Wolpert C, Jung W, Spehl S, Schumacher B, Omran H, Esmailzadeh B, Lüderitz B
Department of Medicine-Cardiology, University of Bonn, Germany.
J Interv Card Electrophysiol. 1998 Dec;2(4):351-5. doi: 10.1023/a:1009708604125.
Documentation of atrial signals in stored endocardial electrograms of modern implantable cardioverter-defibrillators (ICD) is a useful tool to classify the underlying arrhythmia leading to device therapy. Newest generations of ICD provide near- and far-field electrograms derived between various endocardial electrodes. The aim of this prospective study was to assess the quality and long-term stability of atrial signals in different far-field configurations including the active can housing.
A total of 300 real-time endocardial electrogram recordings in 60 consecutive patients with a modern ICD in subpectoral position were analysed at the time of implant, pre-hospital discharge, 1, 3 and 12 months follow-up. Four different configurations were evaluated: right ventricular coil to can housing, can housing to pace/sense ring, right ventricular coil to pace/sense tip, and pace/sense tip to pace/sense ring. The best visibility of p-waves at an ECG-resolution of 0.5 mV/mm was seen in the can to coil configuration (77% of the patients). In the can to pace/sense ring electrogram p-waves could be observed in 58% of the patients. No p-waves were visible to pace/sense tip to pace/sense ring. At a resolution of 1.0 mV/mm p-waves were only visible in 10% of all patients exclusively in the can housing to right ventricular coil configuration. The results were stable (100% of the patients) over a follow-up of one year.
Endocardial far-field electrograms, derived from the can housing and the right ventricular coil provide a p-wave visibility in 77% of the patients and demonstrate a long-term stability over at least one year, provided that the ECG-resolution is set at 0.5 mV/mm. Since the electrogram resolution of stored electrograms depends on the EGM-range, and the ECG-resolution at an EGM-range of 15 mV would be 1 mV/mm, the EGM-range is recommended to be programmed to 7.5 mV to ensure an ECG-resolution of at least 0.5 mV/mm for stored electrograms.
