Abstract
Cold agglutinins are commonly found in the sera of healthy persons but rarely become clinically important because most agglutinins exert their greatest reactivity at low temperatures. This report describes a patient who successfully underwent aortic valve replacement in the presence of cold agglutinins; it discusses the management of patients with cold agglutinins who undergo open-heart surgery with core hypothermia. Changes in the cell membrane occur when cold circulating antibody combines with complement and antigen present on the surface of the red cell membrane, causing intravascular hemolysis. Two conditions are necessary for the reaction to occur to any appreciable extent: there must be a high enough titre of cold agglutinin and the reactive thermal range must be attained. To avoid these conditions, the core hypothermia should not reach the reactive thermal range or the titre should be reduced either by the standard hemodilution techniques for cardiopulmonary bypass or by plasmapheresis.