Evaluation of Heparin Rebound in Cardiac Surgery

This study will assess how much protamine is required to neutralize residual heparin perioperatively in cardiac surgery through measurement of functional assays of heparin (anti-Xa and anti-IIa levels). In the first phase of this study, protamine titration assays will be carried out on normal pooled plasma incubated with heparin in the laboratory.

Once the correct dose of protamine required to neutralize the heparin is established in the laboratory, the second phase will begin. Herein, plasma samples from patients undergoing cardiac surgery (with anticoagulation with two different commercial preparations of heparin) will be evaluated for residual heparin (Anti-Xa and anti-IIa levels). Protamine titration assays wil then be carried out in vitro to assess neutralization of heparin.

Inclusion criteria

• Age >18 years
• Written consent
• Scheduled for cardiac surgery under CPB (cardiopulmonary bypass)--(elective or emergency)
• 10 patients undergoing cardiac surgery where CPB time is anticipated to be short (isolated primary CABG (coronary artery bypass graft);isolated mitral-valve repair or aortic-valve replacement)
• 10 patients undergoing cardiac surgery where CPB time is anticipated to be longer (CABG + valve surgery combined; reoperations)

Exclusion criteria

• Known coagulopathies
• Liver dysfunction
• Patients receiving unfractionated or low molecular weight heparin thrombin inhibitors, warfarin, antiplatelets within the past 7 days
• Patients expected to undergo hypothermic CPB or circulatory arrest