Pulmonary hypertension - classification, etiology, pathogenesis, and clinical manifestation.
Pulmonary hypertension is defined as mean pulmonary arterial pressure (mPAP) ≥25 mmHg at rest, measured by right heart catheterization.
Classification (WHO groups)
Etiology
Group 1: PAH
- Idiopathic.
- Heritable (BMPR2 mutation).
- Connective tissue diseases (scleroderma).
- HIV infection.
- Drugs/toxins (e.g., appetite suppressants).
Group 2: Left heart disease
- Left ventricular systolic or diastolic dysfunction.
- Valvular diseases (mitral stenosis or regurgitation).
Group 3: Lung diseases/hypoxia
- COPD.
- Interstitial lung disease.
- Sleep apnea.
- Chronic high-altitude exposure.
Group 4: Chronic thromboembolic PH
- Recurrent pulmonary emboli leading to obstruction.
Group 5: Multifactorial/other
- Hematologic disorders (e.g., chronic hemolytic anemia).
- Systemic disorders (e.g., sarcoidosis).
Pathogenesis
- 1 Increased pulmonary vascular resistance (PVR):
- Vasoconstriction (hypoxia-induced or due to endothelial dysfunction).
- Vascular remodeling (smooth muscle hypertrophy, intimal fibrosis).
- In situ thrombosis or thromboembolic obstruction.
- 2 Increased pressure load on the right ventricle:
- Right ventricular hypertrophy.
- Eventual right heart failure (cor pulmonale).
Clinical manifestations
Early (mild or moderate PH)
- Dyspnea on exertion.
- Fatigue.
- Weakness.
Progressive disease
- Syncope (due to reduced cardiac output on exertion).
- Chest pain (right ventricular ischemia).
- Palpitations.
Advanced (right heart failure)
- Peripheral edema.
- Ascites.
- Hepatomegaly.
- Jugular venous distension.
Auscultatory signs
- Loud P2 (pulmonic component of second heart sound).
- Right-sided S3 gallop.
Summary table