What is the recommended workup for a patient with suspected pulmonary hypertension?

Workup for Suspected Pulmonary Hypertension

Begin with transthoracic echocardiography as your first-line diagnostic test, followed by a structured algorithmic approach that includes ventilation/perfusion scanning, right heart catheterization for definitive diagnosis, and comprehensive testing to identify the underlying etiology 1.

Initial Screening and Detection

First-Line Imaging

• Echocardiography is the mandatory initial test when PH is suspected 1, 2
• Assess echocardiographic probability of PH (high, intermediate, or low based on tricuspid regurgitation velocity and additional signs)
• If low probability: stop workup and consider alternative diagnoses with follow-up
• If intermediate or high probability: proceed with comprehensive evaluation

Essential Baseline Studies

Obtain these tests concurrently with echocardiography 1:

• Routine biochemistry and hematology
• Immunology panel, HIV testing, and thyroid function tests (to identify associated conditions in PAH)
• Lung function tests with DLCO measurement
• Arterial blood gas analysis
• ECG and chest radiograph
• High-resolution CT of the chest (should be considered in all patients)
• Abdominal ultrasound (screening for portal hypertension)

Etiologic Classification

Distinguishing CTEPH from Other Forms

Ventilation/perfusion (V/Q) or perfusion lung scan is mandatory in all patients with unexplained PH to exclude chronic thromboembolic disease 1:

• Multiple segmental perfusion defects → suspect CTEPH (Group 4)
  • Proceed to CT pulmonary angiography (required for CTEPH workup)
  • Pulmonary angiography should be considered
  • Refer for right heart catheterization
• Normal or subsegmental patchy defects → suspect PAH (Group 1) or Group 5
  • Continue workup for pulmonary arterial hypertension

Critical Pitfall

CT pulmonary angiography alone may miss the diagnosis of CTEPH 1. Always perform V/Q scanning first—it is more sensitive for detecting chronic thromboembolic disease.

Definitive Diagnosis

Right Heart Catheterization

• Required for definitive diagnosis before initiating PAH-specific therapy 3, 4, 5
• Provides direct measurements of:
  • Mean pulmonary artery pressure
  • Pulmonary arterial wedge pressure
  • Cardiac output
  • Pulmonary vascular resistance
• Acute vasoreactivity testing should be performed in selected cases during catheterization (defined as ≥10 mmHg decrease in mean PA pressure to ≤40 mmHg with normal/high cardiac output) 5
• Must be performed at a PH expert center

When to Refer to PH Expert Center

Refer early if 1:

• Echocardiographic high or intermediate probability of PH
• Severe PH and/or RV dysfunction on any imaging
• V/Q scan shows segmental perfusion defects
• Patient belongs to high-risk population (connective tissue disease, portal hypertension, congenital heart disease, family history)

What NOT to Do

Open or thoracoscopic lung biopsy is NOT recommended in patients with PAH 1. This carries significant morbidity risk without diagnostic benefit in the modern era.

Algorithmic Summary

1. Suspect PH → Clinical symptoms (exertional dyspnea, syncope, fatigue) + risk factors
2. Detect PH → Echocardiography + baseline labs/imaging
3. Classify etiology → Exclude left heart disease (Group 2) and lung disease (Group 3) with clinical assessment, PFTs, and high-resolution CT
4. Distinguish CTEPH → V/Q scan (if multiple segmental defects → CT angiography)
5. Confirm diagnosis → Right heart catheterization at expert center
6. Refine diagnosis → Specific testing based on suspected PAH subtype (immunology, genetics, abdominal ultrasound)

The 2015 ESC/ERS guidelines 1 provide the most comprehensive framework, emphasizing that proper phenotyping requires systematic exclusion of common causes (Groups 2 and 3) before pursuing invasive confirmation and PAH-specific therapy. The ACR guidelines 2 reinforce the imaging algorithm with updated appropriateness criteria for each modality.