis
ECG: P pulmonale, RAD, RVH, RV strain pattern, ± RBBB; in acute PE: S1Q3T3, sinus tachycardia
Acute cor pulmonale (e.g., massive PE) is a medical emergency with acute RV dilatation (no time for hypertrophy) → shock → death
Secondary polycythaemia from chronic hypoxia worsens pHTN by increasing blood viscosity
Hypoxic pulmonary vasoconstriction is partially reversible — this is the rationale for long-term oxygen therapy (LTOT) in COPD

Active Recall - Cor Pulmonale

^[1] Senior notes: Maksim Medicine Notes.pdf (Respiratory medicine — COPD section, p.298–300) ^[2] Senior notes: Ryan Ho Respiratory.pdf (Pulmonary Hypertension section, p.137–138; COPD section, p.107–108) ^[3] Lecture slides: GC 083. Shortness of breath in a construction site worker.pdf ^[4] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf ^[5] Lecture slides: Three Cases SOB 20211.pdf ^[6] Senior notes: Ryan Ho Rheumatology.pdf (MCTD section, p.86) ^[7] Senior notes: Block A - Three Cases of Dyspnea .pdf (PAH classification and evaluation, p.4) ^[8] Senior notes: Ryan Ho Haemtology.pdf (VTE section, p.131) ^[9] Senior notes: Ryan Ho Critical Care.pdf (Shock evaluation, p.17)

Differential Diagnosis of Cor Pulmonale

The clinical challenge with cor pulmonale is that patients present with a combination of dyspnoea and signs of right heart failure — and there are many conditions that can mimic this picture. You need a systematic framework to distinguish cor pulmonale from its mimics and, equally importantly, to identify the underlying cause of the cor pulmonale itself.

The differential diagnosis operates on two levels:

Level 1 — "Is this really right heart failure from lung disease (cor pulmonale), or is it something else causing similar signs?" — i.e., the differential of the clinical syndrome
Level 2 — "If it IS cor pulmonale, what is the underlying aetiology?" — i.e., the differential of the cause

Level 1: Differential Diagnosis of the Clinical Syndrome

A patient presenting with dyspnoea + peripheral oedema + raised JVP ± hepatomegaly could have any of the following. The key question is: is the right heart failure primary, secondary to lung disease (cor pulmonale), or secondary to left heart disease?

Feature	Cor Pulmonale	Left Heart Failure
Definition	RV failure due to lung/pulmonary vascular disease	LV failure (± secondary RV failure)
Underlying cause	Lung disease (COPD, ILD, etc.)	IHD, valvular disease, cardiomyopathy, HTN
Lung auscultation	Clear lungs (crackles if present are from underlying lung disease, NOT pulmonary oedema)	Bilateral basal crepitations (pulmonary oedema)
Orthopnoea / PND	Less prominent (unless coexisting LHF)	Classic features — due to pulmonary venous congestion worsening when supine ^[10]
CXR	Prominent hilar vessels + peripheral pruning; signs of underlying lung disease; usually no upper lobe venous diversion	Upper lobe venous diversion, Kerley B lines, bat-wing perihilar haziness, pleural effusions ^[10]
BNP / NT-proBNP	Mildly elevated or normal (unless severe RV failure)	Significantly elevated — BNP > 400 pg/mL strongly suggests CHF ^[10]^[11]
Echo	RV dilatation/hypertrophy, ↑RVSP, normal LV function	↓LVEF (HFrEF) or diastolic dysfunction (HFpEF), ± secondary RV involvement
ECG	P pulmonale, RAD, RVH ^[1]^[2]	LVH, LBBB, AF, Q waves (old MI), ST/T changes

Critical Distinction — Cor Pulmonale vs Biventricular Failure

Left heart disease is EXCLUDED by definition in cor pulmonale ^[2]. However, in clinical practice, many COPD patients ALSO have coexisting IHD or hypertensive heart disease (shared risk factor: smoking). When you see a COPD patient with peripheral oedema, you must actively evaluate for LV dysfunction — if present, it is biventricular failure, not pure cor pulmonale. BNP/NT-proBNP is extremely helpful here: it can distinguish cardiac from respiratory causes of dyspnoea ^[10]^[11].

"Only a cardiac cause of shortness of breath would result in elevated BNP. Respiratory causes would not affect this." — However, BNP has limited specificity; noncardiac causes of raised BNP include lung disease (with cor pulmonale), renal disease, and anaemia ^[11].

Feature	Cor Pulmonale	Constrictive Pericarditis
Mechanism	RV failure from ↑afterload (pHTN)	Rigid pericardium restricts ALL chambers → impaired diastolic filling
JVP	Raised, with prominent 'a' or 'v' waves	Raised with prominent x and y descents (Friedreich's sign — rapid y descent)
Kussmaul's sign	May be present	Classically present — paradoxical ↑JVP on inspiration
Pericardial knock	Absent	Present — early diastolic sound (higher pitched than S3)
Pulsus paradoxus	Usually absent (unless severe)	May be present
Echo	RV hypertrophy/dilatation, ↑RVSP	Thickened pericardium, septal bounce, respiratory variation in mitral/tricuspid inflow
CT/MRI	Pulmonary artery dilatation	Pericardial thickening/calcification
History	Chronic lung disease history	Previous pericarditis, cardiac surgery, TB, radiation

Why does constrictive pericarditis mimic cor pulmonale? Because both produce systemic venous congestion (raised JVP, hepatomegaly, oedema, ascites) with relatively clear lungs. The pericardial "shell" prevents all chambers from expanding → back-pressure into systemic veins. But in constrictive pericarditis, the lungs are normal — there is no lung disease and no pulmonary hypertension (or only mild secondary pHTN).

Feature	Cor Pulmonale	Restrictive Cardiomyopathy
Mechanism	↑PVR → RV pressure overload	Stiff myocardium → impaired ventricular filling (diastolic dysfunction) ^[12]
Presentation	Signs of RHF + underlying lung disease	HFpEF with preserved EF, but arrhythmias (bradyarrhythmias) possible ^[12]
Echocardiography	RV hypertrophy/dilatation, ↑RVSP, normal LV	Normal/↓ ventricular size, biatrial enlargement, restrictive filling pattern
CT/MRI	Lung disease + PA dilatation	May show infiltrative changes (e.g., amyloidosis)

Restrictive cardiomyopathy has functional resemblance with constrictive pericarditis — both impair ventricular filling and appear as fluid overload in the peripherals ^[12].

Massive PE is the classic cause of acute cor pulmonale ^[8]^[9]^[13]. A patient presenting with sudden dyspnoea, chest pain, syncope, and shock with raised JVP and RV failure signs must have PE excluded urgently.

Feature	Chronic Cor Pulmonale	Acute Cor Pulmonale (Massive PE)
Onset	Gradual, on background of chronic lung disease	Sudden — pleuritic chest pain, dyspnoea, haemoptysis, syncope ^[8]
Risk factors	Smoking, occupational exposure	Immobility, recent surgery, DVT, malignancy, OCP, pregnancy ^[13]
ECG	P pulmonale, RVH, RAD	Sinus tachycardia, S1Q3T3, RBBB, RV strain pattern ^[8]^[9]
D-dimer	Not typically elevated	Elevated (sensitive but not specific) ^[14]
CTPA	May show dilated PA, no filling defects	Filling defect in pulmonary arteries
Leg signs	No DVT	Unilateral leg swelling (DVT) may be present ^[13]

High Yield — PE Differential

When a patient presents acutely with dyspnoea + chest pain + raised JVP + RV strain on ECG, the three "CANNOT miss" differentials are: (1) massive PE, (2) acute MI, (3) aortic dissection ^[15]. In the context of acute cor pulmonale, PE is the most likely culprit. Ask about DVT risk factors, check D-dimer, and arrange CTPA.

PAH causes RV failure through pulmonary vascular disease WITHOUT primary lung parenchymal disease. While it technically can cause "cor pulmonale" in a broad sense, it is usually classified separately.

Feature	Cor Pulmonale (Group 3 PH)	PAH (Group 1 PH)
Patient	Older, smoker, known lung disease	Younger (20–30y), F > M, may have CTD or drug exposure ^[2]^[7]
Lung parenchyma	Abnormal (COPD/ILD findings)	Normal
Spirometry	Obstructive or restrictive pattern	Normal (or ↓DLCO only)
Right heart catheterisation	Pre-capillary PH: mPAP > 20, PAWP ≤ 15, PVR ≥ 3 WU	Same haemodynamic profile ^[2]
Specific Rx	Treat underlying lung disease + LTOT	PAH-specific therapies (5 classes): PDE5 inhibitors, ERAs, prostanoids, sGC stimulators, IP receptor agonists ^[7]

Condition	Why It May Mimic Cor Pulmonale	Key Distinguishing Features
Tricuspid valve disease (TR, TS)	Raised JVP, hepatomegaly, oedema	Primary valvular pathology on echo; no lung disease
RV infarction	Raised JVP, hypotension, clear lungs	Acute setting with inferior STEMI; ST elevation in V4R
Superior vena cava obstruction	Facial/upper body oedema, raised JVP	No hepatomegaly; distended neck/face veins; usually lung Ca ^[16]
Cardiac tamponade	Raised JVP, hypotension, muffled heart sounds	Beck's triad; pulsus paradoxus; echo shows pericardial effusion
Severe anaemia / high-output HF	Dyspnoea, tachycardia, oedema	Pallor, ↑↑CO state; causes include thyrotoxicosis, anaemia, Paget's, pregnancy, AV fistula
Nephrotic syndrome / renal failure	Peripheral oedema, dyspnoea	Hypoalbuminaemia (nephrotic); ↑creatinine (renal failure); no raised JVP in nephrotic
Hepatic cirrhosis	Ascites, oedema	Stigmata of chronic liver disease; normal JVP; low albumin

Once you have established that a patient has cor pulmonale (i.e., RV failure from pulmonary hypertension due to lung/pulmonary vascular disease), you must identify which lung disease is responsible. This follows the WHO classification of pulmonary hypertension ^[2]^[7]:

Key Clinical Clues for Identifying the Underlying Cause

Underlying Cause	Key Clinical Clues
COPD	Chronic smoker, productive cough ≥ 3 months in 2 consecutive years, wheeze, barrel chest, hyperinflation on CXR, post-BD FEV1/FVC < 0.7 ^[1]^[5]
ILD / IPF	Progressive dyspnoea, dry cough, Velcro crackles at bases, clubbing, reticular opacities on CXR/HRCT
Pneumoconiosis	Construction worker / mining history, progressive dyspnoea, upper-zone nodules (silicosis), eggshell calcification of hilar LN ^[3]
Bronchiectasis	Chronic productive cough with purulent sputum, coarse crackles, clubbing, past TB or childhood infections
OSA / OHS	Obese, daytime somnolence, loud snoring, witnessed apnoeas, short thick neck
Kyphoscoliosis	Visible spinal deformity, restrictive spirometry
CTEPH	History of PE/DVT, progressive dyspnoea after PE episode, ventilation-perfusion mismatch on V/Q scan
PAH (idiopathic)	Young woman, progressive dyspnoea without lung disease, may have CTD features (Raynaud, skin changes in SSc) ^[6]^[7]
CTD-associated (SSc, MCTD)	Raynaud phenomenon, skin thickening, anti-Scl-70 or anti-centromere Ab (SSc), anti-U1 RNP (MCTD); in MCTD, pHTN is a major cause of mortality ^[6]

In the Hong Kong context, always consider: (1) COPD (smoking), (2) Silicosis (construction workers), (3) Post-TB bronchiectasis, (4) OSA/OHS (rising obesity prevalence) ^[1]^[3]^[4].

The clinical approach involves three key questions:

Is there lung disease? → History (smoking, occupation, recurrent infections), examination (barrel chest, clubbing, crackles, wheeze), CXR, spirometry, HRCT
Is there pulmonary hypertension? → Loud P2, RV heave, ECG (P pulmonale, RVH), echo (↑RVSP, RV dilatation), ± right heart catheterisation
Is LV function normal? → BNP/NT-proBNP ^[10]^[11], echocardiography (LVEF, diastolic function) — if LV is abnormal, it is NOT cor pulmonale (or it is biventricular failure)

Clinical Pearl — The BNP Decision Point

BNP helps distinguish cardiac from respiratory causes of dyspnoea ^[11]. In cor pulmonale, BNP may be mildly elevated from RV strain, but will not reach the very high levels seen in decompensated LV failure (BNP > 400). A BNP < 100 pg/mL essentially rules out significant heart failure as the cause of dyspnoea. Remember: noncardiac causes of raised BNP include pulmonary hypertension (cor pulmonale itself), renal disease, and anaemia — so interpret in clinical context ^[11].

Feature	Cor Pulmonale	LHF	Constrictive Pericarditis	Cardiac Tamponade	Acute PE
Dyspnoea	✓	✓	✓	✓	✓ (sudden)
Raised JVP	✓	±	✓✓	✓✓	✓
Peripheral oedema	✓	✓	✓	±	±
Hepatomegaly	✓	±	✓✓	±	±
Lung crackles	From lung disease	Pulmonary oedema	Clear	Clear	±
Orthopnoea/PND	±	✓✓	±	±	±
CXR	Lung disease + PA dilatation	Pulmonary oedema + cardiomegaly	Calcified pericardium	Globular heart	Oligaemic lung
ECG	P pulmonale, RVH	LVH, LBBB	Low voltage, ?	Low voltage, electrical alternans	S1Q3T3, sinus tachycardia
Key Ix	Echo + spirometry	Echo + BNP	CT/MRI	Echo (effusion)	CTPA + D-dimer

High Yield Summary — Differential Diagnosis of Cor Pulmonale

The most important differential to exclude is LEFT heart failure — cor pulmonale by definition excludes LV disease. Use BNP/NT-proBNP and echocardiography to distinguish.
Constrictive pericarditis and restrictive cardiomyopathy can mimic cor pulmonale (systemic venous congestion with clear lungs) — look for pericardial calcification, restrictive filling pattern, biatrial enlargement.
Massive PE is the classic cause of ACUTE cor pulmonale — sudden onset, DVT risk factors, S1Q3T3 on ECG, positive CTPA.
PAH (Group 1) causes RV failure without lung parenchymal disease — suspect in young women with progressive dyspnoea and no lung findings.
In HK, the top underlying causes to consider are: COPD (smoking), pneumoconiosis (construction workers), post-TB bronchiectasis, and OSA/OHS.
The diagnostic approach is: (1) Confirm lung disease, (2) Demonstrate pulmonary hypertension, (3) Exclude LV dysfunction.

Active Recall - Differential Diagnosis of Cor Pulmonale

References

^[1] Senior notes: Maksim Medicine Notes.pdf (COPD section, p.298–300) ^[2] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39; PH classification, p.137–138; COPD section, p.107–108) ^[3] Lecture slides: GC 083. Shortness of breath in a construction site worker.pdf ^[4] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf ^[5] Lecture slides: Three Cases SOB 20211.pdf ^[6] Senior notes: Ryan Ho Rheumatology.pdf (MCTD section, p.86–87; SSc section, p.83) ^[7] Senior notes: Block A - Three Cases of Dyspnea .pdf (PAH classification and evaluation, p.1–4) ^[8] Senior notes: Ryan Ho Haemtology.pdf (VTE section, p.131) ^[9] Senior notes: Ryan Ho Critical Care.pdf (Shock evaluation, p.17) ^[10] Senior notes: Maksim Medicine Notes.pdf (Heart failure section, p.16–18) ^[11] Senior notes: Block A - Shortness of breath on exertion_ heart failure.pdf (BNP utility, p.11) ^[12] Senior notes: Block A - Inherited Cardiac conditions.pdf (RCM section, p.17) ^[13] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (p.21–22) ^[14] Senior notes: Block A - Introduction to Haematological investigations (CBP, Clotting).pdf (D-dimer, p.23) ^[15] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (Chest pain DDx, p.399) ^[16] Lecture slides: General clerkship Teaching Clinic - Haemoptysis_Prof MSM Ip_25 October 2024.pdf (Physical signs, p.48)

Diagnostic Criteria, Algorithm, and Investigations for Cor Pulmonale

Diagnostic Criteria

Unlike conditions such as heart failure (which has the Framingham criteria ^[11]) or rheumatic fever (Jones criteria), cor pulmonale does not have a single universally accepted set of formal diagnostic criteria. Instead, the diagnosis is established by demonstrating three components simultaneously:

The diagnosis of cor pulmonale requires demonstration of: (1) an underlying lung/pulmonary vascular disease, (2) pulmonary hypertension, and (3) right ventricular structural/functional abnormality (hypertrophy, dilatation, or failure) — with exclusion of left heart disease as the primary driver ^[2].

Must be established by history, examination, spirometry, imaging (CXR/HRCT), and/or pulmonary function tests.
The lung disease must be of sufficient severity to cause pulmonary hypertension.
In COPD: diagnosis requires risk factors (e.g., chronic smoker) + symptoms (dyspnoea, cough, sputum) + spirometry showing post-bronchodilator FEV1/FVC < 0.7 ^[1]^[5].

Pulmonary hypertension is defined haemodynamically as mean pulmonary arterial pressure (mPAP) > 20 mmHg at right heart catheterisation ^[2]^[7].
In clinical practice, pHTN is often inferred non-invasively from:
- Echocardiographic estimation of RVSP (right ventricular systolic pressure) using the tricuspid regurgitation jet velocity + estimated RAP. RVSP > 35–40 mmHg suggests pulmonary hypertension.
- ECG findings: P pulmonale (tall P waves), RAD, RVH, RV strain ^[1]^[2].
- CXR findings: dilated pulmonary trunks with peripheral pruning, RV dilatation ^[2].
Right heart catheterisation (Swan-Ganz catheter) is the gold standard for confirming pulmonary hypertension and distinguishing pre-capillary from post-capillary PH ^[7]:

Parameter	Pre-capillary PH (cor pulmonale)	Post-capillary PH (LHF)
mPAP	> 20 mmHg	> 20 mmHg
PAWP	≤ 15 mmHg	> 15 mmHg
PVR	≥ 3 Wood units	< 3 WU (isolated post-capillary)

The wedge pressure (PAWP) is crucial: it directly measures post-capillary (left-sided) pressure. In cor pulmonale, PAWP is LOW (≤ 15 mmHg) because the problem is BEFORE the capillary bed, not from left heart back-pressure. A high PAWP points to left heart disease — which EXCLUDES cor pulmonale by definition ^[7].

Demonstrated by echocardiography (RV dilatation, hypertrophy, systolic dysfunction, TR) and/or clinical signs of RV failure (raised JVP, hepatomegaly, oedema).
Echo also critically confirms that LV systolic function is preserved — excluding LV failure as the cause ^[17]^[18].

When Is Right Heart Catheterisation Needed?

In practice, right heart catheterisation is NOT routinely performed in straightforward COPD cor pulmonale where the clinical picture is clear ^[2]. It IS indicated when: (1) diagnosis is uncertain, (2) PAH-specific therapy is being considered (Group 1 PH), (3) pre-operative assessment (e.g., before lung transplant), (4) PAWP needs to be measured to exclude left heart contribution. Echo is usually not done if clinical manifestations are straightforward, especially in COPD as lungs are hyperinflated — making echo windows poor ^[2].

The approach to diagnosing cor pulmonale follows a stepwise algorithm: suspect → confirm lung disease → demonstrate pHTN and RV dysfunction → exclude LHF → identify the aetiology.

Investigation Modalities: Detailed Interpretation

ECG ± echocardiogram should be performed to assess for cor pulmonale ^[5].

The ECG is a first-line, bedside, readily available investigation. It is insensitive (sensitivity ~25–40% for RVH) but highly specific when positive. In cor pulmonale, ECG changes reflect RA enlargement, RV hypertrophy, and RV strain.

ECG Finding	What It Means	Why It Occurs
P pulmonale	Tall, peaked P wave > 2.5 mm in lead II	RA dilatation/hypertrophy from chronic ↑RA pressure. The RA takes longer to depolarise and generates more voltage → taller P wave ^[1]^[2]^[19]
Right axis deviation (RAD)	QRS axis > +90° (negative QRS in lead I, positive in aVF)	The hypertrophied RV dominates the electrical vector, pulling the mean QRS axis rightward ^[1]^[2]
RV hypertrophy (RVH)	Dominant R wave in V1 (R > S), deep S in V5/V6, R/S ratio > 1 in V1	Normally the LV dominates V1 (large S wave). When RV hypertrophies, it generates more rightward/anterior voltage → R wave becomes dominant in V1 ^[1]
RV strain pattern	ST depression + T-wave inversion in V1–V3 and inferior leads (II, III, aVF)	Subendocardial ischaemia of the hypertrophied RV from ↑wall stress and ↑O₂ demand ^[2]
RBBB	RSR' pattern in V1, wide QRS ≥ 120 ms	RV dilatation/hypertrophy causes delayed RV conduction ^[1]
Low voltage QRS	QRS amplitude < 5 mm in limb leads	Hyperinflated lungs (COPD) → ↑distance from heart to electrodes + ↑air insulation → attenuated signal ^[1]
Poor R-wave progression	R wave fails to grow normally from V1→V6	RV dominance and/or hyperinflation rotating the heart ^[7]
S1Q3T3 (acute cor pulmonale)	Deep S in I, Q wave in III, inverted T in III	Acute RV dilatation → rightward shift of axis + acute RV strain. Classic for massive PE but not specific ^[8]^[9]
Multifocal atrial tachycardia	≥ 3 different P-wave morphologies, irregular rhythm	Hypoxia/hypercapnia + atrial stretch → multiple ectopic foci in atria. Associated with severe lung disease

High Yield ECG Interpretation

In a COPD patient, look for: P pulmonale (tall P waves), RVH +/- RV strain, RBBB ^[1]. The combination of P pulmonale + RAD + RVH + low voltage QRS in a chronic smoker is essentially diagnostic of COPD with cor pulmonale on ECG.

CXR is essential for two purposes: (1) identifying the underlying lung disease and (2) detecting signs of pulmonary hypertension and RV enlargement.

CXR Finding	Interpretation	Pathophysiological Basis
Enlarged right descending pulmonary artery ( > 16 mm diameter)	Pulmonary artery dilatation from pHTN	↑PA pressure → progressive dilatation of central pulmonary arteries
Prominent hilar vessels with peripheral pruning	Central arteries dilated, distal arteries narrowed	Proximal vessels dilate under pressure; distal vessels are obliterated by disease or vasoconstriction → "pruning" ^[2]^[10]
RV enlargement	Filling of retrosternal space on lateral CXR; apex uptilted on PA view	RV hypertrophy and dilatation pushes the heart anteriorly and superiorly
Cardiomegaly	CTR > 0.5 (adults)	RV ± RA dilatation increases overall cardiac silhouette ^[17]
Signs of underlying COPD	Hyperinflation, flattened diaphragm, long narrow heart shadow, hyperlucency of lung fields ^[1]	Air trapping → ↑lung volume → diaphragm pushed down, ribs splayed
Signs of underlying ILD	Reticulonodular opacities, honeycombing, traction bronchiectasis	Fibrotic lung changes, typically basal and peripheral ^[15]
Cor pulmonale features on CXR (in COPD):	Prominent lung vessels and cardiomegaly	Combined effect of PA dilatation and RV enlargement ^[10]

CXR in COPD should be evaluated for complications including pneumonia, pneumothorax, and cor pulmonale with prominent lung vessels and cardiomegaly ^[10].

ABG is essential to assess for respiratory failure — the driving force behind cor pulmonale ^[1]^[5].

ABG Finding	Interpretation	Clinical Significance
↓PaO₂ (hypoxaemia)	Respiratory failure — the trigger for hypoxic pulmonary vasoconstriction	Type 1 respiratory failure (T1RF): ↓PaO₂ with normal/↓PaCO₂ — seen in ILD, early COPD, PE
↑PaCO₂ (hypercapnia)	Alveolar hypoventilation — worsens pulmonary vasoconstriction	Type 2 respiratory failure (T2RF): ↓PaO₂ with ↑PaCO₂ — seen in advanced COPD, OHS, neuromuscular disease ^[1]
↑A-a gradient	V/Q mismatch or shunt	Elevated in most lung diseases causing cor pulmonale
Respiratory acidosis ± metabolic compensation	Chronic CO₂ retention with renal HCO₃⁻ retention	↑HCO₃⁻ indicates chronicity; acidosis potentiates pulmonary vasoconstriction
Metabolic acidosis	Tissue hypoperfusion (lactic acidosis)	Seen in massive PE with obstructive shock or severe decompensated cor pulmonale ^[8]

Mechanisms of respiratory failure in COPD: (1) V/Q mismatch (most common), (2) Alveolar hypoventilation, (3) Shunting (if complicated by pneumonia/CHF) ^[1].

Test	Expected Finding	Why
CBC: secondary polycythaemia	↑Hb, ↑Hct	Chronic hypoxia → ↑EPO → ↑RBC production ^[1]. EPO is produced by peritubular fibroblasts in the kidney in response to hypoxia. The ↑viscosity worsens PVR
WBC	May be ↑ if acute exacerbation/infection precipitating decompensation	Infection is the commonest precipitant of acute-on-chronic cor pulmonale
BNP / NT-proBNP	Mildly to moderately elevated	Released from ventricular myocytes under stretch/pressure. In cor pulmonale, RV strain causes BNP release — but typically lower than in LV failure. BNP < 100 pg/mL essentially rules out significant HF; BNP > 400 pg/mL suggests CHF ^[10]^[11]. Intermediate values require clinical correlation
Troponin	May be mildly elevated in massive PE or severe RV strain	RV subendocardial ischaemia → myocyte damage → troponin leak. Prognostic marker in PE ^[8]
LFT	AST > ALT pattern in congestive hepatopathy	Hepatic congestion from RHF → zone 3 hepatocyte ischaemia (centrilobular necrosis). Congestive heart failure characteristically shows AST > ALT ^[20]
RFT (U&E, Cr)	May show ↑creatinine (cardiorenal syndrome)	↓CO → ↓renal perfusion → pre-renal AKI
D-dimer	Elevated if PE/CTEPH is the cause	Fibrin degradation product; sensitive but not specific — can be elevated in inflammation, infection, malignancy, post-surgery ^[14]. Very helpful in outpatient setting; if normal, can basically exclude VTE ^[13]
Thyroid function	R/o thyrotoxicosis (high-output state) or hypothyroidism	Part of aetiological workup
Autoimmune screen	ANA, anti-Scl-70, anti-centromere, anti-U1 RNP	If CTD-associated PAH suspected (SSc, MCTD) ^[6]

Echocardiography is the single most important non-invasive investigation for cor pulmonale — it simultaneously assesses RV structure/function, estimates pulmonary artery pressure, evaluates for TR, and confirms normal LV function ^[2]^[17]^[18].

Echo Finding	Interpretation	Significance
RV dilatation	RV basal diameter > 42 mm; RV:LV ratio > 1.0	Indicates chronic pressure overload has exceeded compensatory hypertrophy
RV hypertrophy	RV free wall thickness > 5 mm (subcostal view)	Compensatory response to chronic ↑afterload
↑RVSP (estimated via TR jet velocity)	RVSP = 4v² + estimated RAP; RVSP > 35–40 mmHg suggests pHTN	Uses the modified Bernoulli equation: the peak velocity of the TR jet reflects the pressure gradient across the tricuspid valve in systole. Add estimated RAP (from IVC diameter/collapsibility) to get RVSP, which approximates pulmonary artery systolic pressure
Tricuspid regurgitation	Functional TR from RV/annular dilatation	Worsens volume overload; severity correlates with prognosis
RV systolic dysfunction	TAPSE < 17 mm; fractional area change < 35%	TAPSE = Tricuspid Annular Plane Systolic Excursion — measures longitudinal RV function. < 17 mm indicates significant RV systolic impairment
Interventricular septal bowing ("D-sign")	Septum pushed leftward in diastole (pressure overload) or throughout cycle (volume overload)	RV pressure/volume overload → interdependence → LV underfilling
IVC dilatation with ↓collapsibility	IVC > 21 mm with < 50% inspiratory collapse → estimated RAP ≥ 15 mmHg	Reflects elevated RA pressure; normally IVC collapses > 50% on sniff
Normal LV systolic function	LVEF ≥ 50%	Critical to confirm — if LV function is reduced, this is biventricular failure, NOT pure cor pulmonale
PA dilatation	PA diameter > 25 mm	Direct sign of pulmonary hypertension

Echo Limitations in COPD

In COPD patients, echocardiographic windows are often poor due to hyperinflated lungs — the air-filled lungs obstruct ultrasound transmission ^[2]. In such cases, subcostal views may be more useful. If echo is suboptimal, consider cardiac MRI as an alternative for accurate RV assessment.

PFTs are essential to identify and characterise the underlying lung disease — the root cause of cor pulmonale.

Test	Expected Finding in Cor Pulmonale	Interpretation
Spirometry: FEV1/FVC < 0.7 (post-bronchodilator)	Obstructive pattern — COPD	Mandatory for COPD diagnosis; PEFR cannot be used as replacement ^[1]
FVC	↓ in restrictive lung diseases (ILD, kyphoscoliosis, NMD)	Restrictive pattern if FEV1/FVC ≥ 0.7 but FVC < 80% predicted
RV (residual volume) and TLC	↑ in COPD (hyperinflation of lung) ^[5]	Air trapping causes ↑RV; ↑TLC reflects hyperinflation
DLCO (diffusion capacity for CO)	↓ in emphysema (destroyed alveoli) and ILD ^[5]	DLCO measures gas transfer at the alveolar-capillary membrane. ↓ because: (1) emphysema destroys alveolar surface area; (2) ILD thickens the alveolar-capillary membrane; (3) pulmonary vascular disease reduces capillary blood volume

COPD investigations include spirometry (FEV1/FVC < 70%), and lung function tests showing ↑RV and TLC (hyperinflation) and ↓DLCO (emphysema with destroyed alveoli) ^[5].

Modality	Indication	Key Findings
HRCT thorax	Characterise underlying lung disease (ILD, emphysema, bronchiectasis)	Honeycombing + traction bronchiectasis (IPF); emphysematous bullae (COPD); ground-glass opacities (inflammatory ILD); eggshell calcification (silicosis)
CTPA (CT Pulmonary Angiogram)	Gold standard for diagnosing PE ^[13]	Filling defect in pulmonary arteries = thrombus. Also shows right heart strain (RV:LV ratio > 1) ^[19]. CT with contrast requires eGFR cutoff > 30 mL/min — if eGFR too low, use V/Q scan instead ^[19]
CT aortogram	If aortic dissection is a differential	Intimal flap, false lumen

Feature	Detail
Indication	Alternative to CTPA when CT is contraindicated (renal impairment with eGFR < 30, contrast allergy, pregnancy) ^[19]
Principle	Compares ventilation (inhaled radiotracer) with perfusion (IV radiotracer). Mismatched defects (normal ventilation with absent perfusion) indicate PE
Role in cor pulmonale	Essential for diagnosing CTEPH (chronic thromboembolic pulmonary hypertension) — V/Q scan is MORE sensitive than CTPA for CTEPH because organised, web-like thrombi may not be seen as discrete filling defects on CTPA

The definitive investigation for confirming and classifying pulmonary hypertension ^[7]^[2].

Parameter Measured	Normal	Cor Pulmonale (Pre-capillary PH)	LHF (Post-capillary PH)
mPAP	< 20 mmHg	> 20 mmHg	> 20 mmHg
PAWP	≤ 15 mmHg	≤ 15 mmHg	> 15 mmHg
PVR	< 3 WU	≥ 3 Wood units	< 3 WU
Cardiac output	4–8 L/min	↓ (in decompensated)	↓

Measure pulmonary arterial pressure through right heart catheterisation (Swan-Ganz). Wedge pressure (PAWP) measures post-capillary pressure — i.e., directly from the left side of the heart. In cor pulmonale (Group 3 PH), wedge pressure is low, indicating the problem isn't coming from the left heart. But the mPAP will be high ^[7].

Investigation	Indication	What It Tells You
Sleep study (polysomnography)	Suspected OSA / OHS	Apnoea-hypopnoea index (AHI ≥ 5 = OSA); nocturnal desaturation
Sputum C/ST	Acute exacerbation of COPD, bronchiectasis	Identifies infective organism (common precipitant of decompensation) ^[1]
α1-antitrypsin level	Young Caucasian with emphysema, no smoking history	AAT deficiency — rare but important genetic cause of emphysema
Autoimmune panel	Young patient, no lung disease, Raynaud, skin changes	SSc (anti-Scl-70, anti-centromere), MCTD (anti-U1 RNP), SLE ^[6]
HIV serology	Risk factors present	HIV-associated PAH
6-minute walk test (6MWT)	Functional capacity assessment	Distance walked correlates with severity and prognosis; desaturation on exercise reveals exercise-induced hypoxia ^[15]
Cardiac MRI	Poor echo windows (hyperinflated COPD), assessment of RV mass/volume/function	Gold standard for RV mass and volume quantification. Superior to echo for RV assessment but less accessible
Liver ultrasound	Hepatomegaly on examination	Enlarged liver with engorged hepatic veins in congestive hepatopathy ^[20]

Priority	Investigation	Purpose
Bedside	ECG, SpO₂, clinical examination	Rapid detection of RVH/strain, hypoxia, signs of RHF
First-line	CXR, ABG, CBC, BNP/NT-proBNP, LFT/RFT	Identify lung disease, assess gas exchange, polycythaemia, rule out LHF, hepatic congestion
Key imaging	Echocardiography	Confirm RV dysfunction + ↑RVSP + normal LV function
Aetiological	Spirometry/PFTs, HRCT thorax, sleep study, autoimmune screen	Identify the underlying cause
When uncertain	Right heart catheterisation	Gold standard for PH classification and haemodynamic confirmation
If PE suspected	CTPA (or V/Q scan if CT contraindicated) + D-dimer	Diagnose acute PE or CTEPH

High Yield Summary — Diagnosis and Investigations

Cor pulmonale is diagnosed by demonstrating: underlying lung disease + pulmonary hypertension + RV dysfunction — with EXCLUSION of left heart disease
ECG: P pulmonale (RA dilatation), RAD, RVH, RV strain ± RBBB — insensitive but specific ^[1]^[2]
CXR: prominent hilar vessels with peripheral pruning, RV enlargement, signs of underlying lung disease ^[2]^[10]
ABG: hypoxaemia ± hypercapnia — the driver of hypoxic pulmonary vasoconstriction ^[1]
CBC: secondary polycythaemia (↑Hb, ↑Hct) from chronic hypoxia ^[1]
BNP/NT-proBNP: mildly elevated in RV strain; helps distinguish from LHF where it is markedly elevated ^[10]^[11]
Echocardiography is the KEY non-invasive test: RV dilatation/hypertrophy, ↑RVSP, TR, normal LV function — but may be limited in COPD due to hyperinflation ^[2]
Right heart catheterisation is the GOLD STANDARD for confirming PH: mPAP > 20 mmHg, PAWP ≤ 15 mmHg, PVR ≥ 3 WU = pre-capillary PH ^[7]
PAWP (wedge pressure) distinguishes cor pulmonale (low PAWP) from left heart disease (high PAWP) ^[7]
Spirometry is mandatory for COPD diagnosis: post-BD FEV1/FVC < 0.7 ^[1]^[5]
CTPA is gold standard for PE diagnosis; V/Q scan is alternative when CT contraindicated ^[13]^[19]

Active Recall - Diagnosis and Investigations of Cor Pulmonale

References

^[1] Senior notes: Maksim Medicine Notes.pdf (COPD section, p.298–300) ^[2] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39; PH classification, p.137–138) ^[5] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (COPD Investigations, p.11) ^[6] Senior notes: Ryan Ho Rheumatology.pdf (MCTD section, p.86–87; SSc section, p.83) ^[7] Senior notes: Block A - Three Cases of Dyspnea .pdf (PAH classification and catheterisation, p.4) ^[8] Senior notes: Ryan Ho Haemtology.pdf (VTE section, p.131) ^[9] Senior notes: Ryan Ho Critical Care.pdf (Shock evaluation, p.17) ^[10] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (COPD CXR/ECG for cor pulmonale, p.222; chest pain DDx, p.399) ^[11] Senior notes: Block A - Shortness of breath on exertion_ heart failure.pdf (BNP utility, p.7–11) ^[13] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (Investigations, p.23) ^[14] Senior notes: Block A - Introduction to Haematological investigations (CBP, Clotting).pdf (D-dimer, p.23) ^[15] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (ILD investigations, p.238) ^[17] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (Echocardiography, p.366) ^[18] Senior notes: MBBS Final MB (Pediatrics) (Felix PY Lai).pdf (Echocardiography, p.217) ^[19] Senior notes: Block A - Chest Pain - Department of Radiology.pdf (CTPA, V/Q scan, p.1) ^[20] Senior notes: Block A - Introduction to GI_Hepatology investigations (LFT, Endoscopy).pdf (AST > ALT pattern in CHF, p.5)

Management of Cor Pulmonale

The management of cor pulmonale rests on a simple but crucial logic: you cannot fix the right heart without fixing the lungs first. The RV failure is a consequence of pulmonary hypertension, which is itself a consequence of lung disease. Therefore:

The cornerstone of cor pulmonale management is treatment of the underlying respiratory disease + correction of hypoxia. Direct treatment of the right heart failure is secondary and supportive. ^[2]

Cor pulmonale is treated similar to other causes of HF ^[2], but with important caveats specific to the pulmonary origin. The management can be organised into:

Treat the underlying lung disease (the root cause)
Correct hypoxia (the main reversible driver of pulmonary vasoconstriction)
Manage right heart failure (symptom relief)
Prevent complications (thromboembolism, arrhythmia)
Advanced therapies (for refractory disease)

Treatment Modalities in Detail

1. Treat the Underlying Lung Disease

This is the most important and highest-yield management step. You are treating the ROOT CAUSE.

Since COPD is the most common cause of cor pulmonale ^[1]^[5], its management dominates the approach:

Intervention	Mechanism / Rationale	Details
Smoking cessation	The single most important intervention to slow COPD progression — removes the ongoing stimulus for airway inflammation, mucus hypersecretion, and parenchymal destruction ^[5]	Behavioural counselling + pharmacotherapy (NRT, varenicline, bupropion). Must have stopped smoking before starting LTOT (fire risk + no benefit if continues smoking) ^[1]^[21]
Bronchodilators	Relieve bronchoconstriction → improve airflow → reduce air trapping → improve V/Q matching → reduce hypoxia	LABA + LAMA combination (e.g., tiotropium + olodaterol) is standard in moderate-severe COPD. Short-acting rescue (SABA/SAMA) for acute relief
Inhaled corticosteroids	Reduce airway inflammation; consider ICS in those with higher peripheral eosinophil count ^[21]	Added to LABA+LAMA if frequent exacerbations + eosinophils ≥ 300 cells/μL
Pulmonary rehabilitation	Improves exercise capacity, breathlessness, quality of life; prevents deconditioning	Includes breathing training (pursed-lip, diaphragmatic), limb aerobic/resistive training, energy conservation, education, psychological support ^[1]
Manage acute exacerbations	Exacerbations worsen hypoxia → worsen pulmonary vasoconstriction → precipitate decompensated cor pulmonale	Antibiotics (if purulent sputum), systemic corticosteroids, optimise bronchodilators, O₂, ± NIV ^[1]
Surgical options in advanced COPD	Lung volume reduction surgery (reduce hyperinflation + improve lung recoil), bullectomy, lung transplant ^[1]^[21]	LVRS indicated in upper-lobe-predominant emphysema with low exercise capacity; endobronchial valves (EBV) as minimally invasive alternative

Intervention	Details
Antifibrotics for IPF	Nintedanib (TKI targeting VEGF-R, FGF-R, PDGF-R) or Pirfenidone (TGF-β inhibitor) — slow FVC decline but do NOT relieve symptoms ^[1]. Extending indications to SSc-related ILD
Immunosuppressants	Indicated for most ILD types EXCEPT IPF and pneumoconiosis (increased mortality with immunosuppression in IPF) ^[1]. Steroids ± azathioprine/cyclophosphamide/MMF
Supportive	O₂, pulmonary rehab, vaccination

Intervention	Details
Lifelong anticoagulation	Prevents further thrombus formation/extension
Pulmonary endarterectomy (PEA)	The treatment of choice for operable CTEPH — surgical removal of organised thrombus from pulmonary arteries. Can be curative
Balloon pulmonary angioplasty	For inoperable CTEPH
Riociguat	sGC stimulator; approved for inoperable/residual CTEPH

Intervention	Details
CPAP / BiPAP	Splints the airway open (CPAP for OSA) or provides ventilatory support (BiPAP for OHS) → corrects nocturnal hypoxia → reverses hypoxic pulmonary vasoconstriction
Weight loss	Reduces chest wall restriction + reduces upper airway obstruction

Complications of bronchiectasis include pulmonary hypertension → cor pulmonale ^[1]. Management:

Intervention	Details
Airway clearance	Chest physiotherapy, postural drainage, nebulised hypertonic saline, mucolytics
Antibiotics	Empirical IV Tazocin for acute exacerbation; macrolide prophylaxis (e.g., azithromycin) if ≥ 3 exacerbations/year ^[1]
Bronchodilators	If coexisting airflow obstruction

LTOT is one of the only interventions proven to improve survival in COPD patients with cor pulmonale ^[1]^[21]. The rationale is straightforward: hypoxia drives hypoxic pulmonary vasoconstriction (HPV) → pHTN → cor pulmonale. By correcting hypoxia, you reverse HPV (at least the reversible component) → ↓PVR → ↓RV afterload → improved RV function and survival.

LTOT — SAQ-Level Detail (High Yield)

Continuous LTOT improves 3-year survival by 50% and prevents progression of complications ^[1].

Prerequisites before starting:

Patient must be clinically stable for 3–4 weeks
ABG confirmed on TWO occasions at least 3–4 weeks apart
After optimisation of all other medical therapy
Must have stopped smoking (fire/explosion risk with supplemental O₂) ^[1]^[21]

Indications (must know):

Criterion	PaO₂ / SaO₂	Additional Requirement
Severe resting hypoxaemia	PaO₂ ≤ 55 mmHg (7.3 kPa) or SaO₂ ≤ 88%	None needed
Moderate resting hypoxaemia with complications (the "3Ps")	PaO₂ 56–59 mmHg (7.4–7.9 kPa) or SaO₂ ≤ 89%	Plus any of: (1) Peripheral oedema suggestive of cor pulmonale, (2) P pulmonale on ECG (P wave > 3 mm in leads II, III, aVF), (3) Polycythaemia (Hct > 56%) ^[1]^[21]

Duration: ≥ 15 hours/day (the more hours, the greater the benefit; 24h/day ideal) ^[1]^[21]

Target: SaO₂ ≥ 90% (PaO₂ ≥ 60 mmHg / 8 kPa) ^[1]^[21]

There is NO survival benefit in moderate resting desaturation (SaO₂ 89–93%) or moderate exercise-induced desaturation ^[21].

Oxygen Therapy in Acute Exacerbation of COPD

In acute settings, oxygen must be used carefully in COPD patients:

Parameter	Detail
Starting dose	1–2 L/min by nasal cannula (or Venturi mask) ^[1]
Target SpO₂	88–92% in COPD (NOT 94–98% as in other patients!) ^[1]
Why not too much O₂?	COPD patients with chronic T2RF have blunted central chemoreceptor response to CO₂; they rely on hypoxic drive (peripheral chemoreceptors). Excessive O₂ → abolishes hypoxic drive → ↓minute ventilation → ↑CO₂ → worsening respiratory acidosis → CO₂ narcosis. Also: Haldane effect (O₂ displaces CO₂ from Hb) + reversal of HPV (worsening V/Q mismatch)
Monitor	ABG 30–60 minutes after initiation of O₂ therapy and modify flow rate according to PaO₂ and pH ^[1]

In acute exacerbation with respiratory acidosis despite controlled O₂, escalate to non-invasive positive pressure ventilation (NIPPV/NIV) or invasive mechanical ventilation ^[1].

3. Manage Right Heart Failure

Cor pulmonale is treated similar to other causes of HF ^[2], but with important differences from LHF management:

Aspect	Detail
Drug	Loop diuretics (furosemide) — first-line for fluid overload ^[2]
Mechanism	Block Na⁺/K⁺/2Cl⁻ cotransporter in thick ascending limb of loop of Henle → ↑Na⁺ and water excretion → ↓intravascular volume → ↓systemic venous congestion → ↓peripheral oedema, ascites, hepatic congestion
Rationale	Relieve symptoms of systemic venous congestion (oedema, hepatomegaly, ascites, raised JVP)
Caution	Use cautiously — the RV in cor pulmonale is preload-dependent. Excessive diuresis can dangerously ↓RV preload → ↓CO → hypotension and shock. Unlike LHF where preload reduction is beneficial, in RV failure you walk a fine line
Monitoring	Daily weights, fluid balance charts, electrolytes (watch for hypokalaemia, hyponatraemia)
Add-on	Spironolactone/eplerenone (MRA) for additional diuresis and to prevent hypokalaemia; however, the evidence for MRA in isolated RHF is less robust than in LHF

Na⁺ restriction ( < 2g/day) to reduce fluid retention
Fluid restriction (1–1.5 L/day) in severe cases with hyponatraemia or refractory oedema

Critical Concept — HFrEF Pillars Do NOT Directly Apply to Cor Pulmonale

The 4 pillars of HFrEF management (ACEi/ARB/ARNI, beta-blocker, MRA, SGLT2i) are evidence-based for left ventricular systolic dysfunction. In cor pulmonale, the LV is normal — the problem is the RV. There is limited evidence for these drugs in isolated RV failure:

ACEi/ARB: May cause systemic hypotension without improving RV function. Not routinely indicated unless coexisting LHF or systemic hypertension.
Beta-blockers: Generally AVOIDED in cor pulmonale from COPD — can worsen bronchospasm (non-selective), blunt hypoxic ventilatory response, and may not benefit the RV. If needed (e.g., rate control for AF), use cardioselective agents (bisoprolol) with extreme caution.
SGLT2i: Emerging evidence in HFpEF/HFrEF but no established role specifically for cor pulmonale.
Digoxin: No role in sinus rhythm cor pulmonale. Only indicated for rate control in atrial tachyarrhythmia ^[2].

RV dysfunction has less evidence-based medication — a lot of stuff to try, but not proven to be effective ^[22].

Agent	Role in Cor Pulmonale
Calcium channel blockers (CCBs)	NOT routinely used in Group 3 PH (COPD/ILD-related). CCBs can worsen V/Q mismatch by vasodilating pulmonary vessels in poorly ventilated areas → ↑shunt → ↓PaO₂. May cause systemic hypotension. Only useful in rare PAH responders (positive vasoreactivity testing)
Nitrates	May be used to reduce RV preload in symptomatic RV dysfunction ^[22]. Nitroglycerin/isosorbide dinitrate reduces venous return → ↓RV preload → ↓RV wall stress. But watch for hypotension
Hydralazine	Rarely used; no significant evidence in cor pulmonale

Aspect	Detail
Indication	Hct > 56% ^[1]^[21] — at this level, blood viscosity significantly ↑PVR
Treatment	Venesection (phlebotomy) — remove 250–500 mL blood to ↓Hct to < 55%. Replace volume with saline to prevent hypovolaemia
Long-term	LTOT should prevent ongoing secondary polycythaemia by correcting chronic hypoxia

5. Prevent Complications

Anticoagulation is recommended to reduce the risk of thromboembolism ^[2].

Rationale	Detail
Why?	Patients with cor pulmonale are at ↑risk of venous thromboembolism due to: (1) sluggish blood flow in dilated, poorly contracting RV; (2) polycythaemia → ↑viscosity → stasis; (3) immobility from dyspnoea
Indications	Definite: documented PE/DVT, AF. Relative: severe RV dilatation, immobility
Agent	Warfarin (target INR 2–3) or DOAC depending on clinical context

Arrhythmia	Management
Atrial fibrillation / atrial tachyarrhythmia	Digoxin for rate control ^[2]. Digoxin is preferred because it does not have negative inotropic effects on the RV (unlike beta-blockers/CCBs). Alternative: amiodarone if digoxin fails
Multifocal atrial tachycardia (MAT)	Correct hypoxia and electrolytes (Mg²⁺, K⁺) — MAT often resolves when the underlying trigger is treated. Avoid digoxin in MAT (ineffective). Consider IV magnesium
Ventricular arrhythmias	Correct hypoxia + electrolytes. Amiodarone if persistent. Avoid class Ic agents

Influenza and pneumococcal vaccination ^[1] — reduces risk of respiratory infections that precipitate acute exacerbations and decompensated cor pulmonale.

Aspect	Detail
In COPD	Pulmocare formula: low carbohydrate but high calorie — rationale: carbohydrate metabolism produces more CO₂ per O₂ consumed (RQ = 1.0) compared to fat (RQ = 0.7). In patients with CO₂ retention, reducing carbohydrate intake → ↓CO₂ production → less respiratory burden ^[23]
General	Maintain muscle mass to prevent cachexia and respiratory muscle wasting. High-protein diet

7. Advanced Therapies

PAH-Specific Drugs — NOT for Group 3 PH

There are 5 classes of drugs specifically to treat Group 1 PAH ^[7]:

Endothelin receptor antagonists (ERAs): Bosentan, ambrisentan, macitentan — block endothelin-1 (potent vasoconstrictor)
PDE-5 inhibitors: Sildenafil, tadalafil — prevent breakdown of cGMP → ↑NO-mediated vasodilation
Prostacyclin analogues: Epoprostenol (IV), iloprost (inhaled), treprostinil — vasodilate + antiproliferative
IP receptor agonists: Selexipag — oral prostacyclin pathway agonist
Soluble guanylate cyclase stimulators (sGC): Riociguat — augments NO pathway

These drugs are SPECIFICALLY for Group 1 PAH. They should NOT be routinely used for Group 3 PH (COPD/ILD-related cor pulmonale) because: (1) they may worsen V/Q mismatch by non-selective pulmonary vasodilation; (2) trials in Group 3 PH have shown no benefit or potential harm. Exercise is also NOT recommended in PAH due to potential arrest ^[7].

Exception: Riociguat is approved for inoperable/residual CTEPH (Group 4).

Aspect	Detail
Indication	End-stage lung disease refractory to optimal medical therapy — the definitive treatment ^[1]
Timing	Early referral recommended; based on decline in FVC, DLCO, exercise tolerance (6MWT), increasing O₂ requirements
Types	Single-lung or bilateral lung transplant (bilateral preferred for bronchiectasis/CF due to infection risk in remaining native lung)
Contraindications	Active malignancy, active infection (extrapulmonary), significant other organ dysfunction, non-compliance, active substance abuse
RV recovery	After successful lung transplant, the RV often recovers significantly as PVR normalises — the RV dysfunction was secondary to afterload

Common indications for cardiac transplantation include idiopathic DCMP (commonest in HK) and IHD. Contraindications include fixed pHTN unresponsive to drugs ^[24]. In cor pulmonale, the approach is lung transplant (not heart transplant) unless the RV is irreversibly damaged, in which case heart-lung transplant may be considered.

Procedure	Indication
Pulmonary endarterectomy (PEA)	Operable CTEPH — curative potential
Lung volume reduction surgery (LVRS)	Selected emphysema patients with upper-lobe predominant disease
Bullectomy	Large bullae compressing functional lung tissue
Atrial septostomy	Last resort in severe PAH — creates R-to-L shunt to decompress the RV (at the cost of cyanosis)

Aspect	Detail
Acute	NIPPV (BiPAP) for acute exacerbation of COPD with respiratory acidosis despite controlled O₂ ^[1]. Reduces work of breathing, improves ventilation, reduces CO₂
Chronic	Long-term domiciliary NIV for OHS, severe stable COPD with chronic hypercapnia, neuromuscular disease

Aspect	Detail
Indication	End-stage lung disease not amenable to transplant
Components	Symptom management (opioids for refractory dyspnoea, anxiolytics), advance care planning, psychosocial support
Consider referral to palliative care service ^[21]	Especially in advanced COPD with frequent hospitalisations

Priority	Intervention	Mechanism
1st	Treat underlying lung disease	Remove the root cause of pHTN
2nd	Correct hypoxia (LTOT ≥ 15h/day)	Reverse hypoxic pulmonary vasoconstriction → ↓PVR → ↓RV afterload
3rd	Diuretics for RHF	Relieve systemic venous congestion (but cautious — RV is preload-dependent)
4th	Anticoagulation	Prevent thromboembolism in high-risk patients
5th	Digoxin (only if atrial tachyarrhythmia)	Rate control; no role in sinus rhythm
6th	Venesection (if Hct > 56%)	Reduce blood viscosity → ↓PVR
7th	Vaccination (influenza + pneumococcal)	Prevent infection-triggered exacerbations
8th	Lung transplant (refractory disease)	Definitive treatment

Drug	Caution / Contraindication	Why
Non-selective beta-blockers	AVOID in COPD cor pulmonale	Worsen bronchospasm (block β₂ receptors in bronchial smooth muscle); blunt hypoxic ventilatory response
Excessive O₂	Target SpO₂ 88–92% in COPD	Abolishes hypoxic drive → CO₂ narcosis; Haldane effect; reversal of HPV → V/Q worsening
CCBs (for PH)	NOT routinely used in Group 3 PH	Worsen V/Q mismatch by vasodilating poorly ventilated areas; systemic hypotension
PAH-specific drugs	NOT for Group 3 PH	No benefit; may harm by worsening V/Q matching
Aggressive diuresis	Use cautiously	RV is preload-dependent; excessive diuresis → ↓RV filling → ↓CO → shock
ACEi/ARB	Not routinely indicated unless coexisting LHF/HTN	May cause hypotension without RV benefit
Sedatives / opioids	AVOID (except palliative care)	Depress respiratory drive → worsen hypoxia and hypercapnia
High-flow O₂ in RV failure from PE	Prefer high-flow nasal cannula over positive pressure ventilation	Positive pressure ventilation increases intrathoracic pressure → ↓venous return → further ↓RV preload → worsens RV failure ^[9]

Why Positive Pressure Ventilation Is Dangerous in Acute RV Failure

In acute cor pulmonale (e.g., massive PE with RV failure), give high-flow nasal cannula oxygen rather than positive pressure ventilation — since positive pressure would just increase the workload of the heart ^[9]. Positive pressure → ↑intrathoracic pressure → ↓venous return (↓RV preload) → further ↓CO in an already failing RV. The RV cannot tolerate both increased afterload AND decreased preload simultaneously.

High Yield Summary — Management of Cor Pulmonale

Treat the underlying lung disease first — this is the root cause (COPD: smoking cessation + bronchodilators + pulmonary rehab; ILD: antifibrotics/immunosuppressants; CTEPH: anticoagulation + PEA; OSA: CPAP)
LTOT is proven to improve survival in COPD cor pulmonale — indicated if PaO₂ ≤ 55 mmHg, OR PaO₂ 56–59 mmHg with the "3Ps" (Peripheral oedema, P pulmonale, Polycythaemia Hct > 56%). Duration ≥ 15h/day. Target SpO₂ ≥ 90%
Diuretics (furosemide) for RHF — but use cautiously as RV is preload-dependent
Anticoagulation for thromboembolic risk reduction
Digoxin ONLY for atrial tachyarrhythmia — no role in sinus rhythm
Venesection if Hct > 56% to reduce viscosity
PAH-specific drugs (5 classes) are for Group 1 PAH ONLY — NOT for Group 3 PH from COPD/ILD
Avoid: non-selective beta-blockers, excessive O₂, aggressive diuresis, sedatives, positive pressure ventilation in acute RV failure
Lung transplantation is the definitive treatment for end-stage disease
The "4 pillars" of HFrEF do NOT apply to isolated cor pulmonale — the evidence base is for LV failure, not RV failure

Active Recall - Management of Cor Pulmonale

References

^[1] Senior notes: Maksim Medicine Notes.pdf (COPD section p.298–302; bronchiectasis p.302–304; ILD/IPF p.304–306; PE management p.287–289) ^[2] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale management, p.39; ILD management, p.121–122) ^[5] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (COPD investigations including ECG ± echo for cor pulmonale, p.11) ^[7] Senior notes: Block A - Three Cases of Dyspnea .pdf (PAH drug treatment — 5 classes for Group 1 PAH, p.4) ^[9] Senior notes: Block A - Chest Pain - Department of Medicine.pdf (RV failure oxygen management — HFNC over positive pressure, p.3) ^[21] Lecture slides: Handbook of Internal Medicine 2024.pdf (LTOT indications including cor pulmonale, p.415) ^[22] Senior notes: Block A - Inherited Cardiac conditions.pdf (RV dysfunction limited evidence-based medication, p.17; DCM management, p.9) ^[23] Senior notes: Ryan Ho Fluids and Nutrition.pdf (Pulmocare formula for COPD, p.9) ^[24] Senior notes: Ryan Ho Cardiology.pdf (Cardiac transplantation indications/contraindications, p.79)

Complications of Cor Pulmonale

The complications of cor pulmonale arise from three interconnected processes: (1) the ongoing pulmonary hypertension itself, (2) the right ventricular failure and its systemic consequences, and (3) the chronic hypoxia that drives the entire disease. Many complications create vicious cycles that accelerate disease progression. Let's walk through each systematically.

This is the defining and most inevitable complication — the natural history of cor pulmonale IS progressive RV failure.

Aspect	Detail
Mechanism	Chronic ↑PVR → RV pressure overload → initial compensatory RV hypertrophy → eventually overwhelmed → RV dilatation → ↓RV contractility → further dilatation (Laplace's law: ↑radius → ↑wall stress for same pressure) → vicious cycle of progressive RV failure ^[2]^[25]
Consequences	Systemic venous congestion (raised JVP, hepatomegaly, peripheral oedema, ascites), ↓cardiac output (fatigue, syncope, hypotension), functional tricuspid regurgitation (further volume-overloading the RV)
Clinical significance	Development of peripheral oedema in COPD cor pulmonale is a poor prognostic sign — 5-year survival approximately 30% once overt RHF develops
Why it matters	Each acute exacerbation of the underlying lung disease further increases PVR and pushes the RV closer to decompensation. The RV may partially recover between exacerbations early on, but repeated insults cause cumulative damage

Complications of COPD include cor pulmonale: chronic hypoxaemia → pulmonary hypertension → RVH and failure (RHF) ^[5].

Arrhythmias are extremely common in cor pulmonale and are a major cause of morbidity and sudden death.

Arrhythmia	Mechanism	Clinical Significance
Atrial fibrillation (AF)	RA dilatation from chronic ↑RA pressure → stretching of atrial myocardium → disrupted conduction → re-entrant circuits. Hypoxia further destabilises atrial electrical activity	Most common sustained arrhythmia in cor pulmonale. ↓CO further (loss of atrial kick — which the failing RV depends on for adequate filling). ↑Risk of thromboembolism
Multifocal atrial tachycardia (MAT)	Multiple ectopic foci in atria firing independently, triggered by hypoxia, hypercapnia, catecholamine surge, and electrolyte disturbances (↓Mg²⁺, ↓K⁺)	Characteristically associated with severe lung disease. ≥ 3 different P-wave morphologies on ECG. Often resolves with correction of hypoxia and electrolytes
Atrial flutter	RA dilatation → macro-re-entrant circuit in RA	Less common than AF, but important to recognise
Ventricular arrhythmias (VT/VF)	Hypoxia → myocardial irritability; RV hypertrophy creates substrate for re-entry; electrolyte disturbances (diuretic-induced hypokalaemia/hypomagnesaemia)	Risk of sudden cardiac death. Drugs like digoxin and theophylline (used in COPD) lower the arrhythmia threshold
Sinus tachycardia	Compensatory sympathetic activation to maintain CO	Universal in decompensated cor pulmonale

Arrhythmia Management Pearl

In cor pulmonale, the FIRST step in managing arrhythmias is correcting the underlying trigger: hypoxia (O₂), hypercapnia (ventilation), electrolytes (K⁺, Mg²⁺), and treating the exacerbation. Many arrhythmias resolve simply by correcting these. Digoxin is only indicated for rate control in atrial tachyarrhythmia ^[2] — it has no role in sinus rhythm and can be pro-arrhythmic in hypoxic patients.

Patients with cor pulmonale are in a pro-thrombotic state due to multiple factors, and thromboembolism creates a vicious cycle that worsens pulmonary hypertension.

Type	Mechanism	Consequences
Pulmonary artery thrombosis (in situ)	Sluggish flow in dilated pulmonary arteries + polycythaemia (↑viscosity) + endothelial dysfunction + hypercoagulability from chronic hypoxia → thrombosis forms within the pulmonary vessels ^[25]	Further ↑PVR → worsens pHTN → worsens RV failure. Can lead to CTEPH if chronic
Deep vein thrombosis (DVT) / Pulmonary embolism (PE)	Immobility (severe dyspnoea limits mobility) + polycythaemia + RV stasis → Virchow's triad fully satisfied	Acute PE superimposed on chronic cor pulmonale is often fatal — the already-compromised RV cannot tolerate an acute increase in afterload
Cerebral embolism	Paradoxical embolism via patent foramen ovale (PFO) — present in ~25% of adults. In cor pulmonale, ↑RA pressure can open a PFO → venous thrombi bypass the lungs and enter systemic circulation → stroke ^[25]	Especially dangerous because the RHF and polycythaemia provide both the source of thrombus and the haemodynamic conditions (raised RAP) for paradoxical embolism

Complications of Eisenmenger syndrome/pHTN include pulmonary artery thrombosis, cerebral embolism ^[25]. The same mechanisms apply in cor pulmonale from any cause.

This is why anticoagulation is recommended in cor pulmonale to reduce the risk of thromboembolism ^[2].

Aspect	Detail
Mechanism	Chronic hypoxia → ↑EPO secretion from kidneys → ↑RBC mass → ↑Hb and Hct ^[1]
Why it's a complication	While initially compensatory (↑O₂-carrying capacity), polycythaemia becomes maladaptive when excessive: ↑blood viscosity → ↑PVR → worsens pulmonary hypertension → worsens RV failure. It is a vicious cycle
Threshold for concern	Hct > 56% ^[1]^[21] — at this level, the viscosity increase outweighs the O₂-carrying benefit
Additional risks	↑Viscosity also ↑risk of thrombosis (both arterial and venous), stroke, and myocardial ischaemia
Management	Venesection to target Hct < 55%; LTOT to correct the underlying hypoxic stimulus

COPD complications include: polycythaemia (secondary to hypoxaemia), cor pulmonale (secondary to pulmonary vasoconstriction), pneumothorax (secondary to rupture of emphysematous bullae) ^[1].

Respiratory failure is both a cause and a complication of cor pulmonale — it creates a bidirectional relationship:

Type	Mechanism	Relation to Cor Pulmonale
Type 1 (hypoxic) respiratory failure	V/Q mismatch, diffusion impairment, shunt	Drives hypoxic pulmonary vasoconstriction → pHTN → cor pulmonale. Worsens during exacerbations
Type 2 (hypercapnic) respiratory failure	Alveolar hypoventilation (respiratory muscle fatigue, ↑dead space ventilation)	Hypercapnia and acidosis potentiate pulmonary vasoconstriction. In COPD, T1RF progresses to T2RF when decompensated ^[1]

As cor pulmonale progresses, ↓CO → ↓mixed venous PO₂ → worsens V/Q mismatch → further ↓PaO₂ → worsens pHTN. Additionally, the RV failure itself can cause hepatic congestion → impaired diaphragmatic excursion (hepatomegaly + ascites push up the diaphragm) → restrictive ventilatory defect → worsens respiratory failure.

Mechanisms of respiratory failure in COPD: (1) V/Q mismatch (most common), (2) alveolar hypoventilation, (3) shunting (if complicated by pneumonia/CHF) ^[1].

Aspect	Detail
Mechanism	↑RA pressure → ↑hepatic venous pressure → chronic hepatic congestion → centrilobular necrosis (zone 3 hepatocytes are most vulnerable to hypoxia as they receive the least oxygenated blood) → fibrosis → eventually "cardiac cirrhosis"
Clinical features	Tender hepatomegaly (early), pulsatile liver (if TR present), jaundice (late), ascites, elevated liver enzymes (AST > ALT pattern is characteristic of congestive heart failure) ^[20]
Ultrasound	Enlarged liver with engorged hepatic veins — dilated IVC and hepatic veins reflect elevated RA pressure ^[20]
Significance	Cardiac cirrhosis is largely irreversible once established. It impairs hepatic synthetic function (↓albumin, ↓clotting factors) → worsens oedema and bleeding risk

Aspect	Detail
Mechanism	↓CO → ↓renal perfusion → pre-renal AKI. Additionally, ↑systemic venous pressure → ↑renal venous pressure → ↓transglomerular filtration gradient → ↓GFR (venous congestion-mediated renal impairment). Diuretics can worsen this if used aggressively
Clinical significance	↑Creatinine, ↓urine output. Creates a therapeutic dilemma: the patient needs diuretics for congestion, but diuretics worsen renal function (cardiorenal syndrome)
Management	Optimise fluid balance; avoid nephrotoxins; sometimes "permissive" mild renal impairment is accepted to achieve adequate decongestion

Aspect	Detail
Mechanism	Rupture of hypertrophied bronchial arteries or rupture of pulmonary arteries in the setting of severe pHTN ^[25]. In bronchiectasis, chronically inflamed/hypertrophied bronchial arteries are prone to rupture
Clinical significance	Life-threatening. Can cause airway flooding and asphyxiation
Management	Emergency bronchial artery embolisation (BAE); maintain airway (patient positioned bleeding-side down); bronchoscopy for localisation; rarely surgical lobectomy

Pulmonary complications of severe pHTN include pulmonary artery thrombosis and massive haemoptysis due to rupture of major vessel ^[25].

Aspect	Detail
Mechanism	Turbulent flow across the tricuspid valve (functional TR) or pulmonary valve → endothelial damage → nidus for bacterial colonisation during transient bacteraemia
Frequency	Rare in cor pulmonale specifically, but should be considered in any patient with unexplained fever and valvular dysfunction ^[25]
Clinical significance	Right-sided IE → septic pulmonary emboli → lung abscesses, empyema

These are not complications of cor pulmonale per se, but complications of the underlying lung disease that can precipitate acute decompensation of cor pulmonale:

Complication	Underlying Disease	How It Worsens Cor Pulmonale
Pneumothorax	COPD (rupture of emphysematous bullae) ^[1]	Acute ↓lung volume → ↑V/Q mismatch → acute ↑PVR → acute RV decompensation
Acute exacerbation of COPD	COPD	Infection/inflammation → ↑airway obstruction → ↑hypoxia → ↑pulmonary vasoconstriction → acute ↑PVR
Pneumonia	Any chronic lung disease	Consolidation → ↑shunt → ↑hypoxia; systemic inflammation → ↑PVR
Pulmonary embolism	Immobility, polycythaemia	Acute ↑PVR from mechanical obstruction

Complications of COPD include: acute exacerbation (pneumothorax, ↑airflow obstruction, infection, respiratory failure), chronic respiratory failure, and cor pulmonale (chronic hypoxaemia → pulmonary HT → RVH and failure) ^[5].

Aspect	Detail
Mechanism	(1) Ventricular arrhythmias (VT/VF) from hypoxia + RVH + electrolyte disturbances; (2) Massive PE; (3) Acute RV failure during exacerbation
Risk factors	Severe RV dysfunction, severe hypoxia, electrolyte abnormalities (especially hypo-K/Mg from diuretics), use of arrhythmogenic drugs (theophylline, digoxin in toxic levels)

This is a somewhat counterintuitive complication:

Aspect	Detail
Mechanism	(1) Ventricular interdependence — dilated RV pushes the interventricular septum leftward → impairs LV diastolic filling → ↓LV output. (2) Shared coronary supply — RV ischaemia from ↑wall stress can affect LV perfusion via shared LAD branches. (3) Chronic pro-inflammatory state — COPD-related systemic inflammation may directly impair LV function
Clinical significance	Cor pulmonale patients are also prone to LV failure (reason unknown, may be due to pro-inflammatory state) ^[2]. The combination of LV and RV failure is particularly devastating

Category	Complications
Cardiac	Progressive RHF, arrhythmias (AF, MAT, VT/VF), sudden cardiac death, IE (rare), LV dysfunction ^[25]
Pulmonary	Pulmonary artery thrombosis, massive haemoptysis, worsening respiratory failure ^[25]
Systemic	Polycythaemia, cerebral embolism/abscess, congestive hepatopathy (cardiac cirrhosis), cardiorenal syndrome ^[25]
Related to underlying disease	Pneumothorax, acute exacerbations, pneumonia ^[1]^[5]

Factor	Detail
Overall	Poor once decompensated — 5-year survival ~30% after development of peripheral oedema in COPD cor pulmonale
Determinants	Severity of underlying lung disease (FEV₁), degree of hypoxaemia, PA pressure, RV function
Improving prognosis	LTOT improves 3-year survival by 50% ^[1]^[21]; smoking cessation; treating the underlying disease; early lung transplant referral
Causes of death	Pneumonia, cor pulmonale (RV failure), respiratory failure, lung malignancy (in IPF) ^[1]

High Yield Summary — Complications of Cor Pulmonale

Progressive RHF is the defining complication — once oedema develops in COPD, 5-year survival is ~30%
Arrhythmias are extremely common — AF (most common sustained), MAT (classic for severe lung disease), VT/VF (sudden death risk). First-line management = correct hypoxia and electrolytes
Thromboembolism — in situ pulmonary artery thrombosis + DVT/PE + paradoxical cerebral embolism via PFO. Multiple mechanisms: polycythaemia, stasis, immobility
Secondary polycythaemia (Hct > 56%) — initially compensatory, becomes maladaptive by ↑viscosity → ↑PVR → vicious cycle
Respiratory failure worsens progressively — T1RF → T2RF in COPD; bidirectional relationship with cor pulmonale
Congestive hepatopathy → cardiac cirrhosis (AST > ALT pattern); renal impairment (cardiorenal syndrome)
Massive haemoptysis — from rupture of hypertrophied bronchial arteries or pulmonary arteries
Acute exacerbations of underlying lung disease are the most common precipitants of decompensation
Management of cor pulmonale complications in COPD: diuretics + salt and fluid restriction for cor pulmonale; controlled O₂, bronchodilators, antibiotics, systemic steroids, NIV for acute exacerbation ^[5]

Active Recall - Complications of Cor Pulmonale

References

^[1] Senior notes: Maksim Medicine Notes.pdf (COPD complications p.298–300; LTOT p.300–302; bronchiectasis complications p.302–304; IPF causes of death p.304–306) ^[2] Senior notes: Ryan Ho Respiratory.pdf (Cor pulmonale section, p.39) ^[5] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf (Complications of COPD p.9; COPD management principles — cor pulmonale: diuretics, salt and fluid restriction p.25) ^[20] Senior notes: Block A - Introduction to GI_Hepatology investigations (LFT, Endoscopy).pdf (AST > ALT pattern in CHF, p.5) ^[21] Lecture slides: Handbook of Internal Medicine 2024.pdf (LTOT indications, p.415) ^[25] Senior notes: Ryan Ho Cardiology.pdf (Eisenmenger syndrome complications, p.186; also Adrian Lui Pediatrics Notes p.193)

High Yield Summary

Cor pulmonale = RV hypertrophy/dilatation/failure due to pulmonary hypertension caused by lung or pulmonary vascular disease (NOT left heart disease)
COPD is the most common cause (> 50% of cases) — through hypoxic pulmonary vasoconstriction, vascular bed destruction, polycythaemia, and remodelling
"Blue bloaters" (chronic bronchitis) develop cor pulmonale more readily than "pink puffers" (emphysema) due to greater hypoxia/hypercapnia
Key pathophysiology: Lung disease → global hypoxia → generalised HPV + vascular remodelling → ↑PVR → pHTN → RV pressure overload → RV hypertrophy → eventual RV failure
Symptoms: Exertional dyspnoea (most common), fatigue, exertional chest pain, syncope, peripheral oedema, abdominal distension — on a background of underlying lung disease symptoms
Signs: (a) pHTN signs — loud P2, RV heave, narrow split S2; (b) RHF signs — raised JVP, hepatomegaly, peripheral oedema, ascites, TR murmur, cyanosis
ECG: P pulmonale, RAD, RVH, RV strain pattern, ± RBBB; in acute PE: S1Q3T3, sinus tachycardia
Acute cor pulmonale (e.g., massive PE) is a medical emergency with acute RV dilatation (no time for hypertrophy) → shock → death
Secondary polycythaemia from chronic hypoxia worsens pHTN by increasing blood viscosity
Hypoxic pulmonary vasoconstriction is partially reversible — this is the rationale for long-term oxygen therapy (LTOT) in COPD

High Yield Summary — Differential Diagnosis of Cor Pulmonale

The most important differential to exclude is LEFT heart failure — cor pulmonale by definition excludes LV disease. Use BNP/NT-proBNP and echocardiography to distinguish.
Constrictive pericarditis and restrictive cardiomyopathy can mimic cor pulmonale (systemic venous congestion with clear lungs) — look for pericardial calcification, restrictive filling pattern, biatrial enlargement.
Massive PE is the classic cause of ACUTE cor pulmonale — sudden onset, DVT risk factors, S1Q3T3 on ECG, positive CTPA.
PAH (Group 1) causes RV failure without lung parenchymal disease — suspect in young women with progressive dyspnoea and no lung findings.
In HK, the top underlying causes to consider are: COPD (smoking), pneumoconiosis (construction workers), post-TB bronchiectasis, and OSA/OHS.
The diagnostic approach is: (1) Confirm lung disease, (2) Demonstrate pulmonary hypertension, (3) Exclude LV dysfunction.

High Yield Summary — Diagnosis and Investigations

Cor pulmonale is diagnosed by demonstrating: underlying lung disease + pulmonary hypertension + RV dysfunction — with EXCLUSION of left heart disease
ECG: P pulmonale (RA dilatation), RAD, RVH, RV strain ± RBBB — insensitive but specific ^[1]^[2]
CXR: prominent hilar vessels with peripheral pruning, RV enlargement, signs of underlying lung disease ^[2]^[10]
ABG: hypoxaemia ± hypercapnia — the driver of hypoxic pulmonary vasoconstriction ^[1]
CBC: secondary polycythaemia (↑Hb, ↑Hct) from chronic hypoxia ^[1]
BNP/NT-proBNP: mildly elevated in RV strain; helps distinguish from LHF where it is markedly elevated ^[10]^[11]
Echocardiography is the KEY non-invasive test: RV dilatation/hypertrophy, ↑RVSP, TR, normal LV function — but may be limited in COPD due to hyperinflation ^[2]
Right heart catheterisation is the GOLD STANDARD for confirming PH: mPAP > 20 mmHg, PAWP ≤ 15 mmHg, PVR ≥ 3 WU = pre-capillary PH ^[7]
PAWP (wedge pressure) distinguishes cor pulmonale (low PAWP) from left heart disease (high PAWP) ^[7]
Spirometry is mandatory for COPD diagnosis: post-BD FEV1/FVC < 0.7 ^[1]^[5]
CTPA is gold standard for PE diagnosis; V/Q scan is alternative when CT contraindicated ^[13]^[19]

High Yield Summary — Management of Cor Pulmonale

Treat the underlying lung disease first — this is the root cause (COPD: smoking cessation + bronchodilators + pulmonary rehab; ILD: antifibrotics/immunosuppressants; CTEPH: anticoagulation + PEA; OSA: CPAP)
LTOT is proven to improve survival in COPD cor pulmonale — indicated if PaO₂ ≤ 55 mmHg, OR PaO₂ 56–59 mmHg with the "3Ps" (Peripheral oedema, P pulmonale, Polycythaemia Hct > 56%). Duration ≥ 15h/day. Target SpO₂ ≥ 90%
Diuretics (furosemide) for RHF — but use cautiously as RV is preload-dependent
Anticoagulation for thromboembolic risk reduction
Digoxin ONLY for atrial tachyarrhythmia — no role in sinus rhythm
Venesection if Hct > 56% to reduce viscosity
PAH-specific drugs (5 classes) are for Group 1 PAH ONLY — NOT for Group 3 PH from COPD/ILD
Avoid: non-selective beta-blockers, excessive O₂, aggressive diuresis, sedatives, positive pressure ventilation in acute RV failure
Lung transplantation is the definitive treatment for end-stage disease
The "4 pillars" of HFrEF do NOT apply to isolated cor pulmonale — the evidence base is for LV failure, not RV failure

High Yield Summary — Complications of Cor Pulmonale

Progressive RHF is the defining complication — once oedema develops in COPD, 5-year survival is ~30%
Arrhythmias are extremely common — AF (most common sustained), MAT (classic for severe lung disease), VT/VF (sudden death risk). First-line management = correct hypoxia and electrolytes
Thromboembolism — in situ pulmonary artery thrombosis + DVT/PE + paradoxical cerebral embolism via PFO. Multiple mechanisms: polycythaemia, stasis, immobility
Secondary polycythaemia (Hct > 56%) — initially compensatory, becomes maladaptive by ↑viscosity → ↑PVR → vicious cycle
Respiratory failure worsens progressively — T1RF → T2RF in COPD; bidirectional relationship with cor pulmonale
Congestive hepatopathy → cardiac cirrhosis (AST > ALT pattern); renal impairment (cardiorenal syndrome)
Massive haemoptysis — from rupture of hypertrophied bronchial arteries or pulmonary arteries
Acute exacerbations of underlying lung disease are the most common precipitants of decompensation
Management of cor pulmonale complications in COPD: diuretics + salt and fluid restriction for cor pulmonale; controlled O₂, bronchodilators, antibiotics, systemic steroids, NIV for acute exacerbation ^[5]

Cor Pulmonale

Definition

Epidemiology

Risk Factors

Anatomy and Functional Considerations

Normal Right Ventricle

Normal Pulmonary Vasculature

Pathological Changes in Cor Pulmonale

Aetiology (with Hong Kong Focus)

Pathophysiology

Step 1: Pulmonary Hypertension Develops

a) Hypoxic Pulmonary Vasoconstriction (HPV) — The Most Important Mechanism

b) Pulmonary Vascular Remodelling

c) Destruction of the Pulmonary Vascular Bed

d) Polycythaemia

e) Other Contributory Factors

Step 2: RV Pressure Overload

Step 3: RV Failure (Decompensated Cor Pulmonale)

Acute vs Chronic Cor Pulmonale

Classification

By Temporal Course

By Functional Status

By Underlying WHO PH Group

Clinical Features

A. Symptoms

B. Signs

Signs of the Underlying Lung Disease

Signs of Pulmonary Hypertension

Signs of Right Ventricular Failure (Decompensated Cor Pulmonale)

Summary of Clinical Features by Stage

ECG Findings in Cor Pulmonale

CXR Findings in Cor Pulmonale

Relationship to COPD — The Most Important Association

Summary Table: Pathophysiology Chain

Active Recall - Cor Pulmonale

References

Level 1: Differential Diagnosis of the Clinical Syndrome

A. Left Heart Failure (The Most Important Differential to Exclude)

B. Constrictive Pericarditis

C. Restrictive Cardiomyopathy (RCM)

D. Pulmonary Embolism (Acute Cor Pulmonale)

E. Primary Pulmonary Arterial Hypertension (Group 1 PAH)

F. Other Mimics

Level 2: Differential Diagnosis of the Underlying Cause of Cor Pulmonale

Approach to Differentiating Cor Pulmonale from Its Mimics

Summary Comparison Table

Active Recall - Differential Diagnosis of Cor Pulmonale

Diagnostic Criteria

Component 1: Underlying Lung or Pulmonary Vascular Disease

Component 2: Pulmonary Hypertension

Component 3: Right Ventricular Structural/Functional Abnormality

Diagnostic Algorithm

Investigation Modalities: Detailed Interpretation

1. Electrocardiogram (ECG)

2. Chest X-ray (CXR)

3. Arterial Blood Gas (ABG)

4. Blood Tests

5. Echocardiography

6. Pulmonary Function Tests (PFTs) / Spirometry

7. CT Imaging

8. V/Q Scan (Ventilation-Perfusion Scan)

9. Right Heart Catheterisation (Swan-Ganz Catheter)

10. Additional Investigations for Aetiological Workup

Summary: Investigation Hierarchy

Active Recall - Diagnosis and Investigations of Cor Pulmonale

Overarching Principles

Management Algorithm

Treatment Modalities in Detail

1. Treat the Underlying Lung Disease

A. COPD (The Most Common Cause)

B. Interstitial Lung Disease

C. CTEPH (Chronic Thromboembolic PH)

D. OSA / Obesity Hypoventilation Syndrome

E. Bronchiectasis

2. Correct Hypoxia — Long-Term Oxygen Therapy (LTOT)

3. Manage Right Heart Failure

A. Diuretics

B. Salt and Fluid Restriction

C. What About the "4 Pillars" of HFrEF?

D. Vasodilators — Use with Extreme Caution