Cryoablation procedure
three‐way stopcock suture, patent foramen ovale
CONTRACTION
At the beginning of the procedure x2 femoral venous access will be achieved using ultrasound guidance. If the patient is in AF then DCCV will be undertaken to cardiovert to sinus rhythm.A multipolar catheter will then be placed in the coronary sinus. The LA will then accessed via trans‐septal puncture or patent foramen ovale. Following left atrial access, IV heparin will be administered as sequential boluses maintaining activated clotting time more than 300 s. Thereafter the TS sheath will be exchanged with a steerable 15 Fr sheath (Flexcath, Medtronic). A 28 mm cryoballoon catheter (Arctic Front Advance, Medtronic) will be advanced through the steerable sheath into the LA with a guide wire or the Achieve mapping catheter in the central lumen.The cryoballoon will be positioned in the ostium of each PV using fluoroscopic guidance and contrast injection with minimal or no dye leak on injection after inflation.Before ablation of the right PVs, the multipolar catheter will be placed in the right subclavian vein to pace the right phrenic nerve (10–20 mA at 1.0–2.0 ms pulse width at a cycle length of 1000 ms). Ablation will be immediately terminated upon any perceived reduction in the strength of diaphragmatic contraction.Cryoablation in each PV will be applied for a minimum duration of 180 s and maximum duration of 240 s. If the temperature has not reached −40 degrees by 60 s then this will be deemed to be an ineffectual ablation and the ablation will be stopped and the balloon repositioned. A further 2 attempts at ablation will be allowed. Entrance and exit block will also be confirmed and if the operator fails to isolate the PV (excluding common ostia) after a minimum of 3 attempted cryoballoon applications then focal ablation with the 8 mm cryocatheter (Freezor Max) targeted to sites of LA‐PV breakthrough will be permitted at operator discretion.At the end of the procedure once sheaths have been removed all patients will have a three‐way stopcock suture to achieve haemostasis.