Management of the clotting system: a European perspective. Curr Opin Anaesthesiol. 2012;25:80-85. [PMID: 22157197 DOI: 10.1097/aco.0b013e32834ef3d1]

Biomaterials-Enabled Antithrombotics: Recent Advances and Emerging Strategies

Antithrombotic and thrombolytic therapies are used to prevent, treat, and remove blood clots in various clinical settings, from emergent to prophylactic. While ubiquitous in their healthcare application, short half-lives, off-target effects, overdosing complications, and patient compliance continue to be major liabilities to the utility of these agents. Biomaterials-enabled strategies have the potential to comprehensively address these limitations by creating technologies that are more precise, durable, and safe in their antithrombotic action. In this review, we discuss the state of the art in anticoagulant and thrombolytic biomaterials, covering the nano to macro length scales. We emphasize current methods of formulation, discuss how material properties affect controlled release kinetics, and summarize modern mechanisms of clot-specific drug targeting. The preclinical efficacy of these technologies in an array of cardiovascular applications, including stroke, pulmonary embolism, myocardial infarction, and blood contacting devices, is summarized and performance contrasted. While significant advances have already been made, ongoing development efforts look to deliver bioresponsive "smart" biomaterials that will open new precision medicine opportunities in cardiology.

Viscoelastic testing in cardiac surgery

Bleeding complications are common in cardiac surgery and lead to an increase in morbidity and mortality. This is multifactorial in aetiology including the effects of cardiopulmonary bypass, the drugs given to manipulate the coagulation system and the vascular nature of the surgery itself. Viscoelastic tests provide a point of care, rapid assessment of coagulation which offer the advantage of faster turnaround times and a nuanced view of the elements of the coagulation system allowing targeted therapy to be delivered quickly. Both thomboelastography (TEG)and thromboelastometry (ROTEM) have been recommended for use in cardiac surgery, both have shown a reduction in transfusion and bleeding when used as part of a testing algorithm. They are particularly useful in assessing residual heparinisation and fibrinogen levels. Additionally, TEG allows the evaluation of the effects of anti-platelet agents on platelet function. This review discusses the mechanisms by which bleeding occurs in cardiac surgery and explores three uses of viscoelastic testing in cardiac surgery: to predict bleeding, to assess platelet function and peri-operative testing to reduce transfusion.

Tranexamic acid in cardiac surgery: a systematic review and meta-analysis (protocol)

INTRODUCTION

Bleeding during cardiac surgery is associated with increased morbidity and mortality. Tranexamic acid is an antifibrinolytic with proven efficacy in major surgeries. Current clinical practice guidelines recommend intraoperative use in cardiac procedures. However, several complications have been reported with tranexamic acid including seizures. This review intends to summarise the evidence examining the efficacy and safety of tranexamic acid in patients undergoing cardiac surgery.

METHODS/DESIGN

We will search MEDLINE, Embase, PubMED, ACPJC, CINAHL and the Cochrane trial registry for eligible randomised controlled trials, the search dates for all databases will be from inception until 1 January 2019, investigating the perioperative use of topical and/or intravenous tranexamic acid as a stand-alone antifibrinolytic agent compared with placebo in patients undergoing open cardiac surgery. We categorised outcomes as patient critical or patient important. Selected patient-critical outcomes are: mortality (intensive care unit, hospital and 30-day endpoints), reoperation within 24 hours, postoperative bleeding requiring transfusion of packed red blood cells, myocardial infarction, stroke, pulmonary embolism, bowel infarction, upper or lower limb deep vein thrombosis and seizures. Those outcomes, we perceived as clinical experts to be most patient valued and patients were not involved in outcomes selection process. We will not apply publication date, language, journal or methodological quality restrictions. Two reviewers will independently screen and identify eligible studies using predefined eligibility criteria and then review full reports of all potentially relevant citations. A third reviewer will resolve disagreements if consensus cannot be achieved. We will present the results as relative risk with 95% CIs for dichotomous outcomes and as mean difference or standardised mean difference for continuous outcomes with 95% CIs. We will assess the quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as primary data will not be collected. The results will be disseminated through a peer-reviewed publication TRIAL REGISTRATION NUMBER: CRD42018105904.

Hemoglobin optimization and transfusion strategies in patients undergoing cardiac surgery

Although red blood cells (RBCs) transfusion is sometimes associated with adverse reactions, anemia could also lead to increased morbidity and mortality in high-risk patients. For these reasons, the definition of perioperative strategies that aims to detect and treat preoperative anemia, prevent excessive blood loss, and define “optimal” transfusion algorithms is crucial. Although the treatment with preoperative iron and erythropoietin has been recommended in some specific conditions, several controversies exist regarding the benefit-to-risk balance associated with these treatments. Further studies are needed to better define the indications, dosage, and route of administration for preoperative iron with or without erythropoietin supplementation. Although restrictive transfusion strategies in patients undergoing cardiac surgery have been shown to effectively reduce the incidence and the amount of RBCs transfusion without increase in side effects, some high-risk patients (e.g., symptomatic acute coronary syndrome) could benefit from higher hemoglobin concentrations. Despite all efforts made last decade, a significant amount of work remains to be done to improve hemoglobin optimization and transfusion strategies in patients undergoing cardiac surgery.

Application of long-acting VLHL PAI-1 during sutureless partial nephrectomy in mice reduces bleeding

PAI-1 prevents lysis of blood clot by inhibiting the urokinase and tPA induced conversion of plasminogen to plasmin. VLHL PAI-1 protein mutant was created to extend half-life over 700 hours. The objective of this paper was to test VLHL PAI-1 effects on bleeding during partial nephrectomy in mice. All animals had a left partial nephrectomy after intravenous infusion of saline or tPA. The animals were divided into four groups. Group 1 was infused with saline and kidney was exposed to saline too; Group 2 was infused with saline and kidney was exposed to PAI-1. Group 3 was infused with tPA and kidney was exposed to saline, while Group 4 was infused with tPA and kidney was exposed to PAI-1. Preweighed gauze containing PAI-1 or saline was then applied to the kidney for 30 minutes. The gauze was afterward weighed and blood loss was measured by subtracting the preweight of gauze from the final weight. We have observed a statistically significant (P ≤ 0.05) reduction of bleeding in PAI-1-treated group in comparison to saline and tPA-treated groups. Based on these results we propose that VLHL PAI-1 can be used therapeutically in limiting the flow of blood from renal wounds.