TY - JOUR
T1 - Enhanced left ventricular systolic performance at high altitude during operation everest II
AU - Suarez, Jose
AU - Alexander, James K.
AU - Houston, Charles S.
N1 - Funding Information:
From the Departments of Medicine, Cardiology Section, Baylor College of Medicine, Houston, Texas, and University of Vermont, Burlington, Vermont. This study was supported by Contract DAMD17-85-5208 from the Army Research and Development Command, and the Arctic Institute of North America. Computational assistance was provided by the CLINFO Project, Grant RR-00350, from the Division of Research Resources of the National Institutes of Health, Bethesda, Maryland. Manuscript received December 8,1986; revised manuscript received February 10,1987, accepted February 17,1987. Address for reprints: James K. Alexander, MD, 6560 Fannin, Suite 817, Houston, Texas 77030.
PY - 1987/7/1
Y1 - 1987/7/1
N2 - Serial rest and upright cycle exercise 2-dimensional echocardiographic studies were performed in 7 healthy young men during acclimatization to a simulated altitude of 29,000 feet (barometric pressure [PB] 240 torr) in a chamber for 40 days. In all subjects left ventricular (LV) end-diastolic, end-systolic and stroke volumes progressively decreased, with mean reductions of 21%, 40% and 14%, respectively, on ascent to 25,000 feet (PB 282 torr) at rest, and reductions of 23%, 43% and 14% during 60-W exercise. At PB 282 torr, mean arterial blood O2 partial pressures were 37 torn (rest) and 32 torr (exercise), with corresponding 02 saturations of 68% and 59%. All 3 indexes of LV systolic function examined-ejection fraction, ratio of peak systolic pressure to end-systolic volume and mean normalized systolic ejection rate at rest-were sustained in all subjects at high altitude despite reduced preload, pulmonary hypertension and severe hypoxemia. Increases in ejection fraction of 6 % at rest and 10% during exercise developed at PB 282 torr and a higher mean normalized systolic ejection rate in association with elevated circulating catecholamines reflecting enhanced sympathetic activity. LV systolic function is not a limiting factor in compromising the exercise capacity of normal humans on ascent to high altitude, even to the peak of Mt. Everest.
AB - Serial rest and upright cycle exercise 2-dimensional echocardiographic studies were performed in 7 healthy young men during acclimatization to a simulated altitude of 29,000 feet (barometric pressure [PB] 240 torr) in a chamber for 40 days. In all subjects left ventricular (LV) end-diastolic, end-systolic and stroke volumes progressively decreased, with mean reductions of 21%, 40% and 14%, respectively, on ascent to 25,000 feet (PB 282 torr) at rest, and reductions of 23%, 43% and 14% during 60-W exercise. At PB 282 torr, mean arterial blood O2 partial pressures were 37 torn (rest) and 32 torr (exercise), with corresponding 02 saturations of 68% and 59%. All 3 indexes of LV systolic function examined-ejection fraction, ratio of peak systolic pressure to end-systolic volume and mean normalized systolic ejection rate at rest-were sustained in all subjects at high altitude despite reduced preload, pulmonary hypertension and severe hypoxemia. Increases in ejection fraction of 6 % at rest and 10% during exercise developed at PB 282 torr and a higher mean normalized systolic ejection rate in association with elevated circulating catecholamines reflecting enhanced sympathetic activity. LV systolic function is not a limiting factor in compromising the exercise capacity of normal humans on ascent to high altitude, even to the peak of Mt. Everest.
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U2 - 10.1016/0002-9149(87)91000-9
DO - 10.1016/0002-9149(87)91000-9
M3 - Article
C2 - 3604926
AN - SCOPUS:0023191005
SN - 0002-9149
VL - 60
SP - 137
EP - 142
JO - The American journal of cardiology
JF - The American journal of cardiology
IS - 1
ER -