Introducing some experimental models of ventricular arrhythmia in rat isolated heart and efficacy of a left ventricular smart ablation protocol in control of arrhythmia

Ventricular fibrillation is one of the main causes of sudden death. In order to evaluate the efficacy and mechanism of anti-arrhythmic drugs, various experimental models of arrhythmia have been developed. In the present study some in vitro models of ventricular arrhythmia in rat isolated heart are presented. Furthermore, efficacy of a smart ablation protocol to suppress ventricular rate is examined.

Five groups of 5 Wistar rats were used in this study. In group I, ventricular fibrillation (VF) was induced in the isolated heart by stepwise increased electrical stimulation (0-5 mA). In group II, VF was induced by stepwise increase in end diastolic pressure (25-100 mmHg). Group III (computerized VF model), computerized electrical stimulation was executed during 2 s in the range of 25-125 ms by AV node pack software. Group IV (hypokalemia-induced VF), VF was induced by diminution of potassium to 2.5-2.9mM in Krebs Henseleit solution. Group V, it was same as group III but smart ablation of the left ventricle was carried out by 110 volt DC power to terminate the VF.

Premature ventricular beat, ventricular tachycardia and VF were successfully induced in the first 4 groups. The minimum and maximum threshold of arrhythmia was observed in groups II (0.1 ± 0.07 mA) and III (1.2 ± 0.05 mA), respectively. The longest duration of arrhythmia induced by hypokalemia (240 ± 45 s), while the shortest one provoked by electrical stimulation (10 ± 4 s). The maximum dominant frequency of arrhythmia was observed in group III (14.9 ± 1.2 Hz), while the lowest dominant frequency was related to group I (7.1 ± 1.6). The mean number of ablation was 20 ± 3 and VF terminated in 10% of all arrhythmias.

Experimental arrhythmia can be induced in rat isolated heart by the all 4 protocols. However, increasing end diastolic pressure and hypokalemia are the most efficient methods for induction of ventricular arrhythmia. Left ventricular ablation by using DC voltage and AV node pack software is a useful method to terminate ventricular arrhythmias.