Farrell Robert M, Syed Amjad, Syed Amina, Gutterman David D
Diagnostic Cardiology, GE Healthcare, Wauwatosa, WI, USA.
J Electrocardiol. 2008 Nov-Dec;41(6):536-45. doi: 10.1016/j.jelectrocard.2008.07.023. Epub 2008 Sep 13.
The effects of three common limb electrode placement configurations on ECG signal morphology were examined, including the standard electrode placement of the electrodes on the extremities, the Mason-Likar placement, and the Lund placement. A non-traditional asymmetric configuration of placing the LA electrode on the upper arm with the RA electrode on the torso (below the clavicle) was also investigated. A series of 16-lead ECGs were acquired from 150 subjects representing a broad range of diseases. Effects of the limb electrode placement on axis measurements, QRS amplitudes, ST levels, and infarctions were studied. On average, the P, QRS, and T axes all exhibited rightward shifts as the electrodes were moved away from the extremities, but more generally, the axis became more vertical, with the largest shifts occurring when the standard ECG axis measurement was close to 0 degrees and tending to exhibit leftward shifts for ECGs with a standard axis measurement between 0 and -90 degrees. Voltage changes were consistent with axis shifts in the frontal plane (decreased lateral and increased inferior lead voltages), with the largest mean change a reduction in R wave amplitude of lead I going from the standard to the Mason-Likar configuration. In the precordial leads, Q and/or S magnitudes decreased in right-sided leads (V4r, V1, V2, V3) and R magnitudes increased in lateral leads (V3-V9) as the arm electrodes moved toward the trunk, suggesting a posterior shift in the mean QRS axis. ST deviations in the lateral and posterior precordial leads tended to be mimicked in lead III when the electrodes were moved from the extremities to the torso. Over half (13 of 25) of the ECGs exhibiting criteria for inferior infarct in the standard configuration had that criteria erased when the electrodes were moved to the Mason-Likar positions. The largest single effect on the ECG resulted from moving the LA electrode from the shoulder to the clavicle. The asymmetric configuration with the RA electrode on the torso and the LA electrode on the upper arm may offer some compromise between noise and faithfulness to the standard configuration in noisy environments such as exercise testing or monitoring.
研究了三种常见的肢体电极放置配置对心电图（ECG）信号形态的影响，包括肢体上电极的标准放置、梅森 - 利卡尔放置法和隆德放置法。还研究了一种非传统的不对称配置，即将左臂（LA）电极置于上臂，右臂（RA）电极置于躯干（锁骨下方）。从150名患有广泛疾病的受试者身上采集了一系列16导联心电图。研究了肢体电极放置对轴测量、QRS波振幅、ST段水平和梗死的影响。平均而言，随着电极远离肢体，P波、QRS波和T波轴均表现出向右偏移，但更普遍的情况是，轴变得更加垂直，当标准心电图轴测量接近0度时偏移最大，而对于标准轴测量在0至 -90度之间的心电图则倾向于表现出向左偏移。电压变化与额面轴偏移一致（外侧导联电压降低，下壁导联电压升高），从标准配置到梅森 - 利卡尔配置时，I导联R波振幅的平均变化最大，为降低。在胸前导联中，随着手臂电极向躯干移动，右侧导联（V4r、V1、V2、V3）的Q波和/或S波幅度降低，外侧导联（V3 - V9）的R波幅度增加，这表明平均QRS轴向后移位。当电极从肢体移动到躯干时，胸前导联外侧和后壁导联的ST段偏移往往在III导联中被模拟出来。在标准配置中表现出下壁梗死标准的心电图中，超过一半（25份中的13份）在电极移动到梅森 - 利卡尔位置时该标准消失。对心电图影响最大的单一因素是将LA电极从肩部移至锁骨。在运动测试或监测等嘈杂环境中，将RA电极置于躯干且LA电极置于上臂的不对称配置可能在噪声和对标准配置的忠实度之间提供一些折衷。
