Heparin anticoagulation during cardiopulmonary bypass in an antithrombin-III deficient patient. Implications relative to the etiology of heparin rebound.

A case of antithrombin-III (AT-III) deficiency was diagnosed on the basis of a diminished anticoagulant effect following the administration of heparin for cardiopulmonary bypass. The clinical evaluation and interpretation of a diminished response to heparin is discussed, as are considerations relative to the treatment of AT-III deficient persons whose disorder is not manifest until they are already anesthetized for cardiovascular bypass. The implications of AT-III deficiency relative to the mechanism of heparin rebound are also discussed.