Diagnosis and Management of Pulmonary Hypertension
The diagnosis of pulmonary hypertension requires a stepwise approach starting with echocardiography as the first-line non-invasive investigation, followed by right heart catheterization to confirm the diagnosis with a mean pulmonary arterial pressure ≥25 mmHg. 1
Definition and Classification
Pulmonary hypertension (PH) is defined as:
- Mean pulmonary arterial pressure (mPAP) ≥25 mmHg at rest as assessed by right heart catheterization 1
- More recent guidelines have lowered this threshold to >20 mmHg 2
PH is classified into five clinical groups:
- Pulmonary arterial hypertension (PAH)
- PH due to left heart disease
- PH due to lung diseases and/or hypoxia
- Chronic thromboembolic PH (CTEPH)
- PH with unclear/multifactorial mechanisms
Diagnostic Algorithm
Step 1: Clinical Suspicion
Look for:
- Breathlessness without obvious heart/lung disease
- Increasing dyspnoea unexplained by underlying disease
- Associated symptoms: fatigue, weakness, angina, syncope, abdominal distension 1
- Physical signs: left parasternal lift, accentuated pulmonary component of S2, tricuspid regurgitation murmur, right ventricular S3 1
- Advanced signs: jugular vein distension, hepatomegaly, peripheral edema, ascites, central cyanosis 1
Step 2: Initial Non-invasive Evaluation
Echocardiography: First-line investigation to estimate probability of PH 1
- Assess right ventricular size and function
- Estimate right ventricular systolic pressure
- Evaluate for left heart disease
- Look for congenital heart defects
Additional tests:
- ECG: May show right ventricular hypertrophy, right axis deviation
- Chest radiograph: Enlarged central pulmonary arteries, right heart enlargement
- Pulmonary function tests with DLCO: Essential for initial evaluation 1
- Arterial blood gases: To assess oxygenation and ventilation
Step 3: Determine PH Group
Ventilation/perfusion (V/Q) scan: Mandatory to rule out CTEPH 1
- Normal or subsegmental "patchy" defects suggest PAH
- Multiple segmental perfusion defects suggest CTEPH
High-resolution CT: Evaluate for lung disease and PVOD 1
Pulmonary angiography: Consider for suspected CTEPH 1
Blood tests: Complete biochemistry, hematology, immunology, HIV, thyroid function 1
Abdominal ultrasound: Screen for portal hypertension 1
Step 4: Confirmation with Right Heart Catheterization
- Mandatory for definitive diagnosis 1, 3
- Measures:
- Mean pulmonary artery pressure (mPAP ≥25 mmHg)
- Pulmonary artery wedge pressure (PAWP ≤15 mmHg in pre-capillary PH)
- Pulmonary vascular resistance (PVR >3 Wood units in PAH)
- Cardiac output
- Acute vasoreactivity testing: Required for idiopathic, heritable, and drug-induced PAH to identify potential responders to calcium channel blockers 3
Risk Assessment and Severity Evaluation
Risk stratification into low, intermediate, or high-risk categories based on:
- WHO functional class
- Exercise capacity (6-minute walk distance)
- BNP/NT-proBNP levels
- Echocardiographic parameters
- Hemodynamic parameters 1
| Risk Parameter | Low Risk (<5%) | Intermediate Risk (5-10%) | High Risk (>10%) |
|---|---|---|---|
| Clinical signs of RV failure | Absent | Absent | Present |
| WHO functional class | I, II | III | IV |
| 6-minute walk distance | >440m | 165-440m | <165m |
| BNP | <50 ng/L | 50-300 ng/L | >300 ng/L |
| NT-proBNP | <300 ng/L | 300-1400 ng/L | >1400 ng/L |
| Imaging (echo, CMR) | RA area <18 cm², no effusion | RA area 18-26 cm², minimal effusion | RA area >26 cm², pericardial effusion |
| Hemodynamics | CI ≥2.5 L/min/m², RAP <8 mmHg | CI 2.0-2.4 L/min/m², RAP 8-14 mmHg | CI <2.0 L/min/m², RAP >14 mmHg |
Management Strategy
General Measures
- Avoid pregnancy (high mortality risk) 1
- Immunization against influenza and pneumococcal infection 1, 3
- Psychosocial support 1, 3
- Supervised exercise training for deconditioned patients 1, 3
- In-flight oxygen for WHO FC III/IV patients 3
Treatment Based on PH Group
Group 1 (PAH)
- Acute vasoreactivity testing to identify responders to calcium channel blockers 3
- Treatment algorithm based on risk assessment:
Low/Intermediate Risk (WHO FC II-III):
High Risk (WHO FC IV):
Inadequate Response:
Group 2 (PH due to Left Heart Disease)
- Focus on treating underlying heart condition
- PAH-specific therapies not recommended 3
Group 3 (PH due to Lung Diseases)
- Optimize treatment of underlying lung disease
- Long-term oxygen therapy for hypoxemic patients
- PAH-specific drugs not recommended 3
Group 4 (CTEPH)
- Pulmonary endarterectomy is treatment of choice
- Balloon pulmonary angioplasty for inoperable cases
- Medical therapy with riociguat for inoperable CTEPH 3
Follow-up and Monitoring
- Regular assessment every 3-6 months for stable patients 3
- Evaluate multiple parameters:
- Clinical assessment and WHO functional class
- Exercise capacity (6-minute walk test)
- BNP/NT-proBNP levels
- Echocardiography
- Hemodynamics when indicated
Common Pitfalls to Avoid
- Delayed diagnosis due to non-specific symptoms 3
- Misclassification of PH group leading to inappropriate treatment 3
- Failure to refer to specialized PH centers 3
- Inadequate follow-up and risk assessment 3
- Underutilization of combination therapy 3
- Failure to recognize treatment failure early enough to escalate therapy 3
- Using PAH-specific therapies in PH groups where they are not indicated or potentially harmful 3
- Riociguat is contraindicated in combination with PDE-5 inhibitors 3
Referral to Expert Centers
Referral to specialized pulmonary hypertension centers is strongly recommended for: