Pulmonary Obstruction and Right Ventricular Strain: Pathophysiology and Consequences

True. Obstruction of pulmonary circulation—whether from pulmonary valve stenosis, pulmonary embolism, chronic thromboembolic disease, or severe pulmonary hypertension—creates a pressure overload on the right ventricle (RV).

Pathophysiological Sequence

1. Increased pulmonary vascular resistance (PVR) → elevated pulmonary artery pressure (PAP).
2. RV afterload rises → RV systolic pressure increases to overcome PVR.
3. Compensatory RV hypertrophy: Concentric wall thickening maintains stroke volume (Laplace’s law).
4. RV dilation & failure: Sustained overload → sarcomere stretch beyond optimal length, reduced contractility, tricuspid annular dilation → functional tricuspid regurgitation.
5. Systemic consequences: Reduced LV preload (ventricular interdependence) → low cardiac output; systemic venous congestion → peripheral edema, ascites, hepatomegaly, renal dysfunction.

Key Echocardiographic Markers

• RV basal diameter >4.1 cm (apical 4‑chamber).
• Tricuspid annular plane systolic excursion (TAPSE) <1.7 cm.
• RV fractional area change (FAC) <35%.
• Estimated RV systolic pressure (TR velocity) >40 mmHg.
• Septal flattening (D‑shaped LV in systole).

Clinical Implications

• Acute massive PE → acute RV failure (obstructive shock); requires emergent reperfusion.
• Chronic pulmonary hypertension → progressive RV failure; targeted PAH therapies (ERAs, PDE‑5i, prostacyclins) improve outcomes.
• Pulmonary valve intervention (balloon valvuloplasty, surgical/transcatheter replacement) relieves obstruction.

Early recognition of RV strain guides timely intervention and improves survival.