*1.2.3 Ventricular arrhythmias*

Development of life threatening ventricular arrhythmias, which range from ventricular premature beats with long coupling intervals to ventricular fibrillation early after onset of reperfusion, also represent a form of reperfusion injury [51, 52]. Although the physiopathology causing ventricular arrhythmias during reperfusion is ill understood they are known to be initiated by complex cellular changes with regard to electrophysiological, metabolic and structural properties [53]; potential chemical mediators of arrhythmogenesis have been presented [54, 55]. In rat hearts subject to brief coronary artery occlusion (~5 minutes) followed by reperfusion severe ventricular arrhythmias occur [56]. However, in larger animal species, incidence of lethal ventricular arrhythmias increases when reperfusion is instituted within 30 minutes after coronary occlusion [57]. The overall incidence of ventricular arrhythmias decreases significantly when reperfusion follows longer durations of ischemia [58, 59].
