Otomo K, Yamanashi W S, Tondo C, Antz M, Bussey J, Pitha J V, Arruda M, Nakagawa H, Wittkampf F H, Lazzara R, Jackman W M
Department of Medicine, University of Oklahoma Health Sciences Center, Department of Veterans Affairs Medical Center, Oklahoma City 73104, USA.
J Cardiovasc Electrophysiol. 1998 Jan;9(1):47-54. doi: 10.1111/j.1540-8167.1998.tb00866.x.
Increasing electrode size allows an increase in radiofrequency lesion depth. The purpose of this study was to examine the roles of added electrode cooling and electrode-tissue interface area in producing deeper lesions.
In 10 dogs, the thigh muscle was exposed and superfused with heparinized blood. An 8-French catheter with 4- or 8-mm tip electrode was positioned against the muscle with a blood flow of 350 mL/min directed around the electrode. Radiofrequency current was delivered using four methods: (1) electrode perpendicular to the muscle, using variable voltage to maintain the electrode-tissue interface temperature at 60 degrees C; (2) same except the surrounding blood was stationary; (3) perpendicular electrode position, maintaining tissue temperature (3.5-mm depth) at 90 degrees C; and (4) electrode parallel to the muscle, maintaining tissue temperature at 90 degrees C. Electrode-tissue interface temperature, tissue temperature (3.5- and 7.0-mm depths), and lesion size were compared between the 4- and 8-mm electrodes in each method. In Methods 1 and 2, the tissue temperatures and lesion depth were greater with the 8-mm electrode. These differences were smaller without blood flow, suggesting the improved convective cooling of the larger electrode resulted in greater power delivered to the tissue at the same electrode-tissue interface temperature. In Method 3 (same tissue current density), the electrode-tissue interface temperature was significantly lower with the 8-mm electrode. With parallel orientation and same tissue temperature at 3.5-mm depth (Method 4), the tissue temperature at 7.0-mm depth and lesion depth were greater with the 8-mm electrode, suggesting increased conductive heating due to larger volume of resistive heating because of the larger electrode-tissue interface area.
With a larger electrode, both increased cooling and increased electrode-tissue interface area increase volume of resistive heating and lesion depth.
增大电极尺寸可增加射频损伤深度。本研究的目的是探讨附加电极冷却和电极 - 组织界面面积在产生更深损伤中的作用。
对10只犬，暴露大腿肌肉并用肝素化血液进行表面灌注。将带有4毫米或8毫米尖端电极的8法国导管放置在肌肉上，使350毫升/分钟的血流围绕电极流动。使用四种方法施加射频电流：（1）电极垂直于肌肉，使用可变电压将电极 - 组织界面温度维持在60摄氏度；（2）除周围血液静止外其余相同；（3）电极垂直放置，将组织温度（3.5毫米深度处）维持在90摄氏度；（4）电极平行于肌肉，将组织温度维持在90摄氏度。比较每种方法中4毫米和8毫米电极之间的电极 - 组织界面温度、组织温度（3.5毫米和7.0毫米深度处）以及损伤大小。在方法1和2中，8毫米电极的组织温度和损伤深度更大。在无血流时这些差异较小，表明较大电极改善的对流冷却导致在相同电极 - 组织界面温度下传递到组织的功率更大。在方法3（相同组织电流密度）中，8毫米电极的电极 - 组织界面温度显著更低。在3.5毫米深度处平行取向且组织温度相同（方法4）时，8毫米电极在7.0毫米深度处的组织温度和损伤深度更大，表明由于更大的电极 - 组织界面面积导致电阻性加热体积增大，从而传导性加热增加。
使用较大电极时，冷却增加和电极 - 组织界面面积增加均会增加电阻性加热体积和损伤深度。
