In order to reduce cumulative energy, minimize barotrauma and infranodal injury, a modified catheter ablation technique was performed on seventeen patients. These patients had drug refractory atrial tachyarrhythmias (AT) consisting of thirteen with paroxysmal atrial fibrillation (PAf), three with sick sinus syndrome (SSS) with PAf, and one having SSS with rapid left atrial tachycardia. This technique, using the femoral approach, consisted of delivering a direct-current (DC) shock using a dual electrode configuration, to the ablation site adjacent the atrioventricular (AV) junction just before the disappearance of His deflection on the His bundle electrogram. After delivering 1-4 DV shock (mean 2.8) (cumulative energy 556 +/- 260 joules), 9 pts had first degree AV block (1st AVB) and 8 pts had complete AV block (CAVB). Only two pts had a right bundle branch block after ablation. During the clinical follow-up (15.4 +/- 2.7 months), sixteen pts were asymptomatic and were free of antiarrhythmic drugs. One pt was asymptomatic with quinidine which was ineffective before ablation. Pacemaker implantation was performed in 10 pts as a back-up for symptomatic SSS and CAVB. The results show this modified technique is relatively safe and effective.