The Changes in Heart Size in Man During Partial Acclimatization to Simulated High Altitudes

Abstract

The heart size, as shown in serial roentgenograms, was determined in the case of 4 young volunteers who were continuously exposed to simulated high altitude over a period of one month. Sufficient adaptation occurred to allow them to remain at progressively higher altitudes up to 22,500 feet. A slight decrease in heart size was observed at all altitudes. This was thought to be due to decreased cardiac filling or smaller stroke volume or both. Doubt is expressed regarding the oft repeated statement that the heart in healthy persons exposed to anoxia readily increases in size.