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Pulmonary Hypertension

Clinical Subject Page

Pulmonary Hypertension

ICD-10

I27.20

Specialty

Cardiology

Onset

Chronic

Reviewed

June 2026

On This Page

Overview

Pulmonary hypertension (PH) is a hemodynamic disorder characterized by elevated pressure in the pulmonary circulation, leading to increased right ventricular afterload, right ventricular dysfunction, and, if untreated, right heart failure.

Etiology & Risk Factors

  • WHO Group 1 – Pulmonary Arterial Hypertension (PAH)

    • Idiopathic
    • Heritable (BMPR2 mutation)
    • Drug/toxin-induced
    • Connective tissue diseases
    • Congenital heart disease
    • Portal hypertension
    • HIV infection

    WHO Group 2 – Due to Left Heart Disease

    • Heart failure (HFrEF/HFpEF)
    • Mitral or aortic valve disease
    • Cardiomyopathy

    WHO Group 3 – Due to Lung Disease/Hypoxia

    • COPD
    • Interstitial lung disease
    • Obstructive sleep apnea
    • Chronic hypoxemia

    WHO Group 4 – Chronic Thromboembolic PH (CTEPH)

    • Chronic pulmonary embolism

    WHO Group 5 – Multifactorial

    • Sarcoidosis
    • Hematologic disorders
    • Chronic kidney disease
    • Other systemic disorders

    Risk Factors

    • Connective tissue disease
    • Congenital heart disease
    • Chronic lung disease
    • Pulmonary embolism
    • Family history
    • HIV infection
    • Portal hypertension
    • Appetite suppressants or methamphetamine use
    • Obesity and sleep apnea

Pathophysiology

    • 2. Pathophysiology of Pulmonary Hypertension (PH)

      Pulmonary hypertension develops when there is an increase in pulmonary vascular resistance, pulmonary venous pressure, or pulmonary blood flow, leading to elevated pressure in the pulmonary circulation.

      Mechanisms

      • Increased pulmonary vascular resistance
        • Occlusive vasculopathy
        • Chronic hypoxic pulmonary vasoconstriction
        • Endothelial dysfunction:
          • ↑ Endothelin
          • ↓ Nitric oxide (NO)
          • ↓ Prostacyclin
        • Inflammation causing vascular remodeling and fibrosis
      • Increased pulmonary venous pressure
        • Due to left-sided heart disease (e.g., mitral valve disease)
      • Increased pulmonary blood flow
        • Left-to-right shunts (e.g., ASD, VSD, PDA)
        • Portopulmonary hypertension
        • Sickle cell disease

      Simple Flow

      ↑ Pulmonary vascular resistance / ↑ Pulmonary venous pressure / ↑ Pulmonary blood flow → ↑ Pulmonary artery pressure → ↑ Right ventricular afterload → Right ventricular hypertrophy and dilation → Right-sided heart failure (cor pulmonale) → Arrhythmias

Clinical Presentation

  1. Symptoms

    • Progressive exertional dyspnea
    • Fatigue
    • Chest pain
    • Palpitations
    • Dizziness
    • Syncope (advanced disease)
    • Peripheral edema
    • Abdominal distension

    Signs

    • Loud P2
    • Right ventricular heave
    • Elevated JVP
    • Tricuspid regurgitation murmur
    • Peripheral edema
    • Hepatomegaly
    • Ascites
    • Cyanosis (advanced disease)

History Taking

    • When did the shortness of breath begin?
    • Does it occur with exertion?
    • Chest pain or syncope?
    • Lower limb swelling?
    • Previous pulmonary embolism?
    • History of COPD or ILD?
    • Congenital heart disease?
    • Autoimmune disease?
    • Family history of PH?
    • Drug or appetite suppressant use?

    Red Flags

    • Syncope
    • Resting dyspnea
    • Chest pain
    • Rapid symptom progression
    • Signs of right heart failure

Classification

Pulmonary Hypertension · WHO Classification

HAEMODYNAMIC DEFINITION: MEAN PAP >20 mmHg AT REST (RIGHT HEART CATHETERISATION) The 2022 ESC/ERS guidelines lowered the diagnostic threshold from ≥25 to >20 mmHg. PH is classified into 5 WHO groups by underlying mechanism — this determines treatment, since pulmonary vasodilators used in Group 1 can be harmful in other groups (esp. Group 2/3).
WHO Groups 1–5
1
Pulmonary Arterial HTN
Idiopathic, heritable, drug/toxin-induced, connective tissue disease, HIV, portal HTN, congenital heart disease.
Pre-capillary
2
PH due to Left Heart Disease
HFrEF/HFpEF, valvular disease (esp. mitral), congenital/acquired left heart inflow/outflow obstruction.
Post-capillary — most common
3
PH due to Lung Disease/Hypoxia
COPD, interstitial lung disease, mixed restrictive/obstructive pattern, sleep-disordered breathing, high altitude.
Pre-capillary
4
PH due to Pulmonary Artery Obstruction
Chronic thromboembolic PH (CTEPH) and other pulmonary artery obstructions (tumour, arteritis).
Pre-capillary — potentially curable
5
PH with Unclear/Multifactorial Mechanisms
Haematologic disorders, systemic disorders (sarcoidosis), metabolic disorders, chronic renal failure with/without dialysis.
Mixed/unclear
WHO Group Haemodynamic Pattern Key Examples Treatment Approach
Group 1 — PAH Pre-capillary mPAP >20, PVR >2 WU, PAWP ≤15 mmHg Idiopathic PAH, scleroderma-associated, congenital heart disease (Eisenmenger), drug-induced PAH-specific therapy — ERAs, PDE5 inhibitors, prostacyclin analogues, soluble guanylate cyclase stimulators
Group 2 — Left Heart Disease Post-capillary mPAP >20, PAWP >15 mmHg HFpEF/HFrEF, mitral/aortic valve disease Treat underlying cardiac disease (diuretics, GDMT); PAH-specific drugs generally avoided/harmful
Group 3 — Lung Disease/Hypoxia Pre-capillary mPAP >20, PAWP ≤15 mmHg COPD, idiopathic pulmonary fibrosis, combined pulmonary fibrosis-emphysema, OSA Optimise underlying lung disease, long-term oxygen therapy; PAH drugs not routinely recommended
Group 4 — CTEPH Pre-capillary mPAP >20, PAWP ≤15 mmHg Chronic thromboembolic PH after incomplete clot resolution; rare pulmonary artery tumour/sarcoma Pulmonary endarterectomy (potentially curative); balloon pulmonary angioplasty or riociguat if inoperable
Group 5 — Unclear/Multifactorial Variable — mixed pre-/post-capillary mechanisms Sarcoidosis, chronic haemolytic anaemia, myeloproliferative disorders, chronic kidney disease Treat underlying systemic disease; individualised, multidisciplinary approach
Haemodynamic Definitions (RHC)
PH (general) — mean PAP >20 mmHg at rest
Pre-capillary PH — mPAP >20, PAWP ≤15 mmHg, PVR >2 Wood units (Groups 1, 3, 4, some 5)
Isolated post-capillary PH — mPAP >20, PAWP >15 mmHg, PVR ≤2 WU (Group 2)
Combined pre- and post-capillary PH — mPAP >20, PAWP >15 mmHg, PVR >2 WU (Group 2 with reactive component)
Severe PAH — PVR >5 Wood units, indicates more advanced pulmonary vascular disease
Diagnostic Workup
Echocardiography — initial screening tool; estimates RVSP/PASP via TR jet velocity, assesses RV size/function
Right heart catheterisation — gold standard for diagnosis and haemodynamic classification
V/Q scan — screens for CTEPH (Group 4); more sensitive than CT pulmonary angiogram for this
PFTs + HRCT chest — identify underlying lung disease (Group 3)
Autoimmune/connective tissue screen — ANA, RF, anti-Scl-70, anti-centromere if PAH suspected
6-minute walk test + BNP/NT-proBNP — functional assessment and risk stratification

Investigations

    • Laboratory

      • CBC
      • Renal & liver function
      • BNP or NT-proBNP
      • ANA and autoimmune screen
      • HIV testing
      • Thyroid function

      ECG

      • Right axis deviation
      • Right ventricular hypertrophy
      • Right atrial enlargement

      Imaging

      • Chest X-ray
      • Transthoracic echocardiography (first-line screening)
      • CT pulmonary angiography
      • High-resolution CT (if ILD suspected)
      • Ventilation/Perfusion (V/Q) scan (best screening test for CTEPH)

      Pulmonary Tests

      • Pulmonary function tests
      • Six-minute walk test

      Gold Standard

      • Right heart catheterization
        • Confirms diagnosis
        • Measures mPAP, PAWP, PVR
        • Guides classification and treatment

Diagnosis

Diagnosis is based on:

  • Clinical suspicion
  • Echocardiographic evidence of elevated pulmonary pressures
  • Identification of the underlying cause
  • Confirmation by right heart catheterization
    • mPAP >20 mmHg at rest
    • Classification according to WHO group
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Management

General Measures

  • Treat the underlying cause
  • Supervised exercise/rehabilitation
  • Oxygen therapy (if hypoxemic)
  • Vaccinations
  • Avoid pregnancy in PAH
  • Diuretics for right heart failure

Medications (Group 1 PAH)

  • Endothelin receptor antagonists (Bosentan, Ambrisentan)
  • PDE-5 inhibitors (Sildenafil, Tadalafil)
  • Soluble guanylate cyclase stimulator (Riociguat)
  • Prostacyclin analogs (Epoprostenol, Treprostinil)
  • Prostacyclin receptor agonist (Selexipag)

Procedures

  • Balloon pulmonary angioplasty (selected CTEPH)
  • Pulmonary endarterectomy (CTEPH)
  • Lung transplantation (advanced disease)

Complications

      • Right ventricular failure (cor pulmonale)
      • Arrhythmias
      • Syncope
      • Hemoptysis
      • Pulmonary artery thrombosis
      • Sudden cardiac death

Prognosis

  • Depends on the underlying cause and disease severity
  • Early diagnosis and targeted therapy improve survival
  • Right ventricular dysfunction is the strongest predictor of mortality
  • Untreated advanced PH carries a poor prognosis

Key Points / Clinical Pearls

  • Pulmonary hypertension is defined as mPAP >20 mmHg on right heart catheterization.
  • Echocardiography is the best initial screening test.
  • Right heart catheterization is required to confirm the diagnosis.
  • Always identify the WHO group before initiating therapy.
  • Progressive dyspnea is the hallmark symptom.
  • Right ventricular failure is the leading cause of death in advanced pulmonary hypertension.