What are the diagnostic criteria for pulmonary hypertension?

From the Guidelines

Pulmonary hypertension is diagnosed when the mean pulmonary arterial pressure (mPAP) is greater than 20 mmHg at rest, as measured by right heart catheterization, with additional criteria including a pulmonary artery wedge pressure of ≤15 mmHg and a pulmonary vascular resistance of >3 Wood units for pre-capillary pulmonary hypertension. This diagnosis is based on the most recent guidelines, including the 2022 update from the American College of Radiology 1. The diagnostic process typically begins with an echocardiogram as a screening tool, which can estimate pulmonary pressures non-invasively by measuring tricuspid regurgitation velocity. However, right heart catheterization remains the gold standard for definitive diagnosis.

Some key points to consider in the diagnosis of pulmonary hypertension include:

• The importance of assessing pulmonary vascular resistance (PVR) in addition to mPAP, with a value greater than 3 Wood units indicating pre-capillary pulmonary hypertension 1.
• The use of echocardiography as a screening tool, with right heart catheterization used for definitive diagnosis 1.
• The need for additional testing, such as pulmonary function tests, ventilation-perfusion scanning, chest imaging (CT or MRI), blood tests for connective tissue diseases, HIV testing, liver function tests, and sleep studies, to identify the underlying cause of pulmonary hypertension 1.

It's worth noting that the diagnostic criteria for pulmonary hypertension have evolved over time, with the threshold for mPAP decreasing from 25 mmHg to 20 mmHg in 2018 1. This change reflects the growing understanding of the disease and the importance of early diagnosis and treatment.

In terms of specific diagnostic criteria, the 2018 updated clinical classification of pulmonary hypertension includes five groups:

• Group 1: Pulmonary arterial hypertension (PAH)
• Group 2: PH due to left heart disease
• Group 3: PH due to lung diseases and/or hypoxia
• Group 4: PH due to PA obstructions
• Group 5: PH with unclear and/or multifactorial mechanisms 1.

Overall, the diagnosis of pulmonary hypertension requires a comprehensive approach, including clinical evaluation, imaging studies, and hemodynamic assessment. Early diagnosis is crucial, as pulmonary hypertension is a progressive condition that can lead to right heart failure if left untreated, and treatment options vary significantly depending on the specific type and cause of pulmonary hypertension 1.

From the Research

Diagnostic Criteria for Pulmonary Hypertension

The diagnostic criteria for pulmonary hypertension (PH) are based on hemodynamic parameters, including mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure (PAWP), and pulmonary vascular resistance (PVR) 2, 3, 4. The key criteria are:

• mPAP > 20 mmHg
• PAWP ≤ 15 mmHg for pre-capillary PH
• PVR > 2 Wood units (WU) for pre-capillary PH
• PAWP > 15 mmHg for post-capillary PH
• PVR ≤ 2 WU for isolated post-capillary PH
• PAWP > 15 mmHg and PVR > 2 WU for combined post- and pre-capillary PH

Classification of Pulmonary Hypertension

PH is classified into five clinical groups based on etiology, pathophysiology, and treatment 3, 4, 5:

• Group 1: Pulmonary arterial hypertension (PAH)
• Group 2: PH associated with left-sided heart disease
• Group 3: PH associated with lung disease
• Group 4: PH associated with pulmonary artery obstructions (e.g., chronic thromboembolic PH)
• Group 5: PH with unclear and/or multifactorial mechanisms

Diagnostic Approach

The diagnostic approach for PH involves a stepwise process, including non-invasive tests and invasive hemodynamic assessment with right heart catheterization 2, 4. The main aim is to discern patients who need to be referred to a PH center and undergo invasive hemodynamic assessment. In cases of high probability of severe pulmonary vascular disease, especially with signs of right heart failure, a fast-track referral to a PH center is recommended.

Key Parameters for Diagnosis

The key parameters for diagnosing PH include:

• mPAP
• PAWP
• PVR
• Cardiac output (CO)
• Pulmonary artery pressure/cardiac output slope during exercise (for exercise PH) 4