Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA (C.D.S.).
Division of Cardiology, VCU School of Medicine, Richmond, VA (J.N.K., K.A.E.).
Circ Arrhythm Electrophysiol. 2020 Feb;13(2):e008092. doi: 10.1161/CIRCEP.119.008092. Epub 2020 Jan 27.
Impedance is the ratio of voltage to current in an electrical circuit. Cardiovascular implantable electronic devices measure impedance to assess the structural integrity electrical performance of leads, typically using subthreshold pulses. We review determinants of impedance, how it is measured, variation in clinically measured pacing and high-voltage impedance and impedance trends as a diagnostic for lead failure and lead-device connection problems. We consider the differential diagnosis of abnormal impedance and the approach to the challenging problem of a single, abnormal impedance measurement. Present impedance provides a specific but insensitive diagnostic. For pacing circuits, we review the complementary roles of impedance and more sensitive oversensing diagnostics. Shock circuits lack a sensitive diagnostic. This deficiency is particularly important for insulation breaches, which may go undetected and present with short circuits during therapeutic shocks. We consider new methods for measuring impedance that may increase sensitivity for insulation breaches.
阻抗是电路中电压与电流的比值。心血管植入式电子设备通过测量阻抗来评估导联的结构完整性和电性能，通常使用亚阈值脉冲。我们回顾了阻抗的决定因素、测量方法、临床测量的起搏和高压阻抗的变化以及作为导联故障和导联-器械连接问题的诊断指标的阻抗趋势。我们考虑了异常阻抗的鉴别诊断以及处理单个异常阻抗测量值这一具有挑战性问题的方法。目前的阻抗提供了一种具体但不敏感的诊断方法。对于起搏电路，我们回顾了阻抗和更敏感的过感知诊断的互补作用。电击电路缺乏敏感的诊断方法。对于绝缘击穿，这一点尤其重要，因为绝缘击穿可能未被发现，并在治疗性电击期间出现短路。我们考虑了用于测量阻抗的新方法，这些方法可能会提高对绝缘击穿的敏感性。
