What is the recommended diagnostic work‑up and initial management for an adult in whom pulmonary hypertension is suspected?

Diagnostic Work-Up and Initial Management of Suspected Pulmonary Hypertension

Begin with transthoracic Doppler echocardiography as the first-line screening test, followed by mandatory right heart catheterization to confirm the diagnosis before initiating any therapy. 1, 2

Initial Screening and Clinical Assessment

Transthoracic echocardiography is the screening test of choice and must be performed immediately in all patients with suspected pulmonary hypertension. 1, 2 The echocardiogram should assess:

• Right ventricular systolic pressure using tricuspid regurgitation velocity (PH likely if velocity >3.4 m/s or estimated PA systolic pressure >50 mmHg) 1, 2
• Right atrial and right ventricular size and function, including TAPSE measurement 2, 3
• Left ventricular systolic and diastolic function to identify Group 2 PH from left heart disease 2, 3
• Valvular abnormalities (mitral and aortic disease) that may cause secondary PH 2, 3
• Pericardial effusion and intracardiac shunts using contrast echocardiography 2, 3

Mandatory Diagnostic Testing

Ventilation-Perfusion (V/Q) Scanning

A V/Q scan is mandatory in all patients with suspected pulmonary arterial hypertension to exclude chronic thromboembolic pulmonary hypertension (CTEPH). 1, 2, 3 Key points:

• A normal V/Q scan effectively excludes CTEPH with 90-100% sensitivity 1, 2, 3
• Do not rely on CT pulmonary angiography alone to exclude CTEPH, as it may miss the diagnosis 2, 3
• Multiple segmental perfusion defects suggest probable CTEPH and require further evaluation with CT angiography and selective pulmonary angiography 3

Pulmonary Function Testing

Perform comprehensive pulmonary function tests including: 1, 3

• Spirometry with lung volumes to characterize obstructive or restrictive patterns 3
• Diffusing capacity for carbon monoxide (DLCO) measurement—reduced DLCO supports pulmonary vascular or interstitial etiology 1, 3
• Arterial blood gas analysis to assess oxygenation and rule out hypoxemia-driven PH 3

High-Resolution CT Chest

HRCT is required to identify interstitial lung disease and emphysema (Group 3 PH) and to detect rare causes such as pulmonary veno-occlusive disease. 1, 3 CT findings may also suggest PH when pulmonary artery diameter ≥29 mm or PA:aorta ratio ≥1.0. 1

Laboratory Evaluation

Obtain the following blood tests in all patients: 3

• Complete blood count to screen for anemia or myeloproliferative disorders 3
• Thyroid function tests (TSH, free T4) to exclude thyroid disease 1, 3
• Autoimmune serology (ANA, anti-Scl-70, anti-centromere, anti-RNP, rheumatoid factor) to identify connective tissue disease-associated PAH 1, 3
• HIV serology in every patient with unexplained PAH 1, 3
• Hepatitis B and C serology to rule out viral hepatitis-related disease 3
• Abdominal ultrasound to screen for portal hypertension in unexplained PAH 4, 3

Definitive Diagnosis: Right Heart Catheterization

Right heart catheterization is mandatory in all patients with suspected pulmonary hypertension to confirm the diagnosis, establish hemodynamic classification, determine severity, and guide therapy before initiating any treatment. 1, 2, 4 This must be performed at an expert pulmonary hypertension center. 4

Hemodynamic Criteria

Measurements must be obtained in triplicate and include: 4, 3

• Mean pulmonary artery pressure (mPAP) >20 mmHg defines pulmonary hypertension 2
• Pulmonary artery wedge pressure (PAWP) ≤15 mmHg for Group 1 PAH 4
• Pulmonary vascular resistance (PVR) >3 Wood units for Group 1 PAH 4
• Cardiac output measured by thermodilution or Fick method 3

When PAWP is unreliable, add left heart catheterization to measure left ventricular end-diastolic pressure. 4

Acute Vasoreactivity Testing

Vasoreactivity testing should be performed ONLY in patients with idiopathic, heritable, or drug-induced PAH. 1, 4 This test is absolutely contraindicated in all other forms of PH. 4

Who Should NOT Be Tested (Class III Contraindication)

• Connective tissue disease-associated PAH 4
• Congenital heart disease-associated PAH 4
• HIV-associated PAH 4
• Portopulmonary hypertension 4
• Pulmonary veno-occlusive disease 4
• All Group 2-5 pulmonary hypertension 4

Testing Protocol

• Preferred agent: Inhaled nitric oxide (10-20 ppm for 5 minutes) 1, 4
• Alternative agents: IV epoprostenol or IV adenosine 1, 4
• Never use oral or IV calcium channel blockers during acute testing 4

Positive Response Criteria (ALL THREE Required)

1. Decrease in mean PAP ≥10 mmHg 1, 4
2. Absolute mean PAP ≤40 mmHg 1, 4
3. Cardiac output unchanged or increased 1, 4

Only approximately 10-15% of idiopathic PAH patients meet these criteria. 4

Initial Management

Referral to Expert Centers

All newly diagnosed patients with PAH should be referred to a pulmonary hypertension center with specialized multidisciplinary expertise before treatment is initiated. 1 These centers should have fast-track policies to review urgent referrals within 1-2 weeks. 1

Calcium Channel Blocker Therapy (ONLY for Vasoreactive Patients)

Calcium channel blockers should be started ONLY in patients with documented positive acute vasoreactivity testing. 1, 4 Dosing far exceeds that used for systemic hypertension:

Drug	Starting Dose	Target Dose	Patient Selection
Nifedipine ER	30 mg twice daily	120-240 mg daily	Resting HR <70-75 bpm [4]
Amlodipine	2.5 mg once daily	Up to 20 mg daily	Resting HR <70-75 bpm [4]
Diltiazem	60 mg three times daily	240-720 mg daily	Resting HR >75-80 bpm [4]

Mandatory reassessment: Repeat right heart catheterization at 3-4 months after CCB initiation to identify non-responders (approximately 50% of acute responders lose efficacy over time). 4

Initial PAH-Specific Therapy (Non-Vasoreactive Patients)

For treatment-naïve patients at low or intermediate risk without significant cardiopulmonary comorbidities: 1

• Initial combination therapy with a PDE5 inhibitor and an endothelin receptor antagonist is recommended 1
• For high-risk patients without significant comorbidities, IV or subcutaneous prostacyclin analogues should be prescribed 1

Supportive Measures

• Diuretics for signs of right ventricular failure or fluid overload 4
• Supplemental oxygen when arterial oxygen tension <60 mmHg to maintain saturations >90% 4
• Oral anticoagulation (target INR 1.5-2.5) may be considered in idiopathic, heritable, or drug-induced PAH 4
• Influenza and pneumococcal vaccination 4
• Supervised exercise rehabilitation for deconditioned patients 4

Risk Stratification and Monitoring

At diagnosis, assess: 1

• WHO functional class 1
• 6-minute walk distance (target >440 m) 1, 2
• NT-proBNP or BNP levels (target <50 ng/L) 1
• Risk assessment using validated tools (ESC/ERS guidelines) 1
• Quality of life using validated instruments 1

Follow-up every 3-6 months in stable patients to reassess these parameters. 4, 3

Critical Pitfalls to Avoid

• Never use calcium channel blockers empirically without documented positive vasoreactivity testing—this can cause life-threatening hypotension, reflex tachycardia, and right ventricular ischemia 1, 2, 4
• Never perform vasoreactivity testing in connective tissue disease PAH, congenital heart disease PAH, HIV-PAH, portopulmonary hypertension, or Groups 2-5 PH—it provides no benefit and adds procedural risk 4
• Never omit the V/Q scan—failure to perform this test can miss surgically curable CTEPH 2, 3
• Never rely on CT pulmonary angiography alone to exclude CTEPH—V/Q scanning remains the most sensitive modality 2, 3
• Never perform open or thoracoscopic lung biopsy in PAH patients due to high procedural risk and limited diagnostic yield 2, 3
• Never omit the 3-4 month repeat RHC in patients treated with CCBs—failure to identify non-responders delays necessary therapy escalation 4
• Never start PAH-specific therapy without right heart catheterization confirmation—echocardiography alone cannot definitively diagnose or classify pulmonary hypertension 2, 3