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目的观察双心室起搏对病态窦房结综合征(sick sinus syndrome,SSS)患者的急性血液动力学变化及心脏绝对不应期电刺激对心功能的影响,通过计算机仿真研究,探讨绝对不应期电刺激的离子流作用机制。方法对10例SSS患者经冠状静脉左室后外侧支和右心室心尖部进行双心室起搏,通过漂浮导管观察起搏前后5 min的血流动力学和心电图变化的指标。应用计算机仿真技术,观察心脏绝对不应期电刺激前后钙浓度的变化。结果双心室起搏时,心脏每分输出量(cardiac output,CO)、心脏排血指数(cardiac index,CI)分别增加16.2%、16.8%,肺毛细血管嵌压(pulmonary capillary wedge pressure,PCWP)下降,跨室壁复极离散度(transmural dispersion of repolarization,TDR)变小,绝对不应期电刺激使仿真的心室肌细胞在绝对不应期正向波刺激,可明显增加Ca2+内流。结论双心室起搏可增加心肌收缩功能,减小跨室壁复极离散度。心脏绝对不应期电刺激可触发电压依赖性钙通道开放,使心肌钙浓度增加,增强衰竭心室肌细胞的收缩功能。
Objective To observe the effects of biventricular pacing on acute hemodynamic changes in patients with sick sinus syndrome (SSS) and the effect of cardiac absolute refractory electrical stimulation on cardiac function. By computer simulation, Mechanism of ion current during electrical stimulation. Methods Ten patients with SSS underwent ventricular pacing via the left ventricular posterior lateral branch of the coronary vein and the right ventricle. The indexes of hemodynamics and electrocardiogram were observed 5 min before and after pacing by floating catheter. The computer simulation technique was used to observe the change of calcium concentration before and after the electrical stimulation of heart absolute refractory period. Results During biventricular pacing, the cardiac output (CO) and cardiac index (CI) increased by 16.2%, 16.8%, pulmonary capillary wedge pressure (PCWP) Decreased transmural dispersion of repolarization (TDR) becomes smaller, the absolute refractory period stimulation of the simulated ventricular myocytes in the absolute refractory period forward wave stimulation, can significantly increase the Ca2 influx. Conclusion Biventricular pacing can increase myocardial contractility and reduce transmural dispersion of repolarization. Absolute heart rate electrical stimulation can trigger the opening of voltage-dependent calcium channels, so that increased cardiac calcium concentration and enhance the contractile function of failed ventricular myocytes.