Vagal stimulation for heart failure: background and first in-man study.

This article reviews the background and rationale that have led to the first in-man study of the effects of direct chronic vagal stimulation for the management of heart failure. Following a brief discussion of the concept of "autonomic imbalance," the focus shifts to the wealth of pathophysiologic information gathered over the years by the in-depth study of an animal model for sudden cardiac death. These data, on the bleak prognostic outcome associated with the presence of depressed vagal reflexes in both animals and men and on the striking reversal in outcome produced in high-risk dogs by direct vagal stimulation, made logical the move toward a human study. The data of the first pilot trial in man are presented and reviewed. The study population consisted of eight patients with advanced heart failure who underwent implantation of a neurostimulator system capable of delivering low-current electrical pulses to stimulate the right vagus nerve. These initial data suggest that chronic vagal stimulation in man is feasible and safe. Furthermore, in this pilot study, the treatment appears to be associated with beneficial effects.