ESTABL ISHMENT OF DIELECTRIC SPECTROSCOPY FOR INSTANTANEOUS EVALUATING MYOCARDIAL VIABILITY

本工作的目的是建立瞬时评价心肌活力的介电光谱。将犬心脏分别浸泡在4 C生理盐水（S组）和4 C UW溶液（U组）中8小时。间歇测量心肌tan δ损失正切（tan δ m）峰值。并将tan δ变化与每2h测得的心肌ATP变化进行比较。在保存过程中，tan δ m （%tan δ m）的变化与ATP （%ATP）的变化具有良好的相关性[S组：r^2=0.81， U组：r^2=0.66]。我们检验了tan δ能否预测再灌注后的心室收缩力。将保存好的猪心脏浸泡在4 -丙酸盐溶液中，间歇测量tan δ。然后进行异位心脏移植。在保存期间（150 ~ 360 min）， tan δ的峰值（tan δ m）从5.5(]SY.+- .[)0.5逐渐降低到3.8(]SY.+- .[)0.8。再灌注2小时后，保存结束时的tan δ m与左室Emax恢复百分比（%Emax）相关（r=0.85），而保存时间与此无关（r=0.37）。电镜观察心肌结构变化，比较保存过程中tan δ的变化。tan δ m的变化与细胞膜结构的破坏有关。心肌电介质谱能反映保存过程中细胞的缺血损伤情况。tan δ m可作为即时评价心肌活力和预测再灌注后心室收缩力的有用参数。

The aim of this work is to establish the dielectric spectroscopy for instantaneous evaluating myocardial viability. Canine hearts were immersed in 4ﾟC saline solution (group S) and 4ﾟC UW solution (group U) for 8 hours. We measured the peak value of tan delta loss tangent (tan delta m) of myocardium intermittently. In addition, changes of tan delta were compared with changes of myocardial ATP measured every 2 hours. During preservation the change of tan delta m (%tan delta m) correlated well with the change of ATP (%ATP) [group S : r^2=0.81, group U : r^2=0.66].And we examined whether tan delta couldpredict ventricular contractility after reperfusion. Preserved porcine hearts were immersed in 4ﾟC saline solution, and tan delta were measured intermittently. Then heterotopic cardiac transplantation followed. During preservation (150 to 360 minutes), the peak value of tan delta (tan delta m) decreased gradually from 5.5(]SY.+-。[)0.5 to 3.8(]SY.+-。[)0.8.Two hours after reperfusion, the tan delta m at the end of preservation was correlated with the percent recovery of left ventricular Emax (%Emax) (r=0.85), while preservation time was not correlated with it (r=0.37). And, changes of tan delta during preservation were compared with myocardial structural changes observed by electron microscopy. The change of tan delta m correlated with the destruction of cellular membrane structure.Dielectric spectroscopy of myocardium can reflect ischemic injury of cell during preservation. The tan delta m may be useful parameter for evaluation of myocardial viability instantaneously and prediction of the ventricular contractility after reperfusion.