Wonnell T L, Stauffer P R, Langberg J J
Joint Graduate Group in Bioengineering, University of California, Berkeley.
IEEE Trans Biomed Eng. 1992 Oct;39(10):1086-95. doi: 10.1109/10.161341.
A highly localized burst of energy applied to the myocardium via a transvenous catheter-mounted power source can be used to destroy endocardial tissue regions which mediate life-threatening arrhythmias. In the past, high-voltage direct current pulses, radio-frequency (RF) current, and laser light have been used as energy sources. In this paper, the use of 2450 MHz microwave energy applied via a miniature coaxial cable-mounted helical coil antenna designed specifically for this application was investigated as a means to increase the treated volume of cardiac tissue in a controllable and efficient manner during ablation. Using an array of fiber optic temperature probes implanted in a saline-perfused, tissue-equivalent gel phantom model designed to simulate the myocardium during ablation, the heating pattern from the microwave antenna was characterized and compared to that induced by a commercial RF electrode catheter at 550 kHz. Effects of variable contact angle between the heat source and heart wall were assessed in terms of the radial penetration and overall volume of heated tissue. Heating patterns from the RF electrodes dropped off much more abruptly both radially and axially than the microwave antenna such that the volume of effectively heated tissue was more than ten times larger for the microwave antenna when the heat sources were well-coupled to the tissue, and more than four times larger for the microwave antenna when the sources were angled 30 degrees away from the tissue surface.
通过安装在经静脉导管上的电源向心肌施加高度局部化的能量脉冲，可用于破坏介导危及生命的心律失常的心内膜组织区域。过去，高压直流脉冲、射频（RF）电流和激光已被用作能量源。在本文中，研究了通过专门为此应用设计的安装在微型同轴电缆上的螺旋线圈天线施加2450 MHz微波能量，作为在消融过程中以可控且高效的方式增加心脏组织治疗体积的一种手段。使用植入盐水灌注的、组织等效凝胶体模模型中的光纤温度探头阵列，该模型旨在模拟消融过程中的心肌，对微波天线的加热模式进行了表征，并与550 kHz的商用RF电极导管所诱导的加热模式进行了比较。根据加热组织的径向穿透和总体积评估了热源与心脏壁之间可变接触角的影响。当热源与组织良好耦合时，RF电极的加热模式在径向和轴向上的下降比微波天线更突然，以至于微波天线有效加热组织的体积比RF电极大十多倍；当热源与组织表面成30度角时，微波天线有效加热组织的体积比RF电极大四倍多。
