起搏/除颤螺旋电极植入心肌的急性力学研究

目的对不同构型的螺旋电极旋入及拔出犬心肌的急性力学行为进行测试，为心肌／电极界面的数字建模提供实验依据。方法将实验用犬麻醉后，开胸直视下暴露心腔，将不同头端构型的螺旋电极垂直旋入心肌，通过特殊设计的力学传感器记录电极头端的轴向及扭转受力情况，对比包括心房、心室共11个位点的差异情况；随即将旋入电极以外力强制拔除，记录受力-时间曲线进行分析。结果排除间断施加力量的影响，电极旋入过程的扭矩曲线接近指数曲线，平均扭矩分布范围为0．0003至0．0015，不同构型的电极有明显不同；拔除位点受力以左心室外膜、右心室游离壁、HIS束区域最大，同时可见到明显的不均质性。结论螺旋电极旋入及拔出心肌的受力情况随植入位点、电极头端构型等而不同；心室的受力明显高于心房，其中最牢固位点分别为左心室外膜、右心室游离壁及希氏束。

Acute Mechanical Study of Cardiac Helix Electrodes Interaction with Canine Cardiac Muscle

Objectives The helix electrode configuration is a new type of heart pacing/defibrillating lead distal tip. We carried out in-vivo experiments that screwed the lead tip into the designated sites of heart, and test the acute mechanical characteristics of the screwing-in and pull-out process. We hope it can provide experimental data for the digital reconstruction of the interaction of the interface of heart/electrodes. Methods We developed a method to measure the lead/heart interaction on anesthetic dogs under two statuses: normal heart beats and heart beats with outside excitations. A special design of the helix tip using strain gauges and fiber optic sensors is instrumental for the measurement. After the canines were pre-sedated and anesthetized with ketamine, the chest was opened, and the cardiac cavity were revealed. The helix electrodes were screwed into different locations of the heart. We obtained the data of forces of lead/heart interactions with 5 different types of helix tips from 13 dogs, and estimated the security of the pacer attachment to the heart muscle by pull-out them by external forces. Results We observed that the torques-time curve has the characteristics like exponential curves to some extents, and the average torques ranges from 0.0003 to 0.0015. There is obvious differences among different tip configurations. The forces need to pull-out the electrodes scatters, and the most firm sites are the lateral epicardium of left ventricle, the lateral wall of right ventricle and His bundle region. Conclusion The torques/forces are needed to screw in and pull out the helix electrodes varies wit!) the types of helix tip, test sites and the canine. The forces in the ventricle were typically larger than those in atrium, the largest forces were obtained at the lateral epicardiuro of left ventricle, the lateral wall of right ventricle and His bundle region.