Cryoablation of atrial arrhythmias

The advent of radiofrequency energy has changed the therapy for supraventricular arrhythmias. Radiofrequency ablation is highly effective and safe. However, the demand for specific ablation lesion characteristic (deep focal lesions or long continuous transmural lesions) has highlighted some of the limitations of radiofrequency as an ablation energy source. Cryothermy as an arrhythmia ablation technology has been well studied and found to be a highly effective and safe technology in the surgical literature. Recently, catheter-based cryoablation has become available. This article reviews some of the unique features of catheter-based cryoablation and highlights some of its potential advantages. Specifically, the ability to reversibly test the functionality of an ablation site prior to the production of a permanent lesion, so called "ice mapping", has obvious appeal. In fact, the ability to ice map para-Hisian pathways or the slow pathway in close proximity to the AV node may make this the technology of choice for such substrates. Recent animal work has re-confirmed the safety of cryothermal ablation within the coronary sinus, in close proximity to epicardial coronary arteries. Also, clinical work suggests that this technology may result in less endothelial disruption and less pulmonary venous stenosis, although this requires confirmation in larger trials. The ultimate role of catheter-based cryoablation remains to be determined. A number of promising aspects of this ablation energy make it an exciting technology.