What are the diagnostic criteria for cor pulmonale?

Diagnostic Criteria for Cor Pulmonale

Cor pulmonale is defined as right ventricular hypertrophy and/or dilation caused by pulmonary hypertension due to diseases affecting the structure and/or function of the lungs. 1

Primary Diagnostic Criteria

• Pulmonary Hypertension: Mean pulmonary arterial pressure (mPAP) >20 mmHg (recently revised from >25 mmHg) 2
• Right Ventricular Enlargement: Demonstrated by imaging studies showing right ventricular hypertrophy and/or dilation 1
• Underlying Pulmonary Disease: Presence of a primary lung disorder (most commonly COPD) that affects lung structure or function 1

Clinical Evaluation

• Physical Examination Signs:

  • Raised jugular venous pressure, right ventricular heave, loud pulmonary second sound, tricuspid regurgitation 3
  • Peripheral edema (may indicate the presence of cor pulmonale, which has prognostic significance) 3
  • Central cyanosis (may be present but its absence does not exclude hypoxemia) 3

• Electrocardiographic Findings:

  • Right axis deviation for age 3
  • Right atrial enlargement 3
  • Right ventricular hypertrophy 3
  • S1Q3T3 pattern, S1S2S3 pattern, negative T waves in right precordial leads, transient right bundle branch block, or pseudoinfarction pattern (signs of acute cor pulmonale) 3

Imaging Studies

• Chest Radiography:

  • Enlargement of the central pulmonary arteries with or without rapid tapering (pruning) 3
  • Right heart chamber enlargement 3
  • Measurement of right interlobar artery >15 mm in women (>16 mm in men) at the hilum 3

• Echocardiography:

  • Two-dimensional and Doppler echocardiography to assess right ventricular size and function 3
  • Estimation of pulmonary artery pressure through tricuspid regurgitant jet velocity 3
  • Right-sided systolic time intervals (not reliable as they do not correlate with pulmonary systolic pressure) 3

• CT Scan:

  • High-resolution CT to evaluate underlying lung disease 4
  • Assessment of pulmonary artery size and right ventricular dimensions 5

Hemodynamic Assessment

• Right Heart Catheterization (gold standard):
  • Confirmation of pulmonary hypertension (mPAP >20 mmHg) 2
  • Measurement of pulmonary vascular resistance (elevated in cor pulmonale) 1
  • Assessment of pulmonary artery wedge pressure (should be ≤15 mmHg in pre-capillary pulmonary hypertension) 1

Disease-Specific Considerations

• COPD-related cor pulmonale:

  • Typically presents with mild to moderate pulmonary hypertension (PAP 20-35 mmHg) 1
  • May worsen during exercise, sleep, and exacerbations 1
  • A minority (<5%) exhibit severe or "disproportionate" PH (PAP >40 mmHg) 1

• Other causes:

  • Idiopathic pulmonary fibrosis 1
  • Obesity-hypoventilation syndrome 1
  • Chronic thromboembolic pulmonary disease 5

Prognostic Indicators

• Enlarged right ventricle on echocardiography is associated with lower survival rates (43.7% vs 90.5% in those with normal-sized right ventricle) 6
• Incomplete respiratory collapse of the inferior vena cava is associated with worse outcomes 6

Diagnostic Algorithm

1. Initial Suspicion: Based on symptoms (dyspnea, fatigue) and signs (peripheral edema, elevated JVP) in patients with known lung disease 3
2. Screening Tests: ECG and chest radiography to detect signs of right heart enlargement 3
3. Echocardiography: To confirm right ventricular enlargement and estimate pulmonary artery pressure 3
4. Pulmonary Function Tests: To assess underlying lung disease and severity 4
5. Definitive Diagnosis: Right heart catheterization to confirm pulmonary hypertension 1

Diagnostic Pitfalls to Avoid

• Relying solely on physical examination, which has poor sensitivity for detecting moderate cor pulmonale 3
• Overlooking cor pulmonale in patients with obesity or other comorbidities that may mask typical signs 3
• Failing to distinguish between cor pulmonale and left heart failure, which require different management approaches 3
• Missing the diagnosis in patients with normal chest radiographs, as radiographic changes may not be apparent in mild disease 3