Acquired von Willebrand syndrome in paediatric patients with congenital heart disease: challenges in the diagnosis and management of this rare condition

Acquired von Willebrand syndrome (AVWS) type 2, characterized by decreased high molecular weight multimers, is common in children with severe pulmonary hypertension (PH)

BACKGROUND AND OBJECTIVES

Emerging evidence suggests that increased degradation of von Willebrand factor and decrease in high molecular weight multimers occurs in patients with pulmonary hypertension (PH). However, the link between acquired von Willebrand Syndrome (AVWS) type 2 and PH remains poorly understood.

MATERIAL AND METHODS

We retrospectively evaluated the charts of 20 children with PH who underwent bilateral lung transplantation (LuTx) between 2013 and 2022. Von Willebrand variables were determined in 14 of these patients; 11 patients had complete diagnostics including multimer analysis.

RESULTS

We confirmed AVWS in 82% of the children studied (9 of 11 patients by multimer analysis). The two remaining patients had suspected AVWS type 2 because of a VWF:Ac/VWF:Ag ratio of <0.7. Platelet dysfunction or suspicion of VWD type 1 were found in two separate patients. All but one of the 14 children with severe PH had a coagulation disorder. Most patients (9 proven, 2 suspected) had AVWS type 2. Notably, 3 of 5 patients (60%) with normal VWF:Ac/VWF:Ag ratio >0.7 had abnormal VWF multimers, indicating AVWS type 2. Hemostatic complications were observed in 4 of 12 (33%) patients with VWS and 3 of 6 (50%) patients without diagnostics and therapy.

CONCLUSION

For children with moderate to severe PH, we recommend systematic analysis of von Willebrand variables, including multimer analysis, PFA-100 and platelet function testing. Awareness of the diagnosis "AVWS" and adequate therapy may help to prevent these patients from bleeding complications in case of surgical interventions or trauma.

Acquired von Willebrand syndrome is common in infants with systemic-to-pulmonary shunts: Retrospective case-series

BACKGROUND

Although acquired von Willebrand syndrome (aVWS) has been described in congenital heart disease before, anatomical features leading to aVWS with characteristic reduction or loss of high molecular weight von Willebrand multimers (HMWM) are not well known. This study assesses the prevalence and effects of aVWS in infants with systemic-to-pulmonary shunts (SPS).

METHODS

This retrospective single-center study analyzes diagnostic data of infants with complex congenital heart defects requiring palliation with SPS. During the study period between 12/15-01/17 fifteen consecutive patients were eligible for analysis. Results of von Willebrand factor antigen (VWF:Ag), collagen binding activity (VWF:CB) and von Willebrand factor multimer analysis were included.

RESULTS

In all 15 patients with SPS an aVWS could be found. Blood samples were collected between 5 and 257 days after shunt implantation (median 64 days). None of the patients demonstrated increased bleeding in everyday life. However, 6 out of 15 patients (40%) showed postoperative bleeding complications after SPS implantation. Following shunt excision multimeric pattern normalized in 8 of 10 (80%) patients studied.

CONCLUSIONS

This study shows that in patients undergoing SPS implantation aVWS might emerge. Pathogenesis can be explained by shear stress resulting from turbulent flow within the shunt. Knowledge of aVWS existence is important for the consideration of replacement therapy with von Willebrand factor containing products and antifibrinolytic treatment in bleeding situations. Implementation of methods for rapid aVWS detection is required to achieve differentiated hemostatic therapy and reduce the risk of complications caused by empiric replacement therapy.

Role of acquired von Willebrand syndrome in the development of bleeding complications in patients treated with Impella RP devices

Axial flow pumps are standard treatment in cases of cardiogenic shock and high-risk interventions in cardiology and cardiac surgery, although the optimal anticoagulation strategy remains unclear. We evaluated whether laboratory findings could predict bleeding complications and acquired von Willebrand syndrome (avWS) among patients who were treated using axial flow pumps. We retrospectively evaluated 60 consecutive patients who received Impella devices (Impella RP: n = 20, Impella CP/5.0: n = 40; Abiomed Inc., Danvers, USA) between January 2019 and December 2020. Thirty-two patients (53.3%) experienced major or fatal bleeding complications (Bleeding Academic Research Consortium score of > 3) despite intravenous heparin being used to maintain normal activated partial thromboplastin times (40–50 s). Extensive testing was performed for 28 patients with bleeding complications (87.5%). Relative to patients with left ventricular support, patients with right ventricular support were less likely to develop avWS (87.5% vs. 58.8%, p = 0.035). Bleeding was significantly associated with avWS (odds ratio [OR]: 20.8, 95% confidence interval [CI]: 3.3–128.5; p = 0.001) and treatment duration (OR: 1.3, 95% CI 1.09–1.55; p = 0.003). Patients with avWS had longer Impella treatment than patients without avWS (2 days [1–4.7 days] vs. 7.3 days [3.2–13.0 days]). Bleeding complications during Impella support were associated with avWS in our cohort, while aPTT monitoring was not sufficient to prevent bleeding complications. A more targeted anticoagulation monitoring might be needed for patients who receive Impella devices.

Management of a Pediatric Patient With a Left Ventricular Assist Device and Symptomatic Acquired von Willebrand Syndrome Presenting for Orthotopic Heart Transplant

We present the successful perioperative management of an 11-year-old patient presenting for heart transplant with a left ventricular assist device, symptomatic acquired von Willebrand syndrome, and recent preoperative intracranial hemorrhage. A brief review of the pathophysiology of acquired von Willebrand syndrome is included. As the number of pediatric patients supported with ventricular assist devices continues to increase, the management of symptomatic acquired von Willebrand syndrome during the perioperative period is an important consideration for anesthesiologists.

Idiopathic pulmonary arterial hypertension - a unrecognized cause of high-shear high-flow haemostatic defects (otherwise referred to as acquired von Willebrand syndrome) in children

Acquired von Willebrand syndrome (AVWS) is reported in high-flow high-shear congenital cardiac disorders. We hypothesized that the narrowed pulmonary vasculature in idiopathic pulmonary arterial hypertension (IPAH) may induce AVWS. We conducted a cross-sectional evaluation of children with IPAH. Patients with bleeding symptoms and/or laboratory abnormalities (thrombocytopenia, anomalies in coagulation screening tests) were tested in-depth for haemostatic defects. Fourteen children were followed with IPAH of which 8 were eligible. Four children exhibited abnormal bleeding scores (International Society on Thrombosis and Haemostasis Bleeding Assessment Tool: 3-5). All 8 patients showed very prolonged platelet function analyser (PFA)-100 closure times. Six children demonstrated either mild thrombocytopenia or low-normal von Willebrand factor (VWF) antigen (VWF:Ag) or VWF activity [mean (range), in iu/dl: VWF:Ag: 70 (61-91); VWF activity: 57 (34-70)]. Average VWF collagen binding capacity (VWF:CB) was 64 iu/dl (range: 53-123 iu/dl), with low-normal VWF activity/VWF:Ag or VWF:CB/VWF:Ag ratios occurring in five patients. All children had normal multimers distribution patterns. One patient underwent a lung transplantation, with normalization of haemostatic abnormalities post-surgery. Overall, 8 out of 14 children with IPAH had mild to moderate bleeding symptoms and/or laboratory abnormalities in keeping with AVWS. Normalization of the haemostatic defects following lung transplantation and lack of family history of bleeding attests to the acquired nature of their defects.

Acquired von Willebrand Syndrome in an Infant With Coarctation of the Aorta and Williams Syndrome

An infant with coarctation of the aorta and Williams syndrome was noted to have petechiae in cardiology clinic prior to planned surgical intervention. Workup revealed acquired von Willebrand syndrome secondary to the high shear force generated by the aortic coarctation. He was treated with intra- and postoperative Humate P; there were no postoperative bleeding complications. His acquired von Willebrand syndrome resolved postoperatively.

Acquired von Willebrand Syndrome: An Under-Recognized Cause of Major Bleeding in the Cardiac Intensive Care Unit

BACKGROUND

Acquired von Willebrand syndrome (AvWS) in the setting of congenital heart disease is an under-recognized cause of bleeding in the pediatric cardiac critical care unit.

METHODS

Fourteen patients diagnosed with AvWS admitted to the cardiac intensive care unit at the Children's National Health System between December 2009 and September 2015 were identified with subsequent chart review and case analysis.

RESULTS

Of the 14 patients included in this study, 4 patients were on ventricular-assist devices, 6 patients were on extracorporeal membrane oxygenation, and 4 were patients with congenital heart disease not receiving any mechanical circulatory support. All patients identified manifested persistent severe bleeding, despite appropriate management of anticoagulation and blood product administration based on the established protocols. Detailed hemostatic testing including quantitative von Willebrand factor (vWF) multimer analysis revealed decreased high-molecular-weight multimers (HMWMs) and absent ultra-HMWM, consistent with AvWS in all patients. Eight patients received treatment with vWF concentrate, one patient with desmopressin, and five recovered without specific treatment. Bleeding ceased in all but one patient.

CONCLUSIONS

Acquired von Willebrand syndrome is an uncommon but important cause of bleeding in pediatric patients with cardiac disease. A high index of clinical suspicion with knowledge of the characteristic clinical scenario in addition to low levels of vWF multimers is required to manage and diagnose AvWS. Although the optimal management of AvWS in this patient population is unclear, vWF concentrates are available and appear to be efficacious for controlling life-threatening bleeding.

Pediatric Acquired von Willebrand Syndrome in Cardiopulmonary Disorders: Do Laboratory Abnormalities Predict Bleeding Risk?

There are conflicting reports on whether or not laboratory abnormalities in pediatric acquired von Willebrand syndrome (AVWS) predict bleeding manifestations in patients with cardiopulmonary disorders (CPD). We retrospectively reviewed charts of patients with AVWS and CPD (n=16) seen at Texas Children's Hospital from 2003 to 2012. The most common CPD were valve stenoses, ventricular septal defects, and pulmonary hypertension. All patients had loss of high molecular weight multimers. Fifteen (94%) patients presented with bleeding symptoms, with menorrhagia and epistaxis being the most common. Von Willebrand ristocetin cofactor activity (VWF:RCo), as well as the use of anticoagulant or antiplatelet medication, did not predict bleeding manifestations (P=0.70 and 0.84, respectively). VWF:RCo/VWF antigen (Ag) ratio of <0.7 was significantly associated with presence of bleeding symptoms. All patients who had complete repair of their cardiac defect experienced normalization of VWF multimers and VWF:RCo/Ag ratio, as well as bleeding symptom resolution. We conclude that increased bleeding risk is associated with low VWF:RCo/Ag ratio in pediatric AVWS due to CPD. However, other laboratory abnormalities such as VWF:RCo level and qualitative multimer analysis, do not appear to predict bleeding. Future studies exploring quantification of multimer loss may be helpful in further assessing bleeding risk associations.

[Haemostatic disorders in children]

Haemorrhagic and thrombotic events occur in both children and adults. The underlying causes are congenital or acquired disorders. In contrast to haemorrhagic disorders, inherited thrombotic disorders nearly exclusively in association with additional external risk factors lead to thrombotic events predominantly during the newborn period and adolescence. It is necessary to be aware of age-specific properties of coagulation in order to correctly interpret clinical and laboratory findings and to provide optimal care for children with haemorrhagic and thrombotic complications.