用实验性心力衰竭制作持续性心房颤动模型

Model of Sustained Atrial Fibrillation in Conscious Dogs With Pacing Induced Heart Failure

为探讨实验性心力衰竭（简称心衰）形成持续性心房颤动（简称房颤）的可行性，用２００～２５０ｐｐｍ的频率以ＶＯＯ方式起搏犬心室３～７周形成实验性心衰，在犬清醒状态下观察心衰前、后刺激诱发的房性快速心律失常。快速起搏右室３～７周，８条犬均发生充血性心衰，３周时体重由心衰前的２８±６ｋｇ降至２４±４ｋｇ（Ｐ＜０．０５）；左室射血分数由０．６４±０．０６降至０．２３±０．０９（Ｐ＜０．０１），右房直径由２５±３ｍｍ增至３６±６ｍｍ（Ｐ＜０．０１），心房不应期由１１６±５ｍｓ增至１３７±１２ｍｓ（Ｐ＝０．０１），不应期离散度无显著性改变（１６±１２ｍｓｖｓ２０±９ｍｓ，Ｐ＝０．２０），心房平均传导时间亦无显著性变化（６１±１９ｍｓｖｓ６６±２４ｍｓ，Ｐ＝０．２０）。１条犬于起搏后第６周夜间突然死亡。心衰前，８条犬均未诱发心房扑动，４条犬诱发短暂房颤；心衰后，８条犬均可反复诱发心房扑动和持续性房颤（持续时间超过１５ｍｉｎ，平均周长９５±５ｍｓ），最长者持续２４ｈ以上。结果表明起搏心室导致犬心衰可形成非瓣膜病性慢性房颤的实验模型。

The purpose of this study was to establish a new animal atrial fibrillation (AF) model that should be highly relevant to clinical conditions and that has arrhythmias sustained longer enough to allow testing various ablation approaches.In 8 dogs,the right ventricle was paced at 200～250 beats per minute for 3 to 7 weeks to induce heart failure.Inducibility of sustained AF was tested from three atrial sites at baseline and once a week after rapid ventricular pacing in the conscious,nonsedated state.The atrial effective refractory periods (AERP) and conduction time were measured and the dispersion of AERP was calculated.Left ventricular ejection fraction (LVEF) and right atrial diameters were measured by echocardiogram.The atrial pressures were monitored with chronically implanted catheters.After 3 to 7 weeks rapid ventricular pacing,all dogs developed heart failure.LVEF decreased from 0.64±0.06 to 0.23±0.09 ( P <0.01).Right atrial diameter increased from 25±3 to 36±6 mm ( P <0.01).Three dogs developed ascites,one dog had sudden cardiac death.At the baseline,4 dogs had inducible non sustained short run of AF with cycle length of 93±4 ms,no dog had inducible atrial flutter (AFL).In congestive heart failure,all dogs had inducible sustained AF with cycle length of 95±5 ms and the longest run of more than 24 hours.All dogs were induced sustained AFL with cycle length of 119±9 ms in heart failure.Compared to baseline,AERP increased (116±5 ms versus 137±12 ms, P =0.01),dispersion of AERP (16±12 ms versus 20±9 ms, P =0.20) and conduction time (61±19 ms versus 66±24 ms, P =0.20) did not change.Pacing induced heart failure makes atria more susceptibel to induce sustained AF and AFL.It provides a new model to study the mechanism of AF associated with congestive heart failure and which may be helpful to develop new ablation approaches to cure AF.