| Objectives: to observe the dynamic changes of QT dispersion(QTd) during 24 hours after acute myocardial infarction(AMI) and reperfusion; and to study the influence of cardiac sympathetic nerve on QTd and ventricular arrhythmias(VA) in experimental rabbits. Methods: The rabbits were divided into group A (without cardiac sympathetic control, including group A0, A1 and A) and group B(with retained cardiac sympathetic control, including group B0 , B1 and B2 ). The model of AMI was made in groups A1, 2~ B~ and B2~ then reperfusion only in group ~ and B1groups A0 and B0 without AMI were served as control. QTd of all groups were measured at a serial of time points during 24 hours of the experimental process, including before and after the excision of cardiac sympathetic nerves and the occurrence of AMI and reperfusion.Electrophysiologic examinations were made to induce VA in all groups. The gained indexes of all groups were analyzed and compared. The QTd of the high risk group, in which VA was induced was compared with the QTd of the low risk group in which VA was not induced . The circadian variation of QTd was also observed in groups A0 and B0 Results: QTd of group A decreased significantly after the cardiac sympathetic nerves were excised(P<0.05);QTd of groups A1, A2, I and B2 increased instantaneously after AMI; QTd of groups A1 and B1 increased once again instantaneously after reperfusion, then decreased at once (J?O. 05); QTd of group A(AO , A1 and A2) was always lower than the QTd of corresponding group B(B0 , ~ and B2) (F?O. 05). The induced VA rate in group B was higher than in group A(P(0.05).QTd of the high risk group was higher than QTd of the low risk group (P |
