心脏房室隔不同区域细胞复极异质性及其形态学特征

目的　研究房室隔内不同部位细胞复极特性及相应的形态学特征。方法　利用标准玻璃微电极技术 ,对30只家兔房室隔内普通房肌、房室结 (atrioventricularnode ,AVN)、射频消融慢径的有效靶点部位 ,即 :希氏束与冠状窦口连线的中 1/3(M区 )及下 1/3(P区 )进行细胞动作电位的引导 ,之后行组织连续切片 ,光镜下观察M区和P区的形态学特点。结果　房室交界区中不同部位细胞动作电位复极特性 :AVN细胞的动作电位复极 90 %时程 APD90 ,( 182± 17)ms]分别长于M区、P区及普通房肌细胞的APD90 ( 16 0± 9)ms,( 15 7± 8)ms ,( 15 1± 10 )ms ,P <0 .0 5 ]。普通房肌细胞的APD50 和APD3 0 ( 90± 6 )ms和 ( 70± 7)ms]分别短于AVN、M及P区过渡细胞的APD50 和APD3 0 ( 12 8± 13)ms和 ( 10 9± 12 )ms ,( 114± 9)ms和 ( 93± 8)ms ,( 10 6± 6 )ms和 ( 87± 6 )ms ,P <0 .0 1]。此外 ,在APD50 和APD3 0 上 ,AVN与P区的细胞间亦有显著性差异 (P <0 .0 5 )。M区可见一大束疏松平行排列的过渡细胞束 ,为房室结后延伸。P区可见一些过渡细胞束分别来自冠状窦口前方、下方和左房后壁。结论　房室交界区不同区域细胞间存在复极异质性。M区和P区的过渡细胞束可能与慢传导有关

Heterogeneity of cellular repolarization in heart atrioventricular septum and correlated light microscopy

Objective To observe the characteristics of cellular repolarization and morphology in different districts of the atrioventricular (AV) septum in rabbits. Methods In 30 rabbits AV septum, the cellular transmembrane action potentials (AP) of ordinary atrial myocardium, the AV node and the effective targets of the radiofrequency (RF) ablation of the slow pathways: the middle 1/3 (M district) and the inferior 1/3 (P district) between His and coronary sinus orifice were recorded with standards intracellular microelectrod. Then, the recorded positions were ascertained under light microscope by continuous tissue slicing. Results ① The APD 90 of the AV node cells (182?ms±17?ms) was longer than that of the cells of M and P districts and ordinary atrial myocardium (160±9)?ms,(157±8)?ms and (151±10)?ms]( P < 0.05 ). The APD 50 and APD 30 of ordinary atrial myocyte (90±6)?ms and (70±7)?ms] were shorter than that of the cells of AV node, M and P districts (128±13)?ms and (109±12)?ms, (114±9)?ms and (93±8)?ms, (106±6)?ms and (87±6)?ms]( P < 0.01 ). In addition, significant differences existed between the AV node cells and P districts cells at APD 50 and APD 30 ( P < 0.05 ). ② Morphological findings: A large and three smaller transitional cellular bundles were located in M and P districts.Conclusion Repolarization heterogeneity exists in the AV septum. The transitional cellular bundles in M and P districts may be related to the slow impulse propagation.