Intracardiac Shunting across a Patent Foramen Ovale May Exacerbate Hypoxemia in High-Altitude Pulmonary Edema

Excerpt Rapid ascent to altitude in susceptible persons may result in severe hypoxemia, pulmonary hypertension, and even pulmonary edema. This life-threatening syndrome affects approximately 1% of climbers who rapidly ascend to more than 3000 m (1). The underlying mechanisms for this problem have yet to be determined. We used bubble contrast and Doppler echocardiography on 12 climbers at 4200 m on Mount McKinley, Alaska, to test the hypothesis that a patent foramen ovale may provide an avenue for right-to-left shunting during high-altitude-induced hypoxia and pulmonary hypertension, resulting in disproportionate hypoxemia and contributing to the development of high-altitude pulmonary edema. Patient and