What are the diagnostic tests and treatment options for pulmonary hypertension?

Diagnostic Tests and Treatment Options for Pulmonary Hypertension

Echocardiography is the recommended first-line diagnostic test for pulmonary hypertension, followed by right heart catheterization for definitive diagnosis, with treatment tailored to the specific type of pulmonary hypertension and risk stratification. 1

Diagnostic Algorithm for Pulmonary Hypertension

Step 1: Initial Screening and Assessment

• Echocardiography: Essential first-line test to estimate probability of pulmonary hypertension 2

  • Evaluates right ventricular/left ventricular basal diameter ratio
  • Measures tricuspid regurgitation velocity
  • Assesses pulmonary artery diameter and right atrial size
  • Detects flattening of interventricular septum

• ECG findings that suggest pulmonary hypertension 3:

  • Right axis deviation (93% positive predictive value)
  • Right ventricular hypertrophy
  • Right bundle branch block

• Laboratory tests:

  • NT-proBNP or BNP levels (elevated in right ventricular strain)
  • Complete blood count
  • Liver function tests
  • Thyroid function tests

Step 2: Probability Classification and Further Testing

Based on echocardiographic findings, patients are classified as 2:

• Low probability
• Intermediate probability
• High probability

For intermediate to high probability, additional tests are required:

• Ventilation/Perfusion (V/Q) Lung Scan: Should be performed to screen for chronic thromboembolic pulmonary hypertension (CTEPH) - has higher sensitivity compared to CT pulmonary angiography 2

• Pulmonary Function Tests: To identify underlying lung disease

• CT Pulmonary Angiography: To evaluate for vascular obstruction and parenchymal lung disease

Step 3: Definitive Diagnosis

• Right Heart Catheterization (RHC): Gold standard for diagnosis 1
  • Diagnostic criteria: mean pulmonary arterial pressure ≥25 mmHg
  • For pulmonary arterial hypertension (PAH): pulmonary artery wedge pressure ≤15 mmHg and pulmonary vascular resistance >3 Wood units

Treatment Options Based on PH Classification

1. Pulmonary Arterial Hypertension (Group 1)

Treatment is based on risk stratification (low, intermediate, high) 2:

• Low/Intermediate Risk Patients:

  • Initial oral combination therapy targeting multiple pathways 1:
    • Endothelin receptor antagonists (ERAs)
    • Phosphodiesterase-5 inhibitors (PDE-5i)
    • Soluble guanylate cyclase stimulators

• High Risk Patients:

  • IV epoprostenol as first-line therapy 4
    • Initial dose: 2 ng/kg/min, increased in increments of 2 ng/kg/min every 15 minutes
    • Administered by continuous IV infusion via central venous catheter
    • May add ERA and/or PDE-5i for combination therapy

2. PH due to Left Heart Disease (Group 2)

• Optimize treatment of underlying heart condition 1
• PAH-specific therapies are not recommended

3. PH due to Lung Diseases (Group 3)

• Optimize treatment of underlying lung disease 1
• Long-term oxygen therapy for hypoxemia (arterial O₂ <60 mmHg)
• Conventional vasodilators not recommended

4. Chronic Thromboembolic PH (Group 4)

• Pulmonary endarterectomy (PEA) is treatment of choice 1
• For inoperable CTEPH:
  • Riociguat (soluble guanylate cyclase stimulator)
  • Balloon pulmonary angioplasty

5. PH with Unclear/Multifactorial Mechanisms (Group 5)

• Treatment directed at underlying condition

Follow-up and Monitoring

Regular assessments every 3-6 months in stable patients 2:

• Functional class assessment
• Exercise capacity (6-minute walk test)
• Biomarker levels (BNP/NT-proBNP)
• Echocardiographic parameters

Important Considerations and Pitfalls

• Never abruptly withdraw pulmonary vasodilator therapy as this can lead to rebound pulmonary hypertension and clinical deterioration 4

• Effective contraception is crucial for women with PAH due to high maternal/fetal mortality risk 1

• Multidisciplinary care at specialized centers is essential for optimal outcomes 1

• Risk stratification should be performed regularly to guide treatment decisions and assess response to therapy 2

• Avoid conventional vasodilators in PH due to left heart disease or lung disease as they may worsen ventilation-perfusion matching 1