Acquired von Willebrand Syndrome in Pediatric Patients during Mechanical Circulatory Support

Objective: Bleeding symptoms can become life-threatening complications in children on mechanical circulatory support (MCS). Clinical phenotyping and comprehensive analyses of the bleeding cause are therefore essential, especially when risk-stratifying patients during MCS work-up. We conducted coagulation analyses and determined von Willebrand factor (VWF) parameters in a pediatric cohort undergoing temporary extracorporeal life support (ECLS) or extracorporeal membrane oxygenation (ECMO) or long-term ventricular assist device (VAD) support.

Methods: We carried out a prospective, observational single-center study including 30 children, median age 5.6 months (range: 3 days–18 years) with MCS (ECLS n = 13, ECMO n = 5, and VAD n = 12). We assessed each study participant’s acquired von Willebrand parameters: collagen-binding capacity (VWF:CB), ratio of collagen-binding capacity to VWF-antigen (VWF:CB/VWF:Ag), and high-molecular-weight (HMW) VWF multimers. Furthermore, we documented bleeding events, transfusion requirement, hemolysis parameters, and surgical interventions.

Results: All children developed acquired von Willebrand syndrome (AVWS) during MCS, usually during the early postoperative course. They presented no AVWS before MCS or after device explantation. We detected a loss of HMW VWF multimers, decreased VWF:CB/VWF:Ag ratios (median 0.26 U/mL during ECLS/ECMO and median 0.44 U/mL during VAD) and reduced VWF:CB levels (median 0.45 U/mL during ECLS/ECMO and median 0.8 U/mL during VAD). Interestingly, children on ECLS/ECMO tended to present lower VWF:CB levels and VWF:CB/VWF:Ag ratios during MCS than the VAD patients. Of the 30 patients, 20 suffered from bleeding complications; about 53% of them required surgical revision. None succumbed to bleeding during support. Discharge home rate was 50% in ECLS/ECMO group and 67% in VAD group.

Conclusion: The AVWS prevalence in pediatric patients on MCS is 100% regardless of device type. The bleeding propensity of AVWS patients varies widely. In those on ECLS and ECMO, the extent of AVWS appears amplified.