Remplacement urgent d’une prothèse mitrale mécanique chez un patient anticoagulé ayant un phénotype érythrocytaire Bombay

Bombay red blood cell phenotype is an extremely rare blood type for which patients can receive only autologous or Bombay phenotype red blood cells. We report a case of urgent repeat sternotomy for replacement of a mechanical mitral prosthesis in a patient with Bombay phenotype anticoagulated with warfarin, to emphasize the transfusion challenges in such patients. A male of Indian descent presented to hospital with New York Heart Association IV symptoms. His medical history revealed previous mitral valve replacement with a mechanical prosthesis in 2005 and Bombay phenotype blood. Preoperative transthoracic echocardiography demonstrated thrombus obstruction of the mitral prosthesis despite anticoagulation with warfarin. Right ventricular systolic pressure was > 100 mmHg with 3+ tricuspid regurgitation. The patient's condition was temporized with diuretics, bronchodilators, and bi-level positive airway pressure ventilation while transfusion medicine and cardiac surgery were consulted for urgent surgery. The patient received vitamin K and prothrombin complex concentrate prior to repeat sternotomy and successful mitral prosthesis replacement. After cardiopulmonary bypass, heparinization was corrected with protamine and followed by a second dose of prothrombin complex concentrate and recombinant activated factor VIIa. Postoperatively, the patient received four units of packed red blood cells, two autologous units and two units of Bombay specific red blood cells. Right ventricular pressures stabilized at 40 mmHg following surgery. The patient recovered following several days of inotropic support with milrinone, diuretics, and bronchodilators. Patients with Bombay phenotype red blood cells present as type O, but they are unable to receive red blood cells from any phenotype other than Bombay phenotype. They are able to receive all other blood products, including fresh frozen plasma, cryoprecipitate, platelets, prothrombin complex concentrate, and recombinant activated factor VIIa. Coordination between Canadian Blood Services, transfusion medicine, surgery, and anesthesia is important in managing these patients.