The Hull York Medical School, Department of Cardiology, Castle Hill Hospital, Castle Road, Cottingham, Hull, UK.
The Royal Prince Alfred Hospital and University of Sydney, Missenden Road, Camperdown, Sydney, Australia.
Europace. 2018 Nov 1;20(FI_3):f451-f457. doi: 10.1093/europace/eux190.
Balloon cryoablation is an accepted method of achieving pulmonary vein isolation for the treatment of atrial fibrillation. The relationship between blood flow in the atrium and cryo energy delivery to the tissue remains poorly understood.
Controlled cryoablations were performed in vitro using a pulmonary vein phantom constructed from bovine muscle, providing a 20 mm vein ostium. A temperature sensor was mounted within the 'vein wall' at a 1 mm tissue depth. Apparatus was constructed to assess the effect of incomplete pulmonary venous occlusion causing a leak, simulated atrial stasis, atrial circulation, and mitral regurgitation. Controlled ablations using the 2nd generation 28 mm cryoballoon catheter were repeated three times and mean values compared. Leak volume significantly affected both balloon temperatures and tissue temperatures. Simulated mitral regurgitation (MR) significantly impaired the effectiveness of cryo energy delivery resulting in significantly warmer balloon and tissue temperatures. With high leak volumes and moderate to severe MR there was a marked disparity between the cryoballoon temperature and the tissue temperature of approximately 60 degrees. Balloon warming times varied inversely with both leak volume and simulated MR flow volume.
Incomplete venous occlusion and MR result in warmer balloon and tissue temperatures, and shorter balloon warming times, and are likely to significantly impair the effectiveness of cryoablation. Balloon temperature is poor indicator of tissue temperature under higher flow conditions.
球囊冷冻消融是实现肺静脉隔离治疗心房颤动的一种可接受的方法。心房内血流与冷冻能量向组织传递之间的关系仍知之甚少。
使用从牛肌肉构建的肺静脉模型在体外进行受控冷冻消融，提供 20mm 静脉口。温度传感器安装在“静脉壁”内，位于 1mm 组织深度处。构建了一种设备来评估不完全肺静脉闭塞导致泄漏、模拟心房停滞、心房循环和二尖瓣反流的影响。使用第二代 28mm 冷冻球囊导管进行三次重复受控消融，并比较平均值。泄漏量显著影响球囊温度和组织温度。模拟二尖瓣反流（MR）显著降低了冷冻能量传递的有效性，导致球囊和组织温度显著升高。在高泄漏量和中度至重度 MR 的情况下，冷冻球囊温度和组织温度之间存在约 60 度的明显差异。球囊升温时间与泄漏量和模拟 MR 流量呈反比变化。
不完全静脉闭塞和 MR 导致球囊和组织温度升高，球囊升温时间缩短，可能会显著降低冷冻消融的有效性。在高流量条件下，球囊温度是组织温度的不良指标。
