兔在体左心室肥厚心肌跨室壁复极不均一性的实验研究

目的　探讨兔在体左心室肥厚心肌跨室壁复极不均一性的变化。方法　以腹主动脉缩窄术制备家兔高血压左心室肥厚模型 (腹主动脉缩窄组 ) ,并设假手术组 (仅游离腹主动脉未缩窄 )作为对照。采用自制复合式电极在兔左心室游离壁同步记录在体心内膜、心肌中层、心外膜心肌单相动作电位 (MAP) ,比较两组间跨室壁复极不均一性的差异。结果　腹主动脉缩窄组平均动脉压、左心室游离壁厚度、全心重量及其与体重比率均大于假手术组。缩窄组三层心肌单相动作电位复极至 10 0 %的时程 (MAPD1 0 0 ) (内膜 191± 19ms,中层 2 44± 2 4m s,外膜 196± 15 ms)均比假手术组 (内膜 170± 18ms,中层 172± 15 ms,外膜 168± 16m s)延长 ,以中层心肌 MAPD1 0 0 的延长最为明显 ;缩窄组跨室壁复极离散度 (TDR) (65± 10 ms)较对照组 (4± 3 m s)明显增大 (P<0 .0 1)。结论　兔在体左心室肥厚心肌跨室壁复极不均一性明显增大 ,可能是肥厚心肌心律失常发生增多的原因之一

Study of the transmural repolarization heterogeneity in intact rabbits with left ventricular hypertrophy

Objective To investigate the change of transmural repolarization heterogeneity in intact rabbits with left ventricular hypertrophy. Methods The rabbit models of ventricular hypertrophy were prepared by a partial constriction of the abdominal aorta(abdominal aorta constriction group),other rabbits designed as sham operation group(only exposure abdominal aorta no constriction). The monophasic action potentials of epicardium(epi), midmyocardium(mid) and endocardium(endo) were recorded simultaneously in left ventricular free wall in vivo by a compound electrode made by ourselves. The transmural repolarization heterogeneity were compared between the two groups. Results Mean arterial pressure, left ventricular wall thickness, left ventricular weight and left ventri cular weight to body weight ratio were increased significantly in abdominal aorta constriction group compared with sham operation group. The monophasic action potential durations at 100% repolarization(MAPD 100 ) of abdominal aorta constriction group (endo 191±19 ms, mid 244±24ms, epi 196±15ms)were significantly longer than that of sham operation group(endo 170±18ms, mid 172±15ms, epi 168±16ms), P <0.05 or P <0.01. This prolongation of MAPD 100 in hypertrophic myocardium was more pronounced in midmyocardium than epicardium and endocardium. The transmural dispersion of repolarization(TDR) in abdominal aorta constriction group(65±10ms) was enlarged significantly compared with that in sham operation group(4±3ms)( P <0.01).Conclusion The transmural depolarization heterogeneity increase significantly in hypertrophic myocardium in rabbits in vivo, that perhaps increase the incidence of arrhythmia in cardiac hypertrophy.