摘要目的 探讨心室颤动(室颤)期间细胞内钙瞬变(CaT)与心脏动作电位(AP)之间的分离是否与室颤时快速的心脏活动频率有关. 方法 使用光学标测系统同步标测9个离体心脏的CaT和AP.Pinacidil用于缩短动作电位时间(APD)以达到快速起搏或诱发室性心动过速(室速)的频率与室颤的频率相近.计算快速起搏、快速室速和室颤时CaT与AP之间的相互关联性(MI). 结果 Pinacidil(40 μmol/L)显著缩短APD.室颤的平均周长为(77±13)ms,而Pinacidil灌注后最快室速的哪周长为76 ms.快速起搏(周长80 ms)的MI(1.13±0.15)bits和快速室速的MI(0.88±0.18)bits均高于基线室颤的MI(0.39 ±0.11)bits、Pinacidil灌注后室颤的MI(0.21±0.07)bits和洗脱Pinacidil后室颤的MI(0.36 ±0.15)bits.快速起搏和快速室速的MI高于相同优势频率室颤的MI. 结论 快速起搏和快速室速时CaT与AP密切关联,室颤时两者MI显著下降.室颤时下降的MI不是继发于快速的心室活动频率.

abstractsObjective The cardiac action potential(AP)and the intracellular Ca2+ transient (CaT)are closely associated under normal physiological conditions.but not during ventricular fibrillation (VF).The purpose of this study Was to determine whether this dissociation is directly related to the higher activation rate during VF.nethods We optically mapped AP and CaT simultaneously in nine isolated rabbit hearts.Pinacidil,a KATP channel opener,was used to shorten the action potential duration(APD)in order to capture tissue at fast pacing rates or to induce ventricular tachyrcardia(VT) comparable to VF activation rates.Mutual information(MI)Was used to calculate the degree of AP and CaT coupling.,Results Pinacidil(40 μmol/L)infusion significantly shortened APD.The averaged cycle length(CL)of VF without Pinacidil was(77 ±13)ms, whereas the shortest CL achieved during VT under Pinacidil infusion Was 76 ms.Mis during fast pacing(1.13 ±0.15)bits and fast VT(0.88 ±0.18)bits were higher than those during baseline VF(0.39 ±0.11)bits, VF with Pinacidil infusion(0.21 ±0.07)bits and VF after Pinacidil washout(O.36 ±0.15)bits.Mis during fast pacing or fast VT were higher than those of VFs at comparable dominant frequencies.Conclusions CaT is closely associated with the AP during fast pacing and fast VT,but not during VF.The reduced MI during VF is not secondary to the fast rate of ventricular activation.