Heart failure in the dog induced by rapid ventricular pacing using a newly designed cardiac pacemaker, MCMS-0102

Abstract

Tahyccardia-induced heart failure is an ideal experimental heart-failure model. We designed a new cardiac pacemaker (MCMS-0102) for rapid ventricular pacing to induce congestive heart filure, and we then implanted and tested this pacemaker in an adult mongrel dog. The dog was paced at 250 beats/min (bpm) for 3 weeks and subsequently paced at 256 bpm for another 3 weeks. After 4 weeks of rapid pacing, the dog showed symptoms of cardiac failure (ascites and edema in the paws), and its body weight increased from 24 to 26 kg. After 6 weeks of pacing, the body weight increased to 28kg, and ascites and edema in the paws were more remarkable than after 4 weeks of pacing. Postmortem examination revealed massive ascites, pleural effusion, cardiomegaly, and liver congestion. The explanted pacemaker showed no mechanical problems. We evaluated neurohumoral changes in the dog before and after rapid pacing. Plasma renin activity increased from 3.2 to 17.9 ng/ml/h, plasma aldosterone from 100 to 2200 pg/ml, plasma norepinephrine from 60 to 861 pg/ml, and atrial natriuretic peptide from 28 to 250pg/ml. This study suggests that the MCMS-0102 has a high potential for use in heart-failure research.