Chung N, Small R S, Kass D A, Bell M R, Ritman E L, Holmes D R, Tockman B A, Salo R W
Yonsei University, Seoul, South Korea.
Biomed Instrum Technol. 1994 Mar-Apr;28(2):113-22.
The accuracy with which a multiple-electrode impedance catheter (IC) tracks instantaneous global, in-situ left ventricular (LV) volumes was tested in 13 anesthetized dogs scanned in the Dynamic Spatial Reconstructor (DSR), a fast volumetric computed tomographic (CT) scanner. All dogs were scanned during control conditions and during an acute hemodynamic intervention. Hypertonic saline calibrations were performed for the IC prior to each DSR scan. In six of the dogs the IC-derived LV end-diastolic volume (Y) correlated with the DSR-derived global LV end-diastolic volume (X) as follows: end-diastolic volume, Y = 1.01X - 9.9, r = 0.812. The IC-derived LV end-diastolic volume, under control conditions, correlated with the DSR-derived truncated (i.e., that region of the LV chamber between the proximal and distal electrodes of the IC catheter) LV end-diastolic volume, Y = 1.00X + 17.4, r = 0.803. Under reduced preload the relation was Y = 1.3X - 15.26, r = 0.911. The segmental volume (between adjacent sensing electrodes on the IC) at the basal portion of the LV correlated poorly (Y = 1.88X + 3.3, r = 0.459 etc.), but correlated better at mid- and more apical LV levels (Y = 0.97X + 2.7, r = 0.762). Correlations between segmental stroke volumes were similar at basal (Y = 1.31X + 1.60, r = 0.815) and mid- and more apical levels (Y = 1.42X + 0.11, r = 0.763). Stroke volume during acute ischemia (two dogs) was Y = 1.33X - 1.41, r = 0.717; during acutely decreased preload (four dogs) it was Y = 1.24X - 2.88, r = 0.572). Thus, the IC tracks the changes in LV-chamber volume throughout a cardiac cycle quite well under a variety of conditions, but accuracy deteriorates as the shape of the LV chamber changes in response to changes in hemodynamic loading or local myocardial ischemia.
在13只麻醉犬中测试了多电极阻抗导管（IC）追踪左心室（LV）瞬时整体原位容积的准确性，这些犬在动态空间重建仪（DSR）（一种快速容积计算机断层扫描（CT）扫描仪）中进行扫描。所有犬在对照条件下和急性血流动力学干预期间均进行扫描。在每次DSR扫描前对IC进行高渗盐水校准。在6只犬中，IC得出的左心室舒张末期容积（Y）与DSR得出的左心室整体舒张末期容积（X）的相关性如下：舒张末期容积，Y = 1.01X - 9.9，r = 0.812。在对照条件下，IC得出的左心室舒张末期容积与DSR得出的截断的（即IC导管近端和远端电极之间的左心室腔区域）左心室舒张末期容积相关，Y = 1.00X + 17.4，r = 0.803。在预负荷降低时，关系为Y = 1.3X - 15.26，r = 0.911。左心室底部的节段容积（IC上相邻传感电极之间）相关性较差（Y = 1.88X + 3.3，r = 0.459等），但在左心室中部和心尖部水平相关性较好（Y = 0.97X + 2.7，r = 0.762）。节段性搏出量之间的相关性在底部（Y = 1.31X + 1.60，r = 0.815）以及中部和心尖部水平相似（Y = 1.42X + 0.11，r = 0.763）。急性缺血期间（2只犬）的搏出量为Y = 1.33X - 1.41，r = 0.717；急性预负荷降低期间（4只犬）为Y = 1.24X - 2.88，r = 0.572）。因此，在各种条件下，IC在整个心动周期中能很好地追踪左心室腔容积的变化，但随着左心室腔形状因血流动力学负荷变化或局部心肌缺血而改变，准确性会下降。
