What is Cor Pulmonale?
Cor pulmonale is right ventricular hypertrophy and/or dilation caused by pulmonary hypertension that results from diseases affecting lung structure, lung function, or the pulmonary circulation—excluding conditions that primarily affect the left side of the heart. 1, 2
Pathophysiologic Definition
The condition represents a heart-lung unit disorder where the right ventricle (RV) undergoes morphological and functional changes secondary to elevated pulmonary vascular resistance (PVR). The key mechanistic driver is chronic alveolar hypoxia, which induces pulmonary vascular remodeling and sustained vasoconstriction 2, 3. This creates a pressure overload on the RV, which is anatomically designed to handle volume rather than pressure changes 4.
Classification
Acute Cor Pulmonale
Occurs when RV afterload increases abruptly from conditions such as:
- Massive pulmonary embolism
- Acute respiratory distress syndrome
- Severe pneumonia
- Acute hypoxia or acidemia
The RV responds poorly to sudden pressure increases, with steep declines in stroke volume even with minimal pressure elevations 4, 5.
Chronic Cor Pulmonale
Develops gradually over time, most commonly from:
- Chronic obstructive pulmonary disease (COPD) - the leading cause 6, 2
- Idiopathic pulmonary fibrosis
- Obesity-hypoventilation syndrome
- Chronic thromboembolic disease
Hemodynamic Characteristics
In chronic respiratory diseases, pulmonary hypertension is typically mild to moderate, with resting mean pulmonary artery pressure (PAP) ranging 20-35 mmHg 2. However, a critical minority (<5%) of patients develop "disproportionate" or severe pulmonary hypertension with PAP >40 mmHg, carrying worse prognosis 2.
A declining PAP in the setting of persistently high PVR is an ominous clinical finding, indicating RV decompensation with falling cardiac output 4.
Pathophysiologic Progression
The compensated RV initially hypertrophies and develops isovolumic contraction/relaxation phases with increased systolic pressure and end-diastolic volume 4. During decompensation:
- PVR and right atrial pressure rise concomitantly
- Cardiac output subsequently declines
- RV dilation causes leftward septal shift (ventricular interdependence)
- LV diastolic filling becomes impaired, reducing systemic perfusion
- Tricuspid regurgitation worsens, creating a vicious cycle 4
Clinical Pitfall
Diagnosis is often difficult early in the disease course because symptoms may be attributed to progression of underlying lung disease rather than cardiac involvement 2, 3. Echocardiography plays the central diagnostic role due to its non-invasive nature and ability to track RV function over time 1.
Updated Diagnostic Threshold
The definition of pulmonary hypertension was recently revised from mean PAP >25 mmHg to >20 mmHg, which may expedite earlier detection of cor pulmonale 6.