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Q1: Define cor pulmonale and classify it within the WHO pulmonary hypertension framework (2 min)
- Cor pulmonale = structural and functional alteration of the right ventricle caused by lung disease producing pulmonary hypertension, in the ABSENCE of left-heart or congenital heart disease.
- Acute (sudden RV overload — e.g. massive PE) vs chronic (progressive — COPD, ILD, OSA/OHS, CTEPH, kyphoscoliosis).
- Sits in WHO Group 3 PH (PH due to lung disease and/or hypoxia). Name all 5 groups: 1 PAH, 2 left-heart, 3 lung disease/hypoxia (cor pulmonale), 4 CTEPH, 5 multifactorial.
- Haemodynamic definition of PH (2022 ESC/ERS): mPAP over 20 mmHg at rest; pre-capillary if PCWP under 15 mmHg and PVR over 2 WU.
Q2: Describe the pathophysiological mechanism (3 min)
- Hypoxic pulmonary vasoconstriction (Euler-Liljestrand reflex) — chronic alveolar hypoxia inhibits KV channels on pulmonary arterial smooth muscle → depolarisation → Ca2+ influx → vasoconstriction. Adaptive locally (redirects blood to ventilated alveoli), pathological when global and chronic.
- Loss of the pulmonary vascular bed — emphysema destroys alveolar-capillary units; fibrosis obliterates vessels → reduces cross-sectional area, raises PVR.
- Secondary remodelling — medial hypertrophy, intimal fibrosis, microthrombi — fix the high PVR even after oxygen.
- RV response — chronic pressure overload → concentric hypertrophy → dilatation and failure (volume overload from TR) → systemic venous congestion.
- The RV is preload-dependent, thin-walled, low afterload-tolerant; perfused in systole and diastole → vulnerable to ischaemia at high PVR.
- Vicious cycle: RV failure → low CO → tissue hypoxia, RAAS activation, worsening afterload and congestion.
Q3: List the bedside and imaging findings (2 min)
- Symptoms: progressive dyspnoea, fatigue, ankle swelling, RUQ discomfort, syncope (severe PH).
- Signs of RV failure: raised JVP (prominent a and v waves), ankle/sacral oedema, hepatomegaly (pulsatile if TR), ascites, cool peripheries.
- Signs of PH: loud palpable P2, pulmonary ejection click, Graham Steell murmur (pulmonary regurgitation), RV heave, right-sided S3/S4, TR pansystolic murmur louder on inspiration (Carvallo's sign).
- ECG: right-axis deviation, P-pulmonale, RBBB, dominant R in V1, S1Q3T3 (acute).
- Echo: RV hypertrophy/dilatation, D-shaped septum, TR, raised RVSP from TR jet velocity, TAPSE; right heart catheterisation is the gold standard.
Q4: Describe the management and the key trials (2 min)
- Treat the underlying lung disease (COPD/ILD), smoking cessation, vaccination, pulmonary rehab.
- LTOT at least 15 h/day for PaO2 under 55 mmHg (or under 59 with cor pulmonale/polycythaemia) — improves survival: MRC (1981, PMID 6110912) and NOTT (1980, PMID 6776858).
- Optimise ventilation — NIV for chronic hypercapnia, CPAP for OSA — lowers PVR.
- Cautious diuretics (furosemide 20-40 mg orally) — the RV is preload-dependent.
- CTEPH is the surgically curable cause — V/Q scan in every unexplained PH; pulmonary endarterectomy is potentially curative.
- Avoid routine pulmonary vasodilators in COPD/ILD Group 3 PH (worsen V/Q mismatch); avoid CCBs without an acute vasodilator study; avoid high-flow oxygen in CO2 retainers (target SpO2 88-92%).
Q5: High-yield exam pearls (1 min)
- Cor pulmonale = RVH/RVF from lung disease via PH (Group 3). Commonest cause is COPD.
- Mechanism: hypoxic pulmonary vasoconstriction + loss of vascular bed → raised PVR.
- ECG cluster: right axis, P-pulmonale, RBBB, dominant R in V1.
- Bedside cluster: loud P2, RV heave, raised JVP, TR, hepatomegaly, ankle oedema.
- LTOT for at least 15 h/day improves survival (MRC/NOTT).
- Every unexplained PH needs a V/Q scan to find curable CTEPH.