The Terminal Portion of the Pulmonary Arterial Tree in People Native to High Altitudes

Abstract

Hemodynamic studies have disclosed that people born and living at high altitudes present a mild degree of pulmonary arterial hypertension and increased vascular resistance. Since the small muscular branches of the pulmonary arterial tree are primarily concerned in determining vascular resistance a study of their characteristics is here presented. Two series of autopsies were investigated. One from Cerro de Pasco at 14,300 feet above sea level, and the other, used as control, from Lima at sea level. Cases were arranged in 2 age groups: from 1 month to 2 years and from 6 to 76 years. Subjects of approximately matching ages were considered in both series. A more extensive muscularization of the peripheral pulmonary arterial branches at all ages: true hypertrophy of the proximal pulmonary arteries in adults; and evidence that some degree of vasocon-striction occur in the distal arteries in younger ages, were found in the high altitude series. The factors which probably give rise to these changes are discussed. It is believed that the results give an anatomical basis for understanding the genesis of high altitude pulmonary hypertension.