Pulmonary Vascular Disease
Domain 6 - Pulmonary Vascular Disease
This domain tests the classification and management of pulmonary hypertension, including pulmonary arterial hypertension, left heart disease, lung disease, chronic thromboembolic disease and multifactorial causes. The exam favours haemodynamic definitions, vasoreactivity testing and treatment selection by WHO group.
Core rules
- Updated haemodynamic definition: mean pulmonary arterial pressure >20 mmHg at rest, pulmonary artery wedge pressure ≤15 mmHg and pulmonary vascular resistance >2 Wood units for precapillary PH.
- WHO groups: 1 pulmonary arterial hypertension; 2 left heart disease; 3 lung disease/hypoxia; 4 chronic thromboembolic PH; 5 multifactorial, including schistosomiasis, sarcoidosis and sickle cell disease.
- Group 1 includes idiopathic, heritable, drug-induced, connective tissue disease and congenital heart disease. Vasoreactivity testing is performed in idiopathic, heritable and drug-induced PAH; a positive response permits calcium channel blockers.
- Risk assessment in PAH uses WHO functional class, 6-minute walk distance, BNP/NT-proBNP, haemodynamics and imaging. Low-risk patients receive initial combination therapy, typically ERA plus PDE5 inhibitor.
- CTEPH is diagnosed after at least 3 months of anticoagulation with persistent perfusion defects. Pulmonary endarterectomy is the treatment of choice; riociguat and balloon pulmonary angioplasty are alternatives.
Worked example
A 35-year-old woman with scleroderma has worsening dyspnoea. Echocardiography shows a tricuspid regurgitant jet of 3.4 m/s. Right heart catheterisation shows mPAP 38 mmHg, PAWP 10 mmHg and PVR 6 Wood units. This is precapillary PH, and the scleroderma makes group 1 PAH likely. She has WHO functional class III and elevated NT-proBNP, so she is intermediate risk. Start combination ERA and PDE5 inhibitor therapy, avoid calcium channel blockers unless vasoreactivity testing is positive, and refer to a PH centre.
Traps that cost marks
- Using PAH-specific drugs in group 2 PH from left heart disease.
- Performing vasoreactivity testing in group 2 or group 3 PH.
- Missing CTEPH in a patient with persistent dyspnoea after PE; anticoagulation alone is not enough.
- Diagnosing PH on echocardiography alone without right heart catheterisation.
- Forgetting schistosomiasis as a group 5 cause in endemic settings.
Key points
- Precapillary PH: mPAP >20, PAWP ≤15, PVR >2 Wood units.
- Group 1 PAH: idiopathic, heritable, drug, connective tissue disease, congenital heart disease.
- Vasoreactivity testing is for idiopathic, heritable and drug-induced PAH.
- CTEPH: persistent defects after 3 months of anticoagulation; surgery is curative.
- Schistosomiasis is a group 5 cause of PH.