Page 26 - ANZCP Gazette November 2021

r9esearch-artic9le2021 9305PRF0010.1177/0267659121999305PerfusionShrimpton et al.
Case Report
Reprinted with kind permission from the journal – PERFUSION
Cardiopulmonary bypass in a child with severe Factor XII deficiency
Nicole Shrimpton,1,2 Aditya Patukale,2,3,4 Mark Rane,5,6 Pasquale Barbaro,5,6 Nelson Alphonso2,3,4 and Prem Venugopal2,3,4
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.
Keywords
Factor XII; prolonged activated partial thromboplastin time; cardiopulmonary bypass; activated clotting time; paediatric
Introduction
Coagulation Factor XII (FXII) is produced and secreted by the liver.1 After activation by intimal injury, it con- tributes to the intrinsic coagulation cascade by activat- ing Factor XI (FXI). Deficiency of FXII is rare and is not associated with clinical bleeding due to the more domi- nant activation of FXI by thrombin during in-vivo coag- ulation.2 FXII deficiency may be diagnosed incidentally during pre-operative assessment as prolonged activated partial thromboplastin time (aPTT). Contact activation based in-vitro diagnostic coagulation tests including aPTT and activated clotting time (ACT) utilise an acti- vator reagent which initiates the contact pathway involv- ing FXII.1,3–5 The baseline prolongation of ACT due to FXII deficiency makes heparin monitoring using ACT unreliable in patients with FXII deficiency undergoing cardiopulmonary bypass (CPB).
This report describes our stepwise approach to the perioperative management of a child with FXII defi- ciency undergoing CPB.
Case history
An otherwise healthy 14.7kg 3-year-old girl presented for repair of sinus venous atrial septal defect with partial anom- alous pulmonary venous return. During pre-operative
workup, a prolonged aPTT of >200 seconds was discov- ered (ACL TOP series analyser, Hemosil APPT-SP reagent; Werfen Australia, NSW) which completely cor- rected to 34seconds on mixing with normal plasma (Figure 1). The patient’s prothrombin time (12 seconds), thrombin time (16 seconds) and fibrinogen level (2.2g/L) were normal. Further investigations revealed normal concentrations of coagulation factors VIII, IX, XI and von Willebrand factor; however, FXII concentra- tions were <1% (HemosIL Factor 12 deficient plasma, HemosIL APTT-SP reagent; Werfen Australia, NSW).
1Perfusion Department, Queensland Children’s Hospital, South Brisbane, QLD, Australia
2Queensland Paediatric Cardiac Research, Centre for Children’s Health Research, South Brisbane, QLD, Australia
3Department of Cardiothoracic Surgery, Queensland Children’s Hospital, South Brisbane, QLD, Australia
4
University of Queensland, Brisbane, QLD, Australia
5Queensland Paediatric Haematology Service, Queensland Children’s
Hospital, South Brisbane, QLD, Australia
6Queensland Children’s Hospital Laboratory, Pathology Queensland,
South Brisbane, QLD, Australia
Corresponding author:
Nicole Shrimpton, Perfusion Department, Queensland Children’s Hospital, 501 Stanley Street, South Brisbane, QLD 4101, Australia. Email: Nicole.Shrimpton@health.qld.gov.au
23 NOVEMBER 2021 | www.anzcp.org
School of Medicine, Children’s Health Queensland Clinical Unit,
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