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Selected Abstracts > Pacemakers

Title: Rate Responsive Pacemakers: A Rapid Assessment Protocol

(PACE Feb2008; 31:192-197)


Background: Rate responsive (RR) pacemakers are commonly implanted with nominal conservative factory-set responsiveness, which is usually accepted because established exercise protocols are timeconsuming.We aimed for efficient assessment of RR pacemaker settings.

Methods: We tested exercise heart rates in controls and paced patients using a brief exercise test that approximates real-life levels of exertion. The test used a nonmotorized treadmill: 30 seconds walking at patient-determined speed followed by 15 seconds brisk exertion. Subjects totaled 110: 26 with RR pacemakers; 22 with non-RR pacers; 27 "sick" nonpaced control patients; and 35 healthy controls. Heart rate (HR) was measured prior to exercise, after 30 seconds of casual walk, after 15 seconds of brisk walk,and 1 minute into recovery. Testing required <5 minutes from set-up to recovery.

Results: The 26 RR pacer patients had a mean HR at rest = 74 ± 10 beats per minute (bpm), walk = 87 ± 14, and brisk = 94 ± 18 (increase 27%). Non-RR pacer patients (n = 22): rest = 73 ± 12 bpm, walk = 88 ± 14, and brisk = 94 ± 17 (increase 24.3%, P = 0.60 vs RR patients). "Sick" controls (n = 27): rest = 78 ± 14 bpm, walk = 102 ± 17, and brisk = 117 ± 18 (increase 51.9%, P< 0.001 vs RR pts). For the healthy controls, HRs were at rest 83+/11 bpm, walk = 104 ± 12, and brisk = 117 ± 13 (P< 0.001 compared to both paced groups; P = NS vs sick controls).

Conclusions: Nominal RR settings may be suboptimal for many patients. The nonmotorized treadmill test allows quick and inexpensive assessment of RR programming, with the potential for efficient RR optimization.

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Title: Comparison of Two Strategies to Reduce Ventricular Pacing in Pacemaker Patients

(PACE Feb 2008; 31:167-176)


Background: Managed Ventricular Pacing (MVP) and Search AV+ (SAV+) are two pacing algorithms designed to reduce ventricular pacing.MVPpromotes conduction by operating in AAI/R mode with backup ventricular pacing during atrioventricular block (AVB). SAV+ operates in DDD/R mode with a nominal AV extension of 290 ms during atrial sensing and 320 ms during atrial pacing. The reduction in ventricular pacing was compared with these two algorithms in pacemaker patients.

Methods: The EnRhythm and EnPulse clinical studies assessed the percentage of ventricular pacing (%VP) after 1 month. Each patient's AVB status was assigned using the following hierarchical categories: persistent third-degree AVB (p3AVB), episodic third-degree AVB (e3AVB), second-degree AVB (2AVB),first-degree AVB (1AVB), and no AVB (nAVB). The%VP was tabulated for each AVB status category.

Results: Data were available from 322 patients of whom 129 received DDD(R) pacing with the MVP algorithm activated and 193 patients with DDD(R) pacing and the SAV+ function activated, each for a month period. MVP resulted in a significantly lower median%VP than SAV+ in all AVB categories except for p3AVB: nAVB (0.3 vs 2.9, P < 0.0001), 1AVB (0.9% vs 80.6%, P < 0.0001), 2AVB (37.6 vs 99.3, P<0.002), e3AVB (1.2 vs 42.2, P = 0.02), p3AVB (98.9 vs 100, P = 1.00).

Conclusion: MVP resulted in a greater reduction in%VP than SAV+ across all patient groups except persistent third-degree AV block. The greatest reduction in%VP was observed in patients with mildly impaired AV conduction.

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Title: Conventional and dedicated atrial overdrive pacing for the prevention of paroxysmal atrial fibrillation: the AFTherapy study

A.J. Camm, N. Sulke, N. Edvardsson, P. Ritter, B.A. Albers, J.H. Ruiter, T. Lewalter,P.A. Capucci, and E. Hoffmann on behalf of the AFTherapy investigators Europace (2007) 9, 1110-1118


 

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Title: Evaluation of pacemaker dependence in patients on ablate and pace therapy for AF

Eraldo Occhetta, Miriam Bortnik, Gabriele Dell’Era, Fabio Zardo, Ermanno Dametto, Biagio Sassone, Luca Gabrieli, and Paolo Marino Europace (2007) 9, 1119–1123


Aims In patients with atrial fibrillation (AF) and uncontrolled ventricular rate, radiofrequency (RF) ablation of the atrioventricular (AV) node and pacemaker (PM) implantation (ablate and pace) is a valid therapeutic approach, especially in elderly patients. The aim of our study was to evaluate the PM dependence and the incidence of correlated clinical phenomena in a patients population with AV block induced by RF ablation of the AV junction....More