Haugh C, Davidson E S, Estes N A, Wang P J
Cardiac Arrhythmia Service, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts, USA.
J Interv Card Electrophysiol. 1997 Feb;1(1):57-65. doi: 10.1023/a:1009770803013.
Microwave energy has been proposed as a possible technique to create large myocardial lesions. Achieving a uniform myocardial temperature gradient during microwave ablation may prevent excessive endocardial temperatures while maintaining temperatures at depth. The goal of the current study was to examine the ability of microwave (MW) pulsing to achieve a more uniform myocardial temperature gradient. Using an in-vitro ovine endocardial model, we measured tissue temperature at 0.5-mm, 2.0-mm, and 3.5-mm depths in a circulating saline bath. MW energy was delivered at 20 W at 915 MHz for 30 seconds. Pulse configurations of 1 second on-1 second off, 3 seconds on-3 seconds off, and 5 seconds on-5 seconds off, with 30 seconds of total MW time were compared with 30-seconds continuous. Maximum temperatures at 0.5 mm were significantly lower at 63.2 +/- 5.89 degrees C for the 1-second pulse compared with 83.5 +/- 7.31 degrees C for the continuous-energy delivery. Pulse configurations 3 seconds on-3 seconds off and 5 seconds on-5 seconds off also resulted in a significantly lower surface temperature than continuous-energy delivery. However, temperature at the 2.0-mm and 3.5-mm depth created by the pulsing delivery were similar to those achieved during continuous-energy delivery. Thus, microwave pulsing achieves a lower endocardial temperature and results in a more uniform temperature gradient. These techniques may prevent the excessive endocardial damage that may result in an increased risk of thrombus formation and embolization.
微波能量已被提议作为一种可能用于制造大面积心肌损伤的技术。在微波消融过程中实现均匀的心肌温度梯度，可在维持深部温度的同时防止心内膜温度过高。本研究的目的是检验微波（MW）脉冲形成更均匀心肌温度梯度的能力。我们使用体外绵羊心内膜模型，在循环盐浴中测量了0.5毫米、2.0毫米和3.5毫米深度处的组织温度。以915兆赫兹的频率、20瓦的功率输送微波能量，持续30秒。将总微波时间为30秒、开1秒关1秒、开3秒关3秒和开5秒关5秒的脉冲配置与持续30秒的连续微波进行了比较。1秒脉冲时，0.5毫米处的最高温度显著低于连续能量输送时的83.5±7.31摄氏度，为63.2±5.89摄氏度。开3秒关3秒和开5秒关5秒的脉冲配置也导致表面温度显著低于连续能量输送时的温度。然而，脉冲输送在2.0毫米和3.5毫米深度产生的温度与连续能量输送时所达到的温度相似。因此，微波脉冲可降低心内膜温度并形成更均匀的温度梯度。这些技术可能会防止心内膜过度损伤，而这种损伤可能会增加血栓形成和栓塞的风险。
