Response of Aortic and Peripheral Hemodynamics and Arterial Stiffness to Acute Normobaric Hypoxia in Alpinists before and after Prolonged Stay in the Mountains
The study was performed to investigate whether resistance to acute normobaric hypoxia and cardiotropic effects of high altitude remain in lowlands. Ten experienced male alpinists were examined at sea level before and 2–4 weeks after a 20-day stay at a height of 4000–7000 m. The tests were performed in three functional states: at rest, in acute 17-min hypoxia (10% O<sub>2</sub>, 80% mean blood oxygen saturation at the end of the bout) and after 12-min recovery. The tests included the applanation tonometry and pulse wave analysis. Before the high altitude stay, we observed an increase in the heart rate, arterial compliance (assessed by the augmentation index) and a decline in subendocardial viability ratio during the acute hypoxic test. After the high altitude stay, arterial elasticity was increased; aortic and peripheral blood pressure was reduced. The left ventricle was unloaded, which improved its diastolic perfusion at rest and during acute hypoxia. Thus, high altitude had long-term positive cardiovascular effect.