A Study of the Safety and Efficacy of the VytronUS Low-Intensity Collimated Ultrasound Ablation System

Inclusion Criteria: * Age 18 to 70 years old. * Recurrent symptomatic paroxysmal atrial fibrillation refractory to at least one antiarrhythmic drug. Exclusion Criteria: * Prior pulmonary vein isolation * Presence of intracardiac thrombus * Indication of inaccessible pulmonary or cardiac anatomy * Myocardial infarction, PCI, or cardiac surgery in prior three months * Moderate to severe valvular disease or prior valve replacement * NYHA Class IV * LVEF \< 40% * Previous stroke or TIA * Serum creatinine \> 2.5mg/dL or allergy to intravenous contrast agents * Existing bleeding diathesis or history of complications with anticoagulation therapy * Women who are nursing, pregnant, or trying to become pregnant * Subjects unwilling or unable to provide consent * Participation in a drug or device trial that would prevent completion of required study procedures * Active implantable devices * Major organ system disease