People with chronic heart failure who underwent two weeks of repeated sauna use experienced decreased ventricular arrhythmias, according to recent research.

Ventricular arrhythmias are irregularities in contractions of the ventricles—the lower heart chambers that pump blood to the lungs and into the aorta to the rest of the body. Ventricular arrhythmias account for about half of all deaths in people with chronic heart failure, according to the study’s authors.

“Effects of Repeated Sauna Treatment on Ventricular Arrhythmias in Patients With Chronic Heart Failure” was conducted by staff of the Kagoshima University Graduate School of Medicine, Departments of Cardiovascular, Respiratory and Metabolic Medicine, Epidemiology and Preventive Medicine, in Kagoshima, Japan.

Thirty people with chronic heart failure participated in the study. All participants were receiving medication for heart failure and arrhythmias, and they were in stable condition, with unchanged medication, for at least one month prior to the study.

Subjects were randomly assigned to either the sauna group or a non-treated group. Those in the sauna group received two weeks of sauna therapy, five days each week, during which they would lay supine in a 60-degree Celsius far infrared-ray dry sauna for 15 minutes, followed by 30 minutes of bed rest with blankets.

Subjects in the non-treated group had 45 minutes of bed rest in a temperature-controlled room five days a week for two weeks.

Baseline measurements of clinical symptoms, such as dyspnea, fatigue, appetite loss and sleeplessness, were taken prior to the first sauna or rest session. Participants evaluated these symptoms on a quality-of-life questionnaire. The questionnaire was filled out again the day after the last sauna or rest session.

A fasting blood sample was also obtained in the morning before the first intervention, to measure participants’ plasma concentrations of neurohormonal factors. Another sample was taken the day after the last intervention.

Premature ventricular contractions were monitored for 24 hours before the first sauna or rest session and for 24 hours after the final intervention, using a Holter monitor. Heart-rate variability was evaluated by measuring the standard deviation of the normal-to-normal beat interval, using a MARS8000 analysis system and the data from the 24-hour Holter recordings.

Results of the research showed that the total number of premature ventricular contractions per 24-hour period was significantly lower in the sauna group as compared with the non-treated group. After the two-week intervention, subjects in the sauna group had approximately 848 premature ventricular contractions in 24 hours, versus roughly 3,097 in the non-treated group.

The research also showed significantly lower plasma concentrations of brain natriuretic peptide for participants in the sauna group after two weeks as compared to those in the non-treated group.

“It is well-established that [brain natriuretic peptide] is secreted predominantly by the ventricle in response to ventricular wall stretch,” state the study’s authors. “[W]e speculate that another mechanism responsible for decreased ventricular arrhythmias may be reduction of ventricular wall stretch.”

As for clinical symptoms, 17 of the 20 participants in the sauna group rated their clinical symptoms as improved, and three said their symptoms were unchanged, following the two-week intervention. In the non-treatment group, symptoms were rated unchanged for all 10 participants.

Source: Kagoshima University Graduate School of Medicine, Departments of Cardiovascular, Respiratory and Metabolic Medicine, Epidemiology and Preventive Medicine, in Kagoshima, Japan. Authors: Takashi Kihara, M.D.; Sadatoshi Biro, M.D.; Yoshiyuki Ikeda, M.D.; Tsuyoshi Fukudome, M.D.; Takuro Shinsato, M.D.; Akinori Masuda, M.D.; Masaaki Miyata, M.D.; Shuichi Hamasaki, M.D.; Yukata Otsuji, M.D.; Shinichi Minagoe, M.D.; Suminori Akiba, M.D.; and Chuwa Tei, M.D. Originally published in Circulation Journal, December 2004, Vol. 68, pp. 1146-1151.