An updated concept of coagulation with clinical implications

Development and verification of a novel blood viscoelastic monitoring method based on reciprocating motion of magnetic bead

Blood coagulation function is an essential index in clinical examination, and it is of great significance to evaluate blood coagulation function comprehensively. Based on the blood viscoelasticity theory and hydrodynamics, we proposed a method to monitor the whole blood coagulation process based on the reciprocating motion of the magnetic bead (magnetic bead method for short). We have established a mathematical model between the moment acting on the magnetic bead and the viscoelasticity of blood in the process of blood coagulation. The change of blood viscoelasticity acks on the magnetic bead in the form of moment changes, which shows that the amplitude of the motion of the magnetic bead varies with the change of blood viscoelasticity. Designed and verified a blood coagulation monitoring device based on the reciprocating movement of the magnetic bead and discussed the device's parameters through the orthogonal experiment. Lastly, the TEG5000 was used as the control group to test the thromboelasticity of four groups of thromboelastography quality control products in the same batch and 10 groups of human whole blood. It verified that our device has good repeatability, and has good consistency with TEG5000, it has particular application potential as a new blood coagulation monitoring method.

Low Bone Mineral Density in Hemophiliacs

Objective

To review the current knowledge on bone health in patients with hemophilia A and the underlying pathogenetic mechanisms.

Data Sources

Original research articles, meta-analyses, and scientific reviews.

Data Synthesis

Already in childhood, patients with hemophilia A are prone to low bone mineral density, leading to osteopenia and/or osteoporosis. Initially associated with the life style of hemophilia, today we are faced with accumulating evidence that coagulation factor VIII is involved directly or indirectly in bone physiology.

Conclusion

Understanding the role of factor VIII and the mechanisms of decreased bone mineral density in hemophilia A is critically important, especially as non-factor replacement therapies are available, and treatment decisions potentially impact bone health.

Antithrombotic Therapy in Patients with Peripheral Artery Disease: A Focused Review on Oral Anticoagulation

Peripheral artery disease (PAD) is a major cause of morbidity and mortality but it is usually underdiagnosed and undertreated. Patients with PAD present dysregulated procoagulant, anticoagulant, and fibrinolytic pathways leading to arterial and venous thrombosis. The risk of several ischemic-related complications could be mitigated with appropriate antithrombotic therapy, which plays a central role in all types of PAD. For years, antiplatelets have been indicated in patients with symptomatic PAD or those who have undergone revascularization. Unfortunately, a non-negligible proportion of patients with PAD will suffer from adverse events during the follow-up, even despite proper medical therapies for the prevention of PAD complications. Thus, there is room for improving clinical outcomes in these patients. Given the implication of both, primary and secondary hemostasis in arterial thrombosis and the pathophysiology of PAD, the combination of antiplatelets and anticoagulants has emerged as a potential antithrombotic alternative to antiplatelets alone. In this narrative review article, we have highlighted the most recent evidence about antithrombotic therapy in PAD patients, with a special focus on oral anticoagulation. Certainly, COMPASS and VOYAGER PAD trials have shown promising results. Thus, rivaroxaban in combination with aspirin seem to reduce cardiovascular outcomes with a similar bleeding risk compared to aspirin alone. Nevertheless, results from real-world studies are needed to confirm these observations, and other trials will provide novel evidence about the safety and efficacy of emerging anticoagulant agents.

Thrombin: A Pivotal Player in Hemostasis and Beyond

The serine protease thrombin, a naturally derived enzyme, plays a key role in hemostasis by converting fibrinogen to fibrin and activating coagulation factor XIII whereby the fibrin clot is stabilized. Furthermore, thrombin activates platelets through protease-activated receptors on the platelet surface. Conversely, thrombin also exerts anticoagulant effects, enhancing the protein C activity while complexed with thrombomodulin. During recent years, it has become evident that thrombin has significant effects beyond hemostasis, as it contributes also to modulation of the endothelium, promotes inflammation and angiogenesis, and plays a role in tumor progression. Yet, due to the very short half-life and almost immediate inhibition in fluid phase by antithrombin, thrombin itself remains elusive, and only indirect measurement of thrombin generation is possible. This review provides a description of structure and mechanisms of action of thrombin both in physiological and pathological processes. Furthermore, it summarizes laboratory tests that measure in vivo or ex vivo thrombin generation, and presents knowledge on the value of these biomarkers in bleeding disorders, cardiopulmonary bypass surgery, and thromboembolic risk assessment in different patient populations. Finally, this review outlines further perspectives on using thrombin generation biomarkers for research purposes and in clinical practice.

Dental extraction in patients receiving dual antiplatelet therapy

Background

Dual anti platelet therapy consists of administering antiplatelet (antiaggregant) drugs (clopidogrel and aspirin) to prevent thrombotic processes, as a preventative measure in patients with acute coronary disease, or in patients subjected to percutaneous coronary intervention.

Objectives

The purpose of this study was to evaluate the efficacy of a protocol for performing dental extraction in patients receiving dual anti platelet therapy.

Material and Methods

Thirty-two patients undergoing dental extractions were included in the study. The variables evaluated were: collagen-epinephrine fraction, collagen- adenosine diphosphate fraction, surgical surface, post-surgical measures, and adverse effects. Alveolar sutures and gauzes impregnated with an antifibrinolytic agent (tranexamic acid), which the patient pressed in place for 30 minutes, were applied to all patients as post-surgical measures. Descriptive statistics were calculated and analyzed with Student’s t-test to compare pairs of quantitative variables; simple regression analysis was performed using Pearson’s correlation coefficient. Statistical significance was set at p<0.05.

Results

Collagen/epinephrine fraction was 264.53±55.624 seconds with a range of 135 to 300 seconds, and collagen/ADP fraction was 119.41±44.216 seconds, both values being higher than normal. As a result of the post-surgical measures taken, no patients presented postoperative bleeding, hematoma or infection.

Conclusions

Dental extraction was safe for patients receiving dual anti-platelet therapy when using sutures and gauze impregnated with tranexamic acid, which the patient pressed in place for 30 minutes.

Key words: Aspirin, clopidogrel, tranexamic acid, dental extraction, platelet function.

Diagnostic morphology: biophysical indicators for iron-driven inflammatory diseases

Most non-communicable diseases involve inflammatory changes in one or more vascular systems, and there is considerable evidence that unliganded iron plays major roles in this. Most studies concentrate on biochemical changes, but there are important biophysical correlates. Here we summarize recent microscopy-based observations to the effect that iron can have major effects on erythrocyte morphology, on erythrocyte deformability and on both fibrinogen polymerization and the consequent structure of the fibrin clots formed, each of which contributes significantly and negatively to such diseases. We highlight in particular type 2 diabetes mellitus, ischemic thrombotic stroke, systemic lupus erythematosus, hereditary hemochromatosis and Alzheimer's disease, while recognizing that many other diseases have co-morbidities (and similar causes). Inflammatory biomarkers such as ferritin and fibrinogen are themselves inflammatory, creating a positive feedback that exacerbates disease progression. The biophysical correlates we describe may provide novel, inexpensive and useful biomarkers of the therapeutic benefits of successful treatments.

Influence of the concomitant use of heparin on the effects of warfarin during catheter ablation for atrial fibrillation

Warfarin is widely used to perform catheter ablation for atrial fibrillation (AF). Heparin is usually administered during this procedure to prevent thromboembolic events, while protamine is used to reduce the incidence of bleeding complications. The purpose of this study was to investigate the influence of heparin and protamine administration on the effects of warfarin and its safety. The subjects included 226 AF patients (206 males, 54.9 ± 9.1 years, paroxysmal/persistent AF: 118/108) undergoing AF ablation with the discontinuation of warfarin administration over 2 days. Heparin was administered to achieve an activated clotting time (ACT) above 300 s during the procedure. Several parameters of the coagulation status, including the prothrombin time international normalized ratio (PT-INR) and ACT values, measured immediately before and after protamine infusion were compared. The mean value of PT-INR prior to ablation was 1.9 ± 0.6. At the end of the procedure, the mean ACT and PT-INR values were 348.0 ± 52.9 and 2.9 ± 0.7, respectively. Following the infusion of 30 mg of protamine, both the ACT and PT-INR values significantly decreased, to 159.6 ± 31.0 (p < 0.0001) and 1.6 ± 0.3 (p < 0.0001), respectively. No cases of symptomatic cerebral infarction were observed, although femoral hematomas developed in 17 (7.5 %) of the patients without further consequence. The concomitant use of heparin augments the effect of warfarin. Meanwhile, protamine administration immediately reverses both the ACT and PT-INR, indicating the applicability of protamine for AF ablation in patients under the mixed administration of heparin and warfarin.

Dental management of patients receiving anticoagulant and/or antiplatelet treatment

Introduction: Adequate hemostasis is crucial for the success of invasive dental treatment, since bleeding problems can give rise to complications associated with important morbidity-mortality. The dental treatment of patients who tend to an increased risk of bleeding due to the use of anticoagulant and/or antiplatelet drugs raises a challenge in the daily practice of dental professionals. Adequate knowledge of the mechanisms underlying hemostasis, and the optimized management of such patients, are therefore very important issues. Objectives: A study is made of the anticoagulant / antiplatelet drugs currently available on the market, with evaluation of the risks and benefits of suspending such drugs prior to invasive dental treatment. In addition, a review is made of the current management protocols used in these patients. Material and Methods: A literature search was made in the PubMed, Cochrane Library and Scopus databases, covering all studies published in the last 5 years in English and Spanish. Studies conducted in humans and with scientific evidence levels 1 and 2 (metaanalyses, systematic reviews, randomized phase 1 and 2 trials, cohort studies and case-control studies) were considered. The keywords used for the search were: tooth extraction, oral surgery, hemostasis, platelet aggregation inhibitors, antiplatelet drugs, anticoagulants, warfarin, acenocoumarol. Results and Conclusions: Many management protocols have been developed, though in all cases a full clinical history is required, together with complementary hemostatic tests to minimize any risks derived from dental treatment. Many authors consider that patient medication indicated for the treatment of background disease should not be altered or suspended unless so indicated by the prescribing physician. Local hemostatic measures have been shown to suffice for controlling possible bleeding problems resulting from dental treatment.

Key words:Tooth extraction, oral surgery, hemostasis, platelet aggregation inhibitors, antiplatelet drugs, anticoagulants, warfarin, acenocoumarol.

[Clinical manifestations of hematological non-neoplastic diseases in Dentistry]

Systemic disease can cause clinical manifestations in the oral and maxillofacial area, which is important to recognize because it could be the first symptom of an undiagnosed illness. There are different oral signs that could suggest the clinician a blood disorder, such as pallor, petechiae, ecchymosis, ulcerations, gingival hypertrophy or spontaneous gingival bleeding. In addition, blood disorders will determine the dental management of these patients and the protocol for limiting possible complications that may arise due to the treatment itself. This paper reviews the oral manifestations and dental management of non-neoplastic alterations of red cells, white cells and hemostasis, with emphasis on two-way relationship that must exist between the dentist and the patient's hematologist for making a treatment plan.

Implication of haematophagous arthropod salivary proteins in host-vector interactions

The saliva of haematophagous arthropods contains an array of anti-haemostatic, anti-inflammatory and immunomodulatory molecules that contribute to the success of the blood meal. The saliva of haematophagous arthropods is also involved in the transmission and the establishment of pathogens in the host and in allergic responses. This survey provides a comprehensive overview of the pharmacological activity and immunogenic properties of the main salivary proteins characterised in various haematophagous arthropod species. The potential biological and epidemiological applications of these immunogenic salivary molecules will be discussed with an emphasis on their use as biomarkers of exposure to haematophagous arthropod bites or vaccine candidates that are liable to improve host protection against vector-borne diseases.