Focuses on the use of transvenous atrial pacing on three occasions in two patients with refractory ventricular tachycardia and ventricular fibrillation occurring in the absence of atrioventricular (AV) block. Potential reasons for the development of arrhythmias; Recommended treatment for ventricular arrhythmias that arise in the presence of normal AV conduction; Risks of precipitating ventricular arrhythmias by conveying electric currents.