الفهرس 
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Abstract
Reperfusion arrhythmia is one of the important complications after open heart surgery. The incidence of ventricular fibrillation (VF) after release of the aortic cross-clamp in patients undergoing cardiac surgery has been reported to be between 45% and 100%.(Samantaray et al., 2010)
Reperfusion injury results in myocyte damage through myocardial stunning, microvascular and endothelial injury, and irreversible cell damage or necrosis.(Yellon & Baxter, 2000)
Ventricular fibrillation is when the heart vibrates instead of pumping due to disorganized electrical activity in the ventricles. Ventricular fibrillation results in cardiac arrest with loss of consciousness, no pulse and death in the absence of treatment.(Baldzizhar et al., 2016)
Ventricular fibrillation may result in increased myocardial oxygen consumption, distension of the ventricle with resultant increases in wall tension, and acidosis of the myocardial tissue and intra-myocardial damage and so deteriorates cardiac output.(Boyd & Thomas, 2000) Reperfusion ventricular fibrillation aggravates the myocardial damage and electrical defibrillation may cause additional injury for the already ischemic myocardium.(Fall et al., 1987)
The prevention of VF by pharmacologic means has been attempted with a view to reducing subsequent myocardial damage.(Mauermann et al., 2012) The gold standard treatment of ventricular fibrillation is internal direct-current shock which may be harmful. It was suggested that defibrillation leads to decreased myocardial performance and microscopic damage to myocytes especially with repeated shocks with a short time interval between shocks.(Yamaguchi et al., 2002) So the prevention of reperfusion ventricular fibrillation or decreasing in the number of defibrillation attempts may be of benefit in preserving myocardial function after cardiopulmonary bypass (CPB).
The aim of Our randomized controlled studyisto compare between the efficacy of a single dose of amiodarone and lidocaine with magnesium sulfate by the way of pump circuit 3 minutes before aortic cross-clamp (ACC) release and compare the results with normal saline as a control group in a randomized, double-blinded, controlled trial.
89 patients were included in the study and randomly divided into three groups (29 patients in each group). We compared between the three groups using computer programs to evaluate the efficacy of each drug.
There was no statistically significant difference between the amiodarone group, the lidocaine with magnesium sulfate group and control group as regarding the basic characteristics, the aortic cross clamp, the cardiopulmonary bypass time, cardioplegia volume, incidence of ventricular fibrillation, incidence of bradycardia or heart block, number of Dc, amount of joules and 24h postoperative troponin level.
In this trial of patients undergoing an aortic valve surgery, neither amiodarone nor lidocaine with magnesium sulfate given 3minutesbefore aortic cross clamp removal decreased the incidence of VF. However, amiodarone, but not lidocaine, decreased the number of shocks required to terminate VF.
The current trial has some limitations. The dose of administered amiodarone may not have been high enough to achieve therapeutic tissue levels given the added circulatory volume of the CPB circuit. Future studies aimed at preventing reperfusion VF may focus on preoperative loading of patients with oral amiodarone.