超声引导心脏靶点起搏和精确消融的初步实验研究

目的 初步建立超声引导监控下的心脏传导系统的靶点起搏和精确消融方法。方法 12只杂种犬急性开胸模型，经颈静脉插入超声导管分别进入上腔静脉，右心房，室或经心脏表面进行心脏扫描，获取并确认心脏传导系统超声解剖结构标志及其心肌激动顺序，确定靶组织空间益关系，引导经股静脉插入的心脏起搏或消融导管和经心脏表面插入的穿刺针到达靶组织并确认心内膜面接触，进行靶点起搏，精确射频及化学消融，超声实时监控全过程，对心脏离体标本进行病检和切片，确认靶点起搏位置，观察消融和起搏对心脏传导系统和组织细胞的损害。结果 超声能够在观察到心脏传导系统重要靶点部位，解剖结构的同时评价其结构内心肌激动的起始和传导顺序，能引导介入导管准确到达靶点组织，监控电极与心内膜央的接触，监控穿刺针在靶点组织内的准确空间位置，避免损伤冠状动脉及传导组织，及时评价起搏和消融损伤效果。确定终止治疗时机并监控并发症的发生，病解和切片表明超声引导心脏射频和化学消融定位准确，效果肯定。结论 超声能够引导心脏介入导管和穿刺针进行心脏靶点起搏和精确消融，定点消融心肌，使起搏和消融治疗更为精确，该方法将为临床心脏电生理疾病的治疗提供一种全新的简便，准确技术方法和手段。

Cardiac target pacing and precision ablation guided by echocardiographic techniques in vivo

Objective To establish the method of cardiac target pacing and precision ablation.Methods After the scanning of detailed anatomic structure,using an intracardiac ultrasonic catheter system(AcuNav,8MHz for gray-scale and 4MHz for tissue Doppler imaging,10 French)and a surface scanning probe (8MHz for gray-scale and 4MHz for Doppler tissue imaging with Sequoia C256),the electrodes of pacing and ablation catheter were guided to reach the targeted tissue and contact the endocardium on 12 opened-chest canine models.The procedure of epicardial penetration using ethanol ablation needle at the specific ablation site(i.e.,upper inter-ventricular septum)and the size of ablation were monitored and controlled via the same ultrasonic techniques. Meanwhile,the surface ECG and intracardiac electro-physiologic,myocardial electro-mechanical effects and gray-scale changes of targeted anatomic structure mapping were examined and the complications of these administrations were evaluated before,during and after pacing and ablation.The specimens at ablation sites were dissected for patho-histological slices after dog sleepaway to ensure the right target site of electrode placement,and assess the tissue effects of RF and chemical ablation and cardiac target pacing.Results The real direct target pacing and precision RF and chemical ablation at different sites(i.e.,superolateral crista terminalis,atrial priority conductive channel,atrial-ventricular node,His bundle,left and right ventricular wall and upper inter-ventricular septum)were realized successfully.But ,the direct sino-atrial node pacing and ablation failed due to the difficult orientation of the electrode of the dedicated pacing lead and ablation catheter and complex shape of the anatomic structure at sino-atrial node site.The results of surface ECG,intracardiac electro-physiologic mapping and patho-histological analysis confirmed the efficiency of target pacing and precision ablation with optimized pacing effect,focused ablation point and normal sequence of ventricular excitation.The ablation lesion,bubble,subendocardial hematoma,sheath thrombus pericardial effusion and wall rupture were visualized instantly during the administration.Conclusion The real direct target pacing and precision ablation of cardiac conductive system guided by surface scanning and intracardiac echocardiographic techniques can be realized.