			Home About us Contact

AV Intervals (av + interval)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Reduction of RV Pacing by Continuous Optimization of the AV Interval

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2006
GORAN MILASINOVIC
Background: In patients requiring permanent pacing, preservation of intrinsic ventricular activation is preferred whenever possible. The Search AV+ (SAV+) algorithm in Medtronic EnPulseÔ 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. [source]

Successful Treatment of Severe Orthostatic Hypotension with Cardiac Tachypacing in Dual Chamber Pacemakers

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2000
HARUHIKO ABE
Orthostatic hypotension is an evolving and disabling disease usually observed in elderly patients with dramatic consequences on morbidity, mortality, and impairing the quality of life. We studied the effects of the pacing rate and AV interval on the blood pressure drop in the upright position in two patients with previously implanted pacemakers for sinus node dysfunction. Although the AV interval did not affect the blood pressure drop in the upright position, tachypacing at 100 paces/min improved it dramatically and prevented syncope. Cardiac tachypacing is a useful therapeutic option in severe refractory Orthostatic hypotensive patients, especially those with chronotropic incompetence. [source]

Severe Atrioventricular Decoupling, Uncoupling, and Ventriculoatrial Coupling During Enhanced Atrial Pacing: Incidence, Mechanisms, and Implications for Minimizing Right Ventricular Pacing in ICD Patients

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2008
MICHAEL O. SWEENEY M.D.
Background: Enhanced AAI/R pacing minimizes right ventricular pacing but may permit or induce AV decoupling (AV-DC) due to unrestricted AV intervals (AVIs). The purpose of this study was to characterize and quantify AVI behavior in a randomized trial of enhanced AAI/R pacing in ICD patients. Methods: One hundred twenty-one patients in the Marquis ICD MVPÔ Study, a randomized 1-month crossover comparison of cumulative% ventricular pacing (Cum%VP) in enhanced AAIR (MVP) vs DDD/R, were analyzed. AV-DC was defined as ,40% AVIs >300 ms; VA coupling (VA-C) was defined as%V-atrial pace (AP) intervals <300 ms. Dynamic AVI behavior and increases in Cum%VP due to AV block (AV uncoupling, AV-UC) were characterized using Holters with real-time ICD telemetry. Results: AV-DC occurred in 17 (14%) of patients. Baseline PR, amiodarone, nighttime, lower rate >60 beats/min, rate response, and Cum%AP were associated with longer AVIs. Logistic regression identified baseline PR (odds ratio [OR]= 1.024, 95% confidence interval [CI] 1.007,1.042; P = 0.005), and Cum%AP (OR = 1.089, 95% CI 1.027,1.154; P = 0.004) as predictors of AV-DC. AV-DC was associated with ,10-fold increases in both Cum%VP (13.6 ± 28.3% vs 1.2 ± 3.9%; P = 0.023) due to transient AV-UC) and VA-C (6.0 ± 17.5% vs 0.5 ± 1.2%, P = 0.028). AV coupling (<40% AVIs >300 ms) was preserved in 104 (86%) patients. Conclusions: AV-DC, VA-C, and AV-UC may be worsened or induced by enhanced AAI/R pacing. Conservative programming of lower rate and rate response should reduce the risk of AV-DC by reducing Cum%AP. [source]

Multicenter, Prospective, Randomized Safety and Efficacy Study of a New Atrial-Based Managed Ventricular Pacing Mode (MVP) in Dual Chamber ICDs

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2005
MICHAEL O. SWEENEY M.D.
Background: Ventricular desynchronization caused by right ventricular pacing may impair ventricular function and increase risk of heart failure (CHF), atrial fibrillation (AF), and death. Conventional DDD/R mode often results in high cumulative percentage ventricular pacing (Cum%VP). We hypothesized that a new managed ventricular pacing mode (MVP) would safely provide AAI/R pacing with ventricular monitoring and DDD/R during AV block (AVB) and reduce Cum%VP compared to DDD/R. Methods: MVP RAMware was downloaded in 181 patients with Marquis DR ICDs. Patients were initially randomized to either MVP or DDD/R for 1 month, then crossed over to the opposite mode for 1 month. ICD diagnostics were analyzed for cumulative percentage atrial pacing (Cum%AP), Cum%VP, and duration of DDD/R pacing for spontaneous AVB. Results: Baseline characteristics included age 66 ± 12 years, EF 36 ± 14%, and NYHA Class II,III 36%. Baseline PR interval was 190 ± 53 msec and programmed AV intervals (DDD/R) were 216 ± 50 (paced)/189 ± 53 (sensed) msec. Mean Cum%VP was significantly lower in MVP versus DDD/R (4.1 ± 16.3 vs 73.8 ± 32.5, P < 0.0001). The median absolute and relative reductions in Cum%VP during MVP were 85.0 and 99.9, respectively. Mean Cum%AP was not different between MVP versus DDD/R (48.7 ± 38.5 vs 47.3 ± 38.4, P = 0.83). During MVP overall time spent in AAI/R was 89.6% (intrinsic conduction), DDD/R 6.7% (intermittent AVB), and DDI/R 3.7% (AF). No adverse events were attributed to MVP. Conclusions: MVP safely achieves functional atrial pacing by limiting ventricular pacing to periods of intermittent AVB and AF in ICD patients, significantly reducing Cum%VP compared to DDD/R. MVP is a universal pacing mode that adapts to AVB and AF, providing both atrial pacing and ventricular pacing support when needed. [source]