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Despite advances in design and materials, as well as pharmacological prophylaxis, hemostatic complications continue to plague device recipients. Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. We examined blood samples from patients with heart failure or in receipt of high fluid shear mechanocirculatory support to assess whether loss of platelet receptors occurs in vivo , and the relationship with acquired von Willebrand syndrome (AVWS) and changes in inflammatory cytokines. Platelet counts, levels of inflammatory cytokines IL-1β, IL-6, TNFα, MCP-1, IL-17A and IFNγ, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 13 continuous flow VAD (CF-VAD), 14 ECMO, and 24 heart failure patients. Levels of platelet receptors were measured by flow cytometry or ELISA. The loss of high molecular weight VWF multimers was observed in 12 of 13 CF-VAD and 7 of 14 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Significant differences in levels of inflammatory cytokines monocyte-chemoattractant protein and tissue necrosis factor-a in a subset of patients with decompensated HF. These data link AVWS and increased platelet receptor shedding in patients with CFVADs or ECMO. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CFVAD and ECMO patients may be linked with extent of inflammation and may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions.

Essentials Relationship of acquired von Willebrand disease (VWD) and platelet dysfunction is explored. Patients with ventricular assist devices and on extracorporeal membrane oxygenation are investigated. Acquired VWD and platelet receptor shedding is demonstrated in the majority of patients. Loss of platelet adhesion receptors glycoprotein (GP) Ibα and GPVI may increase bleeding risk.Background Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. Objectives To investigate whether loss of platelet receptors occurs in vivo, and the relationship with acquired von Willebrand syndrome (AVWS). Methods Platelet counts, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 21 continuous flow VAD (CF-VAD), 20 ECMO, 12 heart failure and seven aortic stenosis patients. Levels of platelet receptors were measured by flow cytometry or ELISA. Results The loss of high molecular weight VWF multimers was observed in 18 of 19 CF-VAD and 14 of 20 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Conclusions These data link AVWS and increased platelet receptor shedding in patients with CF-VADs or ECMO for the first time. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CF-VAD and ECMO patients may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions.

Aim Red cell antigen phenotypes vary between different ethnic groups. The demographics of the Australian population have changed with waves of immigration. We examined whether this impacts observed patterns of red cell phenotypes and allo-antibodies. Methods We reviewed results on patient samples referred to our laboratory in two cohort periods: 1997 and 2012. Results For the 2 cohort years 1997 and 2012 we observed: (242, 537) antibodies identified in (148, 351) patient samples. Antibody frequencies: Rh (28%, 30%), K (7%, 4%), Fy (7%, 5%), Jk (6%, 4%), ≥2 alloantibodies (41%, 38%). Three patients were identified with the Jk(a-b-) phenotype in 1997 (2%), and six in 2012 (1.7%). For the Fy(a-b-) phenotype, in 1997 no patients were reported. In 2012 there were seven patients with this phenotype. Conclusion Comparing our 1997 and 2012 cohorts, we observed no major change in the pattern of the clinically significant red cell allo-antibodies. There was an increased number of patients with Fy(a-b-) phenotype. This likely reflects immigration from Africa over the last decade. Providing compatible blood for these patients can be challenging. We encourage blood donation from diverse ethnic groups, to enrich the range of red cell phenotypes available to patients.

A 75-year-old male was admitted for investigation of acute kidney injury. His medical history was significant for hypothyroidism and transfusion-dependent myelodysplastic syndrome. A bone marrow biopsy 1 month prior to admission had categorized him as having refractory anaemia with excess blasts (RAEB) Stage-II. His medications included thyroxine, cholecalciferol and the cytotoxic agent azacitadine. Over the preceding 6 months, he had noticed progressive lethargy, loss of weight and functional decline. Examination was unremarkable. Biochemistry demonstrated a serum creatinine level of 350 µmol/L, which had markedly worsened over 2 months. This was associated with 1.06 g/day proteinuria but no haematuria. Haematology showed normocytic anaemia (Hb 70 g/L), thrombocytopaenia (Plt 48 × 109/L) and marked leucocytosis (WCC 38.8 × 109/L). Dysplastic changes and occasional blasts were noted on the blood film (Figure 1). Serum protein electrophoresis, uric acid, autoimmune studies, hepatitis and HIV serology were unremarkable. Ultrasound demonstrated normal-sized kidneys of normal echogenicity and no evidence of obstruction. Fig. 1. May–Grunwald–Giemsa staining of the peripheral blood film shows pleomorphic population of blasts with an open chromatin and high nuclear:cytoplasmic ratio (thick arrows). Dysplastic neutrophils are also noted with abnormal segmentation ... A renal biopsy was performed, which showed renal cortex with heavy infiltration of atypical cells within the interstitium and lumina of small vessels. These cells had irregular nuclear membranes, prominent nucleoli and granular cytoplasm, and showed positive immunoperoxidase staining with myeloperoxidase, confirming the diagnosis of acute myeloid leukaemia (AML) with renal infiltration (Figures 2 and ​and33). Fig. 2. Highly cellular infiltration in the renal interstitium, atypical myeloid blasts with irregular nuclear membranes, prominent nucleoli and granular basophilic cytoplasm (H&E ×200). Fig. 3. Positive immunohistochemical staining for myeloperoxidase (MPO IHC ×100). A repeat bone marrow biopsy was subsequently performed which showed transformation into AML. The cause of the progressive kidney dysfunction was thus attributed to renal infiltration from AML. In view of the patient's poor prognosis and functional state, community-based palliative care was instituted. He passed away several weeks later. Malignant infiltration of the kidneys as a cause of renal failure has been well described [1–3]. The commonest causes are low-grade non-Hodgkin's lymphoma and acute lymphocytic leukaemia [4]. AKI due to diffuse kidney infiltration from AML has been reported in the setting of other precipitants [5]. Our case is unique, in that it demonstrates acute kidney injury resulting directly from malignant infiltration of renal parenchyma from AML. Conflict of interest statement. None declared.

Aim Ventricular assist devices (VADs) and extracorporeal membrane oxygenation devices (ECMO) are associated with bleeding, not fully explained by anticoagulant or anti-platelet therapy. Acquired von Willebrand syndrome (AVWS) may contribute to bleeding in patients with these devices. We investigated the relationship between AVWS and platelet dysfunction, through the loss of von Willebrand factor (VWF) receptor, GPIb (of the GPIb-IX-V complex) and the major collagen receptor, GPVI. GPIb and GPVI are crucial for platelet function at arterial shear rates and we have shown that metalloproteolytic shedding of GPVI is triggered on exposure of platelets to high shear (Al-Tamimi et al. Blood, 2012). Methods A pilot analysis was performed in 21 VADs patients (0.5-30 months post-implant) and 13 ECMO patients (1-9 days post-implant). All patients were in receipt of at least one anticoagulant and/or one anti-platelet therapy. Platelet counts, coagulation tests and VWF analyses including VWF multimers were performed. Levels of platelet surface and shed receptors were measured by flow cytometry-based assays or ELISA developed in-house. The in-house assays are unaffected by routine therapeutics used in these patients. Data were analysed by non-parametric Wilcoxon-Mann-Whitney test. The National Cancer Institute (NCI) bleeding score was used and VADs patients were grouped into major (NCI ≥3) or non-major (NCI Results We demonstrated loss of high molecular weight VWF multimers in most VADs patients (19 of 21) and 60% of the ECMO patients (6 of 10, VWF multimer analysis was not performed in 3 patients), consistent with AVWS. In VADs patients, platelet receptor shedding was demonstrated by significantly elevated plasma soluble GPVI levels (p=0.025), and reduction in surface GPVI (p=0.0003) and GPIb levels (p=0.0008) compared to healthy donors (Table 1). Similarly, ECMO patients demonstrated significantly elevated plasma soluble GPVI levels (p=0.0002), and reduction in surface GPVI (p=0.001) and GPIb levels (p=0.001) compared to healthy donors (Table 1). Five patients with VADs (24%) had major bleeding however platelet receptor levels were not analysed prior to the bleeding event. Table 1. Platelet receptor levels in VADs or ECMO patients: p values reflect comparison to healthy donor Test Parameters Healthy Donors; n=40Median (range) VADs; n=21Median (range) p value ECMO; n=13Median (range) p value Surface GPIb 823 (406-1764) 546 (230-1069) 0.0008 452 (11-1030) 0.001 Surface aIIb 224 (60-581) 206 (65-482) NS 236 (11-331) NS Surface GPVI 183 (11-474) 100 (42-292) 0.0003 99 (7-200) 0.001 Soluble GPVI 26 (3.2-50) 30.6 (23.4-66.2) 0.025 41 (21-77) 0.0002 Conclusion We linked AVWS for the first time with loss of platelet adhesion receptors in patients with VADs or ECMO. Loss of platelet surface receptors GPIb or GPVI may impact platelet adhesion/activation and limit thrombus formation under pathologic shear conditions. Further investigation will elucidate mechanisms of platelet receptor loss and assess whether temporal changes in platelet receptor levels are associated with bleeding outcomes in these patients. Disclosures No relevant conflicts of interest to declare.