An experimental device for low-energy, precise ablation of AV conduction

A combination suction catheter-bipolar lead system permits precise ablation of AV conduction with low energy. The electrode is positioned to maximize the bipolar His potential, then to maximize the HP between the tip and a surface electrode. With the tip held in place by 100-200 mmHg of suction, this site is paced. If the St-V interval is short and the ventricular morphology is similar to a sinus beat, a shock of 10 or 20 J is delivered. If complete heart block does not result, additional shocks are delivered. The device was used in eight dogs. When the St-V was close to the unpaced H-V interval, a shock of 20 J always produced permanent CHB. In contrast, an initial shock of 10 J always failed, and more shocks of up to 30 J were required to produce CHB which, even then, did not always persist. At 60 days the hearts were healed with a round, white, dense scar of about 2 mm in diameter just above the leaflet of the tricuspid valve. This device can produce permanent dissociation of the atria and ventricles with a shock of 20 J. It also enables precise positioning of the electrode.