Enhancement of efferent vagal tone in humans

Increased sympathetic tone with a concomitant depressed vagal tone predisposes cardiac patients to unstable tachyarrhythmias and sudden cardiac death. Enhancement of vagal tone has been suggested as a possible tool to counter the deleterious effects of increased sympathetic activity. The authors have examined four methods of increasing vagal tone in humans: through pharmacological means, electrical and mechanical stimulation of the esophagus and exercise training. Power spectral analysis of the heart rate variability has been used to monitor the effects of these interventions in healthy controls and patients.<>