Using heart medicine to stop irregular heartbeats during dog mitral

Abstract

INTRODUCTION/OBJECTIVES: Reperfusion ventricular fibrillation (VF) commonly occurs during open-heart surgery in dogs and humans. Pharmacological defibrillation using cardioplegia is a potential option; however, the standard technique remains unclear in dogs. We examined the clinical utility of pharmacological defibrillation in canine mitral valve repair. ANIMALS, MATERIALS, AND METHODS: We retrospectively investigated 402 client-owned dogs that underwent mitral valve repair between January and December 2021. RESULTS: Ventricular fibrillation after cross-clamp release occurred in 70 of 397 cases (17.6%). Pharmacological defibrillation was attempted in 69 patients by administering 40 mEq/L potassium crystalloid cardioplegia via an aortic root catheter. If defibrillation was not achieved or VF recurred, the administration was repeated identically. In all cases, VF resolved after pharmacological defibrillation alone, without electrical defibrillation. Defibrillation was achieved with a single dose in 45 cases (median, 3.90 mL/kg; interquartile range [IQR], 2.95-4.95]), while multiple doses (range: 2-5) were necessary for 24 cases (median initial dose, 3.05 mL/kg [IQR, 2.07-4.14]). Predictors of reperfusion VF included body temperature at cross-clamp release (risk ratio, 0.82 per 1.0 °C) and pre-operative left ventricular internal dimension at end-diastole normalized to body weight (risk ratio, 1.11 per 0.1 unit). STUDY LIMITATIONS: The retrospective nature of the study led to variability in personnel, absence of a control group, and limited data availability. CONCLUSIONS: Reperfusion VF occurred in 17.6% of the canine mitral valve repair cases. Pharmacological defibrillation is a feasible option in such cases. Approximately 4.0 mL/kg of cardioplegia was effective for a single dose, whereas lower doses required multiple administrations.