Response of Aortic and Peripheral Hemodynamics and Arterial Elasticity to Acute Normobaric Hypoxia in Alpinists before and after a Prolonged Stay in Mountains

Resumo

The study was aimed at determining whether the cardiotropic effects elicited by staying in highlands and the resistance to acute normobaric hypoxia are preserved after returning to the lowlands. Ten trained male alpinists were investigated twice before and one to three weeks after a 20-day stay at altitudes of 4000–7000 m. They were investigated in the lowlands in three functional states: at rest, after a 17-min exposure to a hypoxic mixture (10% O₂ and the group mean blood oxygen saturation at 80% at the end of the procedure), and after a 12-min recovery period. Applanation tonometry and pulse-wave analysis have shown increases in heart rate (HR) and the elasticity of major arteries of the limbs in terms of augmentation index; a decline in the subendocardial viability ratio (SEVR) was diagnosed during the acute hypoxic test before the ascent. Staying in the mountains increases arterial elasticity, decreases aortic and peripheral blood pressure, discharges the left ventricle, and thus improves its diastolic perfusion at rest and in acute hypoxia, which evidences delayed positive cardiovascular effects of high altitude conditions.