Abstract
We experienced an ablation case of drug refractory ventricular parasystole. Case: A 73-year-old man presented with complete atrioventricular block. Conduction failure was in the distal to the His bundle and escape QRS complexes were right bundle branch block with inferior axis. After DDD pacemaker implantation, electrocardiogram showed paced QRS beat (R) and broad QRS complexes (X) same morphology as the escape beats. There was no fixed relationship in R-X intervals, as would be expected if the broad beats (X) were linked to paced beats (R). A parasystole was the most likely explanation. Intravenous injection of 5 mg verapamil suppressed this broad complexes (X) only for some minutes. Application of 8 mg adenosine triphosphate prolonged and then shortened the cycle length. Cibenzoline (1.4 mg/kg) was not effective. Catheter ablation was performed for this highly symptomatic parasystole. The earliest activation site was located at the left antero-septal region and the fractionated intracardiac electrograms were recorded. No purkinje potentials were observed. Delivery of radiofrequency energy at a successful site resulted in a rapid ventricular response. Distance between successful site and His bundle region was 2.5 cm. Conclusions: The detailed pharmacological testing and intracardiac mapping may be helpful to better understand the ventricular parasysytole. Catheter ablation could be a choice of therapy.
