What is cor pulmonale?

What is Cor Pulmonale

Cor pulmonale is right ventricular enlargement, hypertrophy, and/or dysfunction resulting from pulmonary hypertension caused by diseases affecting the structure or function of the lungs or pulmonary vasculature, excluding left heart disease. 1, 2, 3

Definition and Pathophysiology

Cor pulmonale specifically refers to right heart pathology secondary to elevated pulmonary artery pressure (mean PAP ≥25 mmHg) from respiratory or pulmonary vascular disorders. 2, 3 The condition develops when the right ventricle, normally adapted to low-resistance pulmonary circulation, faces chronically increased afterload from pulmonary hypertension. 1

Key Mechanisms

• Hypoxic pulmonary vasoconstriction is the primary driver, where chronic alveolar hypoxia causes pulmonary vascular remodeling and increased pulmonary vascular resistance (PVR). 2, 4

• Mechanical vascular obstruction from parenchymal lung destruction, thromboembolism, or vascular obliteration contributes to elevated PVR. 2, 4

• Right ventricular adaptation initially involves hypertrophy with development of isovolumic contraction/relaxation phases, but eventually progresses to dilation and failure. 1

• Ventricular interdependence occurs when RV dilation causes leftward septal shift, compressing the LV cavity and impairing LV filling, which reduces cardiac output. 1

Clinical Classification

Acute Cor Pulmonale

Acute cor pulmonale develops from sudden increases in RV afterload (massive pulmonary embolism, acute respiratory failure) or decreased RV contractility (RV infarction, myocarditis). 1 The RV, poorly adapted to pressure changes, experiences steep declines in stroke volume with minimal pressure increases. 1

Echocardiography shows severely dilated hypokinetic right ventricle with septal deviation into the left ventricle. 1 Regional wall motion abnormalities sparing the RV apex are 77% sensitive and 94% specific for acute pulmonary embolism. 5

Chronic Cor Pulmonale

Chronic cor pulmonale most commonly results from chronic obstructive pulmonary disease (COPD), followed by idiopathic pulmonary fibrosis and obesity-hypoventilation syndrome. 1, 2 In COPD, pulmonary hypertension is typically mild to moderate (mean PAP 20-35 mmHg), though <5% develop "disproportionate" severe PH (PAP >40 mmHg). 2

Diagnostic Approach

Physical Examination

Look for left parasternal lift, accentuated pulmonary component of S2, RV S3 gallop, pansystolic murmur of tricuspid regurgitation, elevated jugular venous pressure, hepatomegaly, ascites, peripheral edema, and cool extremities. 1, 5 Physical examination has poor sensitivity for detecting moderate cor pulmonale, particularly in obese patients. 5

Electrocardiography

ECG findings include right axis deviation, P pulmonale, RV hypertrophy, RV strain pattern, right bundle branch block, and QTc prolongation. 1, 5 RV strain is more sensitive than RV hypertrophy alone. 1 In acute cor pulmonale, look for S1Q3T3 pattern, S1S2S3 pattern, negative T waves in right precordial leads, or transient RBBB. 5

Chest Radiography

Central pulmonary artery dilation contrasts with peripheral vascular "pruning." 1, 5 Right atrium and RV enlargement appear in advanced cases. 1 If the right descending pulmonary artery diameter exceeds 16 mm or pulmonary artery diameter >25 mm, pulmonary hypertension is likely. 1, 5

Echocardiography

Echocardiography is the primary diagnostic modality for identifying and characterizing cor pulmonale. 5, 6

Diagnostic Criteria:

• RV/LV basal diameter ratio >1.0 indicates RV enlargement. 5
• LV eccentricity index >1.1 (systole and/or diastole) suggests RV pressure overload from septal flattening. 5
• Tricuspid regurgitation velocity >3.4 m/s (PA systolic pressure >50 mmHg) indicates likely pulmonary hypertension. 5
• RV outflow Doppler acceleration time <105 msec or midsystolic notching suggests increased PVR. 5
• Early diastolic pulmonary regurgitation velocity >2.2 m/sec indicates elevated PA pressure. 5
• IVC diameter >21 mm with decreased inspiratory collapse (<50% with sniff or <20% with quiet inspiration) suggests elevated right atrial pressure. 5
• Right atrial area >18 cm² indicates RA enlargement. 5

Severity Grading:

• No cor pulmonale: TR velocity ≤2.8 m/s, PA systolic pressure ≤36 mmHg. 5
• Mild cor pulmonale: TR velocity 2.9-3.4 m/s, PA systolic pressure 37-50 mmHg. 5
• Moderate to severe cor pulmonale: TR velocity >3.4 m/s, PA systolic pressure >50 mmHg. 5

Common pitfall: Echocardiographic assessment is challenging in patients with hyperinflated lungs from COPD; use subcostal views for adequate visualization. 5

Right Heart Catheterization

Right heart catheterization remains the gold standard for confirming pulmonary hypertension with mean PAP ≥25 mmHg. 5 This distinguishes pre-capillary PH (pulmonary wedge pressure ≤15 mmHg) from post-capillary PH due to left heart disease. 1

Underlying Etiologies

Cor pulmonale results from three main categories:

• Lung parenchymal diseases: COPD, interstitial lung disease, mixed restrictive/obstructive patterns. 1, 2
• Ventilatory disorders: Obesity-hypoventilation syndrome, sleep-disordered breathing, alveolar hypoventilation, neuromuscular diseases. 1, 4
• Pulmonary vascular diseases: Chronic thromboembolic disease, primary pulmonary hypertension, pulmonary veno-occlusive disease. 1, 7

Critical distinction: Cor pulmonale excludes pulmonary hypertension from left heart disease (systolic/diastolic dysfunction, valvular disease), which is classified separately. 1

Prognostic Implications

Declining pulmonary artery pressure in the setting of persistently high PVR is an ominous finding indicating decompensated RV failure with reduced cardiac output. 1 Right heart function status is a major determinant of outcome in pulmonary hypertension. 8 Supraventricular arrhythmias (atrial flutter, atrial fibrillation) occur in 25% of patients after 5 years and almost invariably lead to clinical deterioration. 1