Percutaneous intracardiac direct-current shocks in dogs: arrhythmogenic potential and pathological changes

In 12 dogs, a total of 65 direct-current (DC) shocks of 100-300 J were delivered through a standard USCI6F tripolar electrode catheter to selected sites in the heart. Severe arrhythmias were more frequent after electric shocks of high energy to the ventricles and AV-nodal or His-bundle region than after comparable shocks to the left or right atria. There was a direct relationship between the strength of the electric shocks, and the extent and severity of the injury. Application of 300 J shocks led to massive necrosis and damage to all components of the myocardium including the walls of small blood vessels. However, perforation of the atrial and ventricular walls or septum did not occur in any of the animals (mean follow-up period 97 days: range 8 to 167 days). Percutaneous DC shocks up to 250 J proved to be a safe technique for closed-chest ablation of conduction tissue in dogs. These might be of value for patients with arrhythmias requiring electrical ablation of accessory pathways or foci situated in various sites in the heart.