17th January 2024

Diagnosis

Once there is clinical suspicion of pulmonary hypertension, patients are often referred to a regional specialist pulmonary hypertension centre for focused investigation and access to a multidisciplinary approach. Depending on the level of clinical suspicion, there are many investigations that can be undertaken.

Investigations

• Blood tests, including FBC, U&E, LFT, TFTs, a full autoimmune screen and thrombophilia screening – whilst these are not diagnostic, they can point towards the aetiology. NT-proBNP is also measured and used as an independent marker of severity in pulmonary hypertension.
• Electrocardiogram (ECG) – can often be normal, but ECG changes associated with right ventricular strain are common, including p pulmonale, right axis deviation, right bundle branch block and QTc prolongation. In advanced disease, there is often also an association with atrial arrhythmias.
• Chest radiograph – can show features of right atrial and ventricular enlargement, pulmonary arterial dilatation as well as clues to the underlying cause of the pulmonary hypertension.
• Pulmonary function tests – most commonly, patients with pulmonary hypertension have a reduced carbon monoxide lung diffusion capacity (transfer factor, or TLCO). Obstructive and restrictive defects from co-existing or related airways or interstitial lung disease can also aid with diagnosis but are best interpreted in the context of cross-sectional imaging.
• Arterial blood gas
• Transthoracic echocardiography – can be used to support a diagnosis of pulmonary hypertension, but, like all of the above tests, is not strictly diagnostic. Peak tricuspid regurgitation velocity is used as a substitute marker for pulmonary arterial pressures – a value of >3.4m/s is highly suggestive of the diagnosis. Other suggestive features include right atrial and ventricular dilatation, pulmonary regurgitation and flattening of the interventricular septum.
• Ventilation/perfusion scan – identifies patients with unmatched perfusion defects as the underlying cause of pulmonary hypertension, indicating CTEPH
• High-resolution computed tomography and pulmonary angiography (HRCT/CTPA) – cross-sectional imaging can reveal features of pulmonary hypertension, such as right ventricular or pulmonary artery dilatation, but is also essential in investigating the underlying cause, such as lung disease or CTEPH. CTPA can help identify the subset of patients with CTEPH who may benefit from intervention with pulmonary endarterectomy.
• Cardiac magnetic resonance imaging (CMRI) – provides detailed assessment of the right ventricular structure as well as function, which can strongly support a diagnosis of pulmonary hypertension but cannot be used to exclude it.
• Abdominal ultrasound scan – to look for the complication of portal hypertension
• Right heart catheterisation – this is the gold standard test for diagnosis. It allows for direct measurement of pulmonary arterial pressures and oxygen saturation levels within the internal vena cava. Left heart catheterisation is often performed at the same time, as it is a requirement for patients likely to proceed to pulmonary endarterectomy, and can be useful diagnostically in patients where left heart disease is a suspected cause.
• 6-minute walking test – used as a marker of severity once the diagnosis has been made. Measures simply the maximum walking distance a patient achieves in the set 6-minute time frame.
• Cardiopulmonary exercise testing (CPET)