Search

On rapidly ascending to high altitudes, approximately one percent of people suffer severe symptoms, such as extremely low blood oxygen levels, pulmonary hypertension (elevated pressures in the circulation of the lungs), and pulmonary edema, an often life-threatening collection of fluid in the lungs. One physical abnormality that might account for this phenomenon is the presence of a patent foramen ovale, an opening between the right and left sides of the heart that usually closes at birth, but can be patent (remain open) in 10 to 30 percent of people. A study was conducted on Mount McKinley to test this theory. A 42-year-old woman who developed severe high altitude symptoms was evacuated to sea level. She climbed again much more slowly, taking 12 days to achieve the same altitude. Upon arrival at the summit, she was tested to assess her blood oxygen level, which was found to be abnormally low, and her pulmonary pressures, which were abnormally high. She later had an echocardiogram which showed shunting of blood from the right to the left side, which is consistent with a patent foramen ovale. Similar echocardiogram results were found in several other patients who had altitude sickness, and two who did not. A patent foramen ovale is a plausible contributor to high altitude sickness. (Consumer Summary produced by Reliance Medical Information, Inc.)