Noninvasive reconstruction of three-dimensional ventricular activation sequence from the inverse solution of distributed equivalent current density
Noninvasive reconstruction of three-dimensional ventricular activation sequence from the inverse solution of distributed equivalent current density
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DOI：
10.1109/tmi.2006.882140
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发表时间：
2006-10-01
影响因子：
10.6
通讯作者：
He, Bin
中科院分区：
文献类型：
--
作者：
Liu, Zhongming;Liu, Chenguang;He, Bin
我们提出了一种新的心电图（ECG）逆方法成像的三维（3-D）心室激动序列的基础上的建模和估计的等效电流密度在整个体积的心室心肌。心室兴奋过程的时空相干性已被用来从等效电流密度的估计时间过程中推导出激动时间。在本研究中，我们探索了四种不同的线性逆算法（最小范数和加权最小范数估计结合两种正则化方案：即时即时正则化和各向同性方法），以估计在心室去极化过程中的每个时刻的电流密度。将心室肌内任何给定位置的激动时间确定为出现最大局部电流密度估计值的时间点。进行计算机模拟，以评估这种方法使用单和双部位起搏协议在生理上现实的细胞自动机心脏模型。所提出的方法的性能和稳定性进行了评估相对于各种水平的测量噪声（0，5，10，20，40，和60 μ V），各种数量的ECG电极和模型误差的躯干几何形状和心脏位置。仿真结果表明：1）在加性高斯白色噪声为20 μ V的情况下，从200通道体表电位图可以很好地重建出单部位起搏的三维激动序列（相关系数= 0.90，相对误差= 0.19，定位误差= 5.49mm）; 2）当从左/右心室（LV/RV）启动激动时，与从隔膜启动激动相比，可以获得更高的成像精度; 3）各向同性方法产生比常规的逐时刻正则化更好的性能; 4）较大的噪声水平、较少的电极数量或体积导体建模误差导致成像精度降低;然而，在60 μ V噪声水平、64个电极或分别在躯干几何形状和心脏位置上的轻微误差的情况下，仍然可以获得合理的成像精度; 5）当两个部位同时起搏或以20 ms的时间延迟起搏时，可以成像双部位起搏的3-D激动序列;（6）当两个起搏部位分别位于心室对侧或心室侧壁和心尖部时，可在成像的三维激动序列中分辨和定位。
We propose a new electrocardiographic (ECG) inverse approach for imaging the three-dimensional (3-D) ventricular activation sequence based on the modeling and estimation of the equivalent current density throughout the entire volume of the ventricular myocardium. The spatio-temporal coherence of the ventricular excitation process has been utilized to derive the activation time from the estimated time course of the equivalent current density. In the present study, we explored four different linear inverse algorithms (the minimum norm and weighted minimum norm estimates in combination with two regularization schemes: the instant-by-instant regularization and the isotropy method) to estimate the current density at each time instant during the ventricular depolarization. The activation time at any given location within the ventricular myocardium was determined as the time point with the occurrence of the maximum local current density estimate. Computer simulations were performed to evaluate this approach using single- and dual-site pacing protocols in a physiologically realistic cellular automaton heart model. The performance and stability of the proposed approach was evaluated with respect to the various levels of measurement noise (0, 5, 10, 20, 40, and 60 mu V), the various numbers of ECG electrodes and the modeling errors on the torso geometry and heart position. The simulation results demonstrate that: 1) the single-site paced 3-D activation sequence can be well reconstructed from 200-channel body surface potential maps with additive Gaussian white noise of 20 mu V (correlation coefficient = 0.90, relative error = 0.19, and localization error = 5.49 mm); 2) a higher imaging accuracy can be obtained when the activation is initiated from the left/right ventricle (LV/RV) compared to from the septum; 3) the isotropy method gives rise to a better performance than the conventional instant-by-instant regularization; 4) a decreased imaging accuracy results from a larger noise level, a fewer number of electrodes, or the volume conductor modeling errors; however, a reasonable imaging accuracy can still be obtained with a 60 mu V noise level, 64 electrodes, or mild errors on both the torso geometry and heart position, respectively; 5) the dual-site paced 3-D activation sequence can be imaged when the two sites are paced either simultaneously or with a time delay of 20 ms; 6) two pacing sites can be resolved and localized in the imaged 3-D activation sequence when they are located at the contralateral sides of ventricles or at the ventricular lateral wall and the apex, respectively.