Nakagawa H, Wittkampf F H, Yamanashi W S, Pitha J V, Imai S, Campbell B, Arruda M, Lazzara R, Jackman W M
Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA.
Circulation. 1998 Aug 4;98(5):458-65. doi: 10.1161/01.cir.98.5.458.
Clinical efficacy has driven the use of larger electrodes (7F, length > or =4 mm) for radiofrequency ablation, which reduces electrogram resolution and causes variability in tissue contact depending on electrode orientation. With active cooling, ablation electrode size may be reduced. The purpose of this study was to examine the effect of electrode length on tissue temperature and lesion size with saline irrigation used for active cooling.
In 11 anesthetized dogs, the thigh muscle was exposed and bathed with heparinized canine blood. A 7F ablation catheter with a 2- or 5-mm irrigated tip electrode was positioned perpendicular or parallel to the thigh muscle. Radiofrequency current was delivered at constant voltage (50 V) for 30 seconds during saline irrigation (20 mL/min) to 148 sites. Tissue temperature at depths of 3.5 and 7 mm and lesion size were measured. In the perpendicular electrode-tissue orientation, radiofrequency applications at 50 V with the 2-mm electrode compared with the 5-mm electrode resulted in lower power at 50 V (26 versus 36 W) but higher tissue temperatures, larger lesion depth (8.0 versus 5.4 mm), and greater diameter (12.4 mm versus 8.4 mm). Also, in the parallel orientation, overall power was lower with the 2-mm electrode (25 versus 33 W), but tissue temperatures were higher and lesions were deeper (7.3 versus 6.9 mm). Lesion diameter was similar (11.1 versus 11.3 mm) for both electrodes.
The smaller electrode resulted in transmission of a greater fraction of the radiofrequency power to the tissue and resulted in higher tissue temperature, larger lesions, and lower dependency of lesion size on the electrode orientation.
临床疗效推动了在射频消融中使用更大的电极（7F，长度≥4mm），这降低了电图分辨率，并根据电极方向导致组织接触的变异性。通过主动冷却，可以减小消融电极的尺寸。本研究的目的是研究电极长度对使用盐水灌注进行主动冷却时组织温度和损伤大小的影响。
在11只麻醉犬中，暴露大腿肌肉并用肝素化犬血冲洗。将带有2或5mm灌注尖端电极的7F消融导管垂直或平行于大腿肌肉放置。在盐水灌注（20mL/min）期间，以恒定电压（50V）施加射频电流30秒，共施加到148个部位。测量3.5和7mm深度处的组织温度和损伤大小。在垂直电极-组织方向上，与5mm电极相比，使用2mm电极在50V下进行射频应用时，50V时的功率较低（26W对36W），但组织温度较高，损伤深度较大（8.0mm对5.4mm），直径也更大（12.4mm对8.4mm）。同样，在平行方向上，2mm电极的总功率较低（25W对33W），但组织温度较高，损伤更深（7.3mm对6.9mm）。两种电极的损伤直径相似（11.1mm对11.3mm）。
较小的电极导致更大比例的射频功率传输到组织中，从而导致更高的组织温度、更大的损伤，并且损伤大小对电极方向的依赖性更低。
