Effects of low altitude on exercise performance in patients with congestive heart failure after healing of acute myocardial infarction.

Patients with chronic congestive heart failure (CHF) have impaired oxygen delivery to working muscles. The Dead Sea, the lowest site on earth, is distinguished by natural oxygen enrichment, low humidity, high barometric pressure, and temperature with increased bromide and magnesium concentrations in the inspired air. The aim of this study is to examine the effects of descent to the Dead Sea on patients with CHF. Twelve patients with CHF and 4 age-matched healthy controls underwent complete echocardiographic studies at rest as well as treadmill and metabolic stress tests, both in Haifa, 130 m above sea level and 3 days after descent to the Dead Sea, 402 m below sea level. Significant changes in parameters at the Dead Sea compared with Haifa included time on treadmill, which increased from 612+/-198 to 672+/-1 86 seconds (p <0.05); the Borg scale decreased by 1 to 2 grades (p <0.05); and oxygen saturation increased by 3% throughout exercise (p <0.05). Systolic blood pressure decreased by 9 mm Hg at rest (p <0.05) and increased by 14 mm Hg at peak exercise at the Dead Sea in patients with CHF (p <0.05). Cardiac output at rest increased by 300 ml/min (p <0.05). Maximum oxygen consumption (VO2max) increased by 126 ml/ min (p <0.05), and even more so in patients with more severe exercise-induced oxygen desaturations, which was associated with lower peak minute ventilation to CO2 production ratio (p <0.05). Thus, descent to the Dead Sea acutely improved exercise performance due to better oxygenation and loading conditions in patients with CHF.