Banville Isabelle, Chattipakorn Nipon, Gray Richard A
Department of Biomedical Engineering, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA.
J Cardiovasc Electrophysiol. 2004 Apr;15(4):455-63. doi: 10.1046/j.1540-8167.2004.03330.x.
The dependence of action potential duration (APD) on the preceding diastolic interval (DI), i.e., restitution, has been purported to predict the development of alternans and reentrant arrhythmias. However, restitution depends on the history of activation (i.e., memory), and its relevance to arrhythmia induction and maintenance is unknown.
Using a dual-camera video imaging system, we recorded action potentials from thousands of sites on the surface of the isolated pig heart. A steady-state pacing (SSP) protocol was performed to generate the SSP APD restitution curve. During SSP, the minimum DI and APD were 57 +/- 6 ms and 107 +/- 6 ms, respectively. The restitution slope was >1 for DIs <85 +/- 5 ms; however, alternans were not observed. Abrupt decreases in cycle length (CL) resulted in a rapid (<5 beats) decrease in APD followed by a slower decrease to "steady state." DI, APD pairs for the initial beats following these rate changes were significantly above the SSP restitution curve. DI, APD pairs measured during sustained ventricular fibrillation clustered significantly below the SSP restitution curve, at significantly shorter APDs (57 +/- 4 ms) and DIs (49 +/- 6 ms) than could be achieved during SSP. In addition, abrupt increases in CL following SSP resulted in APDs significantly shorter than those predicted from the SSP restitution curve.
Our results indicate that the responses of APD and DI to sudden rate changes and during arrhythmias are not predicted by the SSP restitution relationship. Acute dynamics act to damp out the proarrhythmic oscillations predicted from the SSP restitution curve.
动作电位时程（APD）对前一心舒张间期（DI）的依赖性，即恢复，被认为可预测交替搏动和折返性心律失常的发生。然而，恢复取决于激动的历史（即记忆），其与心律失常的诱发和维持的相关性尚不清楚。
使用双摄像头视频成像系统，我们记录了离体猪心表面数千个位点的动作电位。进行了稳态起搏（SSP）方案以生成SSP APD恢复曲线。在SSP期间，最小DI和APD分别为57±6毫秒和107±6毫秒。对于DI<85±5毫秒，恢复斜率>1；然而，未观察到交替搏动。周期长度（CL）的突然缩短导致APD迅速（<5次搏动）缩短，随后缓慢下降至“稳态”。这些心率变化后最初搏动的DI、APD对显著高于SSP恢复曲线。在持续性室颤期间测量的DI、APD对显著低于SSP恢复曲线，APD（57±4毫秒）和DI（49±6毫秒）显著短于SSP期间所能达到的。此外，SSP后CL的突然增加导致APD显著短于根据SSP恢复曲线预测的值。
我们的结果表明，SSP恢复关系无法预测APD和DI对突然心率变化及心律失常期间的反应。急性动力学作用可抑制根据SSP恢复曲线预测的促心律失常振荡。
