Defibrillation of German shepherds with inherited ventricular arrhythmias and sudden death

Abstract

Objective To characterize defibrillation success in German shepherd (GS) dogs with inherited ventricular arrhythmias and sudden death. Background Ventricular tachycardia (VT) degenerates to ventricular fibrillation (VF) as the cause of death in GS dogs. To test the hypothesis that GS dogs are more difficult to defibrillate than other dogs, we sought to compare defibrillation success of induced VF in affected GS dogs to a control group of beagles. Methods ECG and monophasic action potential (MAP) recordings were acquired during VF and transthoracic defibrillation in anesthetized GS dogs ( n = 13) and normal beagles ( n = 7). Shock efficacy, energy requirements, VF frequency and post-defibrillation rhythms were compared between the 2 groups. Results First shock success of all episodes of VF was lower in GS dogs (10 of 18) than beagles (46 of 47) ( p < 0.0001). However, when evaluated by dog, shock success was not different between GS and beagles (7 of 13 and 6 of 7, respectively; p = 0.15). Multiple shock success (≤3 consecutive shocks) resulted in a poorer defibrillation success of all episodes of VF in GS dogs (15 of 18) as compared to beagles (47 of 47) ( p < 0.02). Multiple shock success evaluated by dog was similar between GS (11 of 13) and beagles (7 of 7) ( p = 0.11). Conclusions Affected GS dogs had lower defibrillation success than beagles; however, defibrillation was possible in the majority of cases.