Circulating anticoagulant to animal plasmas in a cardiac patient.

A circulating anticoagulant against bovine, equine, guinea pig, and sheep plasmas developed in a 15-year-old cardiac patient. He had been exposed to both bovine and porcine heparin over a period of 13 years, and had a porcine valve placed four years before the anticoagulant was noted. There was no anticoagulant activity detected against human, rat, or porcine plasma, and an equivocal reaction against rabbit plasma. There was no apparent clinical significance to the anticoagulant. It did, however, confuse the interpretation of coagulation factor assays based on animal substrate plasmas.