Right Heart Failure and Cor Pulmonale

Core Idea

Cor pulmonale is right heart dysfunction secondary to pulmonary hypertension from lung disease (COPD, ILD) or pulmonary vascular disease. Chronic pulmonary hypertension causes RV hypertrophy and eventually RV dilation and failure. Acute cor pulmonale (from massive PE or severe respiratory failure) manifests as acute RV dysfunction without prior adaptation. Right heart failure causes elevated central venous pressure, hepatomegaly, peripheral edema, and reduced cardiac output. Unlike LV failure, RV failure from pulmonary disease cannot be effectively treated with pulmonary vasodilators unless directed at the underlying lung pathology.

How It's Best Learned

Compare chronic (hypertrophy, preserved function initially) versus acute cor pulmonale (sudden dysfunction from increased afterload). Study how COPD and interstitial lung disease cause pulmonary hypertension through hypoxic vasoconstriction and vascular remodeling.

Common Misconceptions

Cor pulmonale is not synonymous with pulmonary hypertension; it requires RV dysfunction from chronic pulmonary disease. Simply treating pulmonary hypertension with vasodilators without addressing underlying lung disease often fails. The treatment is directed at the lung disease (oxygen for hypoxemia, bronchodilators for obstruction).

Explainer

To understand cor pulmonale, start with the two-pump model of the heart. The left ventricle (LV) pumps blood at high pressure into the systemic circulation; the right ventricle (RV) pumps blood at low pressure into the pulmonary circulation. The RV is built for low-resistance work — its wall is thin relative to the LV, and it tolerates volume loads well but handles pressure loads poorly. Normal pulmonary artery pressure is around 25 mmHg mean. When pulmonary vascular resistance rises chronically, the RV is asked to do work it was not designed for.

The mechanism connecting lung disease to RV failure runs through hypoxic pulmonary vasoconstriction. In healthy lungs, this reflex is useful: alveoli with poor ventilation get less blood, directing flow to better-ventilated areas. But in COPD or interstitial lung disease, where hypoxia is widespread and chronic, the reflex fires throughout the pulmonary vasculature. Chronic hypoxia also triggers vascular wall remodeling — smooth muscle hypertrophy and fibrosis that structurally narrow the vessels and permanently elevate resistance. The RV, pumping against this elevated afterload, compensates initially by hypertrophying. For a time, the hypertrophied RV maintains cardiac output. This is chronic cor pulmonale — adapted, but fragile.

Eventually the RV dilates and fails. When the RV cannot effectively empty, pressure backs up into the systemic venous circulation — the right side of the heart is obstructed. This backpressure produces the hallmark signs of right heart failure: elevated jugular venous pressure, hepatomegaly (the liver is directly downstream of the right atrium via the hepatic veins), peripheral edema (elevated venous pressure forces fluid into interstitial spaces), and eventually ascites. Critically, pulmonary edema is absent — that is a left heart failure sign. Right heart failure causes peripheral congestion, not pulmonary congestion.

Acute cor pulmonale is a different beast. A massive pulmonary embolism suddenly obstructs a large fraction of the pulmonary vascular bed, acutely raising RV afterload to levels the thin-walled RV cannot overcome. Without time to hypertrophy, the RV acutely dilates, interventricular septal shift compromises LV filling (D-sign on echocardiography), and cardiac output collapses — a true cardiovascular emergency. The treatment logic follows the pathophysiology: chronic cor pulmonale targets the underlying lung disease (oxygen to reverse hypoxic vasoconstriction, bronchodilators for COPD), while acute cor pulmonale from PE targets reperfusion (thrombolytics or embolectomy) to rapidly restore RV outflow.