Related Experiment Video
Updated: Nov 15, 2025
Author Spotlight: Simulating Pediatric Cardiac Surgery Using a Neonatal Piglet Model
Published on: May 26, 2023
Cardiopulmonary bypass in a child with severe Factor XII deficiency
Nicole Shrimpton1,2, Aditya Patukale2,3,4, Mark Rane5,6
1Perfusion Department, Queensland Children's Hospital, South Brisbane, QLD, Australia.
Insights
Factor XII deficiency prolongs activated partial thromboplastin time but does not cause bleeding. Replenishing Factor XII in a child undergoing cardiopulmonary bypass enabled safe monitoring of heparin anticoagulation.
Area of Science:
- Hematology
- Coagulation Science
Background:
- Factor XII (FXII) deficiency is characterized by prolonged activated partial thromboplastin time (aPTT) without significant bleeding risk.
- Activated clotting time (ACT) is crucial for monitoring unfractionated heparin anticoagulation during cardiopulmonary bypass (CPB).
- Standard ACT reagents rely on contact activation pathways, which are FXII-dependent.
Observation:
- A pediatric patient with severe FXII deficiency (<1%) and markedly prolonged aPTT (>200 seconds) required CPB.
- The patient's FXII levels were insufficient for standard ACT testing during CPB.
Findings:
- Fresh-frozen plasma transfusion successfully replenished FXII levels in the patient.
- Restored FXII concentrations enabled reliable ACT monitoring of heparin anticoagulation throughout the CPB procedure.
Implications:
- This case highlights the critical role of FXII in ACT assay performance during CPB.
- Management strategies involving FXII replacement may be necessary for patients with FXII deficiency undergoing procedures requiring anticoagulation monitoring.
- Ensures patient safety during complex cardiac surgeries requiring extracorporeal circulation.
Abstract:
Factor XII (FXII) deficiency presents as a prolonged activated partial thromboplastin time (aPTT) but is not associated with clinically significant bleeding. Activated clotting time (ACT) is used routinely to monitor anticoagulation with unfractionated heparin in patients undergoing cardiopulmonary bypass (CPB). The coagulation activator reagents in most ACT tests are dependent on adequate FXII concentrations to initiate contact factor coagulation pathways. We report the case of a 14.7 kg girl undergoing CPB with a pre-admission FXII concentration of <1% and aPTT >200 seconds. The child was transfused with fresh-frozen plasma to replenish FXII, allowing safe ACT monitoring of heparin anticoagulation throughout CPB.
