Sauna-induced myocardial ischemia in patients with coronary artery disease

Finnish sauna bathing and vascular health of adults with coronary artery disease: a randomized controlled trial

Regular Finnish sauna use is associated with a reduced risk of cardiovascular mortality. However, physiological mechanisms underlying this association remain unknown. This study determined if an 8-wk Finnish sauna intervention improves peripheral endothelial function, microvascular function, central arterial stiffness, and blood pressure in adults with coronary artery disease (CAD). Forty-one adults (62 ± 6 yr, 33 men/8 women) with stable CAD were randomized to 8 wk of Finnish sauna use (n = 21, 4 sessions/wk, 20-30 min/session, 79°C, 13% relative humidity) or a control intervention (n = 20, lifestyle maintenance). Brachial artery flow-mediated dilation (FMD), carotid-femoral pulse wave velocity (cf-PWV), total (area under the curve) and peak postocclusion forearm reactive hyperemia, and blood pressure (automated auscultation) were measured before and after the intervention. After the sauna intervention, resting core temperature was lower (-0.27°C [-0.54, -0.01], P = 0.046) and sweat rate during sauna exposure was greater (0.3 L/h [0.1, 0.5], P = 0.003). The change in brachial artery FMD did not differ between interventions (control: 0.07% [-0.99, +1.14] vs. sauna: 0.15% [-0.89, +1.19], interaction P = 0.909). The change in total (P = 0.031) and peak (P = 0.024) reactive hyperemia differed between interventions due to a nonsignificant decrease in response to the sauna intervention and an increase in response to control. The change in cf-PWV (P = 0.816), systolic (P = 0.951), and diastolic (P = 0.292) blood pressure did not differ between interventions. These results demonstrate that four sessions of Finnish sauna bathing per week for 8 wk does not improve markers of vascular health in adults with stable CAD.NEW & NOTEWORTHY This study determined if unsupervised Finnish sauna bathing for 8 wk improves markers of vascular health in adults with coronary artery disease. Finnish sauna bathing reduced resting core temperature and improved sweating capacity, indicative of heat acclimation. Despite evidence of heat acclimation, Finnish sauna bathing did not improve markers of endothelial function, microvascular function, arterial stiffness, or blood pressure.

Reallocation of cutaneous and global blood circulation during sauna bathing through a closed-loop model

OBJECTIVE

Sauna bathing (SB) is an important strategy in cardiovascular protection, but there is no mathematical explanation for the reallocation of blood circulation during heat-induced superficial vasodilation. We sought to reveal such reallocation via a simulated hemodynamic model.

METHODS

A closed-loop cardiovascular model with a series of electrical parameters was constructed. The body surface was divided into seven blocks and each block was modeled by a lumped resistance. These resistances were adjusted to increase skin blood flow (SBF), with the aim of reflecting heat-induced vasodilation during SB. Finally, the blood pressure was compared before and after SB, and the blood flow inside the aorta and visceral arteries were also analyzed.

RESULTS

With increasing SBF in this model, the systolic, diastolic, and mean blood pressure in the arterial trunk decreased by 13-29, 18-36, and 19-37 mmHg, respectively. Despite the increase in the peak and mean blood flow in the arterial trunk, the diastolic blood flow reversal in the thoracic and abdominal aortas increased significantly. Nevertheless, the blood supply to the heart, liver, stomach, spleen, kidney, and intestine decreased by at least 25%. Moreover, the pulmonary blood flow increased significantly.

CONCLUSION

Simulated heat-induced cutaneous vasodilation in this model lowers blood pressure, induces visceral ischemia, and promotes pulmonary circulation, suggesting that the present closed-loop model may be able to describe the effect of sauna bathing on blood circulation. However, the increase of retrograde flow in the aortas found in this model deserves further examination.

Extreme Heat and Cardiovascular Health: What a Cardiovascular Health Professional Should Know

As global temperatures continue to rise, extreme heat events are becoming more frequent and intense. Extreme heat affects cardiovascular health as it is associated with a greater risk of adverse cardiovascular events, especially for adults with preexisting cardiovascular diseases. Nonetheless, the pathophysiology underlying the association between extreme heat and cardiovascular risk remains understudied. Furthermore, specific recommendations to mitigate the effects of extreme heat on cardiovascular health remain limited to guide clinical practice within the context of a warming climate. The overall objective of this review article is to raise awareness that extreme heat poses a risk for cardiovascular health. Specifically, the review discusses why cardiovascular healthcare professionals should care about extreme heat, how extreme heat affects cardiovascular health, and recommendations to minimise the cardiovascular consequences of extreme heat. Future research directions are also provided to further our understating of the cardiovascular health consequences of extreme heat. A better awareness and understanding of the cardiovascular consequences of extreme heat will help cardiovascular health professionals assess the risk and optimise the care of their patients exposed to an increasingly warm climate.

Blood pressure-lowering effect of repeated Waon therapy in non-smokers with hypertension

Waon therapy (WT) has been used as a thermal therapy in chronic heart failure patients. However, its effect in patients with hypertension is unclear. This study aimed to reveal the hypotensive effect of WT in patients with hypertension. WT was performed on 31 patients with hypertension (63.9 ± 11.9 years, male: 17) on standard hypertension treatment focusing on lifestyle modification and medication. Systolic and diastolic blood pressures were measured before and after WT using an upper arm automated sphygmomanometer. We investigated the effect of single and repeated (1 time/d, >5 times) WT sessions on blood pressure and further compared its effect between current smoking (n = 11, 55.4 ± 6.4 years, 8.5 ± 2.4 times) and non-smoking (n = 11, 66.9 ± 8.5 years, 12.2 ± 5.9 times) groups. A total of 370 sessions of WT were conducted. Systolic and diastolic blood pressures significantly decreased after a single WT session (systolic blood pressure: 118.5 ± 10.1 to 115.1 ± 9.0 mm Hg, P < .001; diastolic blood pressure: 70.5 ± 6.4 to 65.9 ± 5.3 mm Hg, P < .001). The blood pressure decrease following repeated WT was not significant when all participants were considered (systolic blood pressure: 122.3 ± 15.2 to 116.9 ± 19.6 mm Hg; diastolic blood pressure: 73.8 ± 16.7 to 68.2 ± 13.2 mm Hg); however, it was significant in the non-smoking group (systolic blood pressure: 124.2 ± 11.3 to 108.8 ± 13.4 mm Hg, P < .001; diastolic blood pressure: 73.6 ± 4.9 to 62.1 ± 7.6 mm Hg, P < .001). Repeated WT (at least 5 sessions) decreased blood pressure in patients with hypertension, especially in non-smokers. WT is a simple method to reduce blood pressure in non-smoking patients with hypertension.

Heat therapy: mechanistic underpinnings and applications to cardiovascular health

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and novel therapies are drastically needed to prevent or delay the onset of CVD to reduce the societal and healthcare burdens associated with these chronic diseases. One such therapy is "heat therapy," or chronic, repeated use of hot baths or saunas. Although using heat exposure to improve health is not a new concept, it has received renewed attention in recent years as a growing number of studies have demonstrated robust and widespread beneficial effects of heat therapy on cardiovascular health. Here, we review the existing literature, with particular focus on the molecular mechanisms that underscore the cardiovascular benefits of this practice.

The blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exercise

OBJECTIVES

In the present study, the reaction of blood pressure and heart rate are examined during and after a single acute sauna application.

DESIGN

In 19 healthy adult volunteers (7 women, aged 46.4±10.2 years, BMI 24.4±2 kg /m²), blood pressure (BP) and heart rate (HR) were measured during a 25-minute sauna session (93°C, 13 % humidity) and during a subsequent 30-minute rest period. The parameters obtained were compared with the BP and HR responses during submaximal dynamic exercise testing.

RESULTS

The heat exposure resulted in a significant (p<0.01) and progressive increase in systolic and diastolic BP. After the sauna bath, BP decreased and showed significantly (p<0.001) lower values compared to baseline. HR also increased continuously during heat application (p<0.001), resulting in a significant increase (p<0.001) in systolic BP x HR as a measure of myocardial oxygen consumption. After the end of the sauna session, both the BP and the HR decreased steadily (p<0.001).When comparing BP and HR during the sauna session with the reaction during a dynamic exercise test, sauna bathing was equivalent to an exercise load of about 60-100 watts.

CONCLUSIONS

Contrary to popular belief, acute sauna use does not lead to a reduction, but to an increase in BP and HR with a consequent increase in myocardial oxygen consumption. The cardiac load during the sauna use corresponds to a moderate physical load of 60-100 watts.

Correlations between Repeated Use of Dry Sauna for 4 x 10 Minutes, Physiological Parameters, Anthropometric Features, and Body Composition in Young Sedentary and Overweight Men: Health Implications

Background

The effect of thermal stress on the physiological parameters of young overweight and sedentary men who sporadically use the sauna remains insufficiently investigated.

Aim

The aim of the study was to determine the effect of sauna bathing on the physiological parameters of young overweight, physically inactive men and to test the correlations between physiological parameters versus anthropometric features and body composition parameters.

Materials and Methods

Forty-five overweight and sedentary men aged 20.76±2.4 y were exposed to four sauna sessions of 10 minutes each (temperature: 90-91°C; relative humidity: 14-16 %) with four 5-minute cool-down breaks. Body composition was determined before sauna, and body mass and blood pressure were measured before and after sauna. Physiological parameters were monitored during four 10-minute sauna sessions.

Results

A significant (p<0.0001) increase in all analyzed physiological parameters was observed during four successive 10-minute sauna sessions. Heart rate, energy expenditure, blood pressure, and body mass loss were most strongly correlated with anthropometric parameters (body mass, body mass index, and body surface area) and body composition parameters (percent body fat, body fat mass, and visceral fat level). The 60-minute treatment resulted in a significant reduction in body mass (0.65 kg).

Conclusions

Repeated use of Finnish sauna induces significant changes in the physiological parameters of young sedentary overweight men, and these changes are intensified during successive treatments. Deleterious cardiovascular adaptations were most prevalent in men characterized by the highest degree of obesity and the largest body size.

Effects of heat and cold on health, with special reference to Finnish sauna bathing

Environmental stress such as extremely warm or cold temperature is often considered a challenge to human health and body homeostasis. However, the human body can adapt relatively well to heat and cold environments, and recent studies have also elucidated that particularly heat stress might be even highly beneficial for human health. Consequently, the aim of the present brief review is first to discuss general cardiovascular and other responses to acute heat stress, followed by a review of beneficial effects of Finnish sauna bathing on general and cardiovascular health and mortality as well as dementia and Alzheimer's disease risk. Plausible mechanisms included are improved endothelial and microvascular function, reduced blood pressure and arterial stiffness, and possibly increased angiogenesis in humans, which are likely to mediate the health benefits of sauna bathing. In addition to heat exposure with physiological adaptations, cold stress-induced physiological responses and brown fat activation on health are also discussed. This is important to take into consideration, as sauna bathing is frequently associated with cooling periods in cold(er) environments, but their combination remains poorly investigated. We finally propose, therefore, that possible additive effects of heat- and cold-stress-induced adaptations and effects on health would be worthy of further investigation.

Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review

Introduction

Many health benefits are claimed by individuals and facilities promoting sauna bathing; however the medical evidence to support these claims is not well established. This paper aims to systematically review recent research on the effects of repeated dry sauna interventions on human health.

Methods

A systematic search was made of medical databases for studies reporting on the health effects of regular dry sauna bathing on humans from 2000 onwards. Risk of bias was assessed according to the Cochrane Collaboration guidelines.

Results

Forty clinical studies involving a total of 3855 participants met the inclusion criteria. Only 13 studies were randomized controlled trials and most studies were small (n < 40). Reported outcome measures were heterogeneous with most studies reporting beneficial health effects. Only one small study (n = 10) reported an adverse health outcome of disrupted male spermatogenesis, demonstrated to be reversible when ceasing sauna activity.

Conclusions

Regular dry sauna bathing has potential health benefits. More data of higher quality is needed on the frequency and extent of adverse side effects. Further study is also needed to determine the optimal frequency and duration of distinct types of sauna bathing for targeted health effects and the specific clinical populations who are most likely to benefit.

Heart rate variability responses to acute and repeated postexercise sauna in trained cyclists

Short- to medium-term (i.e., 4-14 days) heating protocols induce physiological adaptations including improved cardiac autonomic modulations, as assessed using heart rate variability, which may contribute to greater exercise performance. Whether similar cardiac autonomic changes occur during an intense heating protocol (sauna) reported to increase plasma volume in athletes remains to be confirmed. This study examined changes in heart rate and its variability during a single extreme heat (sauna) exposure and repeated exposures in athletes. Six well-trained male cyclists undertook sauna bathing (30 min, 87 °C, 11% relative humidity) immediately after normal training over 10 consecutive days. Heart rate recordings were obtained during each sauna bout. Heart rate and its variability (natural logarithm of root mean square of successive differences, lnRMSSD) were analysed during 10-min periods within the first bout, and changes in heart rate and lnRMSSD were analysed during each bout via magnitude-based inferences. During the first sauna bout, heart rate was almost certainly increased (∼32%, effect size 1.68) and lnRMSSD was almost certainly reduced (∼62%, effect size -5.21) from the first to the last 10-min period, indicating reduced parasympathetic and (or) enhanced sympathetic modulations. Acute exposure to extreme heat stress via sauna produced alterations in heart rate and cardiac autonomic modulations with successive postexercise heat exposures producing unclear changes over a 10-day period. The physiological benefits of intense heating via sauna on cardiac control in athletes remain to be elucidated.

Sauna Bathing and Incident Hypertension: A Prospective Cohort Study

BACKGROUND

Sauna bathing is associated with reduced cardiovascular risk, but the mechanisms underlying this beneficial effect are not entirely understood. We aimed to assess the relationship between sauna bathing and risk of incident hypertension.

METHODS

Frequency of sauna bathing was ascertained using questionnaires in the Kuopio Ischemic Heart Disease Study, a prospective cohort study conducted in Eastern Finland that comprised a population-based sample of 1,621 men aged 42 to 60 years without hypertension at baseline. The incidence of hypertension was defined as a physician diagnosis of hypertension, systolic blood pressure (SBP) >140 mm Hg, diastolic blood pressure >90 mm Hg, or use of antihypertensive medication.

RESULTS

During a median follow-up of 24.7 years, 251 incident cases (15.5%) were recorded. In Cox regression analysis adjusted for baseline age, smoking, body mass index, and SBP; compared to participants reporting 1 sauna session per week, the hazard ratio for incident hypertension in participants reporting 2 to 3 sessions and 4 to 7 sessions was 0.76 (95% confidence interval: 0.57-1.02) and 0.54 (0.32-0.91), respectively. The corresponding hazard ratios were similar after further adjustment for glucose, creatinine, alcohol consumption, heart rate, family history of hypertension, socioeconomic status, and cardiorespiratory fitness: 0.83 (95% confidence interval: 0.59-1.18) and 0.53 (0.28-0.98), respectively.

CONCLUSIONS

Regular sauna bathing is associated with reduced risk of hypertension, which may be a mechanism underlying the decreased cardiovascular risk associated with sauna use. Further epidemiological and experimental studies could help elucidate the effects of sauna bathing on cardiovascular function.

Sauna stroke syndrome

This report describes a 64-year-old man with a large cerebral infarction during sauna bathing. He had no typical cerebrovascular risk factors. Transesophageal echocardiography revealed a patent foramen ovale of 5-mm diameter. In this patient a causal relationship between stroke and sauna bathing is considered and described by the term "sauna stroke syndrome."

Efeitos da sauna sobre doenças cardiovasculares e doenças relacionadas com o estilo de vida

Freqüentar a sauna é uma prática popular de jovens, adultos e idosos saudáveis. Os médicos do esporte são, com freqüência, solicitados a opinar sobre o impacto da sauna nas doenças e na saúde de modo geral. A sauna pode ser benéfica ou maléfica, dependendo do uso que fazemos dela. Nos últimos anos, a sauna está sendo considerada benéfica para os portadores de doenças cardiovasculares como a insuficiência cardíaca e doenças relacionadas com o estilo de vida, principalmente por melhorar a função endotelial periférica, via aumento do débito cardíaco e vasodilatação periférica. A disfunção endotelial está presente em quase todas as doenças cardiovasculares. O presente artigo pretende fazer uma revisão sobre os efeitos da sauna sobre o sistema cardiovascular em indivíduos saudáveis e em determinadas doenças cardiovasculares.

Sauna as a Therapeutic Option for Cardiovascular Disease

The physiologic effect of the sauna in human beings has been studied extensively, but only recently have there been studies to suggest sauna can be an effective therapeutic modality for patients with cardiovascular disease, especially for those with congestive heart failure. The data reported to date have been promising, but definitive studies are not possible because sauna treatment would be difficult to evaluate in a double-blind, placebo-controlled study.

Benefits and risks of sauna bathing

Although sauna bathing causes various acute, transient cardiovascular and hormonal changes, it is well tolerated by most healthy adults and children. Sauna bathing does not influence fertility and is safe during the uncomplicated pregnancies of healthy women. Some studies have suggested that long-term sauna bathing may help lower blood pressure in patients with hypertension and improve the left ventricular ejection fraction in patients with chronic congestive heart failure, but additional data are needed to confirm these findings. The transient improvements in pulmonary function that occur in the sauna may provide some relief to patients with asthma and chronic bronchitis. Sauna bathing may also alleviate pain and improve joint mobility in patients with rheumatic disease. Although sauna bathing does not cause drying of the skin-and may even benefit patients with psoriasis-sweating may increase itching in patients with atopic dermatitis. Contraindications to sauna bathing include unstable angina pectoris, recent myocardial infarction, and severe aortic stenosis. Sauna bathing is safe, however, for most people with coronary heart disease with stable angina pectoris or old myocardial infarction. Very few acute myocardial infarctions and sudden deaths occur in saunas, but alcohol consumption during sauna bathing increases the risk of hypotension, arrhythmia, and sudden death, and should be avoided.

The Finnish sauna bath and its use in patients with cardiovascular disease

The Finnish tradition of sauna bathing is meant to be an experience in relaxation, and the length of time spent in the sauna and the preferred temperature vary considerably among individuals. The pleasures of sauna bathing can be considered safe and without undue risk of cardiac complications even for CVD patients, providing bathing is conducted sensibly for an appropriate period of time, and extremes in temperature are voided.