Repeated
sauna treatment, known as Waon
therapy, has been shown to improve cardiac function as well as exercise tolerance in patients with chronic
heart failure. However, the underlying mechanisms of this
therapy regarding these improvements remain to be elucidated. Forty-one patients with chronic
heart failure (mean age 68.3 ± 13.5 years old) underwent Waon
therapy 5 times a week for 3 weeks. Before and
after treatment, a number of assessments were performed in all subjects: 6-minute walk test, echocardiography, determination of neurohumoral factors and number of circulating CD34(+) cells, and a flow-mediated dilation (FMD) test of endothelial function. Cardiopulmonary exercise testing was also performed in 20 patients. Waon
therapy increased the left ventricular ejection fraction (from 30.4 ± 12.6% to 32.5% ± 12.8%, p = 0.023) and reduced plasma levels of
norepinephrine (from 400 ± 258 to 300 ± 187 pg/ml, p = 0.015) and
brain natriuretic peptide (from 550 ± 510 to 416 ± 431 pg/ml, p = 0.035). Waon
therapy increased the 6-minute walk distance (from 337 ± 120 to 379 ± 126 m, p <0.001) in association with an improvement in FMD (from 3.5 ± 2.3% to 5.5% ± 2.7%, p <0.001) and an increase in the number of circulating CD34(+) cells (p = 0.025). Changes in 6-minute walk distance were correlated positively with those in the left ventricular ejection fraction and FMD and negatively with those in plasma levels of
norepinephrine and
brain natriuretic peptide levels. A multivariate analysis revealed that an increase in FMD was the only independent determinant of 6-minute walk distance improvement. Finally, Waon
therapy significantly increased peak Vo(2), and this increase was also correlated with changes in FMD. In conclusion, repeated
sauna therapy in patients with chronic
heart failure improves exercise tolerance in association with improvement in endothelial function.