Abstract
Introduction of a pacemaker that senses and paces in both the atrium and ventricle (DDD) has presented the problem of pacemaker mediated arrhythmia. Endless loop-tachycardia (ELT) is a reentrant arrhythymia, involving artificially placed accessory pathway as the antegrade limb and ventriculoatrial (VA) conduction as the retrograde limb. In three cases with ELT, the trigger, frequency and duration of it, and its clinical features were analyzed.
All patients underwent implantation of DDD pacemaker for treatment of atrioventricular conduction disturbance. One of them had retrograde VA conduction, but others showed no predicitive findings for tachycardia in pre-implantation electrophysiological study. Post-implantation Holter ECG revealed that the patient with VA conduction had the most frequent attacks of ELT and the duration of it was the longest among them. All patients were asymptomatic during ELT attacks. ELT was prevented by reprogramming some parameters of pacemaker.
These results suggest that not only the evaluation of retrograde VA conduction before implantation, but also the follow-up study of patients with Holter ECG and intracardiac ECG from the implanted pacemaker, is important for the detection and prevention of ELT.
