The Efects Of Concomitant Use Of Ibutilide And Amiodarone On Cardiac Electrophysiological Mechanism In Rabbit Letfventricule

Ibutilide is a class Ⅲ antiarrhythmic drugs, which has become a commonly used drugsof clinical cardioversion for atrial fibrillation. However, some patients come across withserious complications such as atrial fibrillation, atrial flutter or even torsades de pointesventricular tachycardia (torsades de pointes, Tdp) using ibutilide to do the cardioversion.And this will somehow limit the use of Ibutilide in clinical. There are studies recentlyresearched show that enlargement of transmural dispersion of repolarization(TDR) mightdue to the inconsistently extension in the internal and the outer layer of cardiac actionpotential, which would cause the Tdp. Meanwhile, the amiodarone, which is believed that itcan reduce TDR, is using as the treatment of arrhythmia. Based on these findings, using therabbit s left ventricular wedge myocardial perfusion model, we will study whether thecombine use of ibutilide with amiodarone can lesser the increasement of TDR in order toreduce the occurrence of Tdp. And provide updates for the clinical rational use of Ibutilidewith a better theoretical basis. Objective1、To study whether the application of Ibutilide after Amiodarone is orally given50mg/kg every day for4weeks can lesser the rabbit myocardium TDR exaltation andreduce the Tdp occurence.2、To study whether the application of Ibutilide after Amiodarone is directlygiven through coronary can lesser the rabbit myocardium TDR exaltation and reduce theTdp occurence.Methods Five left ventricular wedge preparations were made in each group from controlgroup, Ibutilide group A(perfused with normal tyrode s solution), Ibutilide groupB(perfused with hypopotassemia and hypomagnesemia tyrode’s solution), amiodarone (50mg/kg amiodarone orally given every day for4weeks) combined with Ibutilide group A(perfusedwith normal tyrode s solution), amiodarone (50mg/kg amiodarone orally given every day for4 weeks) combined with Ibutilide group B(perfused with hypopotassemia andhypomagnesemia tyrode’s solution), amiodarone (directly given through coronary)combined with Ibutilide group A(perfused with normal tyrode s solution), amiodarone(directly given through coronary) combined with Ibutilide group B(perfused withhypopotassemia and hypomagnesemia tyrode’s solution). Transmural ECG and actionpotentials from both endocardium and epicardium were simulta neously recorded．Thechanges of TDR and Tdp were analyzed．Results The TDR value in amiodarone (directly given through coronary) combined withIbutilide group A is41.2±4.15ms, which has no significantly difference with41.5±14.77msin control group. With hypopotassemia and hypomagnesemia tyrode’s solution, the TDRcame as51.6±2.6ms in AICB,41.5±14.77ms in control group and66.96±12.12ms inIbutilide group B. Each is significantly different from the other two group. Besides, the Tdpoccurs as often as the Ibutilide group B(perfused with hypopotassemia andhypomagnesemia tyrode’s solution) and the control group.And the TDR value inamiodarone (50mg/kg amiodarone orally given every day for4weeks) combined withIbutilide group A is26.12±4.95ms which is significantly different with41.5±14.77ms incontrol group. With hypopotassemia and hypomagnesemia tyrode’s solution, the TDR cameas31.56±4.73ms in AIOB,41.5±14.77ms in control group and66.96±12.12ms in Ibutilidegroup B. Each is significantly different from the other two group. Besides, the Tdp occursmuch lesser then the Ibutilide group B(perfused with hypopotassemia and hypomagnesemiatyrode’s solution) and similar as the control group.Conclusion The application of Ibutilide after Amiodarone is orally given50mg/kg everyday for4weeks can much lesser the TDR exaltation and reduce the appearance of Tdp。 Objective To study whether the use Amiodarone orally given50mg/kg every day for4weeks is better or the other.Methods Process the data we collect from above, and analyze the TDR and Tdp betweenamiodarone (50mg/kg amiodarone orally given every day for4weeks) combined Ibutilide groupA(perfused with normal tyrode s solution) and amiodarone (directly given throughcoronary) combined with Ibutilide group A(perfused with normal tyrode s solution),amiodarone (50mg/kg amiodarone orally given every day for4weeks) combined with Ibutilidegroup B(perfused with hypopotassemia and hypomagnesemia tyrode’s solution) andamiodarone (directly given through coronary) combined with Ibutilide group B(perfusedwith hypopotassemia and hypomagnesemia tyrode’s solution). The changes of TDR and Tdpin paired groups were analyzed．Results The TDR value in amiodarone (50mg/kg amiodarone orally given every day for4weeks) combined with Ibutilide group A is26.12±4.95ms which is significantly differentwith41.2±4.15ms in amiodarone (directly given through coronary) combined with Ibutilidegroup A(perfused with normal tyrode s solution). Besides, the Tdp occurs much lesser inamiodarone (50mg/kg amiodarone orally given every day for4weeks) combined with Ibutilidegroup B(perfused with hypopotassemia and hypomagnesemia tyrode’s solution) then theamiodarone (directly given through coronary) combined with Ibutilide group B(perfusedwith hypopotassemia and hypomagnesemia tyrode’s solution) and similar as the controlgroup.Conclusion The application of Amiodarone orally given50mg/kg every day for4weekscan do much better than directly given through coronary.