<qa>  What is the number of pulmonary vein isolation therapy for atrial fibrillation?The number of pulmonary vein isolation PVI therapy for atrial fibrillation AF is increasing. Multiple femoral vein cannulation is mandatory for this procedure. There are mainly two methods to cannulate the femoral vein; by anatomical landmark or by under real-time ultrasound-guided. As high anticoagulant level is required for the procedure, there are 0-13 of vascular access complication. 