Biomedical subjects

J Russell Bailey

Publications and source records attributed to J Russell Bailey.

3 recordsLinked to original sources

PubMed2006

Reduction of RV pacing by continuous optimization of the AV interval.

BACKGROUND: In patients requiring permanent pacing, preservation of intrinsic ventricular activation is preferred whenever possible. The Search AV+ (SAV+) algorithm in Medtronic EnPulsetrade mark dual-chamber pacemakers can increase atrioventricular (AV) intervals to 320 ms in patients with intact or intermittent AV conduction. This prospective, multicenter study compared the percentage of ventricular pacing with and without AV interval extension. METHODS: Among 197 patients enrolled in the study, the percentage of ventricular-paced beats was evaluated via device diagnostics at the 1-month follow-up. Patient cohorts were defined by clinician assessment of conduction via a 1:1 AV conduction test at the 2-week follow-up. The observed percentage of ventricular pacing with SAV + ON and the predicted percentage of ventricular pacing with SAV + OFF were determined from the SAV + histogram data for the period between the 2-week and 1-month follow-up visits. RESULTS: Of 197 patients, 110 (55.8%) had intact 1:1 AV conduction, of which 109 had 1-month data. SAV + remained ON in 99/109 patients; 10 patients had intrinsic A-V conduction intervals beyond SAV + nominal and therefore SAV + disabled. The mean percentage of ventricular pacing in the 109 patients was SAV+ ON = 23.1% (median 3.7%) versus SAV + OFF = 97.2% (median 99.7%). In 87 patients without 1:1 AV conduction, SAV + was programmed OFF in 6, automatically disabled in 52, and remained ON in 29. In 8 of these patients, 80-100% reduction in ventricular pacing was observed with SAV + ON. CONCLUSION: The Search AV+ algorithm in the EnPulse pacemaker effectively promotes intrinsic ventricular activation and substantially reduces unnecessary ventricular pacing.

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PubMed2005

Automatic measurement of atrial pacing thresholds in dual-chamber pacemakers: clinical experience with atrial capture management.

BACKGROUND: The Medtronic EnPulse pacemaker incorporates the new atrial capture management (ACM) algorithm to automatically measure atrial capture thresholds and subsequently manage atrial pacing outputs. OBJECTIVES: The purpose of this study was to evaluate the clinical performance of ACM. METHODS: Two hundred patients with an indication for a dual-chamber pacemaker underwent implantation. ACM thresholds and manually measured atrial pacing thresholds were assessed at follow-up visits. Clinical equivalence was defined as the ACM-measured threshold being within -0.25 V to +0.5 V of the manually measured threshold. The clinician analyzed all ACM measurements performed in-office for evidence of proarrhythmia. RESULTS: All 200 implanted patients had a 1-month visit, and validated manual and in-office ACM threshold data were available for 123 patients. The ACM threshold was 0.595 +/- 0.252 V, and the manual threshold was 0.584 +/- 0.233 V. The mean difference was 0.010 V with a 95% confidence interval of (-0.001, 0.021). The mean difference over all visits was 0.011 V. For all patients, the individual threshold differences were within the range of clinical equivalence at all visits. No atrial arrhythmias were observed during 892 ACM tests in 193 patients. CONCLUSION: This study demonstrated that the ACM algorithm is safe, accurate, and reliable over time. ACM was demonstrated to be clinically equivalent to the manual atrial threshold test in all patients at 1 month and over the entire follow-up period of up to 6 months. ACM ensures atrial capture, may save time during follow-up, and can be used to manage atrial pacing outputs.

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PubMed2003

Bachmann's bundle versus right atrial appendage capture.

The tissue in the high intraatrial septum in the region of Bachmann's Bundle (BB) exhibits electrophysiological properties that differ from the right atrial appendage (RAA). As BB pacing emerges as an alternative to RAA pacing, the feasibility of using automatic capture recognition technology in this location should be examined. At implant, active-fixation leads were consecutively placed in the RAA, then the BB in 18 patients (55.5% men, mean age 77.1 +/- 9.1). There was no significant difference between BB and RAA in the average capture threshold (1.12 vs 1.77 V, P = 0.09), sensing threshold (3.85 vs 3.69 mV, P = 0.84), impedance (508 vs 529 Ohms, P = 0.64), evoked response (1.78 vs 1.67 mV, P = 0.83), and polarization (0.41 vs 0.46 mV, P = 0.84) between. The difference in tissue characteristics was not associated with a different evoked response measured by the ventricular capture recognition algorithm. Based on the analogous evoked response and polarization values, capture recognition technology designed for the atrium will most likely be applicable at both pacing sites.

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