Altitude-Induced Pulmonary Hypertension on One-Day Rapid Ascent of Mount Fuji: Incidence and Therapeutic Effects of Sildenafil

Aims: Exposure to high altitudes especially with rapid ascent may induce hypoxic pulmonary vasoconstriction (HPV) and pulmonary hypertension (PH) possibly leading to life-threatening high-altitude pulmonary edema (HAPE). The aim of the study was to evaluate the incidence of PH on a 1-day rapid ascent up Mount Fuji (3775 m) in recreational climbers and also to determine the effectiveness of sildenafil for this rapid ascent-induced PH as measured by echocardiography. Methods and results: Twenty-five subjects who climbed Mount Fuji showed significantly increased pulmonary artery systolic pressure (PASP) from 22.3 ± 5.3 mmHg at sea level to 29.4 ± 8.7 mmHg at 3775 m. Five subjects showed PASP >35 mmHg (35.6–46.2 mmHg, average 42.0 ± 3.9 mmHg) and took oral sildenafil 50 mg after which PASP decreased significantly to 24.5 ± 4.6 mmHg (18.7–31.0 mmHg) after 30 minutes. Conclusions: One-day rapid ascent of Mount Fuji may induce mild-to-moderate PH and intervention with sildenafil can reduce this PH, suggesting that the therapeutic use of sildenafil would be more reasonable for the relatively infrequent occurrence of altitude-induced PH than its prophylactic use.