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目的观察双心室起搏(BivP)对病态窦房结综合征(SSS)患者的急性血液动力学变化和心脏绝对不应期电刺激(ARPES)对豚鼠衰竭心室肌细胞钙离子流的影响。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BivP,观察起搏前后5 min的心脏每分输出量(CO)、心脏排血指数(CI)、肺毛细血管嵌压(PCWP)和心电图QRS离散度(QRSd)、QT离散度(QTd)、跨室壁复数离散度(TDR)的变化。应用单细胞收缩动缘检测仪和膜片钳技术,观察ARPES前后单个豚鼠衰竭心室肌细胞收缩幅度、ICa-L、Ca-T的变化。结果BivP时CO、CI分别增加16.2%、16.8%,PCWP下降,TDR变小,表明BivP可增加心肌收缩功能,减小跨室壁复极离散度。ARPES使单个衰竭心室肌细胞收缩幅值和Ca-T分别增高15.5%和16.8%。结论ARPES可触发ICa-L开放,增加Ca-T,增强豚鼠衰竭心室肌细胞的收缩功能。BivP时一个电信号必然进入另一个电信号的绝对不应期,因此BivP-ARPES时ICa-L开放,Ca-T增加等,可能也是其改善心脏收缩功能的机制之一。
Objective To investigate the effects of biventricular pacing (BivP) on calcium currents in ventricular myocytes from guinea pigs undergoing acute hemodynamic changes in patients with sick sinus syndrome (SSS) and absolute refractory electrical stimulation (ARPES). Methods BivP was measured in 10 patients with SSS via the left ventricular posterior lateral branch and the right ventricular apex. The cardiac output (CO), cardiac output index (CI), pulmonary capillary embolism (PCWP) and ECG QRSd, QTd, and TDR. The contractile amplitude, ICa-L and Ca-T of ventricular myocytes of single guinea pig before and after ARPES were observed by single-cell contractile mobility detector and patch-clamp technique. Results The CO and CI of BivP increased by 16.2% and 16.8% respectively, PCWP decreased and TDR became smaller, which indicated that BivP could increase myocardial contractile function and reduce transmural dispersion of repolarization. ARPES increased the amplitude of contraction and Ca-T of single-ventricular myocytes by 15.5% and 16.8%, respectively. Conclusion ARPES can trigger the opening of ICa-L, increase Ca-T and enhance the contractile function of ventricular myocytes in guinea pig failure. BivP when an electrical signal is bound to enter the absolute refractory period of another electrical signal, so BivP-ARPES open ICa-L, Ca-T increased, may also be one of its mechanisms to improve cardiac contractility.