Cardioversion of supraventricular tachycardia using lidocaine in five dogs

Sustained supraventricular tachycardia (SVT) may lead to life-threatening complications such as tachycardia-induced myocardial failure. We report the use of intravenous lidocaine in 5 dogs with SVT. Two dogs had evidence of an accessory conduction pathway, 2 were suspected of having an accessory pathway, and the mechanism of SVT was unknown in the remaining dog, which subsequently developed dilated cardiomyopathy 2 years later. In all cases there was rapid conversion to normal sinus rhythm, which was then maintained with oral mexilitene (4 dogs) or mexilitene combined with propranolol (1 dog).