Freezor max

After optical mapping, cardiac disks were attached to the center of the hydrogel-based soft-pressure sensor. Then, 100 µL bioink was added to the edge of the disk and crosslinked to stabilize the structure. The testbed was then transferred to a 37 °C water bath containing sterile phosphate-buffered saline solution (PBS), and the ablation catheter (Freezor MAX, Medtronic, Minneapolis, MN, USA) was applied to the cardiac disk surface at a location 7.5 mm away from the disk center. The contact force was calibrated by the pressure sensor and set at either 0.1 N as the normal therapy condition or 0.01 N as the failed contact condition. Ablation duration was set via the CryoConsole™ to 60 s. A group with 0.1 N contact force was treated with the same process without turning on the CryoConsole™ as a contact-force-only control. After cryoablation, cardiac disks were gently detached from the pressure sensor by a stainless-steel spatula and used for the post-ablation calcium assessment.

The detailed procedure has been described elsewhere.¹⁶ The fourth‐generation CB will be used in the CB ablation group. In brief, an 8.5‐F sheath (SL0, Abbott) will be exchanged for a 15‐F steerable sheath (FlexCath, Medtronic) after the transseptal puncture, and a 28‐mm CB will be introduced into the LA through the sheath. The CB will be inflated proximal to each PV and pushed gently to seal the antral aspect of the PV through a circular catheter (Achieve). Injection of contrast medium will be performed to confirm the relative position of the CB and PV antrum. A 180 s or time to isolation plus a 120‐s freeze cycle will be performed at each PV.¹⁶, ¹⁷ When the initial freezing fails to isolate the PV, the CB will be repositioned, and a second freezing cycle will be applied. When the CB ablation cannot achieve the PVI, additional focal ablation will be performed with a Freezor Max (Medtronic) or RF catheter.

The detailed procedure has been described elsewhere.¹¹ The fourth‐ or second‐generation CBs will be used in the CB ablation group. In brief, an atrial transseptal puncture will be performed using a standard Brockenbrough technique. The 28 mm CB will be introduced into the LA through a steerable sheath (FlexCath Advance, Medtronic) and be inflated proximal to each PV and pushed gently, aiming for complete sealing at the antral aspect of the PV. Contrast medium will be injected from the distal lumen of the CB to confirm the exact position of the inflated balloon in relation to the PV ostium. A 180 second freeze cycle will be performed at each PV.¹¹ When the initial freezing fails to isolate the PV, the CB will be repositioned and a second freezing cycle will be applied. No further freezing cycle will be applied when PVI cannot be achieved after a maximum of five freezing cycles per vein. When the CB ablation cannot achieve the PVI, the steerable sheath (FlexCath Advance) will be exchanged to another sheath (SL0 or Agilis, Abbott) and additional focal ablation will be performed with Freezor Max (Medtronic) or RF catheter.