Objective: To characterize the hemodynamic changes of chronic congestive heart failure(CHF) model induced by rapid right ventricular pacing after myocardial infarction in awake Beagle dogs.
Methods: Five healthy adult male Beagle dogs were prepared for surgery. After the probes for measurement and the pacing leads were implanted, the left anterior descending artery was ligated during the surgery to induce myocardial infarction in the anterior wall of the left ventricle close to the apex. Six weeks after the surgery, rapid right ventricular pacing was initiated at the rate of 220 to 260 beats per minute for 4 weeks to induce CHF. Echocardiography was performed before the surgery. Both echocardiography and hemodynamic measurement were carried out before the rapid pacing and 4 weeks after the rapid pacing when the Beagle dogs were awake.
Results: There was no significant difference in left ventricle end diastolic diameter (LVEDD), left ventricle ejective fraction (LVEF), and fractional shortening (FS) between pre-operation and pre-pacing. LVEDD [(44.71+/-3.35) vs. (38.01+/-1.54) mm] and left ventricle end diastolic pressure (LVEDP) [(25.63+/-1.86) vs. (10.58+/-1.23) mmHg] at 4 weeks after pacing significantly increased compared with the pre-pacing data(P<0.05). LVEF, FS, and LV dp/dt max were significantly declined (P<0.01).
Conclusion: Left ventricle remodeling and hemodynamic changes in the Beagle dog CHF models produced by rapid right ventricular pacing after myocardial infarction are similar to the changes observed in CHF of human beings.