Noninvasive detection of the limitation of simple cold storage of the heart by myocardial electrical impedance

The purpose of this study was to determine if graft viability during simple cold storage can be monitored from alteration of myocardial electrical impedance. Twelve anesthetized dogs were underwent rapid cardiac extripation and were placed in simple cold storage. They were divided into two groups according to preserved solution. Group S was preserved in 12 hours in saline. Group U was preserved in 24 hours in the University of Wisconsin (UW) solution. Myocardial electrical impedance was measured serially by use of a LCR meter and analyzed the changes of myocardial resistivity during preservation. Myocardial specimens were taken for myocardial ATP measurement with high-performance liquid chromatography and for water content in two groups. Moreover in order to predict the cardiac function after transplantation in two groups, heterotopic cardiac transplantation in the neck was performed in mongrel dogs and left ventricular (LV) Emax was measured. Myocardial resistivity increased significantly until 5.5 hours in group S, 13 hours in group U. ATP remained above 50% at 5.5 hours in Group S, 13.7 hours in Group U. Resistivity increase rate was over 0.1 omega cm/min in the period ATP remained above 50%. Myocardial water content increased during preservation in group S, but did not in group U. There was no relationship between the increase of resistivity and myocardial water content. LVEmax at 120 min after reperfusion was over 90% of preischemic value in 4 hour preserved heart in saline and 12 hour preserved heart in UW. Measurement of myocardial resistivity during simple cold storage may be feasivle as a monitor of graft viability.