Localization of the neurally mediated arrhythmogenic properties of digitalis

Available evidence suggests that the propensity of digitalis glycosides to produce cardiac arrhythmias is due in part to their neuroexictatory effects. We have performed experiments in cats which support the existence of a neurogenic component in the etiology of digitalis-induced ventricular arrhythmias. Our data further indicate that the locus of this neural effect lies within an area of the medulla 2 millimeters above to 2 millimeters below the obex. These findings, when considered with the effects of polar cardiac glycosides that do not cross the blood-brain barrier, suggest that the area postrema may be the site of neural activation.