Implanting dual-chamber pacemaker through right thoracotomy to establish a canine tachycardia-mediated cardiomyopathy model / 第二军医大学学报

ABSTRACT

Objective To create a canine model of premature ventricular contraction-induced tachycardia-mediated cardiomyopathy, and to explore the effect of frequent premature ventricular contraction on the function of the left ventricular function. Methods Sixteen mongrel dogs were randomly divided into sham operation group and paced group. Animals in the paced group underwent the implantation of a dual-chamber pacemaker through right thoracotomy, and the pacemaker was connected to two epicardial right ventricular leads, with one creviced in the cardiac apex and the other one in the outflow tract of the right ventricle, with an atrioventricular delay adjusted to ensure the presence of coupled pacing to simulate ventricular bigeminy. Dogs in the control group were not connected to the leads. Echocardiographic measurements were obtained before and 4 weeks after operation. Results One dog in the paced group died of infection after 4 weeks. In the paced group (n = 7), LV end-diastolic diameter (LV-EDD) increased from (2. 86 ± 0. 10) cm before operation to (3. 35 ± 0. 27) cm after operation (P< 0. 05) and LV end-systolic diameter (LV-ESD) increased from (2. 07 ± 0. 20) cm before operation to (2. 72 ± 0. 21) cm after operation (P<0. 05). In addition, the left ventricular ejection fraction (LVEF) decreased from (67. 57 ± 4. 49)% before operation to (43. 66 ± 3. 88) % after operation (P<0. 05). No significant changes in LV dimensions or function were noted before and after operation in the control group. Conclusion It is feasible to simulate ventricular bigeminy with coupled pacing in canines. Premature ventricular contraction-induced cardiomyopathy can lead to increased LV dimensions and decreased LV.