Scientific Computing and Imaging Institute, University of Utah, SLC, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, SLC, UT, USA; Department of Biomedical Engineering, University of Utah, SLC, UT, USA.
Scientific Computing and Imaging Institute, University of Utah, SLC, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, SLC, UT, USA; Department of Biomedical Engineering, University of Utah, SLC, UT, USA; School of Medicine, University of Utah, SLC, UT, USA.
Comput Biol Med. 2021 Jul;134:104476. doi: 10.1016/j.compbiomed.2021.104476. Epub 2021 May 15.
Electrocardiographic forward problems are crucial components for noninvasive electrocardiographic imaging (ECGI) that compute torso potentials from cardiac source measurements. Forward problems have few sources of error as they are physically well posed and supported by mature numerical and computational techniques. However, the residual errors reported from experimental validation studies between forward computed and measured torso signals remain surprisingly high.
To test the hypothesis that incomplete cardiac source sampling, especially above the atrioventricular (AV) plane is a major contributor to forward solution errors.
We used a modified Langendorff preparation suspended in a human-shaped electrolytic torso-tank and a novel pericardiac-cage recording array to thoroughly sample the cardiac potentials. With this carefully controlled experimental preparation, we minimized possible sources of error, including geometric error and torso inhomogeneities. We progressively removed recorded signals from above the atrioventricular plane to determine how the forward-computed torso-tank potentials were affected by incomplete source sampling.
We studied 240 beats total recorded from three different activation sequence types (sinus, and posterior and anterior left-ventricular free-wall pacing) in each of two experiments. With complete sampling by the cage electrodes, all correlation metrics between computed and measured torso-tank potentials were above 0.93 (maximum 0.99). The mean root-mean-squared error across all beat types was also low, less than or equal to 0.10 mV. A precipitous drop in forward solution accuracy was observed when we included only cage measurements below the AV plane.
First, our forward computed potentials using complete cardiac source measurements set a benchmark for similar studies. Second, this study validates the importance of complete cardiac source sampling above the AV plane to produce accurate forward computed torso potentials. Testing ECGI systems and techniques with these more complete and highly accurate datasets will improve inverse techniques and noninvasive detection of cardiac electrical abnormalities.
心电图正向问题是无创性心电图成像（ECGI）的关键组成部分，它从心脏源测量值计算体腔电势。正向问题的误差源很少，因为它们在物理上是良好定义的，并得到成熟的数值和计算技术的支持。然而，在正向计算的体腔信号与实测信号之间的实验验证研究中，报告的残余误差仍然高得惊人。
检验假设，即不完全的心脏源采样，特别是在房室（AV）平面以上，是正向解误差的主要原因。
我们使用改良的 Langendorff 制剂悬挂在人形电解体腔罐中，并使用新颖的心包膜笼记录阵列来彻底采样心脏电势。通过这种精心控制的实验准备，我们最大限度地减少了可能的误差源，包括几何误差和体腔不均匀性。我们逐步从 AV 平面以上去除记录信号，以确定不完全源采样如何影响正向计算的体腔罐电势。
我们总共研究了两个实验中每个实验的三种不同激活序列类型（窦律、左心室后壁前后起搏）记录的 240 个心搏。通过笼状电极的完全采样，计算出的和实测的体腔罐电势之间的所有相关度量值都高于 0.93（最大值为 0.99）。所有心搏类型的平均均方根误差也较低，小于或等于 0.10 mV。当我们仅包括 AV 平面以下的笼状电极测量值时，正向解的准确性急剧下降。
首先，我们使用完整心脏源测量值进行的正向计算电位为类似研究设定了基准。其次，这项研究验证了在 AV 平面以上进行完整心脏源采样对于产生准确的正向计算体腔电势的重要性。使用这些更完整和高度准确的数据集测试 ECGI 系统和技术将改进逆技术和对心脏电异常的无创检测。
