Amy L. Dunn

Arthroscopic synovectomy for hemophilic joint disease in a pediatric population

Summary: Children with hemophilia can develop progressive arthropathy. Arthroscopic synovectomy has been used to reduce hemarthroses, but few long-term results have been published. In this article the authors review their first 12 years of experience. Data are reported on 44 pediatric patients (69 joints: 39 ankles, 21 elbows, 7 knees, 2 shoulders). The median age at surgery was 10 years Median follow-up was 79 months. Joints with sufficient follow-up data showed a median bleeding frequency decline of 84% (P < 0.001). Median arc of motion was stable or improved in the year after surgery in ankles, elbows, and shoulders. Complications were rare. Radiographic scores worsened slightly. In this largest analysis of arthroscopic synovectomy for children with hemophilia, rehabilitation was not problematic.

Leukemia and P32 radionuclide synovectomy for hemophilic arthropathy

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Pathophysiology, diagnosis and prevention of arthropathy in patients with haemophilia.

Summary.  Recurrent haemarthroses in patients with severe and moderate haemophilia can result in the development of one or more target joints and subsequent degenerative joint disease. This debilitating process is characterized by physical and physiological changes in articular cartilage, synovium and bone. Models of degenerative joint disease have been examined after the addition of whole blood or blood components to cell cultures or animal joints, or by monitoring biomarkers in individuals with and without haemophilia. Inhibition of cartilage‐based proteoglycan synthesis and induction of proliferative synovitis are commonly observed in these models of degenerative joint disease. Clinical evaluation of joint disease includes use of specially designed physical examination and radiographic tools. Efforts to prevent or limit arthropathy include the use of prophylactic factor infusion regimens, surgical joint intervention or both.

Crucial role for the VWF A1 domain in binding to type IV collagen

Von Willebrand factor (VWF) contains binding sites for platelets and for vascular collagens to facilitate clot formation at sites of injury. Although previous work has shown that VWF can bind type IV collagen (collagen 4), little characterization of this interaction has been performed. We examined the binding of VWF to collagen 4 in vitro and extended this characterization to a murine model of defective VWF-collagen 4 interactions. The interactions of VWF and collagen 4 were further studied using plasma samples from a large study of both healthy controls and subjects with different types of von Willebrand disease (VWD). Our results show that collagen 4 appears to bind VWF exclusively via the VWF A1 domain, and that specific sequence variations identified through VWF patient samples and through site-directed mutagenesis in the VWF A1 domain can decrease or abrogate this interaction. In addition, VWF-dependent platelet binding to collagen 4 under flow conditions requires an intact VWF A1 domain. We observed that decreased binding to collagen 4 was associated with select VWF A1 domain sequence variations in type 1 and type 2M VWD. This suggests an additional mechanism through which VWF variants may alter hemostasis.

Adenotonsillectomy in patients with desmopressin responsive mild bleeding disorders: a review of the literature

Summary.  Many patients with mild inherited bleeding disorders such as von Willebrand disease (VWD), mild haemophilia A (HA) and platelet function defects (PFD) undergo adenoidectomy and/or tonsillectomy (AT) procedures each year. Management of bleeding in these patients can be challenging, as little published data exist to guide haemostatic management during these relatively common procedures. Therefore, the literature was reviewed to identify AT procedures in patients with 1‐deamino‐8‐D‐argine vasopressin responsive mild bleeding disorders. The review revealed no randomized prospective trials of haemostatic management in this patient population. Case reports and small case series identified 144 patients who had AT procedures. Frequency of desmopressin and antifibrinolytic dosing varied widely. Fifteen percentage of patients experienced postoperative bleeding with nearly half being early (<24 h) bleeding and half being late (>24 h) bleeding. Hyponatraemia complicated the procedures in 47% of cases and six hyponatremic seizures were reported. Issues identified by this review that need to be addressed in future clinical trials include type and amount of fluid restriction when utilizing desmopressin, duration of antifibrinolytic therapy and duration and frequency of desmopressin dosing.

Current Issues in Prophylactic Therapy for Persons with Hemophilia

Factor VIII or IX replacement in a prophylactic manner is utilized for many patients with moderate to severe hemophilia A or B. Studies have shown it to be effective in reducing or preventing degenerative joint disease in many but not all patients. However, many unanswered questions still exist and optimization of this expensive treatment regimen is needed. This paper recounts the current products that are available for use and explores the literature regarding different treatment regimens. It explores age at initiation, dose, interval between infusions, joint health outcomes, barriers to compliance and age at discontinuation of prophylaxis. Individualized treatment is recommended. Collaborative efforts are needed to improve outcomes for all persons with hemophilia.

No increase in bleeding identified in type 1 VWD subjects with D1472H sequence variation

The diagnosis of von Willebrand disease (VWD) is complicated by issues with current laboratory testing, particularly the ristocetin cofactor activity assay (VWF:RCo). We have recently reported a sequence variation in the von Willebrand factor (VWF) A1 domain, p.D1472H (D1472H), associated with a decrease in the VWF:RCo/VWF antigen (VWF:Ag) ratio but not associated with bleeding in healthy control subjects. This report expands the previous study to include subjects with symptoms leading to the diagnosis of type 1 VWD. Type 1 VWD subjects with D1472H had a significant decrease in the VWF:RCo/VWF:Ag ratio compared with those without D1472H, similar to the findings in the healthy control population. No increase in bleeding score was observed, however, for VWD subjects with D1472H compared with those without D1472H. These results suggest that the presence of the D1472H sequence variation is not associated with a significant increase in bleeding symptoms, even in type 1 VWD subjects.

Characterization of the anti-factor VIII immunoglobulin profile in patients with hemophilia A by use of a fluorescence-based immunoassay

The development of neutralizing antibodies, referred to as inhibitors, against factor VIII is a major complication associated with FVIII infusion therapy for the treatment of hemophilia A (HA). Previous studies have shown that a subset of HA patients and a low percentage of healthy individuals harbor non‐neutralizing anti‐FVIII antibodies that do not elicit the clinical manifestations associated with inhibitor development.

Recombinant tissue plasminogen activator may reduce frequency of central venous access device infection in hemophilia patients undergoing immune tolerance therapy

Many patients with hemophilia, particularly those with inhibitory antibodies, utilize central venous access devices (CVADs) to facilitate frequent infusions. Infection of these devices is a common complication of factor replacement therapy. This communication reports our centers experience with CVAD infection in three patients with severe hemophilia A undergoing immune tolerance therapy (ITT) in whom intermittent infusions of recombinant tissue plasminogen activator (rTPA, Cathflo™ Activase®) were utilized. In this small experience, patients experienced a decreased frequency of gram‐positive infections when receiving routine rTPA treatments. Larger randomized trial should be performed in this patient population at high risk of CVAD infection. Pediatr Blood Cancer 2008;50:627–629.

Prevalence of malignancies among U.S. male patients with haemophilia: a review of the Haemophilia Surveillance System

Summary.  The prevalence of malignancies in US male patients with haemophilia, with or without concomitant viral infections, remains unknown. To estimate the prevalence of malignancy in US male patients with haemophilia. We investigated the prevalence of malignancies among male patients with haemophilia using data from a six‐state haemophilia surveillance project. Case patients with malignancies were identified using International Classification of Diseases, 9th Revision, Clinical Modification codes abstracted from hospital records and death certificates during the surveillance period. Cancer prevalence rates were calculated for each year during the surveillance and compared with age‐ and race‐specific prevalence rates among the U.S. male population obtained from the Surveillance, Epidemiology and End Results (SEER) Program. A total of 7 cases of leukaemia, 23 cases of lymphoma and 56 classifiable solid malignancies were identified among 3510 case patients during a total of 15 330 annual data abstraction collections. The rates of leukaemia, lymphoma and liver cancer among case patients were significantly higher than the rates among U.S. males as judged by prevalence ratios of 3.1 [95% confidence interval (CI) = 1.4–7.0] and 2.9 (95% CI = 1.8–4.6), respectively. In contrast, the prevalence ratio of prostate cancer was lower than expected at 0.49 (95% CI = 0.31–0.77). Overall the prevalence of most cancers among case patients was similar to that of the U.S. male population. However, patients with haemophilia who have unexplained symptoms should be evaluated for malignancy.