Department of Cardiovascular, Endocrine-Metabolic Diseases and Aging, National Institute of Health, Viale Regina Elena 299, 00161, Rome, Italy.
Department of Information Engineering, Electronics and Telecommunications of the University of Rome "Sapienza", Rome, Italy.
MAGMA. 2021 Aug;34(4):619-630. doi: 10.1007/s10334-021-00909-0. Epub 2021 Feb 8.
To propose and validate a variation of the classic techniques for the estimation of the transfer function (TF) of a real pacemaker (PM) lead.
The TF of three commercially available PM leads was measured by combining data from experimental measurements and numerical simulations generated by three sources: a) the experimental local SAR at the tip of the PM lead (single measurement point) exposed to a 64 MHz birdcage body coil; b) the experimental current distribution along the PM lead, obtained by directly injecting a 64 MHz signal inside the lead; c) the electric field (E-field) simulated with a computational model of the 64 MHz birdcage body coil adopted in the experimental measurement performed in a). The effect of the lead trajectory on the estimation of the TF was also estimated.
The proposed methodology was validated by comparing the SAR obtained from the PM lead TF with experimental measurements: a maximum difference of 2.2 dB was observed. It was also shown that the estimation of the TF cannot be considered independent with the lead trajectory: a variation of the SAR estimation up to 3.4 dB was observed.
For the three PM lead tested, the error in the SAR estimation is within the uncertainty level of SAR measurements (± 2 dB). Additionally, the estimation of the TF using the reciprocity principle is influenced by the particular lead trajectory adopted, even if the consequent variability in the SAR estimation is still close to the uncertainty level of SAR measurements.
提出并验证一种经典技术在估计实际起搏器（PM）导联传递函数（TF）方面的变化。
通过结合来自三个来源的数据来测量三个市售 PM 导联的 TF：a）暴露于 64 MHz 鸟笼体线圈的 PM 导联尖端的实验局部 SAR（单点测量）；b）通过直接在导线上注入 64 MHz 信号获得的 PM 导联沿导线上的实验电流分布；c）在 a）中进行的实验测量中采用的 64 MHz 鸟笼体线圈的计算模型模拟的电场（E 场）。还估计了导联轨迹对 TF 估计的影响。
通过将 PM 导联 TF 获得的 SAR 与实验测量进行比较验证了所提出的方法：观察到最大差异为 2.2 dB。还表明，TF 的估计不能被认为与导联轨迹独立：SAR 估计值的变化高达 3.4 dB。
对于测试的三个 PM 导联，SAR 估计中的误差在 SAR 测量的不确定度范围内（±2 dB）。此外，即使 SAR 估计中的随后变化仍然接近 SAR 测量的不确定度水平，使用互易原理估计 TF 也会受到所采用的特定导联轨迹的影响。
