Radiofrequency catheter ablation of cavo-tricuspid isthmus as treatment of atrial flutter in two dogs.

Two dogs were presented for episodic weakness caused by a very rapid supraventricular tachycardia with a ventricular rate of 360 bpm and 300 bpm, respectively. Electrocardiography showed narrow QRS complex tachycardia in both subjects, the first one with a fixed 2:1 atrioventricular block, and the second with variable degrees of atrioventricular block from 6:1 to 2:1. The electrophysiological studies revealed bidirectional and typical cavo-tricuspid isthmus-dependent atrial flutter, respectively. Radiofrequency catheter ablation was performed in both dogs and a bidirectional cavo-tricuspid isthmus block was successfully achieved. On follow-up, Holter monitoring confirmed resolution of the arrhythmias in both dogs.