A rat model of ischemic cardiomyopathy for investigating left ventricular volume reduction surgery.

Objective: The effects of volume reduction surgery (VRS) for ischemic cardiomyopathy are not fully understood. The development of a proper animal model will help to resolve this issue.

Methods: Study 1 (Noninvasive study): Twenty-six rats developed large akinetic left ventricular (LV) aneurysms or ischemic cardiomyopathy after anterior descending artery ligation (first surgery). Four weeks after the surgery, 13 rats underwent volume reduction surgery (second surgery) (VRS group), while 13 underwent rethoracotomy alone (sham group). Before the first surgery, and before and after the second surgery, the LV dimensions were measured by echocardiography, and the heart rate and systolic blood pressure were recorded by the tail cuff method. Study 2 (Invasive study): In 7 rats undergoing the VRS and 9 undergoing the sham operation, LV pressure was measured with a manometer-tipped catheter, immediately before and after the second surgery.

Results: Study 1: All rats survived the second surgery, after which LV end-diastolic diameter decreased and LV fractional shortening increased (both p < 0.001) in the VRS group. This group also increased heart rate after the second surgery (p < 0.05). Study 2: There were no differences in LV end-systolic or end-diastolic pressure between the two groups before and after the second surgery.

Conclusions: This model enables reproducible physiological evaluation of the LV after VRS, and since the rats show postoperative survival, it provides a useful tool for various investigations.