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 d elivery to working muscles. The Dead Sea, the lowest site on earth, is dist inguished by natural oxygen enrichment, low humidity, high barometric press ure, and temperature with increased bromide and magnesium concentrations in the inspired air, The aim of this study is to examine the effects of desce nt to the Dead Sea on patients with CHF. Twelve patients with CHF and 4 age -matched healthy controls underwent complete echocardiographic studies at r est as well as treadmill and metabolic stress tests, both in Haifa, 130 m a bove sea level and 3 days after descent to the Dead Sea, 402 m below sea le vel. Significant changes in parameters at the Dead Sea compared with Haifa included time on treadmill, which increased from 612 +/- 198 to 672 +/- 186 seconds (p <0.05); the Borg scale decreased by 1 to 2 grades (p <0.05); an d 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). Card iac output at rest increased by 300 ml/min (p <0.05). Maximum oxygen consum ption (VO(2)max) increased by 126 ml/min (p <0.05), and even more so in pat ients with more severe exercise-induced oxygen desaturations, which was ass ociated 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. (C)1999 by Excerpta Medico, Inc.