Cardiac Effects of Water Immersion in Healthy Volunteers

To evaluate cardiac chamber size and ejection fraction during head-out immersion of patients in the semisitting position in neutral temperature water bath, 12 volunteers were studied using transthoracic echocardiography (TTE). In this open, controlled, prospective clinical study, left ventricular end-systolic, end-diastolic volumes, and ejection fraction were measured in 12 adult awake healthy volunteers using TTE with the patient in a semisitting position pre-, during, and postimmersion in the Dornier extracorporeal shock wave lithotriptor water bath at 35 degrees C. Left ventricular end-diastolic volume significantly increased from an average of 96.0 +/- 10.8 to 130 +/- 19 cm(3), P < 0.0001 and left ventricular end-systolic volume increased from an average 38.9 +/- 6.9 to 45.2 +/- 8.0 cm(3), P < 0.01. Left ventricular ejection fraction increased significantly from control to water immersion from 0.59 +/- 0.1% to 0.65 +/- 0.1% (P < 0.001). The results of this study demonstrate that water immersion in normal healthy volunteers significantly increases both left ventricular diastolic and systolic volume, and that there is a significant increase in left ventricular ejection fraction after water immersion, (e.g., bathing, lithotripsy). While this increased cardiac filling is well-tolerated in most patients, it may not be well-tolerated in some patients who have limited cardiac reserve, including patients with heart failure.