Comparison of Clinical Scoring Tools to Predict Heparin-Induced Thrombocytopenia in Cardiac Surgery

The 4Ts and HIT-Expert Probability (HEP) scoring tools for heparin-induced thrombocytopenia (HIT) have not been validated in cardiac surgery patients, and the reported sensitivity and specificity of the Post-Cardiopulmonary Bypass (CPB) scoring tool vary widely in the 2 available analyses. It remains unclear which of the available scoring tools most accurately predicts HIT in this population. Forty-nine HIT-positive patients who underwent on-pump cardiac surgery within a 6-year period were loosely matched to 98 HIT-negative patients in a 1:2 case-control design. The 4Ts, HEP, and CPB scores were calculated for each patient. Sensitivity and specificity of each tool were calculated using standard cut-offs. The Youden method was utilized to determine optimal cut-offs within receiver operating characteristic (ROC) curves of each score, after which sensitivities and specificities were recalculated. Using standard cut-offs, the sensitivities for the CPB, HEP, and 4Ts scores were 100%, 93.9%, and 69.4%, respectively. Specificities were 51%, 49%, and 71.4%, respectively. The AUC of the scoring tool ROC curves were 0.961 for the CPB score, 0.773 for the HEP score, and 0.805 for the 4Ts score. Using the Youden method-derived optimal cut-off of  ≥3 points on the CPB score, sensitivity remained 100% with improved specificity to 88.9%. The CPB score is the preferred HIT clinical scoring tool in adult cardiac surgery patients, whereas the 4Ts score performed less effectively. A cut-off of ≥ 3 points on the CPB score could increase specificity while preserving high sensitivity, which should be validated in a prospective evaluation.

North American Physician Practice Patterns in the Management of Anticoagulation in Pregnancy

Background: During pregnancy and in the postpartum period women are at increased risk of venous thromboembolism (VTE) owing to hypercoagulability and mechanical issues, as well as nonpregnancy conditions including inherited and acquired thrombophilia. Although guidelines exist for the use of thromboprophylaxis in this setting, there are differences in the specifics of the recommendations among expert societies. We assessed the current practice patterns of North American providers in the prevention of pregnancy-associated VTE in women with thrombophilia. Methods: A survey was created and distributed with case studies and questions addressing VTE prevention during the antepartum and postpartum periods. Results: Surveys were completed by 28% of adult providers queried, with broad geographic representation. There was consistent use of a prophylactic dose of low-molecular weight heparin (LMWH) ante- and postpartum for individuals with low-risk thrombophilia and past estrogen-provoked VTE but a lack of a consensus of anticoagulant (AC) use and dose in individuals with higher risk thrombophilia. There was variability in the dose selection and monitoring of AC when using induction versus spontaneous labor, with 47% of providers switching from LMWH to unfractionated heparin for those not having a scheduled delivery, and there were differences in the duration of postpartum prophylaxis based upon delivery mode. Conclusion: In this survey of North American experienced specialists' responses to a variety of commonly encountered scenarios of thrombophilia and pregnancy and the management of AC were not always consistent with published guidelines.

Healthcare resource utilization and costs associated with venous thromboembolism in cancer patients treated with anticoagulants

Objective: The standard of care for cancer-related venous thromboembolism (VTE) has been low molecular weight heparin (LMWH), but oral anticoagulants are also widely prescribed. This study compared VTE-related healthcare resource utilization and costs of cancer patients treated with anticoagulants. Methods: Claims data from Humana Database (January 1, 2013-May 31, 2015) were analyzed. Based on the first anticoagulant received, patients were classified into LMWH, warfarin, or rivaroxaban cohorts. Characteristics were evaluated during the 6 months pre-index date (i.e. the first VTE); VTE-related resource utilization and costs were evaluated during follow-up. Cohorts were compared using rate ratios, and p-values and 95% confidence intervals were calculated. Healthcare costs were evaluated per-patient-per-year (PPPY) and compared using mean cost differences. Results: A total of 2,428 patients (LMWH: n = 660; warfarin: n = 1,061; rivaroxaban: n = 707) were included. Compared to patients treated with LMWH, patients treated with rivaroxaban had significantly fewer VTE-related hospitalizations, hospitalization days, and emergency room and outpatient visits, resulting in an increase of $12,000 VTE-related healthcare costs PPPY with LMWH vs rivaroxaban. Patients treated with rivaroxaban had significantly lower VTE-related resource utilization compared to patients treated with warfarin; however, VTE-related costs were similar between cohorts. The higher drug costs ($1,519) were offset by significantly lower outpatient (-$1,039) and hospitalization costs (-$522) in rivaroxaban relative to the warfarin cohort. Conclusions: Healthcare resource use and costs associated with VTE treatment in cancer patients are highest with LMWH relative to warfarin and rivaroxaban.

Multicenter analysis of the use of transjugular intrahepatic portosystemic shunt for management of MPN-associated portal hypertension

BCR-ABL1-negative myeloproliferative neoplasms (MPNs) are clonal stem cell disorders defined by proliferation of one or more myeloid lineages, and carry an increased risk of vascular events and progression to myelofibrosis and leukemia. Portal hypertension (pHTN) occurs in 7-18% of MPN patients via both thrombotic and nonthrombotic mechanisms and portends a poor prognosis. Transjugular intrahepatic portosystemic shunt (TIPS) has been used in the management of MPN-associated pHTN; however, data on long-term outcomes of TIPS in this setting is limited and the optimal management of medically refractory MPN-associated pHTN is not known. In order to assess the efficacy and long-term outcomes of TIPS in MPN-associated pHTN, we performed a retrospective analysis of 29 MPN patients who underwent TIPS at three academic medical centers between 1997 and 2016. The majority of patients experienced complete clinical resolution of pHTN and its clinical sequelae following TIPS. One, two, three, and four-year overall survival post-TIPS was 96.4%, 92.3%, 84.6%, and 71.4%, respectively. However, despite therapeutic anticoagulation, in-stent thrombosis occurred in 31.0% of patients after TIPS, necessitating additional interventions. In conclusion, TIPS can be an effective intervention for MPN-associated pHTN regardless of etiology. However, TIPS thrombosis is a frequent complication in the MPN population and indefinite anticoagulation post-TIPS should be considered.

Anti-Xa monitoring of low-molecular-weight heparin in adult patients with cancer

A 68-year-old man developed a right femoral vein deep vein thrombosis and bilateral pulmonary embolism while receiving chemotherapy for stage IV prostate cancer. His creatinine at diagnosis is 1.4 mg/dL, with an estimated clearance of 63 mL/min. In patients with cancer, should low-molecular-weight heparin treatment be dosed according to weight, or adjusted using anti-Xa levels?

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia

Thrombophilias are hereditary and/or acquired conditions that predispose patients to thrombosis. Testing for thrombophilia is commonly performed in patients with venous thrombosis and their relatives; however such testing usually does not provide information that impacts management and may result in harm. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance for thrombophilia testing in five clinical situations: following 1) provoked venous thromboembolism, 2) unprovoked venous thromboembolism; 3) in relatives of patients with thrombosis, 4) in female relatives of patients with thrombosis considering estrogen use; and 5) in female relatives of patients with thrombosis who are considering pregnancy. Additionally, guidance is provided regarding the timing of thrombophilia testing. The role of thrombophilia testing in arterial thrombosis and for evaluation of recurrent pregnancy loss is not addressed. Statements are based on existing guidelines and consensus expert opinion where guidelines are lacking. We recommend that thrombophilia testing not be performed in most situations. When performed, it should be used in a highly selective manner, and only in circumstances where the information obtained will influence a decision important to the patient, and outweigh the potential risks of testing. Testing should not be performed during acute thrombosis or during the initial (3-month) period of anticoagulation.

Abstract 128: Risk Factors for Hospital-associated Venous Thromboembolism in Critically-ill Children with Cardiac Disease Undergoing Cardiothoracic Surgery or Cardiac Catheter-based Therapeutic Intervention

Background: Pediatric hospital-acquired venous thromboembolism (HA-VTE) has dramatically risen in recent years. Children with congenital or acquired heart disease are at particular risk and have not been addressed by recent, novel retrospectively-derived risk scores.

Aims: We sought to develop a risk model for HA-VTE in critically-ill children with cardiac disease.

Methods: We conducted a retrospective, case-control study of children admitted to the CVICU at All Children's Hospital Johns Hopkins Medicine (St. Petersburg, FL, USA) from January 2006 - April 2013. We identified cases via ICD-9 codes, and employed case validation via review of radiologic records. Two controls were randomly selected for each case. Associations between putative risk factors and HA-VTE were estimated using odds ratios (ORs) and ninety-five percent confidence intervals (95%CIs) from univariate and multivariate logistic regression analyses. Variables with P-values < 0.1 in univariate analyses were included in the multivariate model. A HA-VTE risk score was developed with weighting based on the relative magnitudes of the individual ORs from the multivariate model.

Results: After adjustment in a multiple logistic regression, length of stay (LOS) >30 days, cardiac catheterization, and major infection were found to be statistically-significant independent risk factors for HA-VTE in these children. An 8-point risk score was developed in which scores of 0-1, 2-6, and 7-8 yielded HA-VTE risks of < 1%, 1-< 2%, and ≥2%, corresponding to conventional thresholds for instituting no prophylaxis, mechanical prophylaxis, and pharmacological prophylaxis (respectively) in hospitalized adults.

Conclusions: LOS >30 days, cardiac catheterization, and major infection are significant independent risk factors for HA-VTE in critically-ill children with cardiac disease leading to the development of a novel HA-VTE risk score in this population. If prospectively validated, this risk score will inform the design of risk-stratified clinical trials of HA-VTE prevention.

Use of heparins in patients with cancer: individual participant data meta-analysis of randomised trials study protocol

INTRODUCTION

Parenteral anticoagulants may improve outcomes in patients with cancer by reducing risk of venous thromboembolic disease and through a direct antitumour effect. Study-level systematic reviews indicate a reduction in venous thromboembolism and provide moderate confidence that a small survival benefit exists. It remains unclear if any patient subgroups experience potential benefits.

METHODS AND ANALYSIS

First, we will perform a comprehensive systematic search of MEDLINE, EMBASE and The Cochrane Library, hand search scientific conference abstracts and check clinical trials registries for randomised control trials of participants with solid cancers who are administered parenteral anticoagulants. We anticipate identifying at least 15 trials, exceeding 9000 participants. Second, we will perform an individual participant data meta-analysis to explore the magnitude of survival benefit and address whether subgroups of patients are more likely to benefit from parenteral anticoagulants. All analyses will follow the intention-to-treat principle. For our primary outcome, mortality, we will use multivariable hierarchical models with patient-level variables as fixed effects and a categorical trial variable as a random effect. We will adjust analysis for important prognostic characteristics. To investigate whether intervention effects vary by predefined subgroups of patients, we will test interaction terms in the statistical model. Furthermore, we will develop a risk-prediction model for venous thromboembolism, with a focus on control patients of randomised trials.

ETHICS AND DISSEMINATION

Aside from maintaining participant anonymity, there are no major ethical concerns. This will be the first individual participant data meta-analysis addressing heparin use among patients with cancer and will directly influence recommendations in clinical practice guidelines. Major cancer guideline development organisations will use eventual results to inform their guideline recommendations. Several knowledge users will disseminate results through presentations at clinical rounds as well as national and international conferences. We will prepare an evidence brief and facilitate dialogue to engage policymakers and stakeholders in acting on findings.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42013003526.

Integrating electronic health records in the delivery of optimized anticoagulation therapy

Integration of accepted practice standards into electronic health record systems can facilitate standardization of anticoagulation care delivery and result in improved anticoagulation safety. However, the majority of commonly used electronic health record systems are lacking the specialized features necessary for optimal anticoagulation management. The Task Force on Electronic Health Records of the New York State Anticoagulation Coalition provides such a Consensus Statement in this issue of the journal. The Anticoagulation Forum endorses these recommendations and advises the electronic health record industry and health information technology programmers at the institutional level to adopt these recommendations in a comprehensive and timely manner.

Bleeding and clotting in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a relatively common inherited vascular disorder that was first described in 1864, and is notable for epistaxis, telangiectasia, and arterial venous malformations. While genetic tests are available, the diagnosis remains clinical, and is based on the Curacao criteria. Patients with HHT are at increased risk for both bleeding and clotting events. Because of these competing complications, hematologists are often faced with difficult clinical decisions. While the majority of management decisions revolve around bleeding complications, it is not infrequent for these patients to require anticoagulation for thrombosis. Any anticoagulation recommendations must take into account the bleeding risks associated with HHT. Recent reviews have found that HHT patients can be safely anticoagulated, with the most frequent complication being worsened epistaxis. Large clinical trials have shown that factor IIa and Xa inhibitors have less intracranial bleeding than warfarin, and basic coagulation research has provided a possible mechanism. This article describes the anticoagulation dilemma posed when a 62-year-old female patient with a history of bleeding events associated with HHT was diagnosed with a pulmonary embolism. The subsequent discussion focuses on the approach to anticoagulation in the HHT patient, and addresses the role of the new oral anticoagulants.

Unfractionated heparin dosing for therapeutic anticoagulation in critically ill obese adults

PURPOSE

Research evaluating unfractionated heparin (UFH) dosing in obese critically ill populations is limited. This study aimed to determine optimal weight-based and total therapeutic infusion rates of UFH in this population.

METHODS

This retrospective cohort study compared adults on UFH infusions in intensive care units from May 2011 through October 2013 across 3 weight strata: 95 to 104 kg (control), 105 to 129 kg (high weight), and greater than or equal to 130 kg (higher weight). Primary outcomes included total and weight-based infusion rates for therapeutic anticoagulation.

RESULTS

To achieve therapeutic activated partial thromboplastin times, higher weight patients had higher mean infusion rates compared with control (2017 vs 1582 U/h; P = .002). Mean weight-based therapeutic infusion rate was lower in the higher weight group compared with control (13.1 vs 15.8 U kg(-1) h(-1); P = .008). Post hoc analyses indicated mean weight-based infusion rate to achieve therapeutic anticoagulation was 15 U kg(-1) h(-1) in patients less than 165 kg and 13 U kg(-1) h(-1) in patients greater than 165 kg.

CONCLUSIONS

Patients greater than or equal to 130 kg have lower weight-based heparin requirements compared with patients 95 to 104 kg. This difference appears to be driven by patients greater than 165 kg. Patients greater than 165 kg have lower weight-based heparin requirements, whereas patients from 105 to 164 kg have weight-based requirements similar to a normal-weight patient population. Initiating heparin at appropriate weight-based doses for obese patients may optimize anticoagulation.

Implementing thrombosis guidelines in cancer patients: a review

Venous thromboembolism is a frequent and serious complication in patients with cancer. It is an independent prognostic factor of death in cancer patients and the second leading cause of death, but physicians often underestimate its importance, as well as the need for adequate prevention and treatment. Management of venous thromboembolism in patients with cancer requires the coordinated efforts of a wide range of clinicians, highlighting the importance of a multidisciplinary approach. However, a lack of consensus among various national and international clinical practice guidelines has contributed to knowledge and practice gaps among practitioners, and inconsistent approaches to venous thromboembolism. The 2013 international guidelines for thrombosis in cancer have sought to address these gaps by critically re-evaluating the evidence coming from clinical trials and synthesizing a number of guidelines documents. An individualized approach to prophylaxis is recommended for all patients.

Risk factors for hospital-sssociated venous thromboembolism in the neonatal intensive care unit

OBJECTIVE

To determine hospital-associated venous thromboembolism (HA-VTE) risk factors in critically ill neonates.

METHODS

We conducted a case-control study in the neonatal intensive care unit (NICU) of All Children's Hospital Johns Hopkins Medicine (St. Petersburg, FL), from January 1, 2006 - April 10, 2013. We identified HA-VTE cases using electronic health record. Four NICU controls were randomly selected for each HA-VTE case. Associations between putative risk factors and HA-VTE were estimated using odds ratios (ORs) and ninety-five percent confidence intervals (95%CIs) from univariate and multivariate regression analyses.

RESULTS

Twenty-three HA-VTE cases and 92 controls were included. The annual HA-VTE incidence was approximately 1.4 HA-VTE cases per 1,000 NICU admissions. In univariate analyses, mechanical ventilation (OR=7.27, 95%CI=2.02-26.17, P=0.002), central venous catheter (CVC; OR=52.95, 95%CI=6.80-412.71, P<0.001), infection (OR=7.24, 95%CI=2.66-19.72, P<0.001), major surgery (OR=5.60, 95%CI=1.82-17.22, P=0.003) and length of stay ≥15days (OR=6.67, 95%CI=1.85-23.99, P=0.004) were associated with HA-VTE. Only CVC (OR=29.04, 95%CI=3.18-265.26, P=0.003) remained an independent risk factor in the multivariate analysis. Based on this result, the estimated risk of HA-VTE in NICU patients with a CVC was 0.9%.

CONCLUSION

This study identifies CVC as an independent risk factor for HA-VTE in critically ill neonates. However, the level of risk associated with CVC is below the conventional threshold for primary anticoagulation thromboprophylaxis. Larger studies are needed to substantiate these findings and identify novel putative risk factors to further distinguish NICU patients at highest HA-VTE risk.

An update on type 2B von Willebrand disease

Type 2B von Willebrand disease (VWD) accounts for fewer than 5% of all VWD patients. In this disease, mutations in the A1 domain result in increased von Willebrand factor (VWF) binding to platelet GPIbα receptors, causing increased platelet clearance and preferential loss of high molecular weight VWF multimers. Diagnosis is complicated because of significant clinical variations even among patients with identical mutations. Platelet transfusion often provides suboptimal results since transfused platelets may be aggregated by the patients' abnormal VWF. Desmopressin may cause a transient decrease in platelet count that could lead to an increased risk of bleeding. Replacement therapy with factor VIII/VWF concentrates is the most effective approach to prevention and treatment of bleeding in type 2B VWD.

The use of novel oral anticoagulants for thromboprophylaxis after elective major orthopedic surgery

Venous thromboembolism is a common cause of morbidity and mortality among patients undergoing elective orthopedic surgery. Due to the high incidence of venous thromboembolism in this setting, perioperative anticoagulation is the recommended approach for thromboprophylaxis. Low molecular weight heparin (LMWH), fondaparinux and warfarin are the agents commonly used for thromboprophylaxis. The well-recognized limitations of warfarin and the inconvenience and discomfort associated with the subcutaneous administration of low molecular weight heparin and fondaparinux inspired intense investigation to develop novel oral anticoagulants (NOACs) with more predictable pharmacokinetics, fewer drug interactions and no need for regular laboratory monitoring. Three NOACs have been demonstrated to be effective for thromboprophylaxis after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in large randomized controlled trials. Here we review the pharmacology of rivaroxaban, dabigatran, and apixaban, summarize the major clinical trials of these agents in thromboprophylaxis after THA and TKA, and discuss the clinical factors to be considered by providers when selecting a NOAC for their patients.

Iliac vein compression as risk factor for left- versus right-sided deep venous thrombosis: case-control study

PURPOSE

To determine if compression of the left common iliac vein (LCIV) by the right common iliac artery is associated with left-sided deep venous thrombosis (DVT).

MATERIALS AND METHODS

This institutional review board-approved case-control study was performed in a cohort of 230 consecutive patients (94 men, 136 women; mean age, 57.5 years; range, 10-94 years) at one institution who had undergone contrast material-enhanced computed tomography of the pelvis prior to a diagnosis of unilateral DVT. Demographic data and information on risk factors were collected. Two board-certified radiologists determined iliac vein compression by using quantitative measures of percentage compression {[1 minus (LCIV diameter at point of maximal compression/distal right common iliac vein diameter)] times 100%}, as well as qualitative measures (none, mild, moderate, severe), with estimates of measurement variability. Logistic regression analysis was performed (independent variable, left vs right DVT; dependent variable, iliac vein compression). Cutpoints of relevant compression were evaluated by using splines. Means (with 95% confidence intervals [CIs]) and odds ratios (ORs) (and 95% CIs) of left DVT per 1% increase in percentage compression were calculated.

RESULTS

Patients with right DVT were more likely than those with left DVT to have a history of pulmonary embolism. Overall, in all study patients, mean percentage compression was 36.6%, 66 (29.7%) of 222 had greater than 50% compression, and 16 (7.2%) had greater than 70% compression. At most levels of compression, increasing compression was not associated with left DVT (adjusted ORs, 1.00, 0.99, 1.02) but above 70%, LCIV compression may be associated with left DVT (adjusted ORs, 3.03, 0.91, 10.15).

CONCLUSION

Increasing levels of percentage compression were not associated with left-sided DVT up to 70%; however, greater than 70% compression may be associated with left DVT.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111580/-/DC1.

Is venous thromboembolism in colorectal surgery patients preventable or inevitable? One institution's experience

BACKGROUND

The rate of venous thromboembolism (VTE) in colorectal surgery patients is reportedly high. Herein, we describe characteristics of patients developing VTE in the early postoperative period.

STUDY DESIGN

A retrospective cohort analysis was conducted using institutional comprehensive data on colorectal surgery patients from the National Surgical Quality Improvement Program. All patients from July 2009 to July 2011 were included. Multivariable logistic regression was used to assess which factors were associated with increased risk of developing VTE within 30 days of operation.

RESULTS

There were 615 patients who underwent colorectal surgery. Twenty-five (4.1%) developed VTE; 16 (2.6%) deep venous thrombosis (DVT), 4 (0.7%) pulmonary embolus (PE), and 5 (0.8%) developed both DVT and PE. Among VTE patients, 23 (92%) were ordered risk-appropriate VTE prophylaxis. On multivariable analysis, risk factors associated with VTE included postoperative infection (odds ratio [OR] 4.21, 95% CI 1.79, 9.89; p = 0.001), disseminated cancer (OR 4.38, 95% CI 1.24, 15.42; p = 0.022), and emergent status (OR 2.80, 95% CI 1.15, 6.85; p = 0.024). Fourteen (56.0%) of the 25 VTE patients also developed infectious complications compared with 168 (28.5%) of patients without VTE (p = 0.001). Organ space surgical site infections were the most common infection, present in 7 VTE patients. The infectious complications in 9 (64.3%) of the 14 patients occurred before or the same day as the VTE.

CONCLUSIONS

Most VTE events occurred in colorectal surgery patients ordered current best practice prophylaxis for VTE. Further investigation is warranted to identify patients at increased risk for VTE and to develop new strategies to further reduce the incidence of postoperative VTE.

Management of acquired thrombophilic disorders in 2011: focus on heparin-induced thrombocytopenia, antiphospholipid syndrome, myeloproliferative neoplasms and paroxysmal nocturnal hemoglobinuria

Arterial and venous thrombosis are interrelated disorders at the interplay of platelets and fibrin. Arterial thrombi are platelet-rich and occur at sites vulnerable to atherosclerotic plaque rupture where blood shear rates are high; on the contrary, venous thrombi occur in association with slow blood flow and shear rates. These differences may underlie why anti-platelet agents are more effective in prevention of arterial thrombosis, while anticoagulants are preferred for venous thrombosis. Although some common thrombophilic disorders (e.g., Factor V Leiden, prothrombin gene mutation, etc.) are almost exclusively associated with venous thromboembolism, there are several disorders that are important to consider when caring for patients with both arterial and venous thromboembolism. This article will review the evidence-based management of heparin induced thrombocytopenia with thrombosis, anti-phospholipid antibody syndrome and catastrophic anti-phospholipid antibody syndrome, thrombohemorrhagic manifestations of Philadelphia chromosome-negative chronic myeloproliferative neoplasms including polycythemia vera, essential thrombocythemia and primary myelofibrosis, as well as paroxysmal nocturnal hemoglobinuria.

Dabigatran etexilate: what do hospitalists need to know?

Dabigatran etexilate (dabigatran) is a novel, oral, reversible, direct thrombin inhibitor that exhibits several advantages over warfarin for therapeutic anticoagulation. The predictable pharmacokinetic profile and minimal food and drug interactions of dabigatran allow for a fixed-dosing regimen and obviate the need for routine laboratory monitoring. Dabigatran has been approved in the United States for prevention of stroke in patients with nonvalvular atrial fibrillation and in the European Union and other countries for primary prevention of thromboembolic events after total knee or hip replacement. More indications for the use of dabigatran are under review by regulatory authorities and are undergoing active clinical investigation. Due to its rapid onset of action, dabigatran may omit the need for a parenteral anticoagulant for acute treatment of thromboembolic conditions. Because wide-scale use of dabigatran is expected in the near future, hospitalists need to familiarize themselves with this agent. The lack of a standardized reliable laboratory method to monitor the anticoagulant effects of dabigatran complicates verifying compliance, measuring the effects of drug interactions, evaluating cases of dabigatran toxicity, and conducting preoperative evaluations. The lack of an antidote to dabigatran complicates the management of toxicity and makes it largely supportive. The elimination of dabigatran is dependent on renal function, with the potential for drug accumulation and toxicity with renal impairment. The noninferiority design of the clinical trials that evaluated dabigatran and the absence of long-term safety and efficacy data and issues related to the cost effectiveness of dabigatran should all be considered when prescribing this agent.

Coronary stent management in elective genitourinary surgery

What's known on the subject? and What does the study add? Withdrawal of dual antiplatelet therapy before the recommended, 12 months for drug-eluting stents and 1 month for bare-metal stents increases the rate of major adverse coronary events and mortality. However, in those undergoing surgery the risk of bleeding is increased substantially for those on antiplatelet agents. Successful management in patients with coronary stents who must undergo elective or non-elective urological surgery should be a multidisciplinary decision. This article reviews the literature and recommends a protocol for clinical management of patients undergoing urological procedures after coronary stent placement. To review the literature on coronary stents and genitourinary surgery and provide a protocol for perioperative. The keywords, 'elective surgery', 'aspirin', 'clopidogrel', 'guidelines for percutaneous coronary intervention', and 'antiplatelet therapy after coronary stent placement' were used to search PubMed for any relevant articles relating to coronary stents. Recommendations were made based on the whether the procedures patients were exposed to placed them at low-, moderate- or high-bleeding risk based on the extent of the procedure. All elective procedures should be delayed for 1 month after bare-metal stent placement and 1 year after drug-eluting stent placement. In patients classified as low risk (endoscopy and laser prostatectomy), aspirin should be continued throughout the perioperative period and dual antiplatelet therapy should continue 24-48 h postoperatively, if there is no concern for active bleeding. In those classified as moderate risk (scrotal procedures, transurethral resection of bladder tumours, transurethral resection of the prostate, urinary sphincter placement) dual antiplatelet therapy should be discontinued 5-7 days before the procedure and continued within 7 days after procedure, if there is no concern for active bleeding, in consultation with cardiology. In high-risk procedures (cystectomy, nephrectomy, prostatectomy, penile prosthesis placement) dual antiplatelet therapy should be discontinued 10 days before the procedure and continued postoperatively within 7-10 days of the procedure, when there is no longer a concern for active bleeding with the assistance of a cardiologist. Coronary artery disease is becoming more prominent in our society, increasing the use of coronary stents and antiplatelet agents. With the proposed protocol, it is safe to proceed with surgical intervention in those that have adequate stent endothelialisation.

Diagnosis and management of venous thromboembolism: an update a decade into the new millennium

Venous thromboembolism refers to thrombotic events in the venous system that are most commonly manifested as deep vein thromboses in the upper or lower extremity and/or pulmonary embolism. Venous thromboembolism is a common disorder that is associated with significant mortality, morbidity and health care-related cost. An array of hereditary and acquired risk factors are associated with venous thromboembolism. In recent years, a number of pivotal studies have expanded our understanding of the pathophysiology of venous thromboembolism, and served as the basis for evidence-based guidelines on prevention, diagnosis and treatment of venous thromboembolism. Furthermore, several novel therapeutic agents with different pharmacokinetics, pharmacodynamics and safety profiles have recently become available for treatment and prevention of venous thromboembolism. The purpose of the current paper is to review the pathogenesis and epidemiology of venous thromboembolism as well as an evidence-based approach to the diagnosis and management of venous thromboembolism.

The chemokine receptor Cxcr3 is not essential for acute cardiac allograft rejection in mice and rats

Chemokine receptors have gained attention as potential targets for novel therapeutic strategies. We investigated the mechanisms of allograft rejection in chemokine receptor Cxcr3-deficient mice using a model of acute heart allograft rejection in the strain combination BALB/c to C57BL/6. Allograft survival was minimally prolonged in Cxcr3-deficient mice compared to wild-type (wt) animals (8 vs. 7 days) and treatment with a subtherapeutic dose of cyclosporine A (CsA) led to similar survival in Cxcr3-deficient and wt recipients (13 vs. 12 days). At rejection grafts were histologically indistinguishable. Microarray analysis revealed that besides Cxcr3 only few genes were differentially expressed in grafts or in spleens from transplanted or untransplanted animals. Transcript analysis by quantitative RT-PCR of selected cytokines, chemokines, or chemokine receptors or serum levels of selected cytokines and chemokines showed similar levels between the two groups. Furthermore, in a rat heart allograft transplantation model treatment with a small molecule CXCR3 antagonist did not prolong survival despite full blockade of Cxcr3 in vivo. In summary, Cxcr3 deficiency or pharmacologic blockade does not diminish graft infiltration, tempo and severity of rejection. Thus, Cxcr3 does not appear to play a pivotal role in the allograft rejection models described here.

Nonbacterial Thrombotic Endocarditis in Cancer Patients: Pathogenesis, Diagnosis, and Treatment

Thrombophilia is a well-described consequence of cancer and its treatment. The pathogenesis of this phenomenon is complex and multifactorial. Nonbacterial thrombotic endocarditis (NBTE) is a serious and potentially underdiagnosed manifestation of this prothrombotic state that can cause substantial morbidity in affected patients, most notably recurrent or multiple ischemic cerebrovascular strokes. Diagnosis of NBTE requires a high degree of clinical suspicion as well as the judicious use of two-dimensional echocardiography to document the presence of valvular thrombi. In the absence of contraindications to therapy, treatment consists of systemic anticoagulation, which may ameliorate symptoms and prevent further thromboembolic episodes, as well as control of the underlying malignancy whenever possible.

Photochemically treated fresh frozen plasma for transfusion of patients with acquired coagulopathy of liver disease

An ex vivo photochemical treatment (PCT) process was developed to inactivate pathogens in fresh frozen plasma (PCT-FFP). A prospective, controlled, double-blinded, randomized study was conducted to evaluate the efficacy and safety of PCT-FFP compared with conventional FFP (C-FFP). Patients (n = 121) with acquired coagulopathy, largely due to liver disease, including hepatic transplantation, were transfused with either PCT-FFP or C-FFP for up to 7 days. Primary end points were changes in the prothrombin time (PT) and the partial thromboplastin time (PTT) in response to the first FFP transfusion. Secondary analyses compared changes in the PT and the PTT, factor VII levels, clinical hemostasis, blood component usage, and safety following FFP transfusions for up to 7 days. Following the first transfusion, correction in the PT and PTT adjusted for FFP dose and patient weight was not different. Changes in the PT were equivalent between treatment groups (P = .002 by noninferiority). Equivalence was not demonstrated for changes in the PTT. Following multiple transfusions, correction of the PT and the PTT was similar between groups. No differences were observed in use of blood components, clinical hemostasis, or safety. These results suggest PCT-FFP supported hemostasis in the treatment of acquired coagulopathy similarly to conventional FFP.

Fresh frozen plasma prepared with amotosalen HCl (S-59) photochemical pathogen inactivation: transfusion of patients with congenital coagulation factor deficiencies

BACKGROUND

Photochemical treatment (PCT) with amotosalen HCl (S-59) was developed to inactivate pathogens and white blood cells in plasma (PCT-FFP) used for transfusion support.

STUDY DESIGN AND METHODS

An open-label, multicenter trial was conducted in patients with congenital coagulation factor deficiencies (factors [F]I, FII, FV, FVII, FX, FXI, and FXIII and protein C) to measure the kinetics of specific coagulation factors, hemostatic efficacy, and safety of PCT-FFP. Posttransfusion prothrombin time (PT), partial thromboplastin time (PTT), and clinical hemostasis were evaluated before and after PCT-FFP transfusions.

RESULTS

Thirty-four patients received 107 transfusions of PCT-FFP for kinetic studies or therapeutic indications (mean dose, 12.8 +/- 8.5 mL/kg). Incremental factor recoveries ranged from 0.9 to 2.4 IU per dL per IU per kg (FII, FV, FVII, FX, FXI, and protein C). Mean pretransfusion PT (20.7 +/- 22.2 sec) corrected after PCT-FFP (13.8 +/- 2.4 sec, p < 0.001). Mean pretransfusion PTT (51.2 +/- 29.3 sec) corrected after PCT-FFP (32.0 +/- 5.1 sec, p < 0.001). Thirteen patients required 77 transfusions for therapeutic indications. PCT-FFP provided effective hemostasis and was well tolerated.

CONCLUSIONS

Replacement coagulation factors in PCT-FFP exhibited kinetics and therapeutic efficacy consistent with conventional FFP.

Miscellaneous conditions about the elbow in athletes

This article reviews some of the conditions about the elbow in athletes or active individuals. The conditions discussed are synovial plica of elbow, radiocapitellar arthritis, congenital dislocation of the radial head, radio-ulnar synostosis, hemophilia and rheumatoid arthritis. In the past, people who had these conditions were instructed to avoid athletic activities; however, they are now being counseled to remain active and to try to exercise on a regular basis.

Von Willebrand factor-cleaving protease activity and proteolysis of von Willebrand factor in bone marrow transplant-associated thrombotic microangiopathy

INTRODUCTION

Thrombotic microangiopathy (TM) of the fulminant type occurring in patients following bone marrow transplant (BMT) has clinical manifestations that are similar to thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome, but the outcome is generally fatal despite conventional therapy. Idiopathic acquired TTP has been associated with IgG inhibitors to the cleaving protease of von Willebrand factor (vWF) in plasma. In this study, we investigated the role of the vWF protease and vWF proteolysis in the pathogenesis of BMT-associated TM of the fulminant type.

METHODS

vWF antigen level, vWF multimeric pattern, and vWF metalloprotease activity were investigated in the plasma samples of six consecutive patients with acute BMT-associated TM. Histologic and immunohistochemical studies were also performed on autopsy kidney specimens from four of the patients. All six patients had the fulminant type of the disorder with a fatal outcome and none of the patients responded to plasma infusion.

RESULTS

The vWF-cleaving protease activity in plasma was normal in all patients. However, analysis of the vWF multimeric pattern showed a decrease of high molecular weight multimers. The decrease of large multimers may be caused by vWF-platelet binding as well as shear enhanced proteolysis of vWF. In the four patients who had an autopsy, a pattern of arteriolar thrombosis, distinct from that of TTP, was detected in the kidneys.

CONCLUSION

These findings suggest that BMT-associated TM of the fulminant type is a heterogeneous process and distinct from TTP in pathogenesis. Analysis of vWF protease and vWF multimeric distribution are valuable tools in making the distinction between BMT-associated TM and TTP.

On the preparative use of recombinant pig alpha(1-3)galactosyl-transferase

A series of non-natural N-acyl derivatives of lactosamine is incubated with recombinant alpha(1-3)galactosyl-transferase and UDP-galactose. The enzyme shows a high promiscuity towards the non-natural acceptors. It selectively transfers a galactose unit onto the 3-OH group of the terminal beta-linked galactose in an alpha-mode to give an array of linear-B trisaccharides.

Enzymatic synthesis of sialyl-Lewis(a)-libraries with two non-natural monosaccharide units

A series of sialylated type-I sugars, which have the natural N-acetyl group of the glucosamine moiety replaced by a wide range of amides, is incubated with recombinant fucosyl-transferase III and non-natural guanosine-diphosphate activated donor-sugars. Surprisingly, the enzyme tolerates the simultaneous alterations on the donor and acceptor to form a wide array of sialyl-Lewis(a)-analogues.

On the preparative use of recombinant beta(1-3)galactosyl-transferase

A number of non-natural N-acyl derivatives of glucosamine is incubated with a recombinant beta(1-3)galactosyl-transferase and UDP-galactose. Surprisingly, the enzyme recognizes the non-natural acceptors as substrates and transfers galactose onto the 3-OH group in a beta-mode to give a series of Lewis(c)-(type 1) disaccharides.

Immunocytochemical localization of alpha2,3(N)-sialyltransferase (ST3Gal III) in cell lines and rat kidney tissue sections: evidence for golgi and post-golgi localization

Sialylation is a biosynthetic process occurring in the trans compartments of the Golgi apparatus. Corresponding evidence is based on localization and biochemical studies of alpha2, 6(N)-sialyltransferase (ST6Gal I) as previously reported. Here we describe generation and characterization of polyclonal antibodies to recombinant rat alpha2,3(N)-sialyltransferase (ST3Gal III) expressed as a soluble enzyme in Sf9 cells or as a beta-galactosidase-human-ST3Gal III fusion-protein from E.coli , respectively. These antibodies were used to localize ST3Gal III by immunofluorescence in various cell lines and rat kidney tissue sections. In transiently transfected COS cells the antibodies directed to soluble sialyltransferase or the sialyltransferase portion of the fusion-protein only recognized the recombinant antigen retained in the endoplasmic reticulum. However, an antibody fraction crossreactive with beta-galactosidase recognized natively expressed ST3Gal III which was found to be colocalized with beta1, 4-galactosyltransferase in the Golgi apparatus of several cultured cell lines. Antibodies affinity purified on the beta-galactosidase-ST3Gal III fusion-protein column derived from both antisera have then been used to localize the enzyme in perfusion-fixed rat kidney sections. We found strong staining of the Golgi apparatus of tubular epithelia and a brush-border-associated staining which colocalized with cytochemical staining of the H+ATPase. This subcellular localization was not observed for ST6Gal I which localized to the Golgi apparatus. These data show colocalization in the Golgi apparatus and different post-Golgi distributions of the two sialyltransferases.

Enzymatic fucosylations of non-natural sialylated type-I trisaccharides with recombinant fucosyl-transferase-III

Recombinant fucosyl-transferase-III (Lewis type enzyme) is used to prepare a series of non-natural sialyl-Lewis derivatives on a preparative scale. The enzyme tolerates a wide range of acceptors which have the natural N-acetyl group of the glucosamine moiety replaced by substituted aromatic and heteroaromatic amides.

Enzymatic alpha(2-3)sialylation of non-natural type-I (Lewisc) disaccharides with recombinant sialyl-transferase

Recombinant alpha(2-3)sialyl-transferase from rat liver is used to sialylate a series of type-I (Lewisc) disaccharides on a preparative scale. The enzyme tolerates a broad array of N-acetyl replacements of the N-glucosamine subunit ranging from small and large lipophilic groups to charged and heterocyclic amides.

Sequence relations among the IncY plasmid p15B, P1, and P7 prophages

Electron microscopic analysis of heteroduplex molecules between the 94-kb plasmid p15B and the 92-kb phage P1 genome revealed nine regions of nonhomology, eight substitutions, and two neighboring insertions. Overall, the homologous segments correspond to 83% of the P1 genome and 81% of p15B. Heteroduplex molecules between p15B and the 99-kb phage P7 genome showed nonhomology in eight of the same nine regions; in addition, two new nonhomologous segments are present and P7 carries a 5-kb insertion representing Tn902. The DNA homology between those two genomes amounts to 79% of P7 DNA and 83% of p15B. Plasmid p15B contains two stem-loop structures. One of them has no equivalent structure on P1 and P7 DNA. The other substitutes the invertible C segments of P1 and P7 and their flanking sequences including cin, the gene for the site-specific recombinase mediating inversion.