Publications (2)18.26 Total impact
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Article: Bradycardia pacing-induced short-long-short sequences at the onset of ventricular tachyarrhythmias: a possible mechanism of proarrhythmia?
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ABSTRACT: The purpose of this study was to characterize interactions between normal pacing system operation and the initiating sequence of ventricular tachycardia (VT)/ventricular fibrillation (VF). Abrupt changes in ventricular cycle lengths (short-long-short, S-L-S) might initiate VT/VF. The S-L-S sequences might be passively permitted or actively facilitated by bradycardia pacing. Initiating sequences of 1,356 VT/VF episodes in the PainFree Rx II (n = 634) and EnTrust Trial (n = 421) were analyzed with stored electrograms and by pacing mode (DDD/R, VVI/R, and Managed Ventricular Pacing [MVP]). Interactions between pacing and VT/VF initiation were classified as: non-pacing associated, pacing associated, pacing permitted, and pacing facilitated. Non-pacing associated (no pacing, no S-L-S) and pacing associated (ventricular pacing without S-L-S) onset accounted for 44.0% and 29.8% of all VT/VF, respectively. Pacing permitted (S-L-S sequences without ventricular pacing) episodes accounted for 6.4% (DDD/R), 20.0% (MVP), and 25.6% (VVI/R) of 1,356 VT/VF episodes. Pacing facilitated onset (S-L-S sequences actively facilitated by ventricular pacing including the terminal beat after a pause) accounted for 8.2% (MVP), 9.4% (VVI/R), and 14.8% (DDD/R) of 1,356 VT/VF episodes. Pacing facilitated S-L-S VT/VF occurred in 2.6% (MVP), 3.3% (VVI/R), and 5.2% (DDD/R) of patients with episodes and was the sole initiating sequence in approximately 1% of patients. Pause durations during pacing facilitated S-L-S differed between modes (DDD/R 793 +/- 172 ms vs. MVP 865 +/- 278 ms vs. VVI/R 1180 +/- 414 ms, p = 0.002). The majority of these episodes were monomorphic VT. Ventricular tachycardia/VF in some implantable cardioverter-defibrillator patients might be initiated by S-L-S sequences that are actively facilitated by bradycardia pacing operation and might constitute an important mechanism of ventricular proarrhythmia.Journal of the American College of Cardiology 09/2007; 50(7):614-22. · 14.16 Impact Factor -
Article: Randomized pilot study of a new atrial-based minimal ventricular pacing mode in dual-chamber implantable cardioverter-defibrillators.
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ABSTRACT: We hypothesized that a new minimal ventricular pacing mode (MVP) that provides AAI/R pacing with ventricular monitoring and back-up DDD/R pacing as needed during AV block (AVB) would significantly reduce cumulative percent ventricular pacing compared to DDD/R. Conventional DDD/R mode often results in high cumulative percent ventricular pacing that may adversely affect ventricular function and increase risk of heart failure and atrial fibrillation. MVP was made operational in 30 patients with DDD/R implantable cardioverter-defibrillators (ICDs) and no history of AVB. Patients were randomized to one week each in DDD/R and MVP. Holter monitor recordings (ECG, intracardiac electrograms, and event markers) and device diagnostics were analyzed for cumulative % atrial paced (Cum%AP), cumulative percent ventricular pacing, and frequency and duration of DDD/R pacing back-up. Diaries were used to report symptoms. Age of the study population was 61 years +/- 12 years and 83% were male. Baseline PR interval was 204 ms +/- 32 ms and programmed AV intervals (DDD/R) were 200 ms +/- 50 ms (paced)/167 ms +/- 54 ms (sensed). Cum%AP was similar between MVP and DDD/R (47.9 +/- 37 vs 46.3 +/- 36). Cumulative percent ventricular pacing was significantly lower in MVP vs DDD/R (3.79 +/- 16.3 vs 80.6 +/- 33.8, P < .0001). Back-up DDD/R pacing during MVP operation due to transient AVB occurred in 10% of patients (9.3 +/- 7.4 [range 1-15] episodes/patient-day, duration 39.7 minutes +/- 156 minutes). Fifteen percent of AV intervals during MVP operation exceeded 300 ms. No significant symptoms were reported during MVP operation. MVP dramatically reduced cumulative percent ventricular pacing compared to DDD/R while maintaining AV synchrony and providing sensor-modulated atrial pacing support. Intermittent oscillations between MVP and DDD/R during transient AV block appeared safe and well tolerated.Heart Rhythm 07/2004; 1(2):160-7. · 4.10 Impact Factor
