Studies on the structure of the pulmonary trunk. III. The thickness of the media of the pulmonary trunk and ascending aorta in high altitude natives.

Measurements of the thickness of the media of the pulmonary trunk and ascending aorta were made in 200 normal autopsy cases ranging in ages from birth to 80 years. One hundred cases were persons who were born and lived permanently in places between 11,300 to 14,900 feet above sea level. One hundred persons of comparable ages, born at sea level, served as control. It is shown that at high altitudes the pulmonary trunk exhibits a thicker media than at sea level, in the course of the whole of life. This fact is explained by the occurrence, at high altitudes, of a mild degree of pulmonary arterial hypertension from birth. The media of the ascending aorta of high altitude natives was found to be thinner than that of sea level inhabitants, after 30 years. This characteristic appears to be related to the existence of a lower systolic pressure at high altitudes than at sea level.