Schiariti M, Puddu P E, Rouet R
Il Cattedra di Cardiologia, University La Sapienza, School of Medicine, Rome, Italy.
Int J Cardiol. 1994 Jun 1;45(1):9-22. doi: 10.1016/0167-5273(94)90050-7.
Guinea-pig ventricular myocardium was partly exposed to normal Tyrode's superfusion and partly to altered conditions (using modified Tyrode's solution) set to simulate acute myocardial ischemia (PO2 80 +/- 10 mmHg; no glucose; pH 7.00 +/- 0.05; K+ 12 mM). Using a double-chamber tissue bath and standard microelectrode technique, the occurrence of spontaneous repetitive responses was investigated during simulated ischemia (occlusion) and after reperfusing the previously ischemic superfused tissue with normal Tyrode's solution (reperfusion). In 62 experiments (42 animals) the effects of: (1) duration of simulated ischemia (1321 +/- 435 s), (2) stimulation rate (1002 +/- 549 ms) and (3) number of successive simulated ischemic periods (occlusions) (1.58 +/- 0.92) on: (1) resting membrane potential, (2) action potential amplitude, (3) duration of 50 and 90% action potentials and (4) maximal upstroke velocity of action potential were studied. All variables were considered as gradients (delta) between normal and ischemic tissue. Both during occlusion and upon reperfusion, spontaneous repetitive responses were coded as single, couplets, salvos (three to nine and > 10) or total spontaneous repetitive responses (coded present when at least one of the above-mentioned types was seen). The incidence of total spontaneous repetitive responses was 31% (19/62) on occlusion and 85% (53/62) upon reperfusion. Cox's models (forced and stepwise) were used to predict multivariately the occurrence of arrhythmic events considered as both total spontaneous repetitive responses and as separate entities. These models were applicable since continuous monitoring of the experiments enabled exact timing of spontaneous repetitive response onset during both occlusion and reperfusion. In predicting reperfusion spontaneous repetitive responses, total spontaneous repetitive responses and blocks observed during the occlusion period were also considered. Total occlusion spontaneous repetitive responses were predicted by: (1) longer delta 50% action potential duration (t = 2.68), (2) shorter delta 90% action potential duration (t = -2.17) and (3) fewer occlusive periods (t = -2.46). Total reperfusion spontaneous repetitive responses were predicted by a longer delta action potential amplitude (t = 2.18). Due to few events during occlusion, prediction of individual arrhythmic entities was not possible. Upon reperfusion single spontaneous repetitive responses were predicted by longer delta maximal upstroke velocity of action potential (t = 2.59) and shorter delta 90% action potential duration (t = -2.55); couplets were predicted by longer delta 50% action potential duration (t = 3.26); longer delta action potential amplitude predicted salvos (> 10) (t = 3.26).(ABSTRACT TRUNCATED AT 400 WORDS)
将豚鼠心室肌部分暴露于正常的台氏液灌流中，部分暴露于模拟急性心肌缺血的改变条件下（使用改良台氏液）（氧分压80±10 mmHg；无葡萄糖；pH 7.00±0.05；钾离子12 mM）。采用双腔组织浴和标准微电极技术，研究了模拟缺血（阻断）期间以及用正常台氏液对先前缺血灌流组织进行再灌注（再灌注）后自发重复反应的发生情况。在62项实验（42只动物）中，研究了：（1）模拟缺血持续时间（1321±435秒）、（2）刺激频率（1002±549毫秒）和（3）连续模拟缺血期（阻断）次数（1.58±0.92）对：（1）静息膜电位、（2）动作电位幅度、（3）动作电位50%和90%持续时间以及（4）动作电位最大上升速度的影响。所有变量均视为正常组织与缺血组织之间的梯度（差值）。在阻断期间和再灌注时，自发重复反应被编码为单个、成对、阵发（3至9次和>10次）或总的自发重复反应（当出现上述至少一种类型时编码为存在）。总的自发重复反应发生率在阻断时为31%（19/62），再灌注时为85%（53/62）。采用Cox模型（强制和逐步）对被视为总的自发重复反应以及单独实体的心律失常事件的发生进行多变量预测。这些模型是适用的，因为对实验的连续监测能够精确确定阻断和再灌注期间自发重复反应开始的时间。在预测再灌注自发重复反应时，还考虑了阻断期观察到的总的自发重复反应和传导阻滞。总的阻断自发重复反应可通过以下因素预测：（1）50%动作电位持续时间差值更长（t = 2.68）、（2）90%动作电位持续时间差值更短（t = -2.17）和（3）阻断期次数更少（t = -2.46）。总的再灌注自发重复反应可通过动作电位幅度差值更长来预测（t = 2.18）。由于阻断期间事件较少，无法预测个体心律失常实体。再灌注时，单个自发重复反应可通过动作电位最大上升速度差值更长（t = 2.59）和90%动作电位持续时间差值更短（t = -2.55）来预测；成对反应可通过50%动作电位持续时间差值更长（t = 3.26）来预测；动作电位幅度差值更长可预测阵发（>10次）（t = 3.26）。（摘要截于400字）
