Transvenous Catheter Cryoablation of the Atrioventricular Node and Visual Assessment of Freezing of Cardiac Tissue Using Intracardiac Echocardiography

We investigated the use of a catheter-based cryoablation system on atrioventricular (AV) junction ablation in dogs. In five dogs, the cryoablation catheter was introduced to the AV junction area in order to create transient high degree or complete AV block. Cryo-freezing energy was applied by lowering the temperature to -75°C for five minutes as a single cycle. This cycle was repeated until significant impairment of the AV conduction appeared. Transient high degree and complete AV block was obtained in all five dogs without any adverse effects. The iceball formation was identified by intracardiac echocardiography. Ablation of the AV junction is effective with several freeze-thaw cycles using a transvenous catheter cryoablation system.