Progressive Left Ventricular Enlargement after Pacemaker Implantation in a Dog

Abstract

Six-year-old female intact mixed breed dog was referred to Azabu University Veterinary Teaching Hospital because of bradycardia. High-grade second-degree atrioventricular block (AV block) was diagnosed. Although the dog was completely asymptomatic and no previous history of cardiac events was noticed, the artificial cardiac pacemaker (AP) was implanted because high-grade second degree AV block may progress to third-degree AV block and left ventricular enlargement was noticed. However, left ventricular function deteriorated over time and left ventricular enlargement worsened. Dilated cardiomyopathy was suspected since worsening of LV enlargement and systolic function. Sixteen months after pacemaker implantation, the dog began to show exercise intolerance. It has been approximately four year at the time of writing, and the dog was medically managed.