Practical approach to anticoagulation for cardiopulmonary bypass in the patient with congenital prolonged activated partial thromboplastin time

Patients with rare, congenital deficiencies of contact proteins (e.g., factor XII, prekallikrein, high-molecular-weight kininogen) present an important challenge with regard to safe anticoagulation during cardiopulmonary bypass. Specifically, activated coagulation time values are obtained with devices that utilize contact protein activators to generate thrombin and assess the efficacy of heparin-mediated antithrombin activation, with an activated coagulation time value of 480 s considered 'safe'. Patients with contact protein deficiencies will routinely have activated coagulation time values that exceed normal baseline values to an unpredictable extent, which, when coupled with heparin administration may well exceed 480 s but still potentially not reflect adequate antithrombin activation. We present the successful management of anticoagulation of a patient with either a prekallikrein or kininogen deficiency during cardiopulmonary bypass for coronary artery bypass graft surgery with Hepcon-based heparin concentration determinations. This approach, and the other alternatives previously mentioned, can be utilized to safely care for these rare patients in the setting of cardiac surgery.