What should the workup for pulmonary hypertension include?

Comprehensive Workup for Pulmonary Hypertension

The workup for pulmonary hypertension should include echocardiography as the first-line non-invasive diagnostic test, followed by ventilation/perfusion scanning, pulmonary function tests with DLCO measurement, routine blood tests, and right heart catheterization for definitive diagnosis. 1

Initial Diagnostic Evaluation

First-Line Testing

• Echocardiography: Essential first screening tool to estimate pulmonary arterial pressure and assess right ventricular function 1
• Electrocardiogram: Evaluate for right axis deviation (93% positive predictive value for PH) 2
• Chest radiography: Assess for enlarged pulmonary arteries and right heart chambers

Laboratory Testing

• Routine biochemistry, hematology, and immunology tests 1
• HIV testing (mandatory for all patients) 1
• Thyroid function tests 1
• NT-proBNP/BNP: Elevated levels correlate with disease severity 1, 2
• Autoimmune screening: If ANA positive, check anti-dsDNA, anti-Scl-70, anti-centromere, anti-RNP, anti-SSA, anti-SSB 1

Pulmonary Assessment

• Pulmonary function tests with DLCO: Essential for initial evaluation 1, 3
• Arterial blood gas analysis: Pattern helps differentiate PH subtypes 3
• Six-minute walk test: Assess exercise capacity and disease severity 1

Imaging Studies

Mandatory Imaging

• Ventilation/perfusion lung scan: Required in all patients with unexplained PH to exclude chronic thromboembolic PH (CTEPH) 1
• High-resolution CT scan: Should be considered in all PH patients to identify underlying lung disease 1

Additional Imaging Based on Clinical Suspicion

• Contrast CT pulmonary angiography: Required for patients with suspected CTEPH 1
• Pulmonary angiography: Should be considered in the workup of CTEPH 1
• Abdominal ultrasound: Recommended for screening of portal hypertension 1

Definitive Diagnosis

Right Heart Catheterization

• Mandatory for definitive diagnosis 1, 4
• Confirms PH: mean pulmonary artery pressure ≥25 mmHg at rest 4
• Determines hemodynamic classification:
  • Precapillary PH: PAWP ≤15 mmHg
  • Postcapillary PH: PAWP >15 mmHg 4
• Assesses pulmonary vascular resistance and cardiac output 4

Diagnostic Algorithm

1. Initial suspicion: Based on symptoms (dyspnea, fatigue, syncope) and risk factors
2. Echocardiography: If intermediate or high probability of PH, proceed with further testing
3. Exclude common causes: Assess for left heart disease and lung disease
4. V/Q scan: If normal or shows only subsegmental defects, consider PAH; if multiple segmental defects, suspect CTEPH
5. Right heart catheterization: For definitive diagnosis and hemodynamic classification

Important Considerations

• Avoid lung biopsy: Open or thoracoscopic lung biopsy is not recommended in patients with PAH 1
• Comprehensive approach: The diagnostic workup should systematically rule out common causes of PH (groups 2 and 3) before establishing a diagnosis of PAH (group 1) or CTEPH (group 4) 1
• Referral to expert centers: Patients with suspected PH should be referred to specialized centers for complete evaluation 1
• Prognostic assessment: Include WHO functional class, exercise capacity (6MWT), echocardiographic findings (pericardial effusion, TAPSE), and hemodynamic parameters (RAP, cardiac index) 1

By following this systematic approach, clinicians can accurately diagnose pulmonary hypertension, determine its etiology, and assess disease severity to guide appropriate treatment decisions.