Effect of Altitude on the Heart and the Lungs

Abstract

T his review focuses on the effects of altitude exposure from 1 to several days or weeks as occurs in tourists, trekkers, and mountaineers who visit high altitude and normally reside near sea level.We briefly review the acute physiological adjustments and early acclimatization that occur in the cardiovascular system and the lungs of healthy individuals.These ensure life-sustaining oxygen delivery to the tissues despite a reduction in the partial pressure of inspired oxygen between 20% and 60% at 2500 and 8000 m, respectively.One of the acute adjustments, hypoxic pulmonary vasoconstriction (HPV), may be disadvantageous in those with a vigorous response and lead to 2 potentially lethal illnesses, high-altitude pulmonary edema (HAPE) and subacute mountain sickness (SAMS), which we present in more detail.Finally, on the basis of knowledge about the acute physiological adjustments and acclimatization and, when available, a review of the literature, we discuss the highaltitude tolerance of patients with coronary artery disease, congestive heart failure, arrhythmias, systemic hypertension, and pulmonary hypertension. HeartThe consequences of acute hypoxia are an increase in heart rate (both at rest and on exercise), myocardial contractility, and cardiac output for the first few days.With acclimatization, cardiac output falls at rest and on exercise in association with a decrease in left ventricular work but an increase in right ventricular work.