Abstract
Autonomic regulation of heart and its influence on cardiovascular disease has been an area of intriguing research for decades. The influence of sympathetic and parasympathetic inputs to heart in governing clinical presentation and outcomes amongst patients with heart failure, rhythm disorders, and sudden cardiac arrest has been established in literature.1, 2 The challenge has been to find the appropriate tools to intervene and modulate this target in order to achieve the desired end points of reduction in morbidity and improvement in survival. Betablockers, stellate ganglion blockade and denervation, ganglion plexus ablation, and vagal nerve stimulation are various methods that have been used successfully to this endpoint in heart failure and rhythm disorders.
Yoga is a mind–body therapy comprising mental, physical, and spiritual practices originating in ancient India. A structured format evolved about 2500 to 3000 years ago with sage Patanjali consolidating some of the practical concepts. 3 The practice of yoga typically involves 3 components—asanas (postures), pranayama (breathing exercises), and gnana (meditation). Control of mind by body postures has been fundamental principle of yoga with the concept that if a sustained mental activity can cause a posture, conversely a sustained posture can affect the mind. Though it resembles physical exercise, particularly the isometric exercise, it differs from it.When one holds a posture for a certain period of time associated with synchronized breathing and mindful awareness, it gradually results in voluntary control of protective reflexes. This also improves sympatho-vagal balance, influences positively the stress-related imbalances through increasing parasympathetic system, and decreases activity of the hypothalamic–pituitary–adrenal axis. The positive clinical effects that result from this are seen when practiced in various cardiovascular disease states. 4 They include decrease in both systolic and diastolic blood pressure, reduction of ectopy burden, reduction in arrhythmia frequency, and increase in heart rate variability.
Another area where benefits of yoga can be perceived is in relation to psychological stress. There is well accepted correlation between emotional stress and arrhythmias. This occurs as positive and negative emotions are transmitted to heart by autonomic nerves deferentially leading to electrical heterogeneity and genesis of arrhythmias. Yoga is known to correct imbalances of stress hormone y-aminobutyric acid (GABA) system, altering vagal tone and reducing systemic inflammatory response markers like cortisol and interleukin-6(IL-6). All these potentially contribute to prevent perpetuation of arrhythmias. The benefits of yoga are not merely theoretical. Positive outcomes have been observed which are clinically relevant. The Yoga My Heart trial was a single-center, prospective cohort study involving 49 participants, a three-month yoga intervention phase in which they were asked to participate in a structured yoga session The study demonstrated statistically significant reduction in symptomatic and asymptomatic Atrial fibrillation (AF) episodes. 5 There is supporting data that yoga reduces ventricular arrhythmia burden and frequency of ICD shocks. Vasovagal syncope is a common clinical condition and its pathophysiology is closely linked to interaction of autonomic nervous system and neurohormones. A simple yoga maneuver has been shown to decrease syncope and near syncope recurrences in a small pilot study from our center. 6
Yoga practitioners have a greater homeostatic capacity and autonomic, metabolic, and physiological resilience.Combined with its beneficial modulation of neurohumoral system, its role in heart failure is being increasingly recognized.
The autonomic nervous system is a principal component of the mind–heart connection and is a fundamental link between thoughts and emotions and the heart. Its role in regulation of cardiovascular physiology and therapeutic benefits of its modulation in various cardiac pathological states is established. With increasing authentic data on effectiveness of yoga in different disease states of cardiovascular system, it is an appropriate time to formalize the introduction of yoga in standard medical algorithms rather than consider it as an alternative medicine.