High-dose Heparin Research Articles

Lupus anticoagulant and valvular cardiac surgery.

Despite its name, lupus anticoagulant (LAC) neither exclusively occurs in lupus nor induces anticoagulation. It is an antiphospholipid antibody found in 2%-4% of the population that promotes clot formation by targeting phospholipid-protein complexes in cell membranes. However, in vitro, LAC exhibits paradoxical effects, prolonging clotting times in phospholipid-dependent assays such as Activated Partial Thromboplastin Time (APTT). This unpredictability extends to point-of-care tests like Activated Clotting Time (ACT), which are frequently used to monitor anticoagulation during cardiac surgeries involving cardiopulmonary bypass (CPB). High doses of unfractionated heparin (UFH) are administered in these procedures, but the presence of LAC complicates ACT measurements, creating challenges for both anesthesiologists and surgeons. This case report highlights the clinical implications of LAC in perioperative management, underscoring the difficulties in ensuring adequate anticoagulation during CPB.

Intraoperative Bleeding Model for Swine Gastric Endoscopic Submucosal Dissection Via Heparinization

Background: Living swine has a high degree of coagulation and aggregation, and training for managing intraoperative bleeding during endoscopic submucosal dissection (ESD) is unsatisfactory. This study aimed to identify the appropriate heparin dose in an intraoperative bleeding model and validate its applicability. Methods: First, we explored the dose of heparin required for a swine bleeding model in which the activated clotting time reached and maintained the upper limit of measurement (1500 s) after 10 min. Second, we compared intraoperative bleeding and hematoma frequency during ESD for 2 cm lesions between the heparinized bleeding model and control groups. Intraoperative bleeding was classified according to the Forrest classification. Results: The combination of a bolus (300 U/kg), continuous infusion (300 U/kg/h), and a bolus dose (150 U/kg) of heparin 10 min after the first infusion was identified as the dose of the bleeding model. Five ESDs were performed in each heparinized bleeding model and the control group. The median number of intraoperative bleeding was significantly higher in the heparinized model than in the control group (5 [interquartile range {IQR}, 4–7] vs. 3 [IQR, 0–4], p = 0.028). All intraoperative bleeding events were not spurting (Forrest Ia) but oozing (Forrest Ib). The median number of hematomas was significantly higher in the heparinized model group than in the control group (3 [IQR, 1–4] vs. 0 [IQR, 0–1], p = 0.023). Conclusion: High doses of heparin significantly increased intraoperative bleeding and hematoma during swine ESD.

Bivalirudin versus heparin in patients with or without bail-out GPI use: a pre-specified subgroup analysis from the BRIGHT-4 trial

BackgroundConflicting results comparing bivalirudin versus heparin anticoagulation in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), in part due to the confounding effect of glycoprotein IIb/IIIa inhibitors (GPI). The aim of the study was to compare the safety and effectiveness of bivalirudin plus a post-PCI high-dose infusion vs heparin with or without bail-out GPI use.MethodsWe conducted a pre-specified subgroup analysis from the BRIGHT-4 trial that randomized 6016 STEMI patients who underwent primary PCI to receive either bivalirudin plus a post-PCI high-dose infusion for 2–4 h or heparin monotherapy. GPI use was only reserved as bail-out therapy for procedural thrombotic complications. The primary outcome was a composite of all-cause death or Bleeding Academic Research Consortium (BARC) types 3–5 bleeding at 30 days.ResultsA total of 5250 (87.4%) patients received treatment without GPI while 758 (12.6%) received bail-out GPI. Bail-out GPI use was associated with an increased risk of the primary outcome compared to non-GPI use (5.28% vs. 3.41%; adjusted hazard ratio (aHR), 1.62; 95% confidence interval (CI), 1.13–2.33; P = 0.009) and all-cause death (5.01% vs. 3.12%; aHR, 1.74; 95% CI, 1.20–2.52; P = 0.004) but not in the risk of BARC types 3–5 bleeding (0.53% vs. 0.48%; aHR, 0.90; 95% CI, 0.31–2.66; P = 0.85). Among patients without GPI use, bivalirudin was associated with lower rates of the primary outcome (2.63% vs. 4.21%; aHR, 0.55; 95% CI, 0.39–0.77; P = 0.0005), all-cause death (2.52% vs. 3.74%; aHR, 0.58; 95% CI, 0.41–0.83; P = 0.003), and BARC types 3–5 bleeding (0.15% vs. 0.81%; aHR, 0.19; 95% CI, 0.06–0.57; P = 0.003) compared with heparin. However, among patients requiring bail-out GPI, there were no significant differences observed in the rates of the primary outcome (5.76% vs. 4.87%; aHR, 0.77; 95% CI, 0.36–1.66; P = 0.50; Pinteraction = 0.07) or its individual components between bivalirudin and heparin groups.ConclusionsBivalirudin plus a post-PCI high-dose infusion was associated with significantly reduced 30-day composite rate of all-cause death or BARC types 3–5 bleeding compared with heparin monotherapy in STEMI patients undergoing primary PCI without GPI use. However, these benefits might be less pronounced in patients requiring bail-out GPI due to thrombotic complications during primary PCI.Trial registrationClinicalTrials.gov NCT03822975.

Antithrombotic efficacy and bleeding risks of vaccine-induced immune thrombotic thrombocytopenia treatments

AbstractCurrent guidelines for treating vaccine-induced immune thrombotic thrombocytopenia (VITT) recommend nonheparin anticoagulants and IV immunoglobulin (IVIg). However, the efficacy of these treatments remains uncertain due to case studies involving small patient numbers, confounding factors (eg, concurrent treatments), and a lack of animal studies. A recent study proposed danaparoid and heparin as potential VITT therapies because of their ability to disrupt VITT IgG-platelet factor 4 (PF4) binding. Here, we examined the effects of various anticoagulants (including unfractionated [UF] heparin, danaparoid, bivalirudin, fondaparinux, and argatroban), IVIg, and the FcγRIIa receptor-blocking antibody, IV.3. Our investigation focused on VITT IgG-PF4 binding, platelet activation, thrombocytopenia, and thrombosis. Danaparoid, at therapeutic doses, was the sole anticoagulant that reduced VITT IgG-PF4 binding, verified by affinity-purified anti-PF4 VITT IgG. Although danaparoid and high-dose UF heparin (10 U/mL) inhibited platelet activation, none of the anticoagulants significantly affected thrombocytopenia in our VITT animal model and all prolonged bleeding time. IVIg and all anticoagulants except UF heparin protected the VITT mice from thrombosis. Direct FcγRIIa receptor inhibition with IV.3 antibody is an effective approach for managing both thrombosis and thrombocytopenia in the VITT mouse model. Our results underscore the necessity of animal model investigations to inform and better guide clinicians on treatment choices. This study provides compelling evidence for the development of FcγRIIa receptor blockers to prevent thrombosis in VITT and other FcγRIIa-related inflammatory disorders.

Clinical Significance of Hyperhomocysteinemia in Free Flap Failure: A Case Report

AbstractFailure of a microvascular free flap remains rare, yet multiple failures can occur, particularly in the presence of hypercoagulable conditions. This case series highlights our experience with a rare hypercoagulable state: hyperhomocysteinemia.We present two cases of patients with hyperhomocysteinemia in this report. High-dose heparinization was administered to both patients, resulting in successful salvage of one flap and failure of the other. Notably, one patient had a history of prior free flap failures. However, after correcting hyperhomocysteinemia, subsequent free flaps were successful.In cases of detected complications, a coagulability study is warranted, and adjustments to anticoagulation treatment may be necessary. Furthermore, when a history of flap failures is evident, screening for hyperhomocysteinemia may be warranted, with correction made prior to reconstruction.

COMPARISON BETWEEN DIFFERENT TRANSRADIAL ARTERY HEMOSTASIS PROTOCOLS IN LIGURIAN CARDIOLOGIES

Abstract Background Transradial artery access (TRA) for coronary angiography and percutaneous coronary intervention is associated with lower bleeding and vascular complications than transfemoral artery access. In our hospital, TRA is widely used and hemostasis is usually achieved using TRBand device. We used to remove the device in about 10 hours according to our protocol. Aims The aim of this study is to describe and compare different TRA hemostasis protocols in order to understand if a shorter protocol could be more effective. Methods This is an observational study performed in all Hospitals of our region (Liguria). All Cardiology Departments were included in this analysis. We requested to all to self–refer: a) which radial hemostasis device was used; b) which deflation protocol (DP) was used. c) If they usually report and analyze adverse events. Adverse events are described as: bleeding, hematoma, ecchymosis, skin damage, local infection, pseudoaneurysm, or artery occlusion. RESULTS In Liguria there are 9 Cardiology Departments with Cath Lab (CL); 8 of them accepted to participate. All the Cath Labs use the TRBAND device but the deflation protocols are very different. 5 Cath Labs follows the DP suggested by the manufacturer. Only 2 CL adopted different DP if and higher dose of heparin was administered. Only one report bleedings or any delete in the DP. None analyze periodically the incidence of adverse events. Conclusions There are different methods to achieve radial hemostasis furthermore with the same device different deflating protocols are used. Further studies are necessary to evaluate the best DP. Regular audits must be strongly suggested in all Cardiology Departments in order to monitorate and improve the adverse events.

Comparison of minimal invasive extracorporeal circulation versus standard cardiopulmonary bypass systems on coronary artery bypass surgery.

In this study, we shared our experience with the minimal invasive extracorporeal circulation system for coronary artery bypass grafting patients. A total of 163 patients were included in the retrospective study, with 83 patients (63 males, 20 females; mean age: 61.9±8.9 years; range, 35 to 81 years) undergoing coronary artery bypass grafting with minimal invasive extracorporeal circulation and 80 patients (65 males, 15 females; mean age: 60.5±8.8 years; range, 43 to 82 years) undergoing coronary artery bypass grafting with conventional cardiopulmonary bypass between July 2021 and April 2023. Elective coronary bypass performed by same surgical team were included in the study. Mortality, major adverse cardiac and cerebrovascular event, hospital stays and transfusion requirements were evaluated. There were no significant differences in sex distribution, age, comorbidities, and blood values between the two groups. Intraoperatively, the minimal invasive extracorporeal circulation group had a slightly higher number of distal anastomoses and comparable times for aortic cross-clamp and cardiopulmonary bypass. Postoperative outcomes such as tamponade, bleeding, atrial fibrillation, left ventricular ejection fraction improvement or reduction, and postoperative drainage were similar between the two groups. However, the minimal invasive extracorporeal circulation group had fewer transfusions of packed red blood cells and fresh frozen plasma and a shorter length of stay in the intensive care unit. The minimal invasive extracorporeal circulation system effectively preserves blood, works with lower activated clotting time values without additional complications in coronary artery bypass grafting, and could present a better option for patients with anemia or patients with a relatively high risk for high-dose heparinization.

Evidence-Based Approaches to Anticoagulation in Reconstructive Microsurgery-A Systematic Literature Review.

This systematic review addresses the crucial role of anticoagulation in microsurgical procedures, focusing on free flap reconstruction and replantation surgeries. The objective was to balance the prevention of thrombotic complications commonly leading to flap failure, with the risk of increased bleeding complications associated with anticoagulant use. A meticulous PubMed literature search following Evidence-Based-Practice principles yielded 79 relevant articles, including both clinical and animal studies. The full-texts were carefully reviewed and evaluated by the modified Coleman methodology score. Clinical studies revealed diverse perioperative regimens, primarily based on aspirin, heparin, and dextran. Meta-analyses demonstrated similar flap loss rates with heparin or aspirin. High doses of dalteparin or heparin, however, correlated with higher flap loss rates than low dose administration. Use of dextran is not recommended due to severe systemic complications. In animal studies, systemic heparin administration showed predominantly favorable results, while topical application and intraluminal irrigation consistently exhibited significant benefits in flap survival. The insights from this conducted systematic review serve as a foundational pillar towards the establishment of evidence-based guidelines for anticoagulation in microsurgery. An average Coleman score of 55 (maximum 103), indicating low overall study quality, however, emphasizes the need for large multi-institutional, randomized-clinical trials as the next vital step.

Anti-PF4/Heparin Monoclonal Antibodies Induce Thrombus Formation in an Ex Vivo Endothelialized Microfluidic System

Introduction: Heparin-induced thrombocytopenia (HIT) is a serious adverse reaction to heparin. Antibodies against platelet factor 4 (PF4) or a heparin/PF4 complex have been reported to activate platelets, neutrophils and possibly endothelial cells, resulting in thrombocytopenia, hypercoagulability and thromboembolic complications. While the impact of anti-PF4/heparin antibodies on platelet, neutrophil and monocyte activation has been extensively studied, the role of endothelial cells in HIT-associated thrombosis remains underexplored. In particular, the interactions between HIT-induced procoagulancy and endothelial cells under dynamic conditions is not completely analyzed. In this report, we investigated how HIT antibodies induce thrombosis in an endothelialized microfluidic system. Methods: Fibrinogen microfluidic channels were coated with confluent monolayer of human umbilical vein endothelial cells (HUVECs). Cells were primed with low-dose TNF-α to induce a sub-thrombotic endothelial activation, prior to perfusion of whole blood. Recalcified unstimulated or Thrombin Receptor Activator Peptide 6 (TRAP-6) activated whole blood was perfused at a venous flow rate. HIT-thrombosis model was established and tested with monoclonal anti-PF4/heparin antibodies in whole blood. In brief, whole blood was pre-incubated with unfractionated heparin (UFH, 0.2 IU/mL and 100 IU/mL). Next, anti-PF4/heparin antibodies were introduced to the whole blood mixture and incubated for 30 minutes. Whole blood was recalcified and perfused over resting or primed endothelial cells at a venous shear stress. Thrombus formation was recorded over time. Results: The endothelialized microfluidic model successfully captures sub-thrombotic conditions under venous shear. Activated platelets induced a procoagulant shift and three-dimensional thrombi. We applied our thrombosis model to investigate thrombus formation induced by a HIT mimicking monoclonal antibody. We show that the heparin-dependent platelet activation predicts the thrombotic response in the microfluidic system: HIT antibodies in absence of heparin did not exert a pro-thrombotic effect on activated endothelial cells. Co-incubation with 0.2 IU/mL UFH induced thrombosis, embolization of thrombus material and channel occlusion only when endothelial cells were primed with TNF-α. The pro-thrombotic effect of HIT antibodies was fully reversed at the super-therapeutic dose of 100 IU/mL UFH. Conclusions: HIT antibodies induce thrombosis and embolization in a system emulating physiological environment. For the first time, we present a comprehensive thrombosis model that incorporates the established thrombogenicity of HIT-mimicking antibodies. We show that our thrombosis model incorporates both endothelial- and blood-based control of thrombosis. Primed endothelial cells and antibody-induced procoagulancy trigger thrombosis in a concerted fashion, allowing investigation of the underlying mechanisms and possible preclinical evaluation of potential inhibitors of HIT-thrombosis. Figure 1, upper panel: Maximal thrombus surface area coverage of TNF-α primed endothelial cells, perfused with unstimulated, TRAP-6 activated or HIT-like IgG/heparin challenged whole blood. HIT-like IgG did not increase thrombus formation in absence of heparin. Addition of low-dose heparin exerted a strong pro-thrombotic effect, that was fully reversible with a super-therapeutic concentration of heparin. Lower panel: representative images of thrombi formed by HIT-like IgG in absence and under low or high-dose heparin. Platelets: green, Calcein-AM. Scale bar: 200 µm.

When HIT Testing Hurts- the Financial and Clinical Repercussions of Heparin Induced Thrombocytopenia Testing: A Single Center Analysis

Introduction: Thrombocytopenia is a common inpatient hematologic concern. Most often, thrombocytopenia is a multifactorial phenomenon, without one clear cause. Heparin Induced Thrombocytopenia (HIT) is a rare but serious hematologic consequence of exposure to heparin. In many hospitalized patients, heparin is routinely used as venous thromboembolism (VTE) prophylaxis or for therapeutic anticoagulation. The incidence of HIT is approximately 0.5-1.0% in patients exposed to unfractionated heparin (UFH). Though rare, there seems to be over-testing of HIT antibody in the inpatient setting. As such, there is potential for high cost with low yield and false positives that alter patient management, resulting in prolonged hospital stays and further complications in patient care. Methods: This was a retrospective, observational study reviewing the indications, results, and patient characteristics of cases in which HIT testing was ordered. Indications for testing and influence of results on management were determined based on clinical documentation. The tests of interest included HIT antibody testing and Seratonin Release Assay (SRA). We analyzed how many times a HIT antibody was positive with a negative result in the SRA. We also determined whether there was an increased length of stay in patients who had HIT testing ordered. The study population included patients who were admitted to University of Florida Shands Medical Center, an academic institution in Jacksonville, FL in 2022. All patients were >18 years of age. Results: 190 patients were identified, for whom 190 HIT antibody tests were ordered and 75 SRAs. All patients who had a SRA performed had exposure to low dose heparin or therapeutic high dose heparin. Out of 190 patients, HIT testing was positive in 30 patients (15.8%). SRA testing was performed on 75 patients despite only 30 positive HIT tests. The true positives were 10 patients who had positive SRA confirmatory testing out of 190 patients with suspected HIT. Based on the results of confirmatory testing, the false positive fraction of HIT testing was 66%. When analyzing the 190 patients who underwent HIT testing, the average length of stay was 14 days. On average, a hospital stay in the US is 5.5 days and evaluation of HIT results in 8.5 additional days of hospital admission at our institution. The prolonged length of stay for HIT testing is likely impacted by awaiting SRA results along with other factors. Conclusion: This analysis examines the relative over-testing for HIT at a single institution. Compared with the known incidence of positive HIT tests, there is a significant number of positive HIT antibody tests at our hospital. The data further reveals a high probability of a false positive HIT antibody test results in the hospitalized patient, possibly due to immune reactivity. Of 190 patients suspected with HIT, only 10 patients had a positive confirmatory SRA, indicating that only 5% of suspected patients truly had HIT. This demonstrates that 95% of the time HIT assays ordered did not provide clinically useful information. From the time work up was initiated to the time of discharge, the average stay length was 14 days in a patient suspected with HIT. Cost burden of HIT testing was evaluated. Each HIT panel is $153.83 and each confirmatory SRA test is approximately $250, at a commercial laboratory. Taken together, the total average cost per patient with suspected HIT is $413.83 in diagnostic testing. Prolonged hospital stay contributes to approximately $25,000 increase in hospital stay per patient being evaluated for HIT. This does not include the cost of further work up or interventions. Changing to an alternate anticoagulant such as Argatroban increased costs by nearly $1,500 per case and this number increased further when adding the daily coagulation panel required while on this drug. In other studies, this cost has been estimated to add $90,000 to the hospital stay. Prolonged hospital stays are also associated with unintended incidents such as GI bleeding leading to blood transfusions, invasive testing (such as endoscopy/colonoscopy) and increased morbidity to the patient. We will use this information to implement a tool in our Electronic Medical Record (EMR) that will require answering the 4T score in order to establish high pre-test probability, prior to ordering HIT antibody testing at the University of Florida in Jacksonville.

The Antineoplastic Effect of Heparin on Colorectal Cancer: A Review of the Literature.

Heparin and derivatives are commonly used for thrombophylaxis in surgical colorectal cancer (CRC) patients. Recent studies have suggested that, besides its protective effect on the incidence of venous thromboembolism, heparin has an anti-cancer effect. The aim of this review was to explore the literature and report the antineoplastic effect of heparin and derivatives on CRC. MEDLINE and EMBASE databases were searched for relevant articles. Nineteen studies were included (n = 19). Fifteen were lab studies conducted in vivo or in vitro on CRC cell lines and/or mice (n = 15). Four were in vivo clinical studies (n = 4). CRC tumor growth was reduced by 78% in one study, (p < 0.01), while tumorigenesis was suppressed in heparin-treated mice in seven studies. A high dose of low molecular weight heparin for extended duration significantly reduced post-operative VEGF, suggesting that such a regime may inhibit tumor angiogenesis and distant metastasis. A randomized trial demonstrated the antineoplastic effect of nadroparin as the 6 month survival in palliative patients increased. Another study has reported that disease-free survival of CRC patients was not affected by a similar tinzaparin regime. The anti-cancer properties of heparin and derivatives are promising, especially in lab studies. Further clinical trials are needed to investigate the anti-cancer benefit of heparin on CRC.

Mortality with bivalirudin plus a high-dose infusion versus heparin in patients with acute coronary syndrome

Abstract Background The use of bivalirudin in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) has been downgraded by recent international guidelines. The reason for this downgrade lies above all on the excess of acute stent thrombosis (ST) associated with bivalirudin, but subsequent studies have suggested that a post-PCI high-dose bivalirudin infusion may mitigate the risk of acute ST related to the short half-life of bivalirudin. Methods We performed an updated meta-analysis of RCTs comparing bivalirudin followed by a post-PCI high-dose infusion versus UFH in ACS. Four RCTs accounting for a total of 16,920 patients were included. Odds ratios (OR) with 95% confidence intervals (CIs) using random effect models were calculated. Number needed to treat (NNT) were also calculated. Clinical outcomes at 30 days were included in the analysis. Results Four RCTs accounting for a total of 16,920 patients were included. We found that bivalirudin is associated with a non-significant reduction of 30-day all-cause death (OR 0.81, 95% CI 0.56-1.16, NNT 250, I2 53%), compared with UFH. Results were consistent at a subgroup analysis of STE-ACS versus NSTE-ACS and in a sensitivity analysis excluding the VALIDATE-SWEDEHEART, the only study using a shorter post-PCI bivalirudin infusion (mean 57 min) that was not used in the totality of patients (65%). Moreover, bivalirudin followed by a high-dose infusion was associated with a significant reduction of net adverse clinical events (NACE) (OR 0.62, 95% CI 0.42-0.90, NNT 31, I2 87%) as defined in each trial and of ST (OR 0.47, 95% CI 0.31-0.71, NNT 200, I2 1%), compared with UFH. Finally, BARC 3-5 bleeding was non-significantly reduced (OR 0.36, 95% CI 0.12-1.02, NNT 143, I2 82%) with bivalirudin compared with UFH. Conclusion We conclude that bivalirudin followed by a high-dose infusion is associated with reduced ST and NACE compared with UFH, but whether it may reduce all-cause mortality requires further investigations.

ELISA-Negative Platelet-Activating Anti-PF4 Antibodies Can Cause HIT and Monoclonal Gammopathy of Thrombotic Significance (MGTS)

We identified a patient with a recently described syndrome, monoclonal gammopathy of thrombotic significance (MGTS; Blood. 2023 Apr 6;141(14):1772-1776), and three additional patients with high 4Ts scores who were consistently negative in the PF4-polyanion HIT ELISA (Lifecodes PF4 IgG, Immucor). The MGTS patient, with a monoclonal IgG kappa, had recurrent thrombosis, and transient mild thrombocytopenia (nadir in the low 100s) over a period of years, and was noted to have a HIT ELISA optical density (OD) of 0.117. The three HIT patients experienced thrombocytopenia and thrombosis with ELISA ODs of 0.37, 0.18 and 0.20. All patients were positive in platelet-activation (functional) testing demonstrating PF4 dependence and inhibited with both high concentrations of heparin (100U/mL) and the FcγRIIa blocking monoclonal antibody (mAb) IV.3, consistent with the presence of anti-PF4 antibodies in the patient samples ( data not shown). Because the serologic profile of these patients suggested a novel HIT subtype characterized by negative HIT ELISA results, we undertook a functional platelet assay screen of 500 consecutive HIT ELISA-negative patients tested in our diagnostic laboratory. Research studies were approved by the Institutional Review Board of Mayo Clinic. Of the 500 patients tested, 20 (4.0%) stimulated platelet activation in the PF4-dependent P-selectin Expression Assay (PEA ≥19%; data not shown). To exclude non-specific activation that can be induced by HLA antibodies, additional testing was performed to evaluate whether platelet activation was PF4-dependent using buffer or PF4-treated platelets. Three patients demonstrated PF4-dependent activation that was inhibited by high heparin concentrations and mAb IV.3, as would be expected for HIT antibodies (ELISA-negative HIT, EN-HIT1-3; Figure 1). On retrospective review, all three patients thus identified had clinical histories and courses consistent with high clinical probability for HIT. To develop tools to study this new class of antibodies, monoclonal HIT antibodies were generated in mice after PF4/heparin immunizations and screened using a novel approach that included simultaneous testing of hybridoma supernatants in the PEA and PF4-polyanion ELISA. This strategy was designed to enabled us to identify mAbs that activated platelets (in the PEA), but that did not bind antigenic targets in the HIT ELISA. A novel mAb 431.4 that was developed using this approach, and the well-characterized HIT-like mAb KKO were evaluated for their abilities to both bind PF4-polyanion targets in ELISA, and to activate PF4-treated platelets in the PEA (Figure 2). In significant contrast to KKO, mAb 431.4 did not bind PF4/polyanion complexes, however, like KKO, strongly activated platelets in a PF4-dependent manner. Activation induced by both KKO and mAb 431.4 was inhibited by high heparin concentrations, as would be expected for HIT antibodies. In vivo murine studies using this novel mAb are pending at this time. In summary, the non-canonical diagnostic profile of HIT ELISA-negative but platelet activation-positive antibodies were found at a relatively high incidence in HIT-suspected patients (0.6%; 3 of 500 ELISA-negative patients). These findings have important diagnostic/management implications and suggest a re-evaluation of ASH's HIT management guidelines as noted in recommendations 2.7 and 2.8 of that document (“In patients with an intermediate (Recommendation 2.7) or high (Recommendation 2.8)-probability 4Ts score and a negative immunoassay, the ASH guideline panel recommends discontinuation of the non-heparin anticoagulant and resumption of heparin, if indicated ”; Blood Adv (2018) 2 (22): 3360-3392). Figure 1. A subset of ELISA-negative HIT-suspected patients harbor anti-PF4 platelet-activating antibodies. Three ELISA-negative (EN) HIT patient samples from a screen of 500 samples demonstrate PF4-dependent platelet activation and inhibition with high heparin concentration and mAb IV.3 incubation. PBS, phosphate buffered saline; IC, isotype control; HDH- high dose heparin (100U/mL). Figure 2. Murine mAb 431.4 serologically mimics pathogenic ELISA-negative HIT/MGTS antibodies. ELISA and PEA testing was performed using the “HIT-like” mAb KKO, novel mAb 431.4, or an isotype control (IC) antibody. PVS-polyvinyl sulfonate (polyanion used in the Immucor IgG ELISA assay).

Competence of Health Care Providers on Clinical Management of Myocardial Infarction in Selected Hospitals with Intensive Care Unit Western Kenya

Background: The capacity of healthcare providers to execute an accurate initial assessment is crucial for recognizing the urgency and treatment needs of patients and for creating baseline data from which any changes in patient status may be monitored. In Western Kenya, there is little evidence of studies carried out on the competence of healthcare providers in the clinical management of myocardial infractions thus this study's main aim was to investigate the competence of healthcare providers in the clinical management of myocardial infractions.&#x0D; Material and Methods: A cross-sectional analytical study design was used. The study population comprised a total sample of 114 healthcare providers. A structured questionnaire and observation checklist were used. Participants will be picked using a systematic sampling method for those who meet the inclusion criteria. The sample size was determined using Fisher's Method. The data collected was compiled using SPSS software version 22. The data was analyzed through the application of descriptive statistical analysis.&#x0D; Findings: Variables that positively influenced the competency are specialization (AOR: 15.1; 95% CI: 2.6 – 87.3; p = 0.002), knowledge (AOR: 5.4; 95% CI: 1.1 – 26.5; p = 0.04) and having a protocol in patient's file (AOR: 10.2; 95% CI: 0.9 – 112.6.5; p = 0.06), although the latter was marginally statistically significant. Healthcare provider's qualification (KRCHN) (AOR: 0.04; 95% CI: 0.008 – 0.219; p = 0.002), filling of the protocol (AOR: 0.03; 95% CI: 0.001 – 0.585; p = 0.02) and use of high dose heparin as opposed to the use of other thrombolytic like Metalase (AOR: 0.1; 95% CI: 0.01 – 0.63; p = 0.02) were all negatively associated with healthcare providers competency.&#x0D; Recommendation/Conclusion: The study recommends the need of specialized training and knowledge advancement for health care providers on critical care nursing. This study found marginal statistical significance between the factors that influence competence among healthcare providers on clinical management of myocardial infraction.

Symptomatic subdural hemorrhage following heart valve surgery: a retrospective cohort study.

Subdural hemorrhage (SDH) has been reported to be the most frequent intracranial hemorrhagic complication following open heart surgery; however, its clinical features and pathophysiology remain unclear. The aim of this retrospective study was to elucidate the incidence, clinical course, and factors associated with the development of symptomatic SDH following heart valve surgery. A retrospective review of medical records on the development of symptomatic SDH after heart valve surgery involving cardiopulmonary bypass (CPB) from April 2011 to March 2016 was performed. Patients who had undergone preoperative cranial computed tomography (CT) or brain magnetic resonance imaging (MRI) were included in this study, and factors associated with SDH following heart valve surgery were analyzed. When neurological symptoms developed after heart valve surgery, cranial CT or brain MRI was performed. A total of 556 patients who had undergone heart valve surgery were analyzed. Among these patients, symptomatic SDH occurred in 11 (2.0%). The mean duration of symptomatic onset was 10.1 days (range 2-37 days). Ten of 11 patients (90.9%) developed SDH in the posterior fossa or occipital convexity. Logistic regression analysis revealed longer aortic clamp time (95% CI 1.00-1.10, p = 0.04), higher dose of heparin after surgery (95% CI 1.00-1.02, p = 0.001), and higher pulmonary artery pressure (PAP) just before disconnection of the CPB (95% CI 1.01-1.37, p = 0.04) as significantly associated with the development of SDH. The incidence of symptomatic SDH following heart valve surgery was 2.0%. Symptoms due to SDH usually developed a few days to 1 month after surgery. Surprisingly, most SDHs developed in the posterior fossa or occipital convexity following heart valve surgery. A longer aortic clamp time, higher dose of heparin after surgery, and higher PAP just before disconnection of the CPB were related to the development of symptomatic SDH following heart valve surgery.

PAD4-Induced NETosis Via Cathepsin G-Mediated Platelet-Neutrophil Interaction in ChAdOx1 Vaccine-Induced Thrombosis.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare syndrome characterized by platelet anti-PF4 (platelet-activating antiplatelet factor 4)-related thrombosis. Platelet-neutrophil interaction has been suggested to play a role, but the underlying mechanism has not been fully elucidated. The study included 10 patients with VITT after ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine administration, 10 patients with ischemic stroke (IS), 10 patients with acute deep vein thrombosis, and 10 control subjects in whom blood levels of neutrophil extracellular traps (NETs), soluble TF (tissue factor), and thrombin generation were examined. Furthermore, we performed in vitro studies comparing the effect of serum from patients and controls on NETs formation. Finally, immunohistochemistry was performed in cerebral thrombi retrieved from a patients with VITT and 3 patients with IS. Compared with patients with IS, patients with deep vein thrombosis, controls, and patients with VITT had significantly higher blood values of CitH3 (citrullinated histone H3), soluble TF, D-dimer, and prothrombin fragment 1+2 (P<0.0001). Blood CitH3 significantly correlated with blood soluble TF (Spearman rank correlation coefficient=0.7295; P=0.0206) and prothrombin fragment 1+2 (Spearman rank correlation coefficient=0.6809; P<0.0350) in patients with VITT. Platelet-neutrophil mixture added with VITT plasma resulted in higher NETs formation, soluble TF and thrombin generation, and platelet-dependent thrombus growth under laminar flow compared with IS and deep vein thrombosis plasma; these effects were blunted by PAD4 (protein arginine deiminase 4) and cathepsin G inhibitors, anti-FcγRIIa, and high doses of heparin. Immunohistochemistry analysis showed a more marked expression of PAD4 along with more diffuse neutrophil infiltration and NETs formation as well as TF and cathepsin expression in VITT thrombus compared with thrombi from patients with IS. Patients with VITT display enhanced thrombogenesis by PAD4-mediated NETs formation via cathepsin G-mediated platelet/neutrophil interaction.

Vapor-based hybrid grafting of heparin-like coating for dialysis membranes with enhanced hemocompatibility

Heparin is commonly used to improve the hemocompatibility of biomaterials, but high doses of heparin may cause significant side effect in clinical applications. Thus, heparin-mimicking surfaces have been urgently explored to reduce the use of heparin. In this work, heparin-like coating was deposited on polylactide (PLA) dialysis membranes using one-step hybrid grafting of a carboxyl-enriched poly(methacrylic acid) (pMAA) coating via initiated chemical vapor deposition (iCVD). The hybrid grafting was conducted by depositing a prime layer of poly(methacrylic acid-co-ethylene glycol dimethacrylate) (p(MAA-co-EGDMA)) copolymer followed by immediate in situ grafting of a pMAA homopolymer layer. The grafting parameters were systematically studied to obtain the maximum grafting density of pMAA. The resulting membrane with maximized surface functionality shows strong hydrophilicity with a water contact angle of 33° without affecting its permeability, excellent suppression of platelet adhesion and deformation, and significantly lengthened clotting time (APTT, TT, and PT prolonged to 308.4 s, 31.0 s, and 31.9 s, respectively). The substantially enhanced hemocompatibility is attributed to the abundant carboxyl groups achieved by hybrid grafting, which effectively disrupts the coagulation cascade. This facile iCVD grafting method can be a promising candidate for improving the hemocompatibility of biomaterials, such as dialysis membranes, catheters, and implants.

Severe Spontaneous Hematomas in Patients Hospitalized with COVID-19.

To describe the epidemiological, clinical, laboratory, and radiological characteristics, medical treatment, and outcomes of a case series of severe spontaneous hematoma in COVID-19. Material and Methods. This retrospective study included patients hospitalized for COVID-19 who were diagnosed with severe spontaneous bleeding complications by following a standardized treatment protocol that included computed tomography angiography (CTA) from 1 March 2020 to 28 February 2022. The main outcomes were embolization and all-cause mortality. Baseline variables were analyzed for their association with mortality using bivariable logistic regression, and results were expressed as odds ratios (OR) and 95% confidence intervals (CI). In total, 2450 adults were hospitalized for COVID-19 in our center during the study period. 20 patients presented severe and spontaneous intramuscular bleeding (8.1 per 1000 COVID-19 admission vs. 0.47 per 1000 non-COVID-19 admissions, p < 0.001); their median age was 68.5 years (interquartile range (IQR) 63, 80), they had high comorbidity (median Charlson comorbidity index 4.5), and 95% were receiving high doses of heparin. The median interval from COVID-19 symptoms to bleeding was 17 days (IQR 13, 24), and 70% reported cough as a previous symptom. Hypovolemic shock, hypotension, and abdominal pain were the most frequent symptoms of the hematoma. All presented decreased hemoglobin, and 95% required transfusion. Intramuscular hematoma occurred most frequently in the rectus sheath, iliopsoas compartment, and femoral-iliac compartment. All patients underwent embolization; mortality was 45%. We did not identify risk factors associated with an increased risk of death. Although severe bleeding is an uncommon complication of COVID-19, its prevalence is higher than in inpatients without COVID-19, it usually needs embolization, and it is associated with high mortality.

Thromboelastometry for predicting hemostasis disorders after cardiopulmonary bypass during cardiac surgery

Introduction. Assessment of the state of the hemostasis system in cardioanesthesiology is carried out both clinically and using standard laboratory tests — thromboelastography (TEG), rotational thromboelastometry (ROTEM), or a combination of both. Both TEG and ROTEM are designed to detect disorders in the hemostasis system in real time. Aim – to evaluate the informativeness of ROTEM performed at the stage of cardiopulmonary bypass (CPB) before neutralization of heparin with protamine and to study the prognostic value of this study in assessing the risk of postoperative bleeding during cardiac surgery with a high risk of bleeding. Materials and methods. The assessment of the diagnostic significance of ROTEM studies at the CPB stage is based on the observation of 31 patients operated on from July to October 2018. The median age of these patients was 55 years (31–72 years). The criteria for inclusion of patients in the study were the performance of planned cardiac surgery with a high risk of bleeding: operations on the aorta, combined operations (coronary bypass surgery and/or surgery on the valve(s), multivalve correction), including repeated. Methods of descriptive statistics, correlation and comparative analyses, and ROC-analysis were used to assess the diagnostic and prognostic capabilities of ROTEM research during CPB against the back=-ground of high doses of heparin. Results. A statistically significant linear correlation was noted between A5 and MCF indicators in EXTEM, FIBTEM and PLTEM tests performed both during and after CPB. The results obtained indicate that determining the cause of bleeding and deciding on the choice of therapy is possible significantly earlier than the MCF indicator is determined, namely 5 minutes after the start of blood clotting in the ROTEM study. The informative value of ROTEM studies performed during CPB is shown, however, when interpreting the results, it is necessary to focus not only on the reference intervals, but also on the obtained cut-off levels for ROTEM parameters during CPB for early detection of hypofibrinogenemia or thrombocytopenia after CPB. Conclusion. ROTEM performed with the use of high doses of heparin during CPB is informative for the choice of pathogenetically justified therapy for possible bleeding.

А clinical case of thrombosis in a teenager in the post COVID-19 period

The article presents a case of a fatal outcome of a 15-year-old teenager with cerebral vascular thrombosis, which developed in the post COVID-19 period. The young man came in with complaints of headache, vomiting, photophobia, hyperacusis. It was known that at an early age he had been operated on for the Arnold – Chiari anomaly, had a subdural-peritoneal shunt. Two weeks before hospitalization, he suffered a new coronavirus infection of mild severity, which was confirmed by a positive analysis of a smear from the oropharynx by polymerase chain reaction. Cephalgia was acute, stopped for a short time after the use of analgesics. During the examination, the patient laid with his eyes closed, asked for silence and blackout in the ward. Any movement of the head was accompanied by dizziness, headache, vomiting. During an objective examination, no pathological changes were found on the part of the internal organs. The neurological status was determined by photophobia, double vision, asymmetric face, asymmetry of the eye slits S &gt; D, drooping of the left corner of the mouth, nystagmus, hyperacusis. There was no rigidity of the occipital muscles. Meningeal signs were negative. There were no pelvic disorders. According to the laboratory examination, lymphocytopenia, thrombocytosis, acceleration of ESR, moderate increase in ferritin, D-dimers were detected. Conducted neuroimaging methods (MSCT of the brain with intravenous contrast, brain MRI, ultrasound diagnostics of cerebral vessels) did not find any blood clots in intracranial and extracranial vessels. Low-positive values of IgM antibodies to cardiolipin were revealed. According to the results of polymerase chain reaction, polymorphism G20210A was detected in the prothrombin gene. The patient received high-dose glucocorticoids and heparin for treatment. Despite the therapy, a month and a half after hospitalization, the teenager died from thrombosis of the central venous sinuses (cavernous sinus on the left, transverse sinuses, jugular veins), which were confirmed on autopsy. This clinical case of venous sinus thrombosis in a teenager in the post COVID-19 period presented diagnostic difficulties, since accurate imaging methods did not detect the presence of a blood clot in the cerebral vessels.