Cardiovascular and neuroendocrine responses to water immersion in compensated heart failure

The hypothesis was tested that cardiovascular and neuroendocrine (norepinephrine, renin, and vasopressin) responses to central blood volume expansion are blunted in compensated heart failure (HF). Nine HF patients [New York Heart Association class II–III, ejection fraction = 0.28 ± 0.02 (SE)] and 10 age-matched controls (ejection fraction = 0.68 ± 0.03) underwent 30 min of thermoneutral (34.7 ± 0.02°C) water immersion (WI) to the xiphoid process. WI increased (P < 0.05) central venous pressure by 3.7 ± 0.6 and 3.2 ± 0.4 mmHg and stroke volume index by 12.2 ± 2.1 and 7.2 ± 2.1 ml · beat−1 · m−2 in controls and HF patients, respectively. During WI, systemic vascular resistance decreased (P < 0.05) similarly by 365 ± 66 and 582 ± 227 dyn · s · cm−5 in controls and HF patients, respectively. Forearm subcutaneous vascular resistance decreased by 19 ± 7% (P < 0.05) in controls but did not change in HF patients. Heart rate decreased less during WI in HF patients, whereas release of norepinephrine, renin, and vas...