Concentrations of factor VIII-related antigen and factor XIII during open heart surgery.

Plasma levels of factor VIII-related antigen (fVIIIRA) and factor XIII S and A subunits (fXIIIS, fXIIIA) were assayed by counterimmunoelectrophoresis before, during, and after cardiopulmonary bypass (CPB) in patients with coronary artery and valvular heart disease to define the basis for clinical and laboratory abnormalities of hemostasis occurring in this form of surgery. During CPB, concentrations of fXIIIA dropped in both patient groups but returned to preoperative levels promptly after pump removal. In contrast, fVIIIRA and fXIIIS, which are not incorporated into the clot, remained unchanged even during fluid administration. These data provide evidence of a transient consumption coagulopathy as a feature of CPB. Hemodilution probably plays a secondary role in these changes.