Heparin Versus Bivalirudin for Anticoagulation in Adult Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis.

Extracorporeal membrane oxygenation (ECMO) poses unique thrombotic and hemorrhagic risks, and the optimal anticoagulant choice is unknown. We systematically searched Ovid EBM Reviews, Ovid Embase, Ovid Medline, Scopus, and Web of Science Core Collection for randomized-, crossover-, retrospective cohort-, or parallel-designed clinical studies of adult patients receiving ECMO that compared heparin recipients with bivalirudin recipients. Meta-analysis was performed with random-effects models. The ROBINS-I tool was used to assess the risk of bias. Six retrospective observational studies met the inclusion criteria for the qualitative summary. Five studies were suitable for meta-analysis. Those who received heparin were more likely to experience circuit-related thrombosis (odds ratio [OR] 2.05, 95% confidence interval [CI] 1.25-3.37, p = 0.005, I2 = 0%) and die (OR 1.62, 95% CI 1.19-2.21, p = 0.002, I2 = 0%) compared with those who received bivalirudin. There were no differences in major bleeding events between heparin and bivalirudin recipients (OR 1.83, 95% CI 0.55-6.09, p = 0.33, I2 = 82.7%). In retrospective settings compared with heparin anticoagulation, bivalirudin was associated with less circuit-related thrombotic events and greater survival in adults supported on ECMO, without contributing to more bleeding complications. Prospective controlled studies comparing heparin and bivalirudin in adult ECMO patients are warranted to corroborate these findings.

Comparison of Bivalirudin Versus Unfractionated Heparin for Anticoagulation in Adult Patients on Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) contributes to coagulopathy, necessitating systemic anticoagulation to prevent thrombosis. Traditionally, unfractionated heparin (UFH) has been the anticoagulant of choice, however, due to many inadequacies new evidence suggests benefit with the use of direct thrombin inhibitors. This retrospective cohort sought to evaluate the safety and efficacy of bivalirudin compared to UFH in ECMO patients. Primary endpoints included incidence of bleeding and thrombosis. Percent time in therapeutic range (TR), time to achieve TR and number of dose titrations required to maintain TR were calculated to assess efficacy of institutional protocols. Overall incidence of thrombosis was low, with one event in the bivalirudin group and no events in the UFH group. No difference was found in rates of bleeding between groups (6% vs . 10%, P = 0.44). Bivalirudin yielded higher percent time in TR (86% vs. 33%, P < 0.001), faster time to TR (2 vs . 18 hr, P < 0.001) and required fewer dose adjustments to maintain TR (2 vs . 11, P < 0.001) compared to UFH. These results suggest bivalirudin and UFH are associated with similar rates of bleeding and thrombosis in patients requiring ECMO support. Our results demonstrate the favorable pharmacokinetic profile of bivalirudin, and its ability to consistently maintain TR when compared to UFH.

Artificial intelligence based identification of the functional role of hirudin in diabetic erectile dysfunction treatment.

Diabetic erectile dysfunction (DED) hugely affected the patients' sexual life quality. However, there are no satisfactory therapeutic methods and intervention targets for this subtype of erectile dysfunction (ED). Inspired by the clinical practice of traditional Chinese medicine (TCM), we found that hirudin, the main active ingredient in the leech, could ameliorate the ED symptoms of the DED mouse model. To further reveal the underlying mechanism of hirudin, we designed a novel strategy to discover potential targets based on the diagnostic system of TCM, and found that myeloperoxidase (MPO) was a promising target of hirudin. Hirudin directly interacts with MPO and inhibits its activity, thus further decreases the content of oxidized low-density lipoprotein (ox-LDL) in serum. Our results demonstrated that the hirudin could ameliorate the symptoms of DED, and revealed the underlying mechanism of hirudin in regulating the activity of MPO.

Effect of hirudin on serum matrix metalloproteinase-9 of acute cerebral infarction: A protocol of systematic review and meta-analysis.

BACKGROUND: This study aims to check the effect of hirudin on serum matrix metalloproteinase-9 (SMMP9) in patients with acute cerebral infarction (ACI). METHODS: For acquisition of obtained data of included studies, we will undertake comprehensive search from the following electronic databases: MEDLINE, Embase, Cochrane Library, CINAHL, WANGFANG database, VIP database, CBM database, and China National Knowledge Infrastructure from their inceptions to the March 31, 2020. No restrictions of language and publication status will be applied to all database sources. Two investigators will independently undertake study selection, data extraction, and study quality. Any different opinions between 2 investigators will be solved by a third investigator through consultation. Study quality will be assessed using Cochrane risk of bias tool, and level of evidence for outcome results will be identified using the Grading of Recommendations Assessment, Development, and Evaluation method. We will use RevMan 5.3 software for statistical analysis. RESULTS: From this study, we will evaluate the effect of hirudin on SMMP9 in patients with ACI. CONCLUSION: The findings of this study will provide evidence to ensure the effect of hirudin on SMMP9 in patients with ACI.

[Effect of natural hirudin on revascularization of ischemic skin flaps in rats by Micro-CT].

OBJECTIVE: To investigate the effect of natural hirudin on revascularization of ischemic skin flap in rats using Micro-CT and three-dimensional (3D) reconstruction. METHODS: Thirty-two Sprague Dawley rats were prepared a ischemic skin flap (8.0 cm×1.8 cm) model on the back and randomly divided into hirudin group and control group (16 rats in each group). At immediate and within 3 days after operation, the rats were treated with hypodermic injection of natural hirudin 0.3 mL (including natural hirudin 6 ATU) every day in hirudin group and the equal amount of normal saline in control group. At 6 days after operation, the survival rate of skin flap was evaluated, histological changes were observed by HE staining, and the volemia, length of blood vessels, and number of blood vessels were analyzed with Micro-CT 3D reconstruction. RESULTS: Both groups of rats survived to the end of the experiment without infection. Different degrees of necrosis occurred in the distal part of the skin flaps in both groups at 6 days after operation, but the flap survival rate of the hirudin group (72.11%±8.97%) was significantly higher than that of control group (58.94%±4.02%) ( t=3.280, P=0.008). Histological observation showed that the histological hierarchy of the hirudin group was clearer than that of the control group, with more microangiogenesis and less inflammatory response and inflammatory cell infiltration. Micro-CT 3D reconstruction showed that the flap vessels in the hirudin group were more and denser, and the volemia, length of blood vessels, and number of blood vessels were significantly higher than those in the control group ( P<0.05). CONCLUSION: Natural hirudin can reduce the inflammation of tissue, promote the regeneration and recanalization of blood vessels in ischemic skin flap, so as to improve the survival rate of the flap.

Hirudin improves renal interstitial fibrosis by reducing renal tubule injury and inflammation in unilateral ureteral obstruction (UUO) mice.

Renal interstitial fibrosis (RIF) often occurs in many chronic kidney diseases (CKD). Hirudin now is applied to treat fibrosis in some organs. In this study, we verified the treatment effects of hirudin on RIF in vivo and in vitro with the underlying mechanism. The RIF in vivo was the unilateral ureteral obstruction (UUO) model and RIF in vitro was the renal tubular epithelial cells induced by TGF-ß. The renal pathological changes and renal fibrosis were observed by hematoxylin and eosin (H&E) staining and Masson staining. The α-SMA in renal tissues was detected by immunohistochemistry. The inflammatory factors were analyzed by the ELISA assay. The cell apoptosis was observed by TUNEL assay. The related proteins of fibrosis, epithelial-mesenchymal transition (EMT) and apoptosis were assessed by western blot analysis. The experimental data demonstrated that hirudin decreased fibrosis, EMT, inflammation and cell apoptosis in renal tissues of UUO rats and TGF-ß-induced renal tubular epithelial cells. Furthermore, hirudin also reduced the expression of collgen-I, FN, α-SMA, N-cad, slug, E-cad, IL-1ß, IL-6 and TNF-α in mice serum and TGF-ß-induced renal tubular epithelial cells. The apoptosis related proteins (pro-caspase3, pro-caspase9, bcl2 and bax) expression was also down-regulated in renal tissues of UUO rats. In conclusion, hirudin depressed the fibrosis in renal tissues and renal tubular epithelial cells by inhibiting the inflammation, regulating the related proteins of fibrosis and ETM and decreasing the apoptosis of renal tubular epithelial cells. These findings may offer an effective treatment method for RIF.

Role of Bivalirudin for Anticoagulation in Adult Perioperative Cardiothoracic Practice.

Bivalirudin, a direct thrombin inhibitor with a fast onset of action and short half-life, is often referred to as an alternative anticoagulant to a heparin/protamine regimen. Bivalirudin demonstrated promising results as an anticoagulant in cardiac surgery with and without cardiopulmonary bypass, postcardiotomy extracorporeal membrane oxygenation, interventional cardiology and endovascular procedures, and particularly in the treatment of patients with heparin-induced thrombocytopenia undergoing high-risk cardiac surgery. Currently, bivalirudin in cardiac surgery with cardiopulmonary bypass has a limited clinical spectrum, likely because the still obvious advantages of its competitor, heparin, outweigh it in terms of medical costs, established point-of-care monitoring systems, and availability of protamine as a reversal agent. The unique pharmacology of the drug also requires adjustment of surgical and perfusion strategy. In contrast, in off-pump coronary artery surgery, established protocols from interventional cardiology can be easily translated into the operating room. In this setting bivalirudin has the potential for a more important role in the future. Through a triple mechanism of action-inhibition of plasma thrombin, clot bound thrombin, and collagen-induced platelet activation-bivalirudin may perform better than heparin by attenuating the immediate postoperative prothrombotic state and thus positively impacting the early coronary graft patency after off-pump coronary artery bypass grafting. Further studies are necessary to better evaluate this niche field and discover further applications for this unique anticoagulant.

Inhibition of fibrin formation reduces neuroinflammation and improves long-term outcome after intracerebral hemorrhage.

BACKGROUND: Intracerebral hemorrhage (ICH) is a severe type of stroke without effective treatment. The coagulation cascade is activated after blood flows into the brain parenchyma. The conversion of fibrinogen to fibrin is an essential step of coagulation processes, but its influences on neuroinflammation and long-term outcome after ICH have not been adequately studied. Hirudin binds to thrombin and inhibits the conversion of fibrinogen to fibrin. We therefore investigated the impact of hirudin treatment on brain inflammation and long-term outcome of ICH in mice. METHODS: Fibrinogen levels were measured in plasma samples from patients with ICH. In mice subjected to collagenase injection, fibrinogen levels were measured in the plasma and brain. The impact of hirudin on neuroinflammation and long-term neurological outcome was determined in ICH mice. RESULTS: Circulating fibrinogen level was increased in patients with ICH at day 1 and day 4 after onset. In ICH mice, fibrinogen levels in the blood and brain were increased at day 7. Delayed daily administration of hirudin from day 7 to day 28 significantly improved long-term outcome in ICH mice. Hirudin treatment reduced leukocyte accumulation in the brain and shifted microglia toward an anti-inflammatory phenotype. In addition, depletion of microglia in ICH mice diminished the benefit of hirudin in ICH mice. CONCLUSIONS: These results suggest that inhibition of fibrin formation alleviates brain inflammation and improves long-term outcome after ICH.

Hirudin ameliorates immunoglobulin A nephropathy by inhibition of fibrosis and inflammatory response.

Immunoglobulin A nephropathy (IgAN) is characterized by mesangial IgA and IgG co-deposition. As the clinical course of IgAN is highly variable, a lot of patients will eventually develop to end-stage renal disease (ESRD) within years. Hirudin, a potent and specific thrombin inhibitor, has been reported to treat IgAN with hematuria, but the mechanism is unclear. Our study aims to explore the potential of hirudin and the underlying mechanism in the treatment of IgAN. The establishment of IgAN model was set up in rats through oral and intravenous immunization with bovine gamma-globulin (BGG). Results suggested that hirudin could reduce the increased level of proteinuria, serum creatinine and urea nitrogen in IgAN models. Besides that, hirudin ameliorated the elevated number of apoptotic bodies and expressions of apoptosis-related proteins (caspase-3 and caspase-9) in IgAN model. The fibrosis indexes (transforming growth factor ß-1 (TGF-ß1), Collagen-IV (CoI-IV) and Fibronectin-1) of kidney were remarkably suppressed in IgAN rats treated with hirudin compared with IgAN rats with no further treatment. IgAN rats exhibited remarkably increased inflammatory factors (IL-1ß, IL-6, and IL-18), while hirudin treatment significantly alleviated these alterations. Moreover, the reduced levels of CD4+CD25+Foxp3+ Treg and CD4+IFN-γ+ Th1/CD4+IL-4+ Th2 could be reversed by hirudin in IgAN model. Furthermore, in the process of IgAN, hirudin could inactivate various pathways (IκBα, NF-κB, TNF-α, and VCAM-1) compared with IgAN model group. Taken together, our study indicated that hirudin could ameliorate IgAN through suppressing fibrosis and inflammatory response. These findings provide a new therapeutic method to treat IgAN.

Effects of Natural Hirudin and Low Molecular Weight Heparin in Preventing Deep Venous Thrombosis in Aged Patients with Intertrochanteric Fracture.

Our objective was to evaluate the efficacy and safety of natural hirudin and low molecular weight heparin (LMWH) in the prevention of perioperative deep venous thrombosis (DVT) in elderly patients with intertrochanteric fracture. From June 2014 to June 2017, 96 patients with intertrochanteric fractures were treated with proximal femoral nail antirotation (PFNA) were randomly divided into two groups. For DVT prevention, 45 patients were treated with oral natural hirudin and subcutaneous LMWH-calcium (test group) and 51 patients were treated with subcutaneous LMWH-calcium (control group). The mean intraoperative bleeding, wound drainage and incisional hematoma were higher in the test group, with no significant differences between the groups. There were significant differences in distal intramuscular venous thrombosis (P = 0.043). Both activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT) lengthened in both groups postoperatively, and there was a significant difference between the two groups two weeks postoperatively. D-dimer were significantly different and platelet count (PLT) did not differ between groups two weeks postoperatively. In elderly patients with unilateral intertrochanteric fracture after PFNA on anticoagulant therapy, the combination of natural hirudin and LMWH was more effective than that of LMWH-calcium alone, with no significant difference with regard to safety.

Standardization of a well-controlled in vivo mouse model of thrombus formation induced by mechanical injury.

OBJECTIVE: Vascular plug formation by mechanical injury that exposes abundant extracellular matrix is an ideal model to mimic thrombus formation. The objective of this study was to standardize our previously established in vivo mouse model of thrombus formation induced by mechanical injury. RESULTS: The mechanical injury was exerted by pinching the abdominal aorta with hemostatic forceps for either 15 (moderate injury) or 60 (severe injury) seconds. Thrombus formation was monitored for 20min in real time using a fluorescent microscope coupled to a CCD camera. In the moderate injury, thrombus formation peaked at approximately 1min after injury and resolved within 3min, with the mean AUC (area under the curve) of 165.2±17.29mm(2), whereas a larger thrombus was observed upon the severe injury, with the mean AUC of 600.5±37.77mm(2). Using scanning electron microscopy and HE staining, a complete deformation of the endothelium in the moderate injury model and the exposure of the media in the severe injury model were observed. The model was also evaluate for its application on the effects of antithrombotic drugs targeting GP IIb-IIIa (eptifibatide), ADP receptor P2Y1 (MRS2500) and P2Y12 (clopidogrel), and thrombin (hirudin) on thrombus formation. CONCLUSIONS: We have improved a vascular injury model with optimal reproducibility and feasibility that allows evaluating the effect of anti-thrombotic drugs on thrombus formation in vivo.

[Analysis of the medicinal leech effects on the state of arterial functions of aged probationers, using hardwarily software system "Angioscan-01"].

The state of elderly patients arterial wall after the putting of one medicinal leech was estimated by use hardwarily software system "Angioscan-01". There was compared the effect of one medicinal leech on indicators of vasomotor function of endothelium of small resistance arteries and of middle arteries of muscular type. Stickiness index and augmentation index were determined in order to evaluate the medicinal leech effect on the rigidity state of arterial wall. It is shown that the putting of one leech stimulates the improving of endothelium vasomotor function and of normalization arterial wall stickiness. It is supposed the participation in this process the secretion of the medicinal leech salivary cells, which, as has been shown recently, is able to activate e-NOS and n-NOS in human endothelium culture (HUVEC) and increase NO level. Elevation of share stress during occlusion test is also stimulated NO production in vascular endothelium.

Poly(lactic-co-glycolic) acid microspheres encapsulated in Pluronic F-127 prolong hirudin delivery and improve functional recovery from a demyelination lesion.

Components of the blood have been proposed as potential therapeutic targets for improving cellular regeneration after injury and neurodegenerative disease. In this work, thrombin is shown to increase endogenous neural progenitor proliferation in the intact murine spinal cord. A local injection of heparin before a spinal cord injury reduces cell proliferation and astrogliogenesis associated with scarring. We sought to create depot-formulations of PLGA microsphere and Pluronic F-127 for sustained local delivery of two thrombin inhibitors, heparin and hirudin. Each hydrogel depot-formulation showed delayed drug release compared to microspheres or hydrogel alone. Animals with a lateral demyelination lesion showed a reduction in CD68+ macrophages when treated with hirudin-loaded PLGA/F-127 gels compared to control and heparin-treated animals. Moreover, hirudin-loaded materials showed an accelerated recovery in coordinated stepping and increased oligodendrocyte densities. Together, these data demonstrate that controlled delivery of hirudin accelerates functional recovery from a demyelination lesion in the spinal cord.

New developments in parenteral anticoagulation for arterial and venous thromboembolism.

The efficacy and safety of heparin and low-molecular-weight heparins (LMWHs) are well documented in venous and arterial thromboembolism. Several drawbacks of heparins have inspired the development of newer parenteral anticoagulants for specific indications, including heparin-induced thrombocytopenia (HIT) and percutaneous coronary interventions (PCI). The direct thrombin inhibitors recombinant hirudin and argatroban are now established alternatives for HIT patients, and bivalirudin is one of the most used anticoagulants in PCI. The pentasaccharide fondaparinux is an alternative for LMWH for thromboprophylaxis in various clinical settings and for patients with an acute coronary syndrome (ACS) not scheduled for PCI. In Europe, it was recently approved for treatment of superficial vein thrombosis. Further development of new parenteral anticoagulants is slow and the emphasis has shifted towards development of new oral anticoagulants and antiplatelet drugs. Still, promising new anticoagulants, some targeting less conventional targets in the coagulation system, have been developed and will undergo further clinical evaluation.

Effects of natural and recombinant hirudin on VEGF expression and random skin flap survival in a venous congested rat model.

We aim to investigate the effects of locally injected natural and recombinant hirudin on vascular endothelial growth factor (VEGF) expression and flap survival in venous congested skin flaps using a rat model. A dorsal random skin flap (10 × 3 cm) was prepared on each of 30 Wistar rats to establish a venous congested model. The rats were randomly divided into 2 treatment groups [receiving subcutaneous injection of either natural hirudin (6 U) or recombinant hirudin (6 U)] and a control group, which received subcutaneous injection of physiologic saline. After treatment, skin flap survival rates were calculated. VEGF messenger RNA levels and VEGF-positive vessel density as a marker for VEGF levels were measured in the flaps during and after treatment. The skin flap VEGF messenger RNA levels increased in the natural hirudin-treated group. The VEGF-positive vessel density was increased in all 3 groups. Statistically significant increases of VEGF levels were observed in the natural and recombinant hirudin-treated groups compared with the control group (P < 0.05). The skin flap survival rates were improved in both hirudin treated groups. Natural and recombinant hirudin can increase VEGF expression in random skin flaps, which can potentially improve random skin flap survival in rats through angio genic mechanisms. Our results showed that hirudin treatment led to an increase in VEGF expression in the congested skin flaps. Natural hirudin demonstrated more pronounced effects than recombinant hirudin. Further studies are needed to understand the specific mechanisms.

Medicinal leech therapy on head and neck patients: a review of literature and proposed protocol.

OBJECTIVES: To this day, a standardized protocol for medicinal leech therapy does not exist. The purpose of this article was to review literature in the hope of proposing a unified, coherent, feasible, and safe protocol for using medicinal leeches when warranted. STUDY DESIGN: A literature search was conducted in the following databases: PubMed, MDConsult, The Cochrane Library, OMIM, and Google. This was supplemented by a search for selected authors. Keywords used were medicinal leech therapy, leech therapy, leeching, replantation, thromboembolism, venous congestion, Hirudo medicinalis, Hirudotherapy, leech protocol, and Hirudo protocol. RESULTS: Based on titles and abstracts, 26 articles and 1 Web site were identified. CONCLUSIONS: Leech therapy can be an excellent alternative for the treatment of venous congestion in free flaps, pedicled flaps, and replanted tissues. Psychological precounseling, antibiotic therapy, number of leeches to be used, length of therapy, and laboratory checks should be taken into consideration before initiating therapy.

Inhibitory effect of r-hirudin variant III on streptozotocin-induced diabetic cataracts in rats.

The in vivo inhibitory effect of r-hirudin variant III (rHV3) on streptozotocin (STZ)-induced diabetic cataracts in rats was investigated. SD-rats were firstly made diabetic by a single intraperitoneal injection of 2% (W/V) STZ (65 mg/kg). Two weeks later, cataract formation was examined by slit lamp microscope, and the cataracted animals were randomly grouped. The animals in the treated groups received rHV3 drops administration to the eyes with various doses. After 4 weeks treatment, the animals were sacrificed to evaluate the biochemical changes of aldose reductase (AR), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels in the eye lens. Meanwhile, the cataract progression was monitored by slit lamp microscope. As a result, rHV3 drops treatment significantly increased the activities of SOD and GSH-Px in the lens in a dose-dependent manner, whereas AR activity and MDA level in the lens were dramatically decreased. Also, the morphological observation further confirmed the inhibition of the development of STZ-induced diabetic cataracts by the rHV3 drops treatment. Thus, our data suggest that rHV3 drops are pharmacologically effective for the protection against STZ-induced diabetic cataracts in rats.

Translational success stories: development of direct thrombin inhibitors.

Anticoagulants are the cornerstone of therapy for conditions associated with arterial and venous thrombosis. Direct thrombin inhibitors (DTIs) are anticoagulants that bind to thrombin and block its enzymatic activity. The bivalent parenteral DTIs hirudin and bivalirudin were based on the observation that the salivary extracts of medicinal leeches prevented blood from clotting. Key events that facilitated the subsequent development of small molecule active site inhibitors, such as argatroban, were the observation that fibrinopeptide A had antithrombotic properties and determination of the crystal structure of thrombin. Hirudin and argatroban have found their niche for the treatment of patients with heparin-induced thrombocytopenia, whereas bivalirudin is approved as an alternative to heparin for patients undergoing percutaneous coronary intervention. The development of orally active direct thrombin inhibitors was challenging because of the need to convert water-soluble, poorly absorbable, active site inhibitors into fat-soluble prodrugs that were then transformed back to the active drug after intestinal absorption. Dabigatran etexilate was the first new oral anticoagulant to be approved for long-term anticoagulant treatment in 6 decades. This Review highlights the development of DTIs as a translational success story; an example in which the combination of scientific ingenuity, structure-based design, and rigorous clinical trials has created a new class of anticoagulants that has improved patient care.