This hormone has two effects on the heart. First, it decreases the rate of rhythm of the Sino-Atrial node which regulates heartbeat rhythm and second it decrease heart conductability into the ventricles. Basically, it dramatically slows and calms the heart and rarely causes Arrythmias. Actually many stress reduction techniques used for Arrythmias attempt to reactivate the parasympathetic nervous system to slow the heart and calm the nervous system. The therapuetic in this article will be focused on parasympathetic reactivation and a reduction in the sympathetic nervous system stress response.
Lets look Ayurvedically at the effects of excess stress and excessive sympathetic stimulation.
The first response to stress is a change in the breathing pattern from a deep to shallow breath rhythm. Under extreme stress we see a hyperventalation response where the breathing becomes shallow, labored and through the mouth. Less extreme stress will also trigger a upper chest shallow mouth breathing pattern. This is an instinctive response necessary to properly activate the emergency nervous system which predominates in the upper lobes of the lungs. If the body is under stress the breath will automatically become shallow to insure the proper emergency hormonal response.