Abstract 4105: Increasing Contact Force Increases Lesion Size during Cryo-Ablation
The purpose of this study was to determine the relationship between electrode-tissue (ET) contact force and lesion size during cryo ablation for two cryo electrode lengths in both perpendicular and parallel orientations using the canine thigh muscle preparation. In 3 anesthetized dogs, the skin over the thigh muscle was incised and raised to form a cradle which was superfused with heparinized blood at 37°C. 10F catheters with 6.5 mm and 10 mm (8.5 mm exposed) cryo electrodes (CryoCor) were held perpendicular and parallel to the thigh muscle at 3 ET contact forces:
0 g (1mm above tissue with only ice ball contact);
2)10 –15g (Low Contact); and
30 –35 g (High Contact). Pulsatile blood flow (0.5 m/sec) was directed at the ablation site.
Two cryo applications (− 90°C for 2 min) were delivered per dog for each of the 3 contact forces, at parallel and perpendicular orientations, for 6.5 and 10 mm electrodes (total 72 cryo). Temperatures were measured at the electrode and within the tissue at depths of 2, 4 and 6 mm. Lesion size was measured using nitroblue tetrazolium. Lesion depth and diameter increased with increasing ET contact force in both electrode orientations and both electrode sizes (Fig⇓). Tissue temperatures (2 mm, 4 mm and 6 mm depths) were significantly lower with ET contact (low and high), compared to no contact (0 g). Compared to 6.5 mm, the 10 mm electrode produced slightly greater lesion diameter in parallel orientation, but did not increase lesion depth. Cryo ablation without ET contact (only ice ball contact) produced little or no lesion. ET contact force facilitates cryo ablation. Ice ball contact alone is insufficient for lesion formation.