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| Chronic Bipolar Intraventricular Electrograms Are Stable During Changes in Body Position and Activity: Implications for Antitachycardia Devices |
| Stephanie A Caswell MSEE, Aliki T Compos BSEE, Janice M Maldonado BSEE, Janice M Jenkins PhD, Lorenzo A DiCarlo MD |
Morphometric analysis of intraventricular electrograms (EGMs) is under consideration for improving tachycardia recognition by implantable antitachycardia devices (ATDs). The addition of such an algorithm to rate-based rules assumes that intraventricular electrograms during sinus rhythm (SR) or atrial fibrillation/flutter (AFF) remain stable. Previous studies, using temporary electrodes in active patients, have suggested otherwise. In this study, chronic (24 + 21 mos) bipolar EGMs were examined in 10 patients (pts) while supine (SUP), sitting (SIT), and standing before (BSTND) and after (ASTND) limited exercise, simulating routine physical activity (26% increase in HR + 16%). EGMs were recorded by telemetry (1-150 Hz) from commercial pacemakersduring SR (8 pts) and AFF (2 pts), digitized (1000 Hz), filtered (1-150 Hz), and compared using correlation waveform analysis (CWA) and normalized difference of area (DOA). A supine EGM template was compared to all other EGMs of the same patient. DOA and CWA coefficients were transformed (Fisher-Z) to ensure normality and analyzed using a standard two-tailed t-test. The relative percentage change in peak-peak amplitude (RAMP) compared to supine amplitude was also calculated. RESULTS (mean+/-stddev for all patients in each of the protocols):
Results: There was no significant difference in intrapatient EGM morphology (p> 0.05) using CWA and DOA in 10/10 patients from supine position compared to sitting, upright, and post exercise despite moderate changes in amplitude. Conclusions: In contrast to EGM morphology observed with temporary electrodes, the morphology of the EGMs of chronic bipolar electrodes does not appear to be affected by patient position or routine physical activity. Thus, a stable EGM is available for arrhythmia detection using template matching morphometric analyses |
| Published in PACE 1995 |
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