Pulmonary Hypertension Classification and Diagnosis

Pulmonary hypertension is a medical condition characterized by increased blood pressure in the pulmonary arteries, which can be caused by a variety of clinical factors. These include damage to the pulmonary vascular bed, increased pulmonary vascular resistance, left heart system changes, and hypoxia-induced vascular resistance. In some cases, the exact cause remains unknown. These contributing factors lead to elevated pulmonary vascular resistance, which in turn raises pulmonary artery pressure.

Defining Pulmonary Hypertension

In clinical settings, pulmonary hypertension is typically defined based on measurements taken during right heart catheterization under resting conditions at sea level. A mean pulmonary artery pressure greater than 25 mmHg is considered elevated. This classification is further broken down into categories: mild elevation (26–35 mmHg), moderate elevation (36–45 mmHg), and severe elevation (>46 mmHg). These classifications help guide treatment and prognosis.

Diagnostic Methods for Assessing Pulmonary Pressure

The gold standard for evaluating pulmonary artery pressure is right heart catheterization. This procedure provides the most accurate and direct measurement of pulmonary hemodynamics. However, not all medical facilities have the capability to perform this test. In such cases, echocardiography may be used as an alternative, assessing pressure indirectly through the measurement of tricuspid or pulmonary valve regurgitation gradients.

Limitations of Non-Invasive Methods

While echocardiography is a valuable tool for initial assessment and monitoring, it provides only an estimate of pulmonary artery pressure and is not considered as accurate as right heart catheterization. Therefore, for a definitive evaluation of pulmonary hypertension severity, especially in clinical decision-making, right heart catheterization under resting conditions remains essential.