Cardiopulmonary bypass in a child with severe Factor XII deficiency

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.

Management of cardiopulmonary bypass in factor XII deficient patients without plasma infusion

“…7 Factor XII deficiency is exceedingly rare. Both, the method described by Shrimpton et al 1 and our method are possible solutions for safe CPB. Anti-Factor Xa based CPB can be done without FFP, but both strategies carry a risk of inadvertent under-dosing of heparin that increases with the duration of CPB.…”

“…The anti-Xa levels declined faster than the ACT after 60 minutes of CPB (Figure 1) and had the surgery not concluded at this time a bolus should have been given. Pre-operative FFP administration 1,4,8,9 improves ACT values, but the rise in Factor XII during CPB is transient, with a rapid return to baseline despite the half-life of 40-50 hours while ACT values remain therapeutic. 5 We think concurrently using ACT and the chromogenic anti-Xa assay to manage anticoagulation during CPB is an effective and safe method for the patient, if rapid turnaround times of 15-20 minutes are feasible in the institution.…”

“…Pre-operative FFP administration 1,4,8,9 improves ACT values, but the rise in Factor XII during CPB is transient, with a rapid return to baseline despite the half-life of 40–50 hours while ACT values remain therapeutic. 5…”

“…We read with interest the recent case report 1 on a child with factor XII deficiency undergoing cardiopulmonary bypass (CPB) with a preoperative dose of fresh-frozen plasma (FFP) to normalise their anticoagulation monitoring.…”

“…Our kaolin based ACT cartridges proved insensitive at baseline Factor XII deficiency. We were interested to see that the Celite based Haemochron LR cartridges used in addition by Shrimpton et al 1 proved more sensitive to the Factor XII deficiency and FFP replacement than the Kaolin based clotting cartridges. Kaolin has considerable more negative charge than Celite and is also unaffected by the presence of approtinin, but the mechanism causing this difference in prolongation of clotting time in factor XII deficiency is unknown.…”