Svehlikova Jana, Teplan Michal, Tysler Milan
Institute of Measurement Science, SAS, Bratislava, Slovakia.
Institute of Measurement Science, SAS, Bratislava, Slovakia.
J Electrocardiol. 2018 May-Jun;51(3):370-377. doi: 10.1016/j.jelectrocard.2018.02.013. Epub 2018 Mar 2.
The inverse problem of electrocardiography for localization of a premature ventricular contraction (PVC) origin was solved and compared for three types of the equivalent cardiac electrical generator: transmembrane voltages, epicardial potentials, and dipoles. Instead of regularization methods usually used for the ill-posed inverse problems an assumption of a single point source representative of the heart generator was applied to the solution as a geometrical constraint. Body surface potential maps were simulated from eight modeled origins of the PVC in the heart model. Then the maps were corrupted by additional Gaussian noise with the signal-to-noise ratio (SNR) from 20 to 10dB and used as the input of the inverse solution. The inverse solution was computed from the first 30ms of the ventricular depolarization. It was assumed that during this period only a small part of the heart volume is activated thus it can be represented by a single point electrical source. Generally, the localization error was more dependent on the PVC origin position than on the type of the used heart generator. The most stable localization error between the inversely found results and the true PVC origin was not larger than 20mm for PVC origins located in the left ventricular wall and on the right ventricular anterior side. For such cases, the localization was robust to the noise up to SNR of 10dB for all studied types of the cardiac generator. For SNR 10dB the results became unstable mainly for the PVC origins in the septum and posterior right ventricle for the dipolar heart generator and for epicardial potentials defined on the pericardium when the range of the localization error increased up to 50mm. When the results for different electrical heart generators were considered altogether, the mean radius of the cloud of results did not exceed 20mm and the localization error of the cloud center was smaller than that obtained for a particular type of the cardiac generator. Combination of results from different models of a single point cardiac electrical generator can provide better information for the preliminary noninvasive localization of PVC than the use of one type of the generator.
解决了用于室性早搏（PVC）起源定位的心电图逆问题，并针对三种等效心脏电发生器类型进行了比较：跨膜电压、心外膜电位和偶极子。对于不适定逆问题，未使用通常采用的正则化方法，而是将代表心脏发生器的单点源假设作为几何约束应用于解。从心脏模型中八个模拟的PVC起源点模拟体表电位图。然后用信噪比（SNR）从20到10dB的附加高斯噪声对这些图进行干扰，并将其用作逆解的输入。逆解是根据心室去极化的前30毫秒计算得出的。假定在此期间只有心脏体积的一小部分被激活，因此可以用单个点电源来表示。一般来说，定位误差更多地取决于PVC起源位置，而非所使用的心脏发生器类型。对于位于左心室壁和右心室前侧的PVC起源点，逆解结果与真实PVC起源点之间最稳定的定位误差不大于20毫米。对于此类情况，对于所有研究的心脏发生器类型，定位对高达10dB SNR的噪声具有鲁棒性。对于10dB SNR，结果变得不稳定，主要是对于偶极心脏发生器以及定义在心脏心包上的心外膜电位而言，当PVC起源点位于室间隔和右心室后侧时，定位误差范围增加到50毫米。当综合考虑不同心脏电发生器的结果时，结果云团的平均半径不超过20毫米，且云团中心的定位误差小于针对特定类型心脏发生器所获得的误差。与使用一种类型的发生器相比，组合来自单点心脏电发生器不同模型的结果可为PVC的初步非侵入性定位提供更好的信息。
