Cryoballoon Ablation Procedure
The general description of a cryoballoon ablation procedure has been previously published6, 7 and each center utilized their own standard-of-care practices during the cryoballoon ablation procedure. Transesophageal echocardiogram was performed prior to each procedure.
Venous access was obtained bilaterally with ultrasound guidance. Number of access sites were determined by the operator but on average, patients had two catheters on each side. In brief, patients were treated under general anesthesia or conscious sedation. A transseptal needle puncture for left atrial access was immediately followed by a heparin bolus delivery. Activated clotting time was monitored (every 15-20 minutes) throughout the procedure and was targeted to ≥ 300 seconds. A purpose-built delivery sheath (FlexCath; Medtronic, Inc, Minneapolis, MN) was used to advance the cryoballoon (23- or 28-mm Arctic Front Advance; Medtronic, Inc) and the Achieve mapping catheter (Medtronic, Inc) into the left atrium. Pulmonary vein occlusion with cryoballoon was assessed by retrograde contrast agent retention under fluoroscopy imaging and/or intracardiac echocardiography under Doppler imaging and pressure wave-form monitoring. 6, 7 The number of freeze applications and duration of freezes were determined by the center’s standard-of-care and individual physician preferences; however, in general, the three centers practiced a freeze dosing methodology that utilized acute time-to-isolation monitoring to adjust cryoballoon freezing durations and overall number of freeze applications.7, 8 Testing for bidirectional block was utilized at each pulmonary vein to establish acute pulmonary vein isolation. At the end of the procedure, intracardiac echocardiogram or transthoracic echocardiogram was performed to exclude pericardial effusion, a protamine delivery was administered when a reversal of heparin was desired, and groin sheaths were pulled with compression on the femoral vein puncture site or insertion of a figure-8 stich. Figure-8 stich was removed 4 hours after the end of the case and patient was ambulated prior to discharge. No closure devices were used in any patient. Antiarrhythmic drugs were utilized within the 90-day blanking period at the discretion of the treating physician.