DIELECTRIC SPECTROSCOPY FOR MONITOR OF INTRA OPERATIVE MYOCARDIUM

我们已经研究了心肌的介电特性，并报道了损耗正切（tan δ m）的峰值，作为表征心肌介电特性的主要参数，与心肌的缺血性损伤相关。我们研究了tan δ m电介质谱是否可以即时评估心肌活力并预测再灌注后的心功能。7个离体猪心脏浸泡在4 -丙酸盐溶液中。我们测量了tan δ m - t心肌。不同保存时间（145 ~ 350分钟）后，分别进行异位心脏移植。比较再灌注后左室收缩力tan δ m的变化。保存期间，tan δ m （5.08(]SY.+- .[)1.05）逐渐降低，直至移植。再灌注后120分钟，左心室Ees较基线恢复51.0% ~ 90.7%。左室Ees的恢复（%基线）与保存结束时的tan δ m相关（范围2.56 ~ 4.49）（r<@D12@>D1=0.867, p<0.01）。我们检查了7例临床病例（59.7(]SY.+- . [)21.2 y.o）。我们测量了ECC期间心肌的tan δ m。在主动脉夹持期间，tan δ m （5.31(]SY.+- .[)0.72）逐渐下降直至消失。为了避免温度效应，我们采用了基于37℃的修正温度公式。比较主动脉交叉夹持期间最小tan δ m值在ECC后120分钟左心室工作指数（%LVWI）从基线恢复的情况（DOA 3or5 γ）。%LVWI与tan δ m最小值相关（范围3.70 ~ 4.59）（r<@D12@>D1=0.960, p<0.01）。电介质谱可以实时评价心肌活力，预测心肌再灌注后的心功能。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。

We have already examined dielectric properties and reported the peak value of the loss tangent (tan delta m), as a primary parameter to represent the dielectric properties, of myocardium was correlated with ischemic injury of the myocardium. We examine whether tan delta m with dielectric spectroscopy can evaluate myocardial viability instantaneously and predict cardiac function after reperfusion. Seven isolated porcine hearts were immersed in 4ﾟC saline solution. We measured tan delta m tof myocardium. After various period of preservation (145 to 350 minutes), heterotopic cardiac transplantation was performed, respectively. Change in tan delta m was compared with left ventricular contractility after reperfusion. During the preservation, tan delta m (5.08(]SY.+-。[)1.05) decreased gradually until transplantation. In 120 minutes after reperfusion, recovery of Ees of left ventricle from baseline was ranging from 51.0% to 90.7%. Recovery of LV Ees (%baseline) was correlated with the tan delta m at the end of preservation (range 2.56 to 4.49) (r<@D12@>D1=0.867, p<0.01). We examined seven clinical cases (59.7(]SY.+-。[)21.2 y.o.). We measured tan delta m of myocardium during ECC.During aortic clamping, tan delta m (5.31(]SY.+-。[)0.72) decreased gradually until declamp. We used corrected formulas of temperature based on 37ﾟC for avoiding temperature effect. Minimum value in tan delta m during aortic crossclamping was compared with recovery of left ventricular work index (%LVWI) from baseline in 120 minutes after ECC (DOA 3or5 gamma). %LVWI was correlated with minimum value in tan delta m (range 3.70 to 4.59) (r<@D12@>D1=0.960, p<0.01). The dielectric spectroscopy might evaluate myocardial viability instantaneously and predict the cardiac function after reperfusion subsequently. The tan delta m may be useful parameter for evaluation of myocardial viability instantaneously and prediction of the ventricular contractility after reperfusion.