Case Presentation
A 55-year-old male patient with a DDD-pacemaker for complete AV-block after septal ablation for hypertrophic obstructive cardiomyopathy presented with symptomatic non-sustained ventricular tachycardia (VT) at a rate of 166 bpm. The patient carried a right-sided transvenous DDD-pacemaker (right atrial lead: Intermedics 432-04; right ventricular lead: Intermedics 430-10). He was completely pacemaker dependent without ventricular escape rhythms. Due to multiple non-sustained VT an upgrade to a dual-chamber ICD was indicated. We decided to perform a left-sided de-novo DDD-ICD implantation and to deactivate the right-sided atrial and ventricular lead which were 21 years old.
An integrated bipolar ICD lead (Boston Scientific 0181) was placed in the right ventricular apex via the left axillary vein paying attention to maintain an adequate distance to the old ventricular lead. A new atrial lead (Boston Scientific 7741) was inserted into the right atrial appendage. The atrial and the ventricular defibrillator lead were connected to the new DF1-generator (Boston Scientific D143 Inogen).
Shortly after explantation of the old pacemaker generator, complete heart block occurred. The old pacemaker battery was quickly reconnected to reestablish pacing and to assess the situation. What is the mechanism of ventricular pacing inhibition, and what is the best solution? [Fig. 1, Fig. 2]