AV Pacing and LV Performance

Coskey, Richard L.; Feit, Theodore S.; Plaia, Rita; Zicari, Tony

doi:10.1111/j.1540-8159.1983.tb05305.x

Cited by 21 publications

(4 citation statements)

References 17 publications

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“…9,10,[33][34][35][36][37][38][39][40] Cardiac output may increase by nearly 30% in AV synchronous pacing compared to ventricular inhibited single chamber pacing. [41][42][43] However, timing of atrial contraction prior to ventricular systole is an important determinant of cardiac output at rest. The most commonly encountered optimal AV interval in our study was 150 ms with a mean value of 154 6 36 ms. Iwase et al 44 maximal left ventricular filling with an AV interval of 150 ms in patients at rest as assessed by Doppler flow of the mitral valve.…”

Section: Discussionmentioning

confidence: 99%

Atrioventricular Interval Optimization and Exercise Tolerance

Khairy

Talajic

Domínguez

et al. 2001

Pacing Clinical Electrophis

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Modern pacemakers offer many programming options regarding the AV interval including the ability to vary AV intervals depending on whether atrial activity is paced or spontaneous and to shorten AV intervals with increasing rates. To determine if optimization of these features improves exercise tolerance, 14 patients with intact sinus node function and AV block treated with dual chamber pacemakers were enrolled in a randomized double-blind crossover trial. Doppler echocardiographic measurements of cardiac index and mitral flow were assessed over a range of programmable AV intervals at rest to determine each patient's optimal AV interval. Eleven patients completed serial graded exercise tests with spiroergometry after randomly programming the AV interval three ways in a crossover manner: fixed AV interval = 150 ms without rate adaptation (150/Fixed), fixed AVinterval = 150 ms with rate adaptation (150/R), or optimized AV interval with rate adaptive AV interval shortening (optimized/R). Exercise capacity was determined by maximum oxygen uptake. Ten men and four women, age 64 +/- 8 years, were enrolled. At rest, optimization of the AVintervalimproved the cardiac index by 21% (P < 0.001) and mitral flow by 13.4% (P < 0.001) when compared to least-favorable AV intervals. During exercise, no differences in maximum heart rates were noted. Maximum oxygen uptake was increased in both groups with rate adaptive AVinterval shortening when compared tofixed AVinterval without rate adaptation: 13.9% (adjusted P < 0.04) and 14.6% (adjusted P < 0.02) in optimized/R and 150/R, respectively. No differences were noted between optimized/R and 150/R. In conclusion, rate adaptive AV interval shortening improved exercise tolerance independent of changes in heart rate. However, optimization of the AV interval with Doppler echocardiography at rest did not further improve exercise capacity.

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Section: Discussionmentioning

confidence: 99%

Atrioventricular Interval Optimization and Exercise Tolerance

Khairy

Talajic

Domínguez

et al. 2001

Pacing Clinical Electrophis

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“…The data from the present study imply that a greater degree of AV synchrony was maintained during AV ON compared with AV OFF, thus resulting in observed differences in the rate of O 2 delivery. Presumably, the mechanism by which V o 2 kinetics were slowed during AV OFF was through a reduction in left ventricular end-diastolic filling 8,26 and hence, a relatively smaller ejection fraction. This is evidenced by the attenuated SVI response during AV OFF (Fig 2) and is further supported by the inverse relationship between SVI and phase II V o 2 (Fig 3).…”

Section: Discussionmentioning

confidence: 99%

Phase I and Phase II Oxygen Uptake Kinetics During Atrioventricular Dyssynchrony in Chronotropically Competent Pacemaker Patients

Tomczak

Wojcik

Busse

et al. 2005

Chest

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“…Previous studies have demonstrated an effect of AVD on CO both in humans and in experimental animals. 5,6 Optimized timing orchestrates the sequence of valve closure and ventricular contraction leading to maximized ventricular filling. In our study, although there were trends toward improved CO at AVDs in the middle of the examined range (Fig.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of Optimized Biventricular Pacing in Pulmonary Stenosis:

Rabkin¹,

Cabreriza²,

Curtis³

et al. 2004

Pacing Clinical Electrophis

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We tested the hypothesis that optimized biventricular pacing (BiVP) enhances cardiac output (CO) during critical pulmonary stenosis (PS) by attenuating distortions in left ventricular (LV) geometry. Following median sternotomy in six anesthetized pigs, heart block was induced by ethanol ablation. During epicardial, DDD BiVP, atrioventricular delay (AVD) was varied from 60 ms to 180 ms in 30 ms increments. At the AVD with the highest CO right-left delay (RLD) was varied from (+) 80 ms (RV first) to (-) 80 ms (LV first) in 20 ms increments. At each pacing setting, aortic flow, ECG, and LV diameter were measured in the control state (CON) and during PS, created by snaring the pulmonary artery until CO decreased 50%. Short axis LV echocardiograms were obtained at (+) and (-) 80 ms. In CON, RLD had no effect on function or geometry. During PS optimum BiVP resulted in significant increases in CO (1.12 L/min +/- 0.13 SEM at RLD =+ 40 ms versus 0.92 +/- 0.12 at RLD = 0 and 0.73 +/- 0.08 at RLD =-80), and LV fractional shortening (8.97%+/- 0.51% at RLD =+ 40 ms versus 7.34%+/- 0.58% at RLD = 0 and 6.21%+/- 0.66% at RLD =-80). In addition, LV eccentricity with (-) RLD was significantly different versus CON at both end-diastole (0.79 +/- 0.07 vs 1.02 +/- 0.03, P = 0.011 Student's t-test) and end-systole (0.83 +/- 0.05 vs 1.00 +/- 0.02, P = 0.017). However, with (+) RLD differences versus CON were not significant at either end-diastole (0.88 +/- 0.06 vs 0.99 +/- 0.03) or end-systole (0.92 +/- 0.03 vs 1.01 +/- 0.03). In swine hearts with PS, optimized BiVP increases CO, fractional shortening, and LV symmetry. BiVP warrants further study as treatment for acute postoperative heart failure.

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AV Pacing and LV Performance

Cited by 21 publications

References 17 publications

Atrioventricular Interval Optimization and Exercise Tolerance

Atrioventricular Interval Optimization and Exercise Tolerance

Phase I and Phase II Oxygen Uptake Kinetics During Atrioventricular Dyssynchrony in Chronotropically Competent Pacemaker Patients

Mechanisms of Optimized Biventricular Pacing in Pulmonary Stenosis:

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