STEPTRACKERRESPIRATORY + CARDIOVASCULAR | PATHOLOGY | HIGH-YIELD REVIEW

Pulmonary Vascular Disease

Pulmonary hypertension by cause, pulmonary embolism pathology, and the right ventricle that pays the price.

FOCUS ON
Know the five PH groups. Left-heart disease is the most common cause; lung disease and hypoxia come next. Group 1 PAH is linked to BMPR2, drugs, scleroderma and HIV, and shows plexiform lesions. Chronic thromboembolic PH can be cured surgically. Any chronic PH ends in cor pulmonale.
TOPIC
CAUSES
PATHOLOGY · MECHANISM
CLUE · TREATMENT
Pulmonary hypertension — definition
Mean PA pressure > 20 mmHg at rest
Medial hypertrophy, intimal fibrosis; atherosclerosis of the pulmonary trunk
Exertional dyspnea, loud P2, RV heave, TR murmur
Group 1 — PAH
Idiopathic (young women), heritable BMPR2 loss, drugs (fenfluramine, methamphetamine), scleroderma/CREST, HIV, portal hypertension, congenital shunts, schistosomiasis
Plexiform lesions; smooth muscle proliferation; ↓ NO and prostacyclin, ↑ endothelin
Endothelin antagonists, PDE-5 inhibitors, prostacyclins; CCB only if vasoreactive
Group 2 — left heart disease
most common
LV failure, mitral stenosis/regurgitation
Back-pressure through pulmonary veins
↑ wedge pressure
Group 3 — lung disease / hypoxia
COPD, ILD, sleep apnea, high altitude
Hypoxic vasoconstriction + vessel loss
Long-term O₂
Group 4 — chronic thromboembolic
Recurrent or unresolved PE
Organized clots narrow pulmonary arteries
Mismatched V/Q defects · endarterectomy (curative), riociguat
Group 5 — multifactorial
Sarcoidosis, sickle cell disease, myeloproliferative neoplasms, CKD
Mixed mechanisms
—
Pulmonary embolism — pathology
Most from deep leg veins
Infarct only when bronchial supply also fails (e.g., HF): wedge-shaped, pleura-based, hemorrhagic
Hampton hump, Westermark sign · clinical PE → page 4.06
Cor pulmonale
Acute (massive PE) or chronic (any PH from lung disease)
RV pressure overload → RVH → RV failure
JVD, hepatomegaly, edema, loud P2
Hepatopulmonary syndrome
Cirrhosis
Intrapulmonary vasodilation → right-to-left shunting
Dyspnea and hypoxemia worse sitting up (platypnea-orthodeoxia)

Mechanism — the path to RV failure

TriggerEndothelial dysfunction, hypoxia, back-pressure, clot
→
Vasoconstriction↓ NO, ↓ PGI₂, ↑ endothelin
→
RemodelingMedial hypertrophy, plexiform lesions
→
↑ PVR
→
RVH → RV failureCor pulmonale

PAH drug classes

CLASS
EXAMPLES
NOTE
Endothelin receptor antagonist
Bosentan, ambrisentan
Hepatotoxic, teratogenic
PDE-5 inhibitor
Sildenafil, tadalafil
↑ cGMP → vasodilation
Prostacyclin analog
Epoprostenol, iloprost
Flushing, jaw pain
sGC stimulator
Riociguat
Also for CTEPH
Calcium-channel blocker
Nifedipine, diltiazem
Only if vasoreactive on testing

How it's tested

COMMON CONFUSIONMost PE does not cause infarction, because the bronchial arteries keep the tissue alive. Infarcts appear when heart failure or lung disease limits that backup.
THE TRAPA patient with limited scleroderma has rising dyspnea and an isolated low DLCO with normal lung volumes. That is pulmonary arterial hypertension, not interstitial fibrosis.
YOUR APPROACHConfirm PH → assign a group from the history (heart, lung, clots, drugs, CTD) → treat the cause; PAH-specific drugs mainly for group 1.

If you see… think…

Young woman, exertional dyspnea, loud P2, BMPR2 mutation → heritable PAH
Plexiform lesions in pulmonary arterioles → severe PAH
PH in long-standing COPD → group 3 — hypoxic vasoconstriction
PH with heart failure → group 2 — most common
Several prior PEs, mismatched V/Q defects → CTEPH — endarterectomy
CREST patient with isolated low DLCO → pulmonary arterial hypertension
History of diet pills or methamphetamine → drug-induced PAH
Loud P2 + RV heave + JVD + edema → cor pulmonale
Cirrhosis, hypoxemia worse when upright → hepatopulmonary syndrome