Management of refractory supraventricular tachyarrhythmias using low-energy transcatheter shocks

Alteration of atrioventricular (AV) conduction was attempted in 7 consecutive patients with severely symptomatic, drug-refractory supraventricular tachyarrhythmias using low-energy, direct-current transcatheter shocks of between 20 and 50 J. A single shock of 50 J or less delivered at the AV junction resulted immediately in complete AV block in 6 of the patients. Complete AV block has persisted in 3 patients, and in another who received a second shock 24 hours after the first. AV conduction was altered in the 3 patients in whom conduction either persisted or returned in such a way that supraventricular arrhythmias no longer occurred or were associated with a much slower ventricular response. After a follow-up of 20 to 37 months (mean 27 +/- 8), all 7 patients have improved symptomatically and 6 are taking no antiarrhythmic drugs. Thus, single low-energy transcatheter shocks can be used to ablate AV conduction. Such shocks may also modify AV conduction without production of complete AV block, but with changes in anterograde or retrograde conduction that may favorably influence recurrent symptomatic supraventricular tachyarrhythmias.