Heparin sensitivity test for patients requiring cardiopulmonary bypass

Area of Science:

• Cardiovascular Surgery
• Anesthesiology
• Hematology

Background:

• Heparin is crucial for anticoagulation during cardiopulmonary bypass (CPB) in open heart surgery.
• Standard activated clotting time (ACT) monitoring may not detect heparin resistance in some patients.
• Heparin resistance can lead to delayed CPB initiation and inadequate anticoagulation, posing risks.

Purpose of the Study:

• To develop and validate a simple, reliable test to predict heparin resistance before CPB.
• To assess the efficacy of a novel anticoagulation sensitivity test (AST) in identifying patients with heparin resistance.
• To reduce delays in CPB initiation by enabling early detection of heparin resistance.

Main Methods:

• An anticoagulation sensitivity test (AST) was developed by adding heparin to the ACT tube.
• Blood samples were drawn pre-anticoagulation, and post-heparin administration (4 mg/kg) for ACT and AST measurements.
• Retrospective review of 300 procedures, analyzing ACT and AST times against target anticoagulation adequacy (≥480 seconds).

Main Results:

• Heparin resistance was observed in approximately 20% of patients (n=61).
• The AST accurately predicted heparin resistance in 54 patients, with a positive predictive value of 90% and a false positive rate of 3%.
• The AST identified patients with both low ACT-AST and ACT-CPB times (<480 seconds) as heparin resistant.

Conclusions:

• The developed AST is an inexpensive and reliable method for predicting heparin resistance in CPB patients.
• Early identification of heparin resistance via AST can prevent CPB delays and ensure adequate anticoagulation.
• This test allows for timely adjustments in heparin dosing or the use of antithrombin III derivatives, improving patient safety.