Plasma dynorphin A1-13 levels were measured in 33 patients with mitral stenosis before and after percutaneous balloon mitral commissurotomy （PBMC）. The results show that the basal levels of plasma dynorphin in blood from the antecubital vein in the patients were significantly higher than those in 31 healthy control subjects. The increase in circulating dynorphin closely correlated with the functional cardiac status and the presence of atrial fibrillation. Ten to fifteen minutes after PBMC

plasma dynorphin levels in blood from the femoral vein increased significantly. Seventy-two hours after the procedure

the levels of plasma dynorphin in blood from the antecubital vein had decreased significantly

but they did not decrease to the normal range. Plasma dynorphin levels in blood from the femoral vein were positively correlated with the mean left atrial pressure and the mean right atrial pressure before the first balloon inflation. Plasma dynorphin levels in blood from the antecubital vein were positively correlated with the heart rate and the mean transmitral pressure gradient

and negatively with the mitral valve area before and 72 hours after PBMC.