Applied Signal Processing Group, Swiss Federal Institute of Technology, Lausanne, Switzerland.
J Cardiovasc Electrophysiol. 2012 Sep;23(9):1003-12. doi: 10.1111/j.1540-8167.2012.02336.x. Epub 2012 May 3.
Kinetics of Atrial Repolarization Alternans.
Repolarization alternans (Re-ALT), a beat-to-beat alternation in action potential repolarization, promotes dispersion of repolarization, wavebreaks, and reentry. Recently, Re-ALT has been shown to play an important role in the transition from rapid pacing to atrial fibrillation (AF) in humans. The detailed kinetics of atrial Re-ALT, however, has not been reported so far. We developed a chronic free-behaving ovine pacing model to study the kinetics of atrial Re-ALT as a function of pacing rate.
Thirteen sheep were chronically implanted with 2 pacemakers for the recording of broadband right atrial unipolar electrograms and delivery of rapid pacing protocols. Beat-to-beat differences in the atrial T-wave apex amplitude as a measure of Re-ALT and activation time were analyzed at incremental pacing rates until the effective refractory period (ERP) defined as stable 2:1 capture.
Atrial Re-ALT appeared intermittently but without periodicity, and increased in amplitude as a function of pacing rate until ERP. Intermittent 2:1 atrial capture was observed at pacing cycle lengths 40 ms above ERP, and increased in duration as a function of pacing rate. Episodes of rapid pacing-induced AF were rare, and were preceded by Re-ALT or complex oscillations of atrial repolarization, but without intermittent capture.
We show in vivo that atrial Re-ALT developed and increased in magnitude with rate until stable 2:1 capture. In rare instances where capture failure did not occur, Re-ALT and complex oscillations of repolarization surged and preceded AF initiation. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1003-1012, September 2012).
心房复极交替的动力学。
复极交替（Re-ALT），即动作电位复极的逐搏交替，促进复极离散、波断裂和折返。最近，Re-ALT 已被证明在人类从快速起搏到心房颤动（AF）的转变中发挥重要作用。然而，迄今为止尚未报道心房 Re-ALT 的详细动力学。我们开发了一种慢性自由行为绵羊起搏模型，以研究作为起搏频率函数的心房 Re-ALT 的动力学。
13 只绵羊被慢性植入 2 个起搏器，用于记录宽带右房单极电图并传递快速起搏方案。作为 Re-ALT 和激活时间的逐搏差异的心房 T 波顶点幅度在递增起搏率下进行分析，直到有效不应期（ERP）定义为稳定的 2:1 捕获。
心房 Re-ALT 间歇性出现，但无周期性，且随着起搏率的增加而增加，直到 ERP。在 ERP 以上 40 ms 的起搏周期长度处观察到间歇性 2:1 心房捕获，并随着起搏率的增加而增加。快速起搏诱导的 AF 发作很少见，且发生在 Re-ALT 或心房复极的复杂振荡之前，但无间歇性捕获。
我们在体内显示，心房 Re-ALT 随着率的增加而发展并增加幅度，直至稳定的 2:1 捕获。在未发生捕获失败的罕见情况下，Re-ALT 和复极的复杂振荡会激增并先于 AF 发作。（J 心血管电生理学，第 23 卷，第 1003-1012 页，2012 年 9 月）。
