McRury I D, Whayne J G, Haines D E
Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
J Cardiovasc Electrophysiol. 1995 Apr;6(4):268-78. doi: 10.1111/j.1540-8167.1995.tb00399.x.
Temperature monitoring has been proposed as a control for lesion occurrence and dimension during radiofrequency transcatheter ablation. Effective temperature measurement depends on thermistor positioning relative to the heated cardiac tissue and the convective cooling effects of the circulation. But the accuracy of a single tip thermistor as a measure of peak electrode-tissue interface temperature is unknown.
A standard 8-French, 4-mm electrode catheter with 5 thermistors (1 tip thermistor, 4 radial thermistors) was used to deliver radiofrequency energy in vitro to 3 porcine right ventricles and in vivo to 7 mongrel dogs. In vitro, the catheter orientation was varied. In vivo the catheter was positioned under fluoroscopy at a variety of atrial, tricuspid annular, and ventricular sites, with no attempt to adjust catheter orientation. In both cases varied discrete power levels were used so that a wide temperature range was attained. Lesions created in vivo with a standard, single thermistor tipped electrode were compared to those of a catheter with a thermistor extending 1 mm from the tip. Power was varied and tip thermistor temperatures recorded. All lesions were examined pathologically. Comparisons of radial thermistor temperature to tip thermistor temperature for 3 catheter orientations in vitro resulted in tip thermistor underestimation of peak electrode-tissue interface temperature by a median of 0.5 degrees C in 35% of the perpendicular orientations, 1.9 degrees C in 82% of the 45 orientations, and 5 degrees C in 83% of the parallel orientations. During in vivo trials, the tip thermistor underestimated the peak electrode-tissue interface temperature during 2 of 51 lesions by 1.2 degrees C and 7.6 degrees C. There was a sudden rise in electrical impedance in 17 of 51 radiofrequency energy deliveries. Only one case was observed where the peak electrode-tissue interface temperature was below 95 degrees C. The normal to extended tip thermistor configurations analysis showed similar relationships between lesion size and temperature.
Accuracy of a single tip thermistor was found to be dependent upon catheter-tissue orientation. With routine catheter positioning in vivo, the tip thermistor was a good indicator of peak electrode-tissue interface temperature. Thus with power regulation to avoid temperatures greater than 90 degrees C, a single flush-mounted tip thermistor is probably adequate for temperature monitoring of lesion formation and avoidance of impedance rises.
温度监测已被提议作为射频导管消融过程中病变发生和大小的控制手段。有效的温度测量取决于热敏电阻相对于受热心脏组织的位置以及循环的对流冷却效应。但单尖端热敏电阻作为电极 - 组织界面峰值温度测量方法的准确性尚不清楚。
使用一根标准的8F、4mm电极导管，带有5个热敏电阻（1个尖端热敏电阻，4个径向热敏电阻），在体外对3个猪右心室以及在体内对7只杂种犬进行射频能量传递。体外实验中，改变导管方向。体内实验中，在荧光透视引导下将导管置于心房、三尖瓣环和心室的多个部位，未尝试调整导管方向。两种情况下均使用不同的离散功率水平，以获得较宽的温度范围。将体内使用标准单热敏电阻尖端电极产生的病变与热敏电阻从尖端延伸1mm的导管产生的病变进行比较。改变功率并记录尖端热敏电阻温度。所有病变均进行病理检查。体外3种导管方向下径向热敏电阻温度与尖端热敏电阻温度的比较结果显示，在35%的垂直方向上，尖端热敏电阻低估电极 - 组织界面峰值温度的中位数为0.5℃；在45°方向的82%中低估1.9℃；在平行方向的83%中低估5℃。在体内试验期间，51个病变中有2个病变的尖端热敏电阻低估电极 - 组织界面峰值温度，分别为1.2℃和7.6℃。在51次射频能量传递中有17次出现电阻抗突然升高。仅观察到1例电极 - 组织界面峰值温度低于95℃的情况。正常与延长尖端热敏电阻配置分析显示病变大小与温度之间存在相似关系。
发现单尖端热敏电阻的准确性取决于导管 - 组织方向。在体内常规导管定位时，尖端热敏电阻是电极 - 组织界面峰值温度的良好指标。因此，通过功率调节以避免温度超过90℃，单个平齐安装的尖端热敏电阻可能足以用于监测病变形成的温度并避免阻抗升高。
