Massive atrial myxoma requiring emergency cardiopulmonary bypass in a patient with heparin resistance

Heparin exhibits complex pharmacology with a wide variation in individual response. Despite this, heparin is the most commonly used anticoagulant during cardiopulmonary bypass. Heparin resistance in the context of a patient with severe cardiovascular compromise presents a potentially life-threatening challenge. A 31-year-old woman was listed for emergency excision of a massive left atrial myxoma. On induction of anaesthesia, she developed marked cardiovascular instability secondary to mitral inflow obstruction. An initial heparin dose of 600 units.kg-1 produced an activated clotting time of 360 s; however, immediate cardiopulmonary bypass was required. Heparin resistance remained problematic throughout the procedure, with an inadequate response to antithrombin three supplementation. Despite a total dose of 120,000 units of heparin, anticoagulation was fully reversed with 500 mg protamine and there was no subsequent re-heparinisation. Heparin resistance, when coinciding with profound cardiovascular instability, requires a pragmatic response to expedite establishment of cardiopulmonary bypass whilst minimising potential harm. In this case, successful cardiopulmonary bypass was achieved with additional heparin boluses from an alternative batch administered both intravenously and via the bypass circuit. We therefore advocate consideration of this approach as one possible solution to achieving safe entry onto cardiopulmonary bypass in a crisis scenario.