Benefit of warm water immersion on biventricular function in patients with chronic heart failure

Background: Regular physical activity and exercise are well-known cardiovascular protective factors. Many elderly patients with heart failure find it difficult to exercise on land, and hydrotherapy (training in warm water) could be a more appropriate form of exercise for such patients. However, concerns have been raised about its safety. The aim of this study was to investigate, with echocardiography and Doppler, the acute effect of warm water immersion (WWI) and effect of 8 weeks of hydrotherapy on biventricular function, volumes and systemic vascular resistance. A secondary aim was to observe the effect of hydrotherapy on brain natriuretic peptide (BNP). Methods: Eighteen patients [age 69 +/- 8 years, left ventricular ejection fraction 31 +/- 9%, peakVO2 14.6 +/- 4.5 mL/kg/min] were examined with echocardiography on land and in warm water (34 degrees C). Twelve of these patients completed 8 weeks of control period followed by 8 weeks of hydrotherapy twice weekly. Results: During acute WWI, cardiac output increased from 3.1 +/- 0.8 to 4.2 +/- 0.9 L/min, LV tissue velocity time integral from 1.2 +/- 0.4 to 1.7 +/- 0.5 cm and right ventricular tissue velocity time integral from 1.6 +/- 0.6 to 2.5 +/- 0.8 cm (land vs WWI, p < 0.0001, respectively). Heart rate decreased from 73 +/- 12 to 66 +/- 11 bpm (p < 0.0001), mean arterial pressure from 92 +/- 14 to 86 +/- 16 mmHg (p < 0.01), and systemic vascular resistance from 31 +/- 7 to 22 +/- 5 resistant units (p < 0.0001). There was no change in the cardiovascular response or BNP after 8 weeks of hydrotherapy. Conclusion: Hydrotherapy was well tolerated by all patients. The main observed cardiac effect during acute WWI was a reduction in heart rate, which, together with a decrease in afterload, resulted in increases in systolic and diastolic biventricular function. Although 8 weeks of hydrotherapy did not improve cardiac function, our data support the concept that exercise in warm water is an acceptable regime for patients with heart failure.