Recently, it has been demonstrated that for a significant portion of AF patients (80% - 95 %) the arrhythmia originates in one of the four pulmonary veins (PV's). Furthermore, it has been shown that isolation of this arrhythmia by ablation can, in the majority of patients (50-70%), eliminate or markedly reduce episodes of AF. Currently, there are a number of modalities being investigated to treat AF. They include radiofrequency, laser, thermal, cryo, microwave, and ultrasound ablation of targeted areas in the atrium and/or PVs.