心律失常-modifiedppt课件.ppt

III类 延长动作电位时程 代表药：胺碘酮、溴苄铵 用于：室上性、室性心律失常 Ⅳ类：阻滞钙通道 代表药：维拉帕米、地尔硫卓。 主要用于：室上性心律失常 抗心律失常药物分类 谢谢!! Once the membrane reaches -40 to -45mV the charge falls quickly to the resting level. The cell membrane once again becomes polarized and the cycle begins again. (Ellenbogen, Kenneth A. Wood, Mark A. Basic Concepts of Pacing. Cardiac Pacing ICDs, 3rd Edition. Malden, MA: Blackwell Science, Inc., 2002: 48-49.) Also see: Fogoros, Richard N. Electrophysiologic Testing, 3rd Edition. Blackwell Science, Inc. 1999. Like automaticity, triggered activity involves the leakage of positive ions into a cell, resulting in new action potentials. However, unlike automaticity, Triggered Activity is not consistently spontaneous. It may be either a single or repetitive firing of a myocardial cell, or group of cells, caused by re-excitation. Ion leakages that occur late in Phase 3 or early in Phase 4 (after cell recovery has begun) are called afterdepolarizations, or late potentials. Afterdepolarizations can be the ‘trigger’ that cause ventricular tachyarrhythmias. For reentry to occur, the following events must take place: A premature impulse occurs in the reentrant circuit at a time when Pathway A (with the short refractory period) is ready to accept the impulse, and Pathway B (with the long refractory period) is still repolarizing from the previous depolarization. The impulse slowly travels through Pathway A and reaches Pathway B just as Pathway B completes it repolarization and is no longer refractory, which means it is ready to accept a stimulus. The impulse travels through Pathway B in a retrograde direction and reenters Pathway A. The impulse is conducted antegrade through Pathway A, and the circuit continues. Reentry does not display a “warm up” or “cool down” period. 窦性P波频率在100～105次/分，偶至200次/分 ECG:窦性P搏的频率﹤60bpm 常伴有窦性心律不齐，PP间期差异﹥0.12s Atrial fibrillation can also result from the rapid discharge of impulses from one or many ectopic (non-sin