Liem L B, Mead R H, Shenasa M, Kernoff R
Cardiac Arrhythmia and Electrophysiology Section, Stanford University, California 94305, USA.
Pacing Clin Electrophysiol. 1996 Nov;19(11 Pt 2):2004-8. doi: 10.1111/j.1540-8159.1996.tb03270.x.
This study was designed to test a microwave (MW) ablation system using approximately 2,450 MHz of energy and a deflectable catheter with forward-firing tip antenna, an early clinical prototype system. In vitro three-dimensional thermal mapping of single and double helix antenna designs was performed. Quantitative measurements of antenna radiation were recorded on tissue phantoms equipped with temperature sensors distributed radially and outwardly. In vivo testing consisted of closed-chest AV junction ablation in three dogs. Thermal mapping showed hemispherical heat distribution from the tip antenna. For the double helix design, this distribution was measured at 8.4-mm diameter with a maximum temperature of 61.62 degrees C. As expected, the single helix design produced less heating with a measured diameter of 6.4 mm and maximum temperature of 55.90 degrees C. The in vivo study produced lesions of geometry and size concordant with these heating patterns. MW ablation produced bundle branch block in one dog and complete AV nodal block in the remaining two, without transvalvular or other structural damage. The histopathology of the lesions was typical of a thermal burn showing hemorrhage and coagulative necrosis with clearly demarcated borders. We conclude that, using this early clinical prototype system with a deflectable catheter and a forward-firing tip antenna design, MW heating can produce a moderate-size lesion and is safe and effective for cardiac ablation.
本研究旨在测试一种微波（MW）消融系统，该系统使用约2450兆赫的能量以及带有前向发射尖端天线的可弯曲导管，这是一种早期临床原型系统。对单螺旋和双螺旋天线设计进行了体外三维热成像。在配备有沿径向和向外分布的温度传感器的组织模型上记录天线辐射的定量测量结果。体内测试包括对三只狗进行闭胸房室交界消融。热成像显示尖端天线呈半球形热分布。对于双螺旋设计，该分布在直径8.4毫米处测量，最高温度为61.62摄氏度。正如预期的那样，单螺旋设计产生的热量较少，测量直径为6.4毫米，最高温度为55.90摄氏度。体内研究产生的病变在几何形状和大小上与这些加热模式一致。微波消融在一只狗中产生了束支传导阻滞，在其余两只狗中产生了完全性房室结传导阻滞，没有瓣膜或其他结构损伤。病变的组织病理学表现为典型的热烧伤，显示出血和凝固性坏死，边界清晰。我们得出结论，使用这种带有可弯曲导管和前向发射尖端天线设计的早期临床原型系统，微波加热可以产生中等大小的病变，并且对心脏消融是安全有效的。
