Establishment of a rabbit chronic atrial fibrillation model with long-term rapid atrial stimulation

AIM: The aim of this study was to investigate the possibility of establishing a chronic atrial fibrillation model with long-term rapid atrial stimulation (1 000 bpm), which was performed in rabbits in vivo. METHODS: 20 rabbits were randomly divided into 2 groups: 1) control group (n=10): pacemaker was implanted but no pacing; 2) experimental group (n=10): a left intercostal thoracotomy was performed and the pericardium was opened to expose the heart and a steel-wire pacing electrode was fixed on the epicardium of the left atria in 10 rabbits. Then the rapid pulse generator was implanted subcutaneously in the left abdominal region and rapid atrial pacing (1 000 beats/min) was initiated and continued for 30 days. Electrocardiogram (ECG) was monitored and recorded on day 1, 3, 5, 7, 14, 21 and 30. The atrial effective refractory period (AERP) was measured before pacing and at the time of fibrillation. RESULTS: On day 14, atrial fibrillation was developed in 8 rabbits (80%) and sustained at least till to day 30 (P＜0.01). There was no atrial fibrillation occurred in control group. The ventricular rate of atrial fibrillation was fast initially (P＜0.05) and decreased gradually later (P＜0.05). The AERP was shortened and the rate adaptation of AERP was lost when atrial fibrillation occurred. CONCLUSION: Long-term rapid left atria stimulating is an effective method in the establishment of a chronic atrial fibrillation model in rabbits.