The Effect Of Diammonii Glycyrrhizinatis On Myocardiac Repolarization After Open Heart Surgery

Objective To explore the effect and mechanism of diammonii glycyrrhizinatis preconditioning on myocardiac repolarization after open heart surgery.Methods Sixty patients with rheumatic valvular disease (ASAâ…¡-â…¢), undergoing valve replacement with cardiopulmonary bypass (CPB), were divided randomly into two groups-diammonii glycyrrhizinatis preconditioning group(n=30) and control group(n=30), Diammonii glycyrrhizinatis (2.5mg/kg) was administrated in 20 minutes between post-anesthesia induction and the beginning of surgical incision in the diammonii glycyrrhizinatis group , and glucose injection was administrated in the control group alone. Electrocardio-grams were recorded before operation, the first and the third day after operation, the QT dispersion (QTd) and corrected value of QT dispersion (QTcd) were measured. Blood samples were taken from center venous for determination of plasma calcitonin-gene-related peptide (CGRP) and endothelin-1 (ET-1) with radioimmunoassay at the time of post-anesthesia induction(T1), fifteenth minute after aorta crossclamping (T2) and fifteenth minute (T3),second hour (T4 ) and twenty-fourth hour (T5) after aorta unclamping, respectively. The ventricular arrhythmia was observed during the 7 days after surgery.Results The QTd and QTcd were increased significantly after operation in both groups ( P<0.01);The value of QTd and QTcd of diammonii glycyrrhizinatis preconditioning group was markedly lower than that of control group at the first and third day after operation (P<0.05). The value of plasma CGRP after aorta crossclamping and during the 24 hours after aorta unclamping was significantly higher than that of post-anesthesia induction in both groups (P <0.01) , and the value of diammonii glycyrrhizinatis preconditioning group was significantly higher than that of control group (P<0.05). The value of ET-1 decreased after aorta crossclamping in both groups (P<0.01),there is no significant difference between the value of T1 and T2 in two groups (P>0.05), then the value of ET-1 increased gradually during the 24 hours after aorta unclamping, and the value of T4 and T5 were higher than that of T1 in both groups(P<0.01) , the value of diammonii glycyrrhizinatis preconditioning group was lower than that of control group during the 24 hours after aorta unclamping (P<0.05) .The incidence of the ventricular arrhythmia during the 7 days after surgery showed no significant difference between the two groups (P >0.05).Conclusion Diammonii glycyrrhizinatis preconditioning can lighten the abnormality of the myocardiac repolarization after open heart surgery, playing a protective role in myocardium from ischemia-reperfusion injury, which is related to the elevation of plasma CGRP during the ischemia and reperfusion period and the depression of ET-1 during the reperfusion period, while there is no significant influence on the ventricular arrhythmia after surgery.