[Staying at high altitudes and plane travel for heart patients]

In a normal lung at an altitude of 2000 meters the pO2 in the alveolar air is 77 mm Hg. At 3800 meters it drops to 57 mm Hg. In the healthy individual increasing hypoxia leads to hypoxemia, tachycardia at low levels of exercise, increased sympathetic tone, pulmonary hypertension and, in some instances, retention of water. Under these circumstances acute mountain sickness or high altitude pulmonary edema may occur. In patients with marginal cardiocirculatory function these effects of hypoxia are potentially dangerous and may lead to cardiac decompensation. Patients with coronary artery disease, congestive heart failure, arrhythmias, pulmonary hypertension and valvular heart disease can tolerate altitude and air travel only if, with adequate therapy, they are either asymptomatic or only slightly symptomatic at rest, or if they show some functional reserve during exercise testing.