The nature and origin of hyperamylasemia following open-heart surgery with extracorporeal circulation.

The nature of the postoperative hyperamylasemia in 27 patients undergoing open-heart surgery was investigated. An increase in serum amylase activity was found in 56% of the patients. Isoamylase analysis revealed that the rise was in the salivary-type isoamylase in all of these patients. Since the level of serum amylase activity was increased in the postoperative state with prolongation of extracorporeal circulation, it is conceivable that cellular hypoxia due to inadequate tissue perfusion may cause disturbances in cellular metabolism with a release of intracellular amylase. The finding of the salivary-type amylase in normal lung tissue, transient salivary-type hyperamylasemia in acute respiratory distress and increased amylase activity of the salivary-type in serum specimens from the left atrium compared to those from the right ventricle suggest that the origin of the amylase responsible for the transient postoperative hyperamylasemia in the salivary-type is due to the amylase released from lung tissues under hypoxia during and after operation.