[Heparin resistance during cardiopulmonary bypass]

A 74-year-old man was scheduled for coronary artery bypass graft surgery with cardiopulmonary bypass. After intravenous heparin (200 U.kg-1), the activated clotting time (ACT) increased from 124 to 436 sec. However, it decreased to 128 sec immediately after cardiopulmonary bypass. The bypass was discontinued because the addition of heparin (200 U.kg-1) proved heparin resistance. The coronary artery bypass procedure was completed uneventfully without cardiopulmonary bypass. Several recent articles have reported that heparin resistance was corrected with antithrombin III concentrates, fresh frozen plasma, or argatroban. In this case, these drugs could not be used because the mechanism of heparin resistance remains uncertain. Thus, the off-pump technique is useful for unknown heparin resistance.