Diagnosis of PAH

PAH is progressive and life-limiting condition making early detection and treatment vital.[1] The symptoms are often and non-specific the condition is often confused for other more common diseases.[2]

This page will explore and investigate the options to diagnose PAH, describing the European Respiratory Society (ERS)/European Society of Cardiology (ESC) diagnostic algorithm and the different investigations that can help diagnosis, including ECHO and right heart catheterisation (RHC).

This page is intended for Health Care Providers. Are you a patient? Visit PH-human to find more information about PAH.

Diagnosis of PAH

Early diagnosis of PAH and timely therapeutic intervention is associated with improved patient outcomes. However, early diagnosis of PAH is often challenging due to the non-specific nature of early symptoms, among other factors.[3] See below for detailed guidance on the diagnostic process for PAH.[4]

2015 ESC/ERS diagnostic algorithm right heart catheterisation (RHC)

PAH should be considered in the differential diagnosis of patients presenting with a constellation of exertional dyspnoea, syncope, angina and/or progressive limitation of exercise capacity. This is of particular concern in patients without apparent risk factors or symptoms/signs of common cardiovascular and respiratory disorders.[4]

Special awareness should be directed towards patients with associated conditions and/or risk factors for the development of PAH, including:[4]
• Family history
• Connective tissue disease
• Congenital heart disease
• Human immunodeficiency virus (HIV) infection
• Portal hypertension
• A history of drug or toxin intake known to induce PAH

It is recommended for patients with suspected PAH to undergo further investigation at a specialist centre, including

to definitively confirm the presence or absence of PAH.[4]

Condensed 2015 ESC/ERS diagnostic algorithm[4]

Adapted from Galiè et al. 2016[4]

Clinical history,

, electrocardiograms (ECG), chest radiographs, echocardiograms, pulmonary function tests (PFTs), computed tomography (CT) of the chest and ventilation/perfusion (V/Q) scans are all necessary to exclude the diagnosis of PAH due to left heart disease or lung disease, or chronic thromboembolic pulmonary hypertension (CTEPH):[4]


ECGs may provide suggestive or supportive evidence of PH by demonstrating right ventricular (RV) hypertrophy, RV strain, right axis deviation, P pulmonale and QTc prolongation.[4]

Echocardiography (echo)


provides information on right heart structure and function, and should always be performed in cases of suspected PH.[4]

Chest radiography

Chest radiographs may show evidence of right atrial and RV enlargement, as well as pulmonary arterial dilatation. They may also show signs of the underlying disease (e.g. lung disease).[4]

Pulmonary function test

Pulmonary function tests and arterial blood gas samples may help identify the contribution of underlying airway or parenchymal lung disease.[4]


CT imaging can provide information such as pulmonary arterial diameter and clues as to the type of PAH (e.g. cardiac defects, oesophageal dilation in scleroderma). High-resolution CT provides detailed views of the lung parenchyma and facilitates the diagnosis of interstitial lung disease and emphysema.[4]

V/Q scan

A V/Q lung scan is used to exclude CTEPH. Where there is evidence of multiple segmental perfusion defects, a diagnosis of CTEPH should be suspected. The final diagnosis of CTEPH requires CT pulmonary angiography, RHC and selective pulmonary angiography.[4]

The role of echo and RHC

Echocardiography (echo) is a key screening tool in the diagnosis of PAH, while right heart catheterisation (RHC) is the gold standard for confirming the diagnosis of PAH.[5][6]

Echo assessment of PAH

Echo should always be performed when PAH is suspected. It may be used to infer a diagnosis of PAH in patients when multiple echo parameters consistent with a diagnosis of PAH are met.[4]

Echo can provide an estimate of the RV systolic pressure, which is equivalent to the systolic pulmonary arterial pressure. Tricuspid regurgitation velocity (TRV) and the presence of other echocardiographic signs should be combined to estimate the probability of PAH. Ensuring adequate right heart assessment assists not only in the diagnosis of PAH but also in monitoring disease progression and/or treatment response.[4]

Based on echocardiographic parameters (peak TRV and the presence of other echocardiographic PH signs), this table gives the echocardiographic probability (low, intermediate or high) of PH.[4]


Adapted from Galiè et al. 2016[4]

This table describes the echocardiographic signs suggestive of PH used to assess the probability of PH.[4]


Adapted from Galiè et al. 2016[4]

*Echocardiographic signs from at least two different categories (A/B/C) from the list should be present to alter the level of echocardiographic probability of PH.[4]


RHC is required for the definitive diagnosis of PAH.[4] RHC involves directing a catheter into the right side of the heart to assess cardiopulmonary haemodynamics.[4]

Diagnostic criteria of PAH measured by RHC:[4]
• Mean pulmonary arterial pressure (mPAP) ≥25 mmHg
• Pulmonary arterial wedge pressure (PAWP) ≤15 mmHg
• Pulmonary vascular resistance (PVR) >3 Wood units
• Excluding other causes of pre-capillary PH

Continue reading

What is PAH

Learn more about PAH, including its clinical classification and various subtypes.

PAH screening & Referral

Find out about the different screening strategies used in at-risk patients. Patients with suspected PAH should be referred to a specialist centre for further investigation.

CT, computed tomography; CTEPH, chronic thromboembolic pulmonary hypertension; DLCO, carbon monoxide diffusing capacity; ECG, electrocardiogram; ERS, European Respiratory Society; ESC, European Society of Cardiology; HIV, human immunodeficiency virus; HPAH, heritable pulmonary arterial hypertension; HRCT, high-resolution computed tomography; mPAP, mean pulmonary arterial pressure; PA, pulmonary artery; PAH, pulmonary arterial hypertension; PAWP, pulmonary arterial wedge pressure; PFT, pulmonary function test; PH, pulmonary hypertension; PVR, pulmonary vascular resistance; RHC, right heart catheterisation; RV, right ventricular; TRV, tricuspid regurgitation velocity; V/Q, ventilation/perfusion