Cardiocirculatory adaptation to chronic hypoxia: comparative study of coronary flow, myocardial oxygen consumption and efficiency between sea level and high altitude residents
Moret, P.; Covarrubias, E.; Coudert, J.; Duchosal, F.
Acta Cardiologica 27(2): 283-305
1972
ISSN/ISBN: 0001-5385 PMID: 4537818 Document Number: 5059
Adaptations to hypoxia and the capacity for effort of persons living in the Himalayas and the high plateaus of the Andes have intrigued physiologists and clinicians for many years. A study of the behaviour and adaptation of the cardiovascular system among men living at three different altitudes was undertaken in Lima, Peru (150 meters or 492 feet), La Paz, Bolivia (3,700 meters or 12,130 feet) and Cerro de Pasco. Peru (4,375 meters or 14,350 feet). Fifty-three normal men, labourers aged 18 to 36 years, were examined for cardiac output, pulmonary and systemic pressure and resistance, and blood gases. Myocardial metabolism (oxygen, lactate, pyruvate, free fatty acids, and some enzymes) was specifically studied in 43 of these subjects. Direct measurement of coronary flow by the Kety and Schmidt method was performed on 23 The present report is concerned with the coronary flow, myocardial oxygen consumption, and myocardial efficiency in these. Resting coronary flow in men residing permanently in high altitudes is found to he significantly lower than in those living at sea level. Myocardial oxygen consumption is also significantly lower. Left ventricular work is practically the same at all three levels, and myocardial efficiency is approximately 30 per cent greater at high altitudes. The lower coronary flow at high altitudes is not adequately explained by different regulation of coronary vascular resistance, by hyperventila. tion or by an increase of oxygen transport capacity resulting from the higher hemoglobin level. It is possibly due to decreased oxygen consumption from cellular adaptation to chronic hypoxia. There are no signs of insufficient coronary flow at high altitudes or of the metabolic disturbances as manifested by patients with chronic cor pulmonale.
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