Electrocardiographic alterations induced by repeated electrical stimulation of the heart at low intensity

Repeated, low-intensity electrical stimulation of the heart gradually leads to the development of electrocardiographic abnormalities that culminate in cardiac arrhythmias, mainly A-V block in the isolated heart frog and ventricular and supraventricular tachyarrhythmias in the canine heart in situ. The pattern of development of these alterations shows some characteristics similar to the kindling phenomenon. Blockade of adrenergic influences on the heart offered complete protection against the development of cardiac arrhythmias. These results support the idea that a kindling-like effect can be induced by the periodic electrical stimulation of structures other than the CNS.