Preparatory Mindset
Cor pulmonale is "right heart disease caused by lung disease" — by definition excluding right-heart failure from left-heart or congenital disease (17CM exam tested). The exam narrative is: chronic lung disease (COPD is the classic) → chronic hypoxia → hypoxic pulmonary vasoconstriction + vascular remodelling → pulmonary hypertension (mPAP >25 mmHg at rest) → right ventricular hypertrophy → right heart failure. Acute cor pulmonale is the PE scenario (acute right-heart strain). Know the mPAP cut-offs (normal 10–25, mean 15; >25 = PH; 26–35 mild, 36–45 moderate, >45 severe), the secondary causes ladder, and the management mantra: treat the underlying lung disease + long-term oxygen therapy — because correcting hypoxia is the only intervention that reliably lowers pulmonary artery pressure.
Core Concepts
Definition
- Cor pulmonale = right ventricular hypertrophy/dilatation and right heart failure secondary to pulmonary hypertension caused by respiratory disease.
- Chronic: severe respiratory disease, slow onset (COPD, interstitial fibrosis).
- Acute: sudden right-heart strain — classically pulmonary embolism.
- Excludes: right-heart disease from left-heart disease or congenital heart disease.
Pulmonary hypertension (PH) — definition & severity
- mPAP >25 mmHg at rest (sea level) = pulmonary hypertension (normal mPAP 10–25, mean ~15 mmHg).
- Severity: mild 26–35; moderate 36–45; severe >45 mmHg.
Classification & aetiology
| Type | Causes |
|---|---|
| Primary (idiopathic) PH | Rare but severe; endothelial dysfunction; female predominance |
| Secondary PH (much more common) | 1. Severe respiratory disease (most common) — COPD, interstitial lung disease; 2. Cardiac disease — left-heart failure, valvular (pulmonary venous hypertension); 3. Chest wall & respiratory muscle disorders — kyphoscoliosis, OSA, neuromuscular disease; 4. Pulmonary vascular diseases — recurrent PE (chronic thromboembolic PH), vasculitis; 5. Other — high altitude, sleep apnoea, connective tissue disease |
Pathogenesis of PH in lung disease
Hypoxia is the central driver:
- Hypoxic vasoconstriction: alveolar hypoxia directly constricts pulmonary arterioles → ↑ pulmonary vascular resistance (the acute, reversible component).
- Hypercapnia: stimulates chemoreceptors → further vasoconstriction.
- Pulmonary vascular remodelling: chronic inflammation → endothelial and smooth-muscle proliferation → vessel-wall thickening (the irreversible component).
- Hypercoagulability: chronic inflammation → endothelial damage → in-situ thrombus.
- Loss of capillary bed: parenchymal destruction (emphysema, fibrosis) → reduced cross-sectional area of the pulmonary circulation.
Compensatory mechanism & right heart failure
- Sustained PH → ↑ afterload during systole → right ventricular hypertrophy (compensatory) → eventually RV dilatation and failure (decompensation): right heart failure.
- Symptoms: dyspnoea, fatigue, exertional syncope, right-upper-quadrant pain (hepatic congestion).
- Signs: raised JVP, peripheral oedema, ascites, hepatomegaly, hepatojugular reflux, loud P₂, right-sided S₃/S₄, parasternal heave; cyanosis, clubbing if underlying lung disease.
Diagnosis
- History + examination (signs of right HF + underlying lung disease).
- CXR: enlarged pulmonary arteries, right heart border; underlying lung disease changes.
- ECG: right axis deviation, right atrial enlargement (P pulmonale), RV hypertrophy (tall R in V1, deep S in V5-6), right bundle branch block.
- Echocardiography: estimate RVSP/mPAP, RV size/function; exclude left-heart and congenital causes.
- ABG: hypoxaemia, hypercapnia (COPD).
- Further: pulmonary function tests, HRCT, V/Q scan/CTPA (chronic thromboembolic disease), overnight oximetry (OSA).
- Bloods: polycythaemia (chronic hypoxia), LFTs (congestive hepatopathy).
Treatment
- Treat the underlying lung disease (bronchodilators, steroids, treat infection, manage OSA with CPAP, anticoagulation for thromboembolism).
- Long-term oxygen therapy (LTOT) for chronic hypoxaemia — the key therapy that reduces PH and improves survival (use ≥15 h/day).
- Diuretics for right-heart failure (fluid overload); cautious (preload dependence).
- Pulmonary vasodilators (endothelin antagonists, PDE-5 inhibitors, prostacyclins) — only in selected PH with a specific indication (e.g., CTEPH: pulmonary endarterectomy); treat the cause first.
- Anticoagulation in chronic thromboembolic disease; avoid hypoxaemia in acute exacerbations.
HKHA Handbook (LMCHK) — Key Points
- The handbook has no dedicated cor pulmonale section — it is managed under the underlying disease (COPD P 14–16, oxygen therapy P 6–7, NIV P 22–24) plus the acute presentations that cause right-heart strain.
- Pulmonary embolism (C 29–30) — the acute cor pulmonale scenario: investigate with D-dimer, CTPA (sens 91%), V/Q scan (high probability sens 41%, spec 97%); risk-stratify by haemodynamic instability (high risk) + RV dysfunction (TTE/CTPA) + troponin + PESI; treat haemodynamically insignificant PE with LMWH → DOAC (rivaroxaban 15 mg bd ×21 days → 20 mg daily; apixaban 10 mg bd ×7 days → 5 mg bd; dabigatran/edoxaban after ≥5 days parenteral), warfarin with LMWH overlap to INR 2–3; haemodynamically significant PE → systemic thrombolysis (rtPA 100 mg IV over 2 h) in ICU/CCU; IVC filter if PE on adequate anticoagulation or absolute contraindication.
- Oxygen therapy (P 6–7): LTOT for chronic hypoxaemic lung disease — the mainstay for cor pulmonale; target saturations per the underlying disease.
High-Yield Points
- Cor pulmonale = right heart disease due to lung disease (exclude left-heart/congenital).
- PH: mPAP >25 mmHg at rest (normal 10–25, mean 15); mild 26–35, moderate 36–45, severe >45.
- Chronic → COPD/interstitial disease; acute → PE.
- Hypoxia is the central driver: hypoxic vasoconstriction (reversible) + remodelling (irreversible).
- Compensation: RV hypertrophy → RV failure (JVD, oedema, ascites, loud P₂).
- LTOT is the key treatment — corrects hypoxia, reduces PH, improves survival.
- ECG: right axis, P pulmonale, RVH pattern.
Topic Summary
Cor pulmonale is right-heart disease caused by respiratory disease — chronic (COPD/interstitial lung disease) or acute (pulmonary embolism). Chronic hypoxia drives pulmonary hypertension (mPAP >25 mmHg) through hypoxic vasoconstriction and vascular remodelling, leading to right ventricular hypertrophy and eventual right heart failure with JVD, oedema, ascites and a loud P₂. Diagnosis integrates CXR, ECG (right axis, P pulmonale), echocardiography and ABG. Management centres on treating the underlying lung disease and long-term oxygen therapy — the only therapy that reliably lowers pulmonary pressure — with diuretics for failure and specific pulmonary vasodilators only in selected cases; acute cor pulmonale from massive PE requires thrombolysis (HKHA C 29–30).