Background: Congenital heart disease (CHD) and infancy are associated with functional abnormalities of the coagulation system, which are further disrupted by the need for cardiac surgery.   The impacts of cardiopulmonary bypass (CPB), deep hypothermic circulatory arrest (DHCA), and the type of CPB prime solution are fully elucidated. Most prior research has utilized traditional coagulation assays which have been shown to be inadequate in assessing coagulopathy.  Therefore, we sought to assess the impact of DHCA and the use of fresh frozen plasma (FFP) in the CPB prime solution on intraoperative coagulopathy in pediatric CHD patients as measured by rotational Thromboelastometry (ROTEM). 

Methods: We performed a single-center retrospective cohort study analyzing intraoperative ROTEM data collected during the rewarming phase of CPB.  We compared infants undergoing surgeries with and without DHCA from March 2019 to November 2021. We performed additional analyses following an institutional practice change from albumin- to FFP-based prime solution in patients age < 6 months during the same period. Patients were excluded for prematurity, diagnosis of coagulopathy or genetic syndrome associated with coagulopathy, previous surgery requiring CPB, or pre-operative systemic anticoagulation. Standard univariate analyses were performed to compare the intraoperative ROTEM data and clinical variables between groups. 

Results: During the study period, 109 patients met criteria, 85 age <1 month: 66 underwent surgeries using an albumin-based CPB prime solution (39 with DHCA vs. 27 without DHCA), 19 underwent surgeries using an FFP-based CPB prime solution (10 with DHCA vs. 9 without DHCA). In the albumin-prime era, there was a shorter intraoperative bleeding time from protamine administration to surgical dressing placement  in the DHCA group compared to the non-DHCA group (median 61 vs. 107 minutes, p<.0001), with an increase in coagulation factor usage in the non-DHCA group (40.7% vs. 12.8%, p=0.01). Addition of FFP to the CPB prime resulted in less clotting factor deficiencies, with decreased FibTEM clotting time (median 135 vs. 83 seconds, p=0.001) and ExTEM clotting time (median 109 vs. 91 seconds, p=0.001), and increased clot firmness as measured by FibTEM A10 (p=0.001) and ExTEM A10 (p=0.02) as well as FibTEM MCF (p=0.001) and ExTEM MCF (p=0.02). Differences with respect to the CPB prime solution were more profound in the DHCA group.  There was no difference in blood product usage between albumin- and FFP-prime groups. While not significant, less patients had an open sternum at end of surgery in the FFP-prime group (31.3% vs. 13.8%, p=0.07). 

Conclusion: Unlike prior studies in adults, we observed shorter bleeding time and decreased coagulation factor usage in patients undergoing complex congenital cardiac surgery requiring DHCA compared to those not requiring DHCA.  This is the opposite of expected but may reflect more aggressive and anticipatory treatment due to the presumption of increased postoperative bleeding with DHCA, which may explain the increase in exogenous coagulation factor usage in the non-DHCA group. Additionally, our findings indicate improved indices of clot formation and clot strength when using FFP-based CPB prime. This may reflect reduced dilutional effect or indeed preservation of coagulation factors during CPB due to anti-thrombin III replenishment. Although we did not observe a difference in blood product usage, our data supports development of blood management programs to improve clot formation and decrease donor blood product usage. Further prospective studies are required using viscoelastic-guided transfusion algorithms to assess the clinical impact of these results.