Which statement defines pulmonary hypertension?

• A. Mean pulmonary artery pressure >25 mmHg on right heart catheterization
• B. Wedge pressure >15 mmHg
• C. PO2 < 80 mmHg on room air
• D. Pulmonary capillary leak on imaging

Answer: (A)

Pulmonary hypertension is defined by elevated pressure in the pulmonary arterial system, best confirmed by direct measurement with right heart catheterization. The benchmark used is a mean pulmonary artery pressure greater than 25 mmHg at rest, which reflects that the pulmonary vascular resistance is high enough to challenge the right ventricle. This invasive measurement is the gold standard for diagnosing PH, since noninvasive clues like symptoms or imaging can be misleading.

Understanding the other statements helps clarify why they don’t define PH. A wedge pressure above 15 mmHg points to elevated left-sided filling pressures, which classifies PH as post-capillary (due to left heart disease) rather than defining PH itself. Low PO2 indicates hypoxemia, not the pulmonary arterial pressure. Imaging showing pulmonary capillary leak suggests edema or capillary injury but does not establish the hemodynamic threshold that defines PH.