Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA.
Am J Physiol Heart Circ Physiol. 2012 Jan 1;302(1):H244-52. doi: 10.1152/ajpheart.00618.2011. Epub 2011 Oct 7.
Single-beat imaging of myocardial activation promises to aid in both cardiovascular research and clinical medicine. In the present study we validate a three-dimensional (3D) cardiac electrical imaging (3DCEI) technique with the aid of simultaneous 3D intracardiac mapping to assess its capability to localize endocardial and epicardial initiation sites and image global activation sequences during pacing and ventricular tachycardia (VT) in the canine heart. Body surface potentials were measured simultaneously with bipolar electrical recordings in a closed-chest condition in healthy canines. Computed tomography images were obtained after the mapping study to construct realistic geometry models. Data analysis was performed on paced rhythms and VTs induced by norepinephrine (NE). The noninvasively reconstructed activation sequence was in good agreement with the simultaneous measurements from 3D cardiac mapping with a correlation coefficient of 0.74 ± 0.06, a relative error of 0.29 ± 0.05, and a root mean square error of 9 ± 3 ms averaged over 460 paced beats and 96 ectopic beats including premature ventricular complexes, couplets, and nonsustained monomorphic VTs and polymorphic VTs. Endocardial and epicardial origins of paced beats were successfully predicted in 72% and 86% of cases, respectively, during left ventricular pacing. The NE-induced ectopic beats initiated in the subendocardium by a focal mechanism. Sites of initial activation were estimated to be ∼7 mm from the measured initiation sites for both the paced beats and ectopic beats. For the polymorphic VTs, beat-to-beat dynamic shifts of initiation site and activation pattern were characterized by the reconstruction. The present results suggest that 3DCEI can noninvasively image the 3D activation sequence and localize the origin of activation of paced beats and NE-induced VTs in the canine heart with good accuracy. This 3DCEI technique offers the potential to aid interventional therapeutic procedures for treating ventricular arrhythmias arising from epicardial or endocardial sites and to noninvasively assess the mechanisms of these arrhythmias.
单心动周期心肌激活成像有望辅助心血管研究和临床医学。本研究通过同步 3D 心内电图（3DCEI）和 3D 心内标测技术验证了该技术，评估其在犬心起搏和室速（VT）时定位心内膜和心外膜激动起始点和成像整体激活顺序的能力。在健康犬的闭胸条件下同步测量体表电位和双极电记录。标测研究后获取 CT 图像构建真实几何模型。对去甲肾上腺素（NE）诱导的起搏节律和 VT 进行数据分析。非侵入性重建的激活序列与同步 3D 心内标测测量结果吻合良好，相关系数为 0.74±0.06，相对误差为 0.29±0.05，在 460 次起搏和 96 次异位（包括室性早搏、成对搏动和非持续单形 VT 和多形 VT）中平均 RMS 误差为 9±3ms。左室起搏时，72%的起搏和 86%的起搏能够成功预测心内膜和心外膜起源。NE 诱导的异位搏动由局灶机制起始于心内膜下。起搏和异位搏动的起始激活点估计距离测量起始点约 7mm。对于多形性 VT，重建可以描绘出起始点和激活模式的逐搏动态变化。本研究结果表明，3DCEI 可以非侵入性地成像 3D 激活序列，并准确定位起搏和 NE 诱导的 VT 在犬心中的激活起源。该 3DCEI 技术有望辅助治疗起源于心外膜或心内膜部位的室性心律失常的介入治疗程序，并无创性评估这些心律失常的机制。
