Alterations in left ventricular function in normal man on exposure to high altitude (3658 m).

Abstract

Left ventricular function was estimated by noninvasive methods in 83 normal volunteers at sea level, at an altitude of 3658 m for 10 days, and on return to sea level. Of these subjects, 50 reached high altitude by air in 55 minutes and the rest by road in 6 hours. Controls comprised 56 permanent residents of high altitude and 59 lowlanders resident at high altitudes for 120 to 180 days. Simultaneous recording of electrocardiogram, phonocardiogram, carotid pulse, and first derivative of electrical im- pedance cardiogram yielded data in respect of pre-ejection period (PEP), left ventricular ejection time (LVET), PEP/LVET ratio, RZ interval, contractility index ( dZ/dt ) stroke index, and cardiac index. A statistically significant reduction of stroke index, cardiac index, and depression of all indices of left ventricular function was observed from the second day of induction to high altitude despite increased urinary catecholamine excretion. On return to sea level all the values returned to normal by the third day. Permanent residents of high altitude had normal left ventricular function and temporary residents a moderate depression. These findings suggest that left ventricular dysfunction occurs on induction to high altitude.