Pulmonary Hypertension and Congenital Heart Defects at High Altitude

Abstract

Around 140 million people in the world, including 4.9 million Bolivians, live 2,500 m above sea level. The barometric pressure and the partial pressure of oxygen in the blood fall in direct proportion to the altitude. The time necessary for a person living at sea level to adapt to the altitude depends, in direct proportion, on the altitude at which that person arrives. Living, working, and playing sports at high altitudes are considered by many a great feat. In fact, there is controversy about the feasibility of playing competitive sports in cities located at very high altitudes. However, native inhabitants may play soccer at altitudes even higher than the summit of Mt Sajama, located 6,000 m above sea level. Traveling to high altitudes as a lowland immigrant is considered a risk. In one renowned article, discussing altitude, it was stated that the altitude causes more than mere muscular fatigue; it affects memory, calculating capacity, decision-making ability, and judging capacity. What are the adaptive mechanisms that help people live and work with relative normality in these high regions? Many working groups have worked to understand the physiological mechanisms of adaptation to the altitude for newcomers and the connotations of living in mountains for many generations. These studies have dealt not only with hypobaric hypoxia, but also with lower temperatures, low humidity levels, and increased solar radiation. Temperature and the amount of UV radiation also vary with the altitude: the temperature decreases by 6.5 degrees C per 1,000 m and the amount of radiation increases at a rate of 4\% per 1,000 m. However, the inhabitant at high altitudes has found a balance based on adaptive processes. With regard to congenital heart defects, the factors mentioned previously, combined with the lower socioeconomic level, have contributed to a higher incidence of these types of disorders at altitude.