Authors

• Nóra Homoródi — University of Debrecen, Faculty of Medicine, Institute of Cardiology, Debrecen, Hungary — ORCID: 0009-0008-5873-8733
• Andrea Szegedi — University of Debrecen, Faculty of Medicine, Institute of Cardiology, Debrecen, Hungary — ORCID: 0009-0004-5779-2472
• Tímea Bianka Papp — University of Debrecen, Faculty of Medicine, Institute of Cardiology, Debrecen, Hungary
• Szabolcs Gergely — University of Debrecen, Faculty of Medicine, Institute of Cardiology, Debrecen, Hungary — ORCID: 0009-0009-0907-2792
• Zoltán Csanádi — University of Debrecen, Faculty of Medicine, Institute of Cardiology, Debrecen, Hungary

Abstract

During the rehabilitation process, the question of recreational activities typically arises in the convalescent phase. Recreation encompasses physical and/or mental activities that fulfill a psychologically and biologically determined need. Tourism includes both physical and mental recreational elements. Regarding distant destinations, air travel raises several concerns, just as domestic tourism frequently involves visits to spas and saunas, both of which may pose risks for patients with cardiovascular conditions. Air travel exposes passengers to physical, psychological, and physiological effects, which can lead to cardiac symptoms, most commonly palpitations and chest pain. Visiting thermal baths and saunas is a popular recreational activity, but it can also be concerning for patients with cardiovascular disease. The degree of temperature elevation and its impact on circulation differ between baths and saunas, making them not universally recommended for these patients. In this review, we summarize the physiological effects of air travel on the human body, as well as international literature and guidelines regarding air travel in various cardiovascular conditions. Furthermore, we detail the circulatory changes induced by Finnish and infrared saunas, as well as hot water baths, and discuss their potential contraindications.

Keywords

cardiac diseases, recreation, aviation, sauna, heat therapy

DOI

Full Text

## The concept of recreation In the course of the rehabilitation process, the issue of recreational activity primarily arises during the convalescent phase as an integral component of returning to everyday functioning. Recreation, or leisure activity, represents the culture of spending free time and fulfills a fundamental human need established from both psychological and biological perspectives. It encompasses a wide range of physical, intellectual, cultural, and sporting activities, through which individuals relieve the tension and fatigue accumulated during their primary daily occupation, with the aim of restoring and enhancing physical, mental, and psychological performance capacity. In very concise terms, the primary objective of recreation can be defined as “engagement in activities different from one’s usual occupation” (1). According to the Hungarian Etymological Dictionary, the term recreation originates from the Latin word recreare, meaning “to refresh” or “to restore,” derived from the elements re (“again”) and creare (“to create”). Recreation comprises a diverse spectrum of activities. The majority of the relevant literature distinguishes three principal domains: intellectual, physical recreation and tourism. Intellectual recreational activities include cultural, entertainment, and educational pursuits, whereas physical recreation refers to physical activity or sport performed voluntarily, for pleasure rather than obligation. Tourism, particularly leisure tourism, constitutes an independent third category; however, its range of activities incorporates elements of both intellectual and physical recreation (2). ## Physiological and health-related effects of air travel For patients living with cardiovascular disease, travel may be associated with an increased level of risk. Consequently, patients appropriately seek advice and guidance from their treating physicians prior to undertaking travel. When travelling abroad, particularly over long distances, air travel is typically the mode of transportation. Air travel presents unique challenges and concerns, some of which are perceived, while others represent real risks. Even for healthy individuals, flying may impose a physiological burden, and the occurrence of an in-flight medical emergency can be a source of significant anxiety. This concern is particularly pronounced among individuals with cardiovascular disease. Precise data regarding the incidence and characteristics of so-called in-flight medical emergencies (IMEs) are limited, primarily due to the absence of standardized international registries (3, 4). According to a summary analysis evaluating data from nearly 12,000 passengers, one medical emergency occurs in approximately 1 out of every 604 flights (5). Other sources estimate the incidence of in-flight medical emergencies to range between 26 and 130 events per one million passengers (6, 7). However, the true incidence is likely higher, as transient conditions that resolve spontaneously or do not require medical intervention are often not reported or formally documented (8). The incidence of in-flight cardiac emergencies has been estimated at approximately 5 cases per one million passengers, with palpitations and chest pain being the most commonly reported symptoms (9). Air travel fundamentally differs from ground transportation due to its unique environmental conditions, exposing passengers to a combination of physiological, physical, and psychological stressors. Psychological stress is primarily related to waiting times and security procedures, whereas physical stress includes prolonged standing in queues, carrying luggage, and extensive walking within airport terminals. These factors may be further exacerbated by destination-specific geographical characteristics, such as ambient temperature or altitude above sea level, as well as by time zone shifts and travel-related sleep deprivation (9). Physiological effects during flight are largely attributable to changes in cabin pressure, temperature, and gas volume. While cabin temperature generally remains stable throughout the flight, both ambient pressure and the partial pressure of oxygen decrease. This reduction may provoke symptoms in patients with cardiovascular or pulmonary disease. Furthermore, pressure changes during flight may lead to the expansion of trapped air following certain medical interventions, such as open-heart surgery, potentially resulting in significant hemodynamic consequences (9). ## Absolute contraindications to air travel Air travel is absolutely contraindicated in the following conditions (10-15): - two to six weeks following an acute myocardial infarction, (in an uncomplicated case for two weeks) - unstable angina - decompensated heart failure - severe, symptomatic valvular heart disease associated with acute decompensation or cyanotic congenital heart disease - following sudden cardiac arrest with successful resuscitation, in the absence of implantable cardioverter-defibrillator (ICD) implantation, if the left ventricular ejection fraction (LVEF) remains persistently below 35%, or in the absence of a correctable reversible cause during the first six months - uncontrolled ventricular or supraventricular arrhythmias - within two weeks following coronary artery bypass grafting (CABG) or other open-heart surgery - Stanford type A aortic dissection - uncontrolled hypertension. ## Detailed recommendations for specific cardiovascular conditions Detailed recommendations for air travel based on the type of cardiovascular disease are shown in **Tables 1-3**Table 2Table 3. ### TABLE 1: Recommendations for air travel in chronic coronary syndrome according to the Canadian Cardiovascular Society classification - based on the Canadian Cardiovascular Society [CCS] Angina Classification) ( 12 , 16 , 17 ). | **Clinical status** | **Medical recommendation** | | --- | --- | | **CCS I-II** | No restrictions regarding air travel | | **CCS III** | • airport assistance is recommended • potential need for in-flight oxygen supplementation | | **CCS IV** | Air travel is not recommended | | **Chronic coronary syndrome + uncomplicated PCI** | No restrictions after 2–3 days following the intervention | | **Chronic coronary syndrome + uncomplicated but complex PCI** | Air travel is recommended after 5–7 days following the intervention | | **Chronic coronary syndrome + complicated PCI** | e.g. coronary dissection, access-site complications – individualized assessment is required | | **Chronic Coronary Syndrome + CABG** | air travel is recommended after 10–14 days following surgery, provided the patient is hemodynamically stable, asymptomatic, and wound healing is satisfactory | [†] CCS = Canadian Cardiovascular Society Angina Classification; PCI = percutaneous coronary intervention; CABG = coronary artery bypass grafting ### TABLE 2: Recommendations for air travel following acute coronary syndrome ( 9 , 11 , 12 ). | **Clinical status** | **Medical recommendation** | | --- | --- | | **Uncomplicated ACS** | **No restrictions within 3-7 days if:** • left ventricular ejection fraction (LVEF) >50% • age <65 years • no mechanical complications are present • no electrolyte disturbances are present | | **ACS with mild complications** | • no restriction after 10-14 days if LVEF is 40-50% and symptoms are mild (CCS class II) • no restrictions after 4-6 weeks if LVEF <40% and CCS class II-III symptoms are present | | **ACS with severe complications** | **Air travel is contraindicated in the presence of:** • mechanical complications (septal rupture, free wall rupture, papillary muscle rupture) • arrhythmias (ventricular tachycardia, ventricular fibrillation, tachy-fibrillation, atrioventricular block) | [†] ACS = acute coronary syndrome; CCS = Canadian Cardiovascular Society Angina Classification; LVEF = left ventricular ejection fraction. ### TABLE 3: Recommendations for air travel in patients with heart failure ( 9 , 11 , 12 , 16 , 17 ). | **Clinical status** | **Medical recommendation** | | --- | --- | | **Acute HF, NYHA class IV** | air travel may be considered 6–8 weeks after hospital discharge | | **Chronic HF, NYHA class II** | no restrictions regarding air travel | | **Chronic HF, NYHA class III** | • airport assistance is recommended • potential need for in-flight oxygen supplementation | | **End-stage HF, NYHA class IV** | • air travel should generally be avoided • if unavoidable, travel may be undertaken with airport assistance and oxygen supplementation | | **LVAD** | **following recent implantation:** • air travel is contraindicated within the first 8 weeks | [†] **3-6 months after the implantation:** • air travel should be considered only if necessary • airport assistance is compulsory • recent INR values, medical documentation, and fully charged batteries must be available • adequate hydration should be ensured, caffeine intake should be avoided [†] HF = heart failure; NYHA = New York Heart Association Functional Classification; LVAD = left ventricular assist device. ## Chronic Coronary Syndrome and Air Travel ## Acute Coronary Syndrome and Air Travel ## Heart Failure and Air Travel ## Air travel following device implantation and open-heart surgery Following open-heart surgery, air travel is generally recommended no earlier than 10–14 days postoperatively, even in uncomplicated cases. The rationale for this recommendation is that residual intrathoracic air—such as asymptomatic pneumothorax, pneumopericardium, or pneumomediastinum—may remain trapped after surgery and can expand at higher altitudes due to reduced ambient pressure, potentially leading to clinically significant consequences. For similar reasons, after implantation of any type of pacemaker or other cardiac electronic device, air travel should be postponed for at least two weeks, if complicated by pneumothorax. In uncomplicated cases, patients may fly as early as two days after the procedure, provided that adequate pain control has been ensured. Following invasive electrophysiological procedures, air travel is generally recommended after seven days, even in uncomplicated cases, due to the risk of thromboembolic events—particularly after left-sided cardiac catheterization. In exceptional and well-justified circumstances, patients may be permitted to fly as early as two days after the procedure. Similarly, following structural cardiac interventions, air travel may be recommended after seven days in the absence of complications. For patients with implanted cardiac devices, it is generally recommended that they carry their device identification card along with relevant medical documentation, including a recent electrocardiogram. Patients should inform airport security personnel about the presence of the implanted device, avoid placing handheld metal detectors directly over the device, and minimize the time spent in close proximity to metal detection systems (9). ## WELLNESS Among domestic recreational options, particularly in light of Hungary’s natural resources, wellness programs and spa visits are highly popular. Consequently, questions regarding the safety of sauna and spa use frequently arise in both rehabilitation and cardiology practice. In order to provide appropriate recommendations, it is essential to understand the different forms of passive heat exposure and their physiological effects on the human body. The traditional Finnish sauna represents one form of passive heat therapy, characterized by high temperatures ranging from 80 to 100°C, low humidity levels of approximately 10–20%, and repeated short exposure sessions lasting 5–20 minutes. Infrared saunas are typically operated at lower temperatures (40–60°C) and are used in repeated sessions lasting 15–30 minutes. Warm-water baths generally have temperatures between 38 and 42°C; however, in these settings, not only thermal effects but also the physiological impact of hydrostatic pressure must be taken into account. ## EFFECTS OF DIFFERENT HEAT MODALITIES ON THE CARDIOVASCULAR SYSTEM ## Increase in core body temperature All forms of passive heat exposure lead to an increase in core body temperature, which in turn initiates a range of hemodynamic changes. In the case of the Finnish sauna, esophageal temperature may reach 39°C within 10 minutes (18). Despite the lower ambient temperature, infrared sauna use may result in a 1.0–1.2°C increase in core body temperature within 15 minutes (19, 20). During warm-water bathing, shoulder-level immersion in 41°C water for 10 minutes induces a similar 1.0–1.2°C rise in core temperature. This effect is attributable both to the approximately 24-fold greater thermal conductivity of water compared with air and to the absence of evaporative cooling through sweating (20). ## Changes in cutaneous circulation and sweating As core body temperature rises, skin temperature increases, leading to peripheral vasodilation and the onset of sweating, which typically occurs when core temperature increases by approximately 0.4°C (21). Owing to the nature of heat exposure, the Finnish sauna induces a greater degree of sweating than other modalities at comparable levels of core temperature elevation. In sauna-acclimatized individuals, sweat-induced fluid loss may reach up to 1.3 L/hour (22). ## Increase in heart rate and cardiac output An increase in body temperature of 1°C is associated with an approximate rise of 30 beats per minute in heart rate. During Finnish sauna exposure, heart rate may reach 120–150 beats per minute, whereas the increase observed with infrared sauna use and warm-water bathing is generally less pronounced (22–25). Heat exposure also leads to an increase in cardiac output. During warm-water bathing, cardiac output may increase by 60–140%, while Finnish sauna use results in variable increases depending on exposure duration and temperature, ranging from mild elevations up to approximately 75%. Infrared sauna use increases cardiac output by 30–50% (26). ## Intracardiac pressures and stroke volume Passive heat exposure results in modality-specific changes in intracardiac pressures and stroke volume. Redistribution of the circulation occurs in all cases as body temperature rises. In Finnish and infrared saunas, where hydrostatic pressure does not play a role, right atrial pressure and left ventricular filling pressures decrease (27, 28). In contrast, during warm-water immersion, hydrostatic pressure increases venous return, leading to elevations in all intracardiac pressures. Based on this key difference, sauna use may be safer for patients with heart failure compared with warm-water bathing (20). However, the hemodynamic changes induced by warm-water immersion are comparable to those observed during moderate-intensity physical exercise, suggesting that warm-water bathing may be more effective in promoting cardiovascular adaptation (26). Stroke volume does not change significantly in response to heat exposure, and no meaningful differences have been observed when comparing sauna use with warm-water bathing (20). ## Blood pressure Heat-induced peripheral vasodilation reduces systemic vascular resistance, resulting in a decrease in systolic and diastolic blood pressure during Finnish and infrared sauna use. During warm-water bathing, however, the hydrostatic pressure partially counteracts the reduction in diastolic blood pressure (20). The blood pressure–lowering effect of passive heat exposure may persist for up to 60 minutes after cessation of heat exposure, similar to the post-exercise hypotensive response observed following physical activity (25)**.****Table 4** summarizes the hemodynamic changes induced by different heat modalities. ### TABLE 4: Cardiovascular effects of different heat modalities ( 18 - 20 , 22 - 28 ). | **Heat modality** | **Heart rate** | **Cardiac output** | **Intracardiac pressure** | **Stroke volume** | **Blood pressure** | | --- | --- | --- | --- | --- | --- | | Finnish sauna | ↑↑ | ~75% ↑ | ↓ | ↔/↑ | ↓ | | Infrared sauna | ↑↑ | 30-50% ↑ | ↓ | ↔/↑ | ↓ | | Warm-water bathing | ↑ | 60-140% ↑ | ↑ | ↔ | ↔/↓ | Among the passive heat modalities discussed, traditional Finnish sauna is the most extensively studied. The beneficial cardiovascular effects of sauna bathing are well established; however, concerns may arise regarding potential adverse effects in individuals with pre-existing cardiovascular disease. Finnish investigators have examined the safety of sauna bathing in a wide range of populations and have reported no adverse effects in patients with stable coronary artery disease, heart failure, or hypertension (29-31). It is important to note that the Finnish population studied typically engage in sauna bathing regularly, often several times per week, which likely results in significant hemodynamic adaptation. Importantly, studies conducted in less sauna-acclimatized populations have likewise not demonstrated adverse events associated with sauna use when performed within safe limits (32, 33). In patients with coronary artery disease, myocardial ischemia may theoretically occur as a consequence of heat-induced increase in heart rate, similar to the physiological response observed during physical exertion. Therefore, the application of heart rate control during sauna bathing may be advisable. Adherence to the heart rate ranges determined and applied during structured cardiac rehabilitation exercise programs may reduce the risk of angina or latent myocardial ischemia. Concerns are also frequently raised regarding the risk of arrhythmias and sudden cardiac death. In a study involving 98 patients with a history of acute myocardial infarction, arrhythmic events were observed in only 8% of participants during sauna bathing, compared with an incidence of 18% during submaximal physical exercise (26). In the majority of reported cases of sauna-associated sudden cardiac death, alcohol consumption was identified as a contributing factor. Alcohol intake in conjunction with sauna use increases the risk of hypotension, cardiac complications, and accidental injuries (24). In individuals who have not previously engaged in regular sauna use, unexpected adverse reactions may occur. Therefore, the implementation of specific safety measures is advisable in sauna-naïve individuals, including shorter sauna sessions, longer recovery periods between sessions, adequate fluid replacement, and avoidance of cold-water immersion. Additionally, unsupervised sauna use or sauna bathing without a companion should be discouraged in this population. ## Contraindications Sauna bathing in any form, as well as the use of warm-water baths, is clearly contraindicated in the following conditions (26): - unstable angina - any unstable clinical condition - severe aortic stenosis - recent myocardial infarction - recent transient ischemic attack or stroke - elderly patients with orthostatic hypotension. ## Conclusion Recreation encompasses physical and/or intellectual activities that fulfill fundamental psychological and biological human needs. During the convalescent phase of rehabilitation following a cardiovascular event, questions regarding participation in recreational activities frequently arise. In previous decades, clinical practice often unnecessarily deprived patients with cardiovascular disease of opportunities related to travel and wellness activities. With a detailed understanding of the physiological and hemodynamic effects associated with air travel and various passive heat modalities, the risks related to flying and wellness activities can be appropriately assessed. As a result, the population of patients for whom these activities are contraindicated has become more narrowly defined, allowing a greater number of individuals with cardiovascular disease to safely benefit from travel and wellness-related recreational opportunities.

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