RESUMEN
OBJECTIVE@#To determine the mechanism of protective effect of noninvasive limb ischemic preconditioning (NIPC) on myocardium of patients with rheumatic heart disease undergoing heart valve surgery under cardiopulmonary bypass (CPB).@*METHODS@#A total of 32 patients with rheumatic heart disease undergoing heart valve surgeries under CPB were randomly divided into 2 groups: a control group(n=16)and an NIPC group(n=16).Tourniguet was used for each patient in the NIPC group around both the upper extremities in turn, inflated for 8 min and deflated for 5 min for 3 cycles. After the anesthesia, the remaining procedures were the same as in the control group. Blood samples were collected from the central vein after the induction of anesthesia (T(1)), 5 min before aortic clamp (T(2)),30 min after aortic opening (T(3)), 6 h after the operation (T(4)), and 24 h after the operation (T(5)) to measure the concentration of cardiac troponin I and creatine kinase MB in the plasma and CGRP and ET-1 in the serum. Pathologic change of the right auricle of the heart tissue during the superior vena cave intubation and extubation was detected.@*RESULTS@#The content of cardiac troponin I and creatine kinase MB at T(4) and T(5) in the 2 groups was higher than that of other time points in the same group, and it reached the peak at T(5). Comparison of the content of cardiac troponin I and creatine kinase MB at T(4) and T(5) in the 2 groups showed significant difference, and that of the NIPC group was lower than the control group(P<0.05).CGRP and ET-1 contents reached the peak at T(2) in the NIPC group and at T(3) in the control group, but the peak of CGRP in the NIPC group was higher than that in the control group(P<0.01).The peak of ET-1 content in the NIPC group was lower than that in the control group(P<0.01). After the CPB, myocardial and mitochondrion impairment was lighter in the NIPC group than in the control group.@*CONCLUSION@#Noninvasive limb ischemic preconditioning can protect the myocardium through increasing CGRP, inhibiting ET-1, and advancing the peak of CGRP and ET-1.