Waon therapy, developed in Japan, is a sauna-like form of hyperthermia therapy for patients with chronic heart failure. Waon is a Japanese word meaning soothing warmth. Waon therapy is proposed to improve prognosis and quality of life. The sauna room is an evenly warmed room at 60 °C (140 °F) with no hydration added. Patients sit in it for 15 minutes, after which, they are wrapped in thermal blankets and laid down to maintain heat for 30 minutes.
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Benefits
Chronic heart failure patients suffer from an inability to pump enough blood to their tissues and heart, resulting in systolic and/or diastolic dysfunction. Waon therapy improves many indicators of heart function including: cardiac output, stroke volume, ejection fraction, while also having benefits in vascular function including decreased vascular resistance and blood pressure. Improvements were also seen in left ventricular diastolic dimension and left atrial dimension.
Risks
Patients with aortic stenosis, obstructive hypertrophic cardiomyopathy and ischemic cardiomyopathies should not use Waon therapy as a treatment. Prohibiting patients with ischemic cardiomyopathies prevents an increase in temperature from further activating the sympathetic nervous system, which could cause tachycardia in these patients.
Mechanisms
Waon therapy increases blood flow by stimulating endothelial nitric oxide synthase protein production (eNOS). eNOS makes nitric oxide, which is a vasodilator and increases blood flow. Waon therapy also increases blood flow by stimulating the mobilization endothelial progenitor cells marked with CD34 molecules. CD34 positive cells promote angiogenesis to increase blood flow, improving cardiac perfusion and decreasing vascular resistance. Nitric oxide is also a regulator of the sympathetic nervous system, and an increase of nitric oxide via endothelial nitric oxide synthase may help to control autonomic nervous system.
In chronic heart failure the sympathetic nervous system is over-activated and the parasympathetic nervous system depressed, increasing stress on the heart. Waon therapy increases parasympathetic activity and decreases the sympathetic activity. These changes decrease stress on the heart by decreasing systemic resistance and increasing cardiac output, which decrease preload and afterload.
Brain natriuretic peptide (BNP) decreases with Waon therapy. BNP is a negative indicator of cardiac function and is released during ventricular stretching.
Long-term results
A 5 year study of Waon therapy showed a decrease in cardiac death and rehospitalisation after cardiac events. This treatment is currently only being used in Japan, but positive results suggest Waon therapy may be a new, non-pharmacological treatment for chronic heart failure patients and other vascular resistance diseases.