REPRODUCIBILITY OF VENTRICULAR-FIBRILLATION CHARACTERISTICS IN PATIENTS UNDERGOING IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR IMPLANTATION

Reproducibility of VF Characteristics. Introduction: The purpose of th is study was to evaluate the immediate reproducibility off local elect rogram characteristics recorded during repeated episodes of induced ve ntricular fibrillation (VF) in patients undergoing implantable cardiov erter defibrillator (ICD) implantation. Methods and Results: Power spe ctral analysis (using a fast Fourier transform algorithm) of electrogr ams recorded during 3 seconds of VF were analyzed in 24 patients under going ICD implantation using a Medtronic Transvene lead, Patients had 2 to 7 episodes of VF that were induced during defibrillation threshol d testing. VF was induced by burst pacing (n = 20) or T wave shock (n = 4). Simultaneous electrograms during VF were recorded from a Medtron ic Transvene lead with the following configurations: (1) a narrow spac ed (12 mm) dedicated bipole used clinically for sensing; (2) a unipola r electrogram from the right ventricular coil; and (3) a widely spaced (18.3 mm) integrated bipole using the distal tip and the coil. Intrac lass correlation coefficients (ICCs) were determined to examine the re producibility of these VF characteristics among VF episodes in each pa tient. Recordings from both bipolar configurations had ICCs from 0.40 to 0.55, whereas unipolar recordings ICCs were below 0.40. Reproducibi lity was similar for dedicated and integrated recordings. Conclusions: Frequency characteristics of repeated episodes of VF induced in the s ame subjects show fair-to-good but not excellent reproducibility. Bipo lar recordings were far more reproducible than unipolar recordings, bu t both bipolar configurations had similar reproducibility. These findi ngs have implications for both the pathophysiology of induced VF and t he design of VF detection algorithms.