Isorhythmic atrioventricular dissociation during anaesthesia in a cat

A 10‐year‐old, male, neutered domestic shorthair cat with suspected hypertrophic cardiomyopathy was referred for cystotomy to remove uroliths present in its urinary bladder. Fifteen minutes after induction of general anaesthesia, atrioventricular dissociation was noted on the electrocardiogram with similar atrial and ventricular firing rates, suggesting an isorhythmic atrioventricular dissociation. Due to the low heart rate and progressive hypotension, anaesthesia was discontinued and atipamezole was administered, with no effect. A bolus of atropine was then administered intravenously, with consequent improvement in pulse quality, heart rate, and restoration of sinus rhythm. The cat was reported to be doing well 6 weeks later, with no signs suggestive of atrioventricular dissociation on the repeated electrocardiogram.