Hindricks G, Haverkamp W, Gülker H, Rissel U, Budde T, Richter K D, Borggrefe M, Breithardt G
Department of Cardiology-Angiology, University Hospital Münster, West Germany.
Eur Heart J. 1989 Nov;10(11):972-84. doi: 10.1093/oxfordjournals.eurheartj.a059422.
To assess the importance of voltage, current, impedance and catheter tip temperature for the prediction of the size of tissue injury induced by transcatheter radiofrequency application, radiofrequency pulses (500 kHz) were delivered both in vitro and in vivo to isolated ventricular preparations and the intact canine heart, respectively. Radiofrequency coagulations were performed using unipolar electrode configuration. Besides measurements of current and voltage which were used to calculate the delivered power and tissue impedance, the catheter tip temperature was monitored during each application using specially designed 6F USCI catheters with a built-in nickel/chromium-nickel thermoelement. Lesion dimensions were measured and the correlation between lesion volume and delivered radiofrequency energy, maximum changes in catheter tip temperature and the integral of the temperature curve were calculated. First, in a pilot in vitro investigation, 50 radiofrequency coagulations (3.2 W-22.4 W, pulse duration 10 s) were performed in ventricular preparations from freshly excised dog hearts. The correlation between applied radiofrequency energy and lesion volume was 0.87; the correlation between maximal catheter tip temperature and lesion volume was 0.82; the correlation between temperature integral and lesion volume was 0.9. In the intact dog heart, 44 radiofrequency pulses were delivered to the left and right ventricular endocardium in 12 anaesthetized dogs (exposure time: 10 s). Delivered power ranged between 5.6 W and 24.6 W; tissue impedance varied between 92 omega and 364 omega; lesion volume measured 0-273 mm3; developed peak temperatures ranged from 16.25 degrees C to 196 degrees C. The calculated integral beneath temperature curves measured 126-1971 degrees C.s. The correlation between applied radiofrequency energy and lesion volume was 0.32; the correlation between maximal catheter tip temperature and lesion volume was 0.61. Temperature integral correlated best with the assessed volume of myocardial necrosis (r = 0.7). No significant arrhythmogenic or haemodynamic side-effects were observed. Macroscopic examination showed a central depression surrounded by a zone of homogeneous coagulation. Vaporization and crater formation up to a depth of 4 mm were observed following three radiofrequency discharges. In two of these cases, rapid changes and oscillation of catheter tip temperature were observed. Thus, monitoring of catheter tip temperature during radiofrequency energy application improves the prediction of lesion size. In addition, temperature monitoring might improve the safety of the procedure with respect to the risk of perforation.
为评估电压、电流、阻抗及导管尖端温度对预测经导管射频应用所致组织损伤大小的重要性，分别在体外和体内对离体心室标本及完整犬心施加射频脉冲（500kHz）。采用单极电极配置进行射频凝固。除测量用于计算传递功率和组织阻抗的电流和电压外，在每次应用过程中，使用带有内置镍/铬-镍热电偶的特制6F USCI导管监测导管尖端温度。测量损伤尺寸，并计算损伤体积与传递的射频能量、导管尖端温度的最大变化以及温度曲线积分之间的相关性。首先，在一项初步体外研究中，对新鲜切除的犬心的心室标本进行了50次射频凝固（3.2W - 22.4W，脉冲持续时间10秒）。施加的射频能量与损伤体积之间的相关性为0.87；导管尖端最高温度与损伤体积之间的相关性为0.82；温度积分与损伤体积之间的相关性为0.9。在完整犬心，对12只麻醉犬的左、右心室内膜施加44次射频脉冲（暴露时间：10秒）。传递功率在5.6W至24.6W之间；组织阻抗在92Ω至364Ω之间变化；损伤体积为0 - 273mm³；产生的峰值温度范围为16.25℃至196℃。温度曲线下计算的积分值为126 - 1971℃·秒。施加的射频能量与损伤体积之间的相关性为0.32；导管尖端最高温度与损伤体积之间的相关性为0.61。温度积分与评估的心肌坏死体积相关性最佳（r = 0.7）。未观察到明显的致心律失常或血流动力学副作用。宏观检查显示中央凹陷，周围是均匀的凝固区。在三次射频放电后观察到高达4mm深度的汽化和火山口形成。在其中两例中，观察到导管尖端温度的快速变化和振荡。因此，在施加射频能量期间监测导管尖端温度可改善对损伤大小的预测。此外，温度监测可能会提高手术在穿孔风险方面的安全性。
