2020 Volume 4 Issue 2 Pages 21-28
A 12-year-old, spayed female, mixed breed dog was referred due to arrhythmia, which was observed on preoperative examination for dental treatment. Auscultation revealed a left apical Grade II/VI systolic murmur, bradycardia, and rhythm irregularity. The patient was diagnosed with complete atrioventricular block (CAVB) by electrocardiography. Administration of cilostazol was initiated per ownerʼs request, but CAVB was not controlled. CABV is caused by blockage of excitatory conduction within the atrioventricular conduction system and may result in bradyarrhythmia and sudden death, therefore pacemaker implantation (PMI) was performed. One day after PMI, the heart rate was stable at 88 bpm, however, two days after PMI, the patientʼs condition deteriorated rapidly and cardiopulmonary arrest occurred. Post-mortem histopathologic examination revealed moderate to severe, acute myocarditis in the ventricular septum, including the area where the pacemaker was implanted in the right ventricular apex, and inflammation was widespread in the septal myocardium. Previous reports of histopathologic evaluation for etiology and outcome of CAVB and PMI are limited. Here we describe clinicopathologic findings of CAVB associated with severe ventricular septal fibrosis and developed acute myocarditis at the site of PMI in a dog.