Verma A, Newman D, Geist M, Greenhut S, Laslop J, DeBellis L, Freeman M R, Dorian P
St Michael's Hospital, University of Toronto, Toronto, Canada.
Can J Cardiol. 2001 Apr;17(4):437-45.
To assess the relative contributions of rate control and rhythm regularization to left ventricular function in atrial fibrillation (AF) patients undergoing atrioventricular nodal ablation. This was performed by assessing the effect of ventricular rhythm regularization on left ventricular function during AF, and the effect of varying heart rate on left ventricular function after ablation.
Eleven patients with continuous AF and V/VI-R pacemakers undergoing therapeutic atrioventricular nodal ablation were studied. Preablation patients underwent two 30 min observation periods in a randomized, blinded fashion during which they were either in baseline AF (pacer set to default V/VI 50/min) or being paced using a rhythm stabilizing algorithm (RSA) designed to regularize rhythm without changing baseline ventricular rate. Six weeks after ablation, patients were again observed during the two following 30 min periods: pacing at a low clinically indicated rate (69+/-9 beats/min), and pacing at the rapid, mean preablation rate. During all observation periods, left ventricular function was measured continuously using a nuclear vest that provided validated measures of heart rate, ejection fraction, and normalized end-systolic volume (ESV) and end-diastolic (EDV) volume.
Before ablation, RSA successfully regularized rhythm, decreasing the coefficient of variation of interbeat intervals 20+/-5% to 10+/-4% (P<0.001). The heart rate with RSA (105+/-19 beats/min) was not significantly different from the baseline AF rate (102+/-21 beats/min). Increased rhythm regularity achieved by RSA significantly improved left ventricular function, decreasing ESV from 62+/-12 units to 57+/-11 units (P=0.03), and increasing the ejection fraction from 31+/-11% to 36+/-11% (P=0.03). After ablation, at the clinically indicated low pacing rate of 69+/-9 beats/min, a much greater improvement in ejection fraction was observed, increasing to 44+/-13% (P=0.005 compared with preablation). However, rapid regular pacing at the mean preablation rate of 110+/-18 beats/min eradicated this improvement, decreasing the ejection fraction to 31+/-8% (P=0.003), and increasing ESV from 53+/-13 units to 62+/-8 units (P=0.006).
Rhythm regularity achieved by a regularizing pacing algorithm can significantly, albeit modestly, improve left ventricular function in AF. However, more marked improvements in left ventricular function seen after ablation are primarily due to rate reduction alone.
评估房室结消融术治疗心房颤动（AF）患者时，心率控制和节律规整对左心室功能的相对贡献。通过评估房颤期间心室节律规整对左心室功能的影响，以及消融后不同心率对左心室功能的影响来进行此项研究。
对11例持续性房颤且植入V/VI-R起搏器并接受治疗性房室结消融术的患者进行研究。消融术前，患者以随机、盲法方式接受两个30分钟的观察期，期间他们要么处于基线房颤状态（起搏器设置为默认的V/VI 50次/分钟），要么使用旨在规整节律而不改变基线心室率的节律稳定算法（RSA）进行起搏。消融术后六周，在接下来的两个30分钟观察期内再次观察患者：以临床指示的低心率（69±9次/分钟）起搏，以及以消融术前的快速平均心率起搏。在所有观察期内，使用核背心连续测量左心室功能，该背心可提供经验证的心率、射血分数、归一化的收缩末期容积（ESV）和舒张末期容积（EDV）测量值。
消融术前，RSA成功规整节律，使心跳间期的变异系数从20±5%降至10±4%（P<0.001）。RSA时的心率（105±19次/分钟）与基线房颤心率（102±21次/分钟）无显著差异。RSA实现的节律规整性增加显著改善了左心室功能，ESV从62±12单位降至57±11单位（P=0.03），射血分数从31±11%增至36±11%（P=0.03）。消融术后，在临床指示的低起搏心率69±9次/分钟时，观察到射血分数有更大改善，增至44±13%（与消融术前相比，P=0.005）。然而，以消融术前的平均心率110±18次/分钟进行快速规则起搏消除了这种改善，射血分数降至31±8%（P=0.003），ESV从53±13单位增至62±8单位（P=0.006）。
通过规整起搏算法实现的节律规整性虽能显著但适度地改善房颤患者的左心室功能。然而，消融后左心室功能更显著的改善主要仅归因于心率降低。
