
Background and Goal of Study: The detection of incomplete heparin reversal is an important part of coagulation management because it can lead to major bleeding. A protamine overdose itself can lead to a thrombocyte associated coagulation disorder. This study aimed to compare different parameters to detect
incomplete heparin reversal in infants undergoing congenital cardiac surgery that were managed with patient-specific heparin and protamine doses.
Materials and Methods:After approval by the local IRB a total of 36 children undergoing cardiac surgery (STS classes 1-5) between 02/2017 - 06/2017 were retrospectively enrolled. Besides the results of the HMS Plus system (Hepcon), pre- and postoperative values of aPTT and ACT and the ratios of the post- to preoperative (PPR) values were analyzed. The ratios of the time to clot initiation (TTC) of the intrinsic
pathway assays to heparinase based assays by the TEG®6s and the ROTEM® delta system were also calculated. Ratios above 1 were considered as a sign for incomplete heparin reversal.
Results and Discussion: The median age was 196days (39.5-573), the median bypass time was 93min (63-138). Median heparin dose was 455IE/kg (368-646) and median protamine dose was 428E/kg (311-599). 8 patients received a second protamine dose (median 450E/kg).
The heparin-protamine-titration assay (Hepcon) showed incomplete heparin reversal in none of the patients. The PPR for aPTT detected 28/36 (77.7%) and the PPR for ACT detected 10/23 (43.5%). The TTC (R-time ratio TEG®6s) detected 33/36 (92%) patients. There was no correlation between the TTC of TEG®6s and the ROTEM® delta (r=0.089, p=0.72), the PPR of the aPTT ratio (r=-0.04, p=0.81) or the PPR of the ACT ratio (r=0.26, p=0.21). In a subset of 18 patients the TTC (CK-time ratio ROTEM®) detected 7/18 (39.9%) whereas the TTC (R-time ratio TEG®6s) detected 17/18 (94.4%). In this subset the level of agreement between the TEG®6s andROTEM® based assays (complete reversal yes or no) revealed a phi coefficient of 0.193.
Conclusion:Our study shows that the studied tests, including the TEG®6s and the ROTEM® systems,are not interchangeable. The new TEG®6s system seems to be very “sensitive” in detecting incomplete heparin reversal. Further studies are warranted to analyze if this truly reflects incomplete heparin neutralization. Test results should always be correlated with clinical signs of bleeding prior to therapy.


06 / Different methods to detect incomplete heparin reversal are not interchangeable in children undergoing congenital cardiac surgery