An animal model of arrhythmogenesis in congestive heart failure

Background: Patients with congestive heart failure (CHF) frequently die from arrhythmias, but models to study arrhythmogenic mechanisms during progressive CHF are lacking. Consequently we examined the feasibility of using dogs with an ischemic insult followed by rapid pacing to study ventricular arrhythmias in CHF. Methods: Eighteen chronically instrumented dogs had ischemic damage induced by inflating a balloon tipped catheter in a coronary artery for 90 min. After 2 weeks recovery, electrophysiologic studies were performed on no drugs, during esmolol infusion, and during isoproterenol infusion. The pacer was turned on at 250 bpm in 12 dogs, but not in six controls, and studies repeated bi-weekly for up to 6 weeks. Results: Serial echocardiograms documented progressive CHF, and serial signal averaged electrocardiograms demonstrated prolongation of total QRS, increased duration of terminal QRS<40 mv, and decreased RMS voltage of the terminal 20 ms of QRS in paced dogs. Arrhythmia severity increased as CHF progressed, but responses were quite variable, unaffected by esmolol, and minimally altered by isoproterenol. Conclusions: Ischemic left ventricular damage followed by rapid ventricular pacing in dogs produces a model that closely mimics patients with CHF and ventricular arrhythmias, including a heterogeneous pathophysiologic response to intervention.