心内组织多普勒超声显像标测心脏传导系统心肌兴奋——心肌电和机械兴奋多参数显像

Cardiac conductive system excitation maps using intracardiac ultrasound catheter with tissue Doppler imaging:multiparametric imaging of electrical and mechanical activation

目的 探讨高分辨力心内超声组织多普勒显像技术标测心脏传导系统心肌电兴奋诱导心肌收缩的可行性和应用范围。方法 用 5条狗开胸模型 ,通过 11F血管鞘从右颈内静脉或股静脉插入 10F心内超声导管分别置留于上腔静脉、右心房和右心室。刺激电极随机置入心室壁内 (心外膜下心肌和心内膜下心肌 )。应用二维灰阶超声观察并测量窦房结、右心房壁、房室交界区、室间隔和左心室游离壁的解剖结构 ;采用心内超声组织多普勒显像技术获取窦性心律上述各点的二维、M型心肌速度和加速度图像 ;在心室起搏时记录心肌速度和加速度起始和分布 ,其心肌机械兴奋的空间部位和时相分别与刺激电极的部位与电刺激时相比较。结果 心内超声清晰显示窦房结、心房壁、房室交界区和室间隔及心室游离壁的细微解剖结构。心电图P波起始后 ,窦房结区域内速度和加速度明显增高。窦性心律心房壁心肌收缩和舒张期为均匀一致速度和加速度分布。心电图P R间期内 ,房室交界区心肌速度或加速度增高起始于其上部并向下分布传导至室间隔上部。心电图QRS波起始处 ,室间隔内心肌速度和加速度分布呈”Y”字形。人工电刺激诱导心室心肌速度和加速度增高的起始点位于电刺激局部 ,直径小于 5mm ;心肌机械收缩延迟小于 7ms(帧频为 14 0帧 /s) ;

Objective To provide a clinically feasible tissue Doppler maps of myocardial contraction in response to electrical activation of cardiac conductive system using intracardiac ultrasound catheter with high resolution tissue Doppler imaging (TDI).Methods Open chest model of five dogs were used. An intracardiac ultrasound catheter with TDI capabilities was introduced into SVC, right atria and ventricle. The stimulating electrode was placed within ventricular subepicardium and subendocardium. 2D gray scale ultrasonic examination was performed to observe the anatomic structure of sino atrial node (SAN), right Koch's triangle, IVS and free ventricular wall. M mode and 2D TDI were obtained to map myocardial velocity and acceleration with normal sinus rhyme at different sites of cardiac conductive system described above. Mapping of ventricular myocardial velocity and acceleration was performed during pacing. The regional myocardial excitation on the 2D TDI images was analyzed using a dedicated method for quantification.Results The detail anatomic structure of SAN with a dramatic increase of velocity and acceleration of SAN was presented at the beginning of atrial electrical excitation. The changes of velocity and acceleration of SAN as a time sequence curve quantitatively demonstrated the process of SAN′s excitation. A high value distribution of velocity and acceleration within right Koch′s triangle progressed into upper IVS before the early ventricular electrical excitation. The ventricular onset of myocardial velocity and acceleration induced by electrical stimulation was exactly at the location of electrical stimulating sites with size less than 5 mm, and coextended as concentric circle within ventricular wall. The delay of myocardial contraction is less than 7 ms.Conclusions The onset and propagation of myocardial velocity and acceleration can be defined within cardiac conductive system using intracardiac ultrasonic catheter with TDI. This techniqne will provide a simultaneous single visualization of anatomy, function and electrical events for the purpose of precision underblood intervention.