From the Guidelines
The diagnostic criteria for pulmonary hypertension using right heart catheterization is a mean pulmonary arterial pressure (mPAP) greater than or equal to 20 mmHg at rest, as defined by the most recent guidelines 1. This represents a change from the previous threshold of 25 mmHg, which was revised in 2018 based on evidence that even mildly elevated pressures between 20-24 mmHg are associated with increased mortality and disease progression. Right heart catheterization is considered the gold standard for diagnosing pulmonary hypertension as it provides direct measurement of pressures within the pulmonary circulation. During the procedure, a catheter is inserted through a vein and advanced into the right side of the heart and pulmonary arteries to measure pressures. Additional hemodynamic parameters that should be assessed include:
- Pulmonary vascular resistance (PVR), which is considered elevated when greater than 3 Wood units
- Pulmonary arterial wedge pressure (PAWP), which helps differentiate between pre-capillary and post-capillary pulmonary hypertension Pre-capillary pulmonary hypertension is characterized by PAWP ≤ 15 mmHg, while post-capillary has PAWP > 15 mmHg. These measurements are essential for proper classification of pulmonary hypertension and subsequent treatment decisions, as outlined in the guidelines 1. It is also important to note that the diagnosis of pulmonary hypertension should be made in expert centers, as it is technically demanding and may be associated with serious complications 1. The classification of pulmonary hypertension into different groups, such as group 1 (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), and group 5 (PH with unclear and/or multifactorial mechanisms), is also crucial for guiding treatment decisions 1.
From the Research
Diagnostic Criteria for Pulmonary Hypertension
The diagnostic criteria for pulmonary hypertension using right heart catheterization to measure pulmonary arterial pressure are as follows:
- Mean pulmonary artery pressure (PAPm) > 25 mmHg, as defined by the European Society of Cardiology guidelines 2
- A distinction between pre- and post-capillary PH is made based on levels of pulmonary artery wedge pressure (PAWP) 2
- Right atrial pressure (RAP), cardiac index (CI), and mixed venous oxygen saturation (SvO2) are used to assess prognosis in patients with pulmonary arterial hypertension (PAH) 2
Classification of Pulmonary Hypertension
Pulmonary hypertension is classified into 5 clinical groups based on etiology, pathophysiology, and treatment 3
- Pulmonary arterial hypertension (PAH) is a subtype of pulmonary hypertension, characterized by pulmonary arterial remodeling 3
- PAH is hemodynamically defined by right heart catheterization demonstrating a mean pulmonary artery pressure greater than 20 mm Hg, a pulmonary artery wedge pressure of 15 mm Hg or lower, and a pulmonary vascular resistance of 3 Wood units or greater 3
Prognostic Parameters
Prognostic parameters for pulmonary hypertension include:
- Right atrial pressure (RAP) > 14 mmHg 2
- Cardiac index (CI) < 2.0 l/min/m2 2
- Mixed venous oxygen saturation (SvO2) < 60% 2
- Patients with these parameters are at high (> 10%) risk of death within the next year 2
Right Heart Catheterization
Right heart catheterization is a safe and essential procedure for the diagnosis and management of pulmonary hypertension 4, 5
- Significant expertise is required for safely performing a full right heart catheterization and for the acquisition of reliable and reproducible information 5
- Physicians performing a right heart catheterization should have adequate training in vascular access, catheter insertion, and manipulation, as well as in the interpretation of waveforms, potential pitfalls, and strict quality control 5