关键词：导管消融，超声；心肌；犬
摘要 评估超声消融损伤灶的组织学改变，探讨各种物理因素对超声损伤范围的影响。使用自行研制的超声导管消融系统，在冠状动脉灌注及表面灌流的犬离体右室或左室游离壁热动力学模型上，以不同的电功率及辐照时间进行心室肌消融。结果：持续45 s的超声消融能造成均一的、边界清楚的心肌坏死灶。电功率与损伤灶深度呈线性相关(Y=2.81+0.4X,r2 =0.745)，电功率23.81 W、超声辐照60 s产生的损伤灶最深，达12.27±1.75 mm。损伤面积与辐照时间呈正相关关系(Y=17.94+0.28X,r2 =0.58)。结论：超声能量可能成为心内消融的能源。与射频消融相比，超声消融可造成更深的心肌损伤灶，提示超声消融有可能消除位于较深层心肌中的致心律失常病灶，这对于心肌梗死后室性心动过速的消融有较大的意义。
中图分类号 R454.3 文献标识码 A
文章编号 1007—2659(2000)03—0195—04
Ultrasound Catheter Ablation of Ventricular Myocardium in an in Vitro Thermodynamic Model:Assessment of Tissue Injury and Factors Influencing Lesion Size.
DONG Jun,LUO Kai-liang,HUANG Jing,et al.
This study was designed to assess tissue injury and investigate the influence of various physical factors on the size of the resultant lesion during ultrasound catheter ablation.Methods:An ultrasound catheter ablation system was constructed and a thermodynamic model in isolated perfused and superfused canine right or left free wall was established.Ultrasound energy was delivered through a small transducer mounted on the tip of a modified 7F radiofrequency catheter.Different levels of electrical power and acoustic time were adopted and the size of the resulting lesions was measured to observe the dose-response relationship.Results:Homogenous and well circumscribed myocardium tissue necrosis could be produced by the application of ultrasound energy for 45 s or longer.There was a linear relationship between increasing electrical power and depth of lesion (Y=2.81±0.4X,r2 =0.745).Myocardial lesions of 12.27±1.75 mm in depth were produced with electrical power of 23.81 watts applied for 60 s.There were also positive relationships between lesion area and sonication time (Y=17.94±0.28X,r2 =0.58).Conclusion:Ultrasound energy could become a new energy source for intracardiac ablation.In comparison with radiofrequency,ultrasound should be able to creat deeper leions that should be beneficial for the treatment of ventricular tachycardia after myocardial infarction.
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