Department of Cardiac Surgery, University of Bonn, Bonn, Germany.
IEEE Trans Biomed Eng. 2011 Jun;58(6):1511-8. doi: 10.1109/TBME.2010.2054090. Epub 2010 Jun 28.
The scope of this paper was to determine whether ischemic and reperfusion damage in cardiac surgery can be detected by measurement of electrical bioimpedance (EBI). Conventional pacing wires were replaced by pacing wires with sputtered iridium coating in order to reduce polarization associated with two-electrode impedance measurements. A custom-built bioimpedance analyzer (Osypka Medical GmbH, Berlin, Germany) measured the real part of impedance Re(Z) and the phase (ϕ) at three frequencies (1, 10, and 1000 kHz) and determined an extracellular space index (EZRI) as the quotient of Re(Z) at 1000 kHz and Re(Z) at 1 kHz. Our study included six patients (conventional coronary artery bypass graft, age 68.1 ± 8.3 years) subject to routine cardioplegic ischemia and reperfusion. Preischemic bioimpedance measurements were not impaired by interference of the beating heart. Intraischemically, bioimpedance at 1 kHz and phase at 10 kHz increased until opening of a bypass graft, which is probably induced by closure of gap junctions and cell swelling processes. After cross clamping, EZRI slowly decreased as an effect of mild cell swelling. After ischemia, values returned almost to baseline measurements, indicating sufficient reperfusion processes. Measurement of EBI correlates with myocardial ischemic injury and is applicable in a two-electrode setup providing low-polarization pacing wires.
本文旨在探讨通过测量电生物阻抗（EBI）是否可以检测到心脏手术中的缺血再灌注损伤。为了降低双电极阻抗测量相关的极化，我们用溅射铱涂层的起搏线取代了传统的起搏线。一台定制的生物阻抗分析仪（Osypka Medical GmbH，柏林，德国）测量了阻抗 Re(Z)的实部和相位（ϕ）在三个频率（1、10 和 1000 kHz），并将细胞外空间指数（EZRI）定义为 1000 kHz 时的 Re(Z)与 1 kHz 时的 Re(Z)的商。我们的研究纳入了 6 名（常规冠状动脉旁路移植术，年龄 68.1±8.3 岁）患者，这些患者经历了常规心脏停搏的缺血再灌注。在预缺血状态下，生物阻抗测量不会受到跳动心脏的干扰。在缺血期间，1 kHz 时的生物阻抗和 10 kHz 时的相位增加，直到旁路移植开放，这可能是由于缝隙连接的关闭和细胞肿胀过程引起的。交叉钳夹后，EZRI 缓慢下降，这是轻微细胞肿胀的结果。缺血后，数值几乎恢复到基线测量值，表明再灌注过程充分。EBI 的测量与心肌缺血损伤相关，并且适用于提供低极化起搏线的双电极设置。
