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Introduction
Waon therapy using an evenly maintained dry sauna system at 60 degree centigrade, that differs from the traditional sauna has been studied exclusively by Tei1) in Japan. They have previously reported that repeated Waon therapy improves the vascular endothelial function, resulting in an improvement in cardiac function and clinical symptoms, in patients with heart failure (HF),2) and even in patients with risk factors for atherosclerosis.3) Furthermore, this therapy improved the cardiac function and exercise tolerance in patients with chronic heart failure (CHF), who suffered from chronic symptoms despite the administration of full medications in patients with high risk.2)4) These effects are attributable to the reduction in the cardiac preload and afterload.4) Waon therapy also has been proved to have beneficial effects on peripheral arterial disease (PAD),5) chronic fatigue syndrome,6) chronic pain,7) and even in patients with mild depression.8)
Waon therapy has been done in a specialized room with unique sauna system. In order to expand the use of Waon therapy, they developed a movable and sitting-position system, in which the temperature at the top and the bottom of the chamber is uniformly maintained at the same temperature of 60℃ (Fig. 1).
The movable sauna system for Waon therapy was installed in our institution for the first time in Korea. It is also the first experience with movable system outside Japan. This was to assess the safety and effect of Waon therapy in Korean patients with heart failure by echocardiography.
Methods
Subjects
Ten patients with CHF were enrolled for this study between September 2006 and November 2007. The inclusion criteria were: 1) they have HF symptoms with more than New York Heart Association (NYHA) class II and with less than 45% of left ventricular ejection fraction (LVEF), 2) no medication change within previous 3 months. The patients who cannot maintain sitting position were excluded. Informed consent was obtained from all of the patients. This protocol was approved by our institutional review board.
Waon therapy
The patients with a light gown were placed in a sitting-position in a 60℃ sauna system (Onda co., Kagoshima, Japan) for 15 minutes, and then after leaving the sauna, they underwent bed rest with a blanket to keep them warm for an additional 30 minutes. Waon therapy was performed once a day (one session), repeated 5 days a week, and recommended for more than 2 weeks and for wanted sessions thereafter. We controlled and maintained the room temperature with about 28℃.
Measurements
The body weight in two decimal places, blood pressure, heart rate, and body temperature were measured before and after the therapy in every session. Heart rate and body temperature immediately after sauna were also measured to assess the brief changes. All patients were allowed for oral hydration with tap water to compensate for weight loss due to perspiration.
Echocardiography and clinical follow up
During two dimensional echocardiography (2DE), we obtained standard views and measured left atrial volume (biplane method of discs), left ventricular (LV) dimensions (2D-guided M-mode), LV volumes (biplane method of discs), LV mass index (truncated ellipsoid method), and calculated LVEF according to published guideline.9) The mitral inflow pulsed wave Doppler was performed to measure early (E) and late (A) velocities, E/A ratio, and deceleration time (DT) of E velocity. To calculate the Tei index, pulsed Doppler study from both LV outflow tract and mitral inflow was performed. Tissue Doppler study from the medial mitral annulus was taken to obtain early (E') and late (A') diastolic velocity, and E/E' ratio as useful parameters in HF patients.10) Follow up echocardiography was taken after the end of 2 weeks' sessions.
All patients were monitored and followed up clinically on outpatient basis even after the discontinuation of Waon therapy. The clinical state of HF was evaluated by NYHA functional class before and after the whole sessions of Waon therapy.
Statistical analysis
All data are given as mean±SD. Statistical analysis was conducted using Statistical Package for Social Science (SPSS) 13.0 for Windows (SPSS Inc., Chicago, IL, USA). Comparisons of all measurements made at baseline with those made during or after Waon therapy were made using the Wilcoxon signed ranks test. Values were considered significantly different at a value of p<0.05.
Results
Baseline clinical characteristics
The baseline clinical characteristics are summarized in Table 1. Three patients (30%) were women and their ages varied from 50 to 78 years. Cause of HF was ischemic in 4 patients. Three patients had diabetes mellitus. The patients stopped the Waon therapy with various session numbers from 1 to 112 times between a day and 255 days. Five (case 2, 3, 8, 9, 10) out of 10 patients continued with Waon therapy for more than 2 weeks as initially planned protocol. Two patients (case 1, 6) were lost from routine follow up in outpatient clinic. Two patients (case 5, 7) could not continue to have daily Waon therapy due to NYHA III class and long distance from their home to the hospital. One patient (case 4) visited our outpatient clinic again 3 months later after first session and then wanted to stop because of no change of HF symptoms.
Symptoms after Waon therapy and discontinuation
Of 5 patients who had been treated with the Waon therapy for more than 2 weeks, 4 patients had significant improvement of HF symptoms at the end of sessions (11 to 112 times) (Table 1). No change in NYHA functional class was reported in other 5 patients after 6-9 times of Waon therapy. However, no one complained of worsening of HF symptoms.
Changes of body weight and vital signs before and after Waon therapy
Body weight in whole session was averaged in each patient before and after Waon therapy, and it decreased significantly after Waon therapy with a mean change -0.2 kg (61.8±10.2 kg vs. 61.6±10.3 kg, p=0.008) (Table 2). Both systolic and diastolic blood pressure decreased in each session (systolic, 119±28 mmHg vs. 111±27 mmHg, p=0.005; diastolic, 69±12 mmHg vs. 63±10 mmHg, p=0.005) (Table 2).
Body temperature measured immediately after 15 minutes' sauna was higher than before sauna (37.0±0.9℃ vs. 35.9±0.4℃, p=0.017), and then decreased to almost the same level with that of before the session (36.1±0.5℃ vs. 35.9±0.4℃, p=0.8). However, heart rate measured immediately after sauna and after the end of session did not change significantly (72±8 beats/min vs. 71±10 beats/min, p=0.8). No adverse events were reported during sauna.
Changes of echocardiographic parameters after Waon therapy
Five patients who were treated with Waon therapy for more than 2 weeks had follow up 2DE study at the end of 2 weeks, and LV volume of both end-diastolic and end-systolic periods decreased significantly after Waon therapy (Table 3, Fig. 2). There were trends in improvement of LVEF after the therapy although statistical significance was lack. Of echocardiographic parameters of LV diastolic function, mitral E/A ratio and E/E' ratio decreased but to a level of insignificance. After Waon therapy, Tei index did not change significantly.
Discussion
This is the first report to present experiences with Waon therapy in Korea. The present study indicates that Waon therapy was found to be safe and improve symptoms in some patients with CHF. No adverse events were recorded during the entire sessions.
Waon therapy uses far infrared-ray dry sauna which has not hydrostatic pressure and so more comfortable than hot bath. Tei et al.4) developed this unique form of thermal therapy and have been investigating the various effects and its mechanisms on several diseases.2)5)7)11)12) Thermal therapy in cardiovascular diseases consists of systemic soothing warmth that comfortably refreshes the mind and body. Therefore, Tei1) changed the name from thermal to "Waon" therapy, since "Waon" in Japanese means soothing warmth. Waon therapy is defined as "therapy in which the entire body is warmed in an evenly heated chamber for 15 min at a temperature that soothes the mind and body, and after the deep body temperature has increased by approximately 1.0-1.2℃, the soothing warmth is sustained by maintaining the warmth at rest for an additional 30 min, with fluids supplied at the end to replace the loss from perspiration".1)
Hemodynamic effects of Waon therapy
Regarding the acute effect of Waon therapy, it has been reported that 60℃ sauna therapy for 15 minutes improved acute hemodynamics in patients with CHF, including cardiac index, mean pulmonary wedge pressure, systemic and pulmonary resistance, and cardiac function.4)
In the present study we used movable and sitting-position sauna system which was developed in order to expand the use of Waon therapy (Fig. 1). In each session body weight (-0.2 kg), systolic blood pressure (-8 mmHg), and diastolic blood pressure (-6 mmHg) were decreased significantly (Table 2). Body temperature immediately after 15 minutes' sauna was about 1.0℃ higher than before sauna, and then decreased to almost the same level with that of before the session after Waon therapy. Heart rate did not change significantly and no adverse hemodynamic events occurred.
Effect of Waon therapy on heart failure
It has been reported that Waon therapy improves hemodynamics and ameliorates symptoms, suppresses ventricular arrhythmias, and improves vascular function in CHF patients.2)4)13)14) Although changes in N-terminal pro-B-type natriuretic peptide (NT-proBNP), which has important roles in CHF but was not included in this study,15-17) and 2DE were not performed in all patients, we noted symptomatic improvement in 4 of 5 patients with CHF with the use of movable and sitting position-sauna system.
Vascular endothelial function significantly improved after two-week Waon therapy in the brachial artery in patients with CHF, and systemic vascular resistance significantly decreased after two-week sauna therapy, suggesting an improvement of endothelial function in resistance vessels.2) Improved endothelial function leads to dilation of vessels by an increase in nitric oxide (NO) production. The fact that two weeks of Waon therapy significantly decreased blood pressure in the present study may reflect the improvement in endothelial function. This results in decreased afterload and, thus, increased cardiac output as previously reported.4) These changes improve peripheral circulation, which is probably res-ponsible for the improvement in clinical symptoms.
The precise mechanisms by which long-term Waon therapy improves endothelial function in patients with CHF has not been clarified. However, Tei et al.4) have previously demonstrated that thermal therapy increases cardiac output in patients with CHF. This results in increased peripheral blood flow, which increases shear stress in the vessels, which, in turn, probably leads to an increase in NO production by the vessels. Repeated Waon therapy upregulates the endothelial NO synthase (eNOS) protein in the arterial endothelium, including the aorta and carotid, femoral and coronary arteries, of hamsters.11)18) Therefore, it is likely that the improvement in endothelial function after long-term, repeated Waon therapy is due to improved NO production by eNOS upregulation in patients with CHF.
Recently Tei et al. conducted a prospective multicenter case-control study to confirm the clinical efficacy and safety of Waon therapy on CHF at 10 hospitals in Japan.19) And they demonstrated that Waon therapy improved clinical symptoms and cardiac function evaluated by 2DE and BNP concentrations, and decreased cardiac size on chest radiography and 2DE after once a day, 2 weeks of Waon therapy in patients with CHF using the movable and sitting-position sauna system.19)
Study limitation
We have several limitations in this study. First and most critical limitation is that it has been conducted in a single center, and limited small numbers of patients were enrolled. Only half of the study patients continued the Waon therapy for more than 2 weeks. Second, although Waon therapy is safe, non-invasive, and may be an important part of nonpharmacological therapy in some diseases including CHF, it should be performed in a specialized sauna system with careful attention of physician or nurses, because most CHF patients might experiences unexpected collapse. Last, more objective tests such as bio-markers or other clinical functional assessment and long-term follow-up in larger cohort of Korean HF patients will be needed to ensure the clinical and prognostic benefits of Waon therapy.
In conclusion, for the first time in Korea, we have experienced 10 CHF patients with Waon therapy which is safe and has some beneficial effects. Large scale randomized study is needed to expand the use of Waon therapy as a promising, safe and effective therapy in Korean HF patients.
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