Diagnostic approach to inherited bleeding disorders

The pleiotropic effects of antithrombotic drugs in the metabolic-cardiovascular-neurodegenerative disease continuum: impact beyond reduced clotting

Antithrombotic drugs are widely used for primary and secondary prevention, as well as treatment of many cardiovascular disorders. Over the past few decades, major advances in the pharmacology of these agents have been made with the introduction of new drug classes as novel therapeutic options. Accumulating evidence indicates that the beneficial outcomes of some of these antithrombotic agents are not solely related to their ability to reduce thrombosis. Here, we review the evidence supporting established and potential pleiotropic effects of four novel classes of antithrombotic drugs, adenosine diphosphate (ADP) P2Y12-receptor antagonists, Glycoprotein IIb/IIIa receptor Inhibitors, and Direct Oral Anticoagulants (DOACs), which include Direct Factor Xa (FXa) and Direct Thrombin Inhibitors. Specifically, we discuss the molecular evidence supporting such pleiotropic effects in the context of cardiovascular disease (CVD) including endothelial dysfunction (ED), atherosclerosis, cardiac injury, stroke, and arrhythmia. Importantly, we highlight the role of DOACs in mitigating metabolic dysfunction-associated cardiovascular derangements. We also postulate that DOACs modulate perivascular adipose tissue inflammation and thus, may reverse cardiovascular dysfunction early in the course of the metabolic syndrome. In this regard, we argue that some antithrombotic agents can reverse the neurovascular damage in Alzheimer's and Parkinson's brain and following traumatic brain injury (TBI). Overall, we attempt to provide an up-to-date comprehensive review of the less-recognized, beneficial molecular aspects of antithrombotic therapy beyond reduced thrombus formation. We also make a solid argument for the need of further mechanistic analysis of the pleiotropic effects of antithrombotic drugs in the future.

Delayed Presentation of Compartment Syndrome of the Thigh in a Previously Undiagnosed Factor VII-Deficient High School Football Athlete: A Case Report

CASE

We describe a case of delayed presentation of compartment syndrome in the anterior aspect of the thigh in a high school athlete. The patient had sustained a blow to the thigh 8 days prior to presentation, and had continued to practice football in the setting of undiagnosed coagulopathy. He presented with severe thigh pain and the inability to contract the thigh muscles.

CONCLUSION

A high index of suspicion for compartment syndrome is indicated for patients with disproportionate pain, especially in the setting of relatively minor trauma. Underlying coagulopathy should be investigated in patients with compartment syndrome because there is a high incidence of bleeding disorders in this population.

The use of frozen plasma samples in thromboelastometry

Thromboelastometry is increasingly used in the clinical and scientific setting. The use of frozen plasma samples may be useful in overcoming certain limitations such as local and timely availability. Whole blood (WB) samples of 20 healthy volunteers were obtained, and plasma was generated. NATEM (n = 20), EXTEM (n = 20) and INTEM (n = 8) analyses were performed in WB, fresh plasma and frozen and thawed plasma. Dabigatran (500, 1000 ng/ml), rivaroxaban (100, 200 ng/ml) or alteplase (333 ng/ml) were added ex vivo to WB, and thromboelastometry was performed in WB and in frozen and thawed plasma samples. Clot formation time, mean clot firmness and the area under the curve were significantly altered in plasma compared to WB. In INTEM and EXTEM analysis, clotting time (CT) was comparable between WB (100%) and fresh (INTEM 114% and EXTEM 93%, ratio of the means) and frozen plasma samples (85 and 99%), whereas in NATEM analysis, the CT increased in fresh (193%) and frozen plasma samples (130%). Dabigatran dose-dependently increased the CT approximately 5- and 9-fold in WB and even more pronounced 10- and 26-fold in plasma. Accordingly, rivaroxaban dose-dependently increased the CT 2- and 2.7-fold in WB, and 3.5- and 4-fold in plasma samples. Hyperfibrinolysis was achieved by addition of alteplase in all WB samples and was reproducible in plasma samples. In conclusion, thromboelastometry, especially INTEM and EXTEM analyses, is possible using frozen and stored plasma samples with comparable results to the corresponding whole blood samples.

Could light meal jeopardize laboratory coagulation tests?

BACKGROUND

Presently the necessity of fasting time for coagulation tests is not standardized. Our hypothesis is that this can harm patient safety. This study is aimed at evaluating whether a light meal (i.e. breakfast) can jeopardize laboratory coagulation tests.

MATERIALS AND METHODS

A blood sample was firstly collected from 17 fasting volunteers (12 h). Immediately after blood collection, the volunteers consumed a light meal. Then samples were collected at 1, 2 and 4 h after the meal. Coagulation tests included: activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen (Fbg), antithrombin III (AT), protein C (PC) and protein S (PS). Differences between samples were assessed by Wilcoxon ranked-pairs test. The level of statistical significance was set at P < 0.05. Mean % differences were determined and differences between and baseline and 1, 2 and 4h samples were compared with reference change value (RCV).

RESULTS

A significantly higher % activity of AT was observed at 1 h and 4 h after meal vs. baseline specimen [113 (104-117) and 111 (107-120) vs. 109 (102-118), respectively; P = 0.029 and P = 0.016]. APTT at 2 h was found significantly lower than baseline samples [32.0 (29.9-34.8) vs. 34.1 (32.2-35.2), respectively; P = 0.041]. The results of both Fbg and PS tests were not influenced by a light meal. Furthermore, no coagulation tests had significant variation after comparison with RCV.

CONCLUSION

A light meal does not influence the laboratory coagulation tests we assessed, but we suggest that the laboratory quality managers standardize the fasting time for all blood tests at 12 hours, to completely metabolize the lipids intake.

Experimental study on the hemostatc activity of Pollen Typhae: a traditional folk medicine used by external and oral application

Pollen Typhae is the traditional Chinese herbal medicine widely used to treat the hemorrhagic diseases both by external and oral application. The present study examines the hemostatic properties and its components of Pollen Typhae. Pollen extract significantly reduced prothrombin time (PT), activated partial prothrombin time (APTT) and recalcification time. Pollen extract directly activated factor XII in the coagulation cascade. Acidic polysaccharide in the pollen that adsorbed to the diethylaminoethyl (DEAE) column was the causative agent of factor XII activation. These results suggested that an electronegative charge attributed to an acidic polysaccharide in the pollen extract contributed to the hemostatic activity. We then examined the hemostatic activity of administered pollen extract in the mouse tail bleeding model. Tail bleeding was significantly decreased after oral administration of the pollen extract, whereas the acidic polysaccharide fraction did not affect the duration of tail bleeding. These results suggest that the oral anticoagulant effect of Pollen Typhae is attributed to compounds other than acidic polysaccharides. We concluded that the activation of the intrinsic coagulation pathway by the acidic polysaccharide contributes to the external hemostatic property of Pollen Typhae, and the action of components such as flavonoids that possess anticoagulant activity are causative agent when orally administered.

Arterial thrombus formation in cardiovascular disease

The pathogenesis of arterial thrombosis is complex and dynamic. Unlike venous thrombi, arterial thrombi typically form under conditions of high blood flow and are mainly composed of platelet aggregates, giving them the appearance of 'white clots'. Strong evidence suggests that arterial thrombi originate as a consequence of an injured atherosclerotic plaque, and that their formation involves the release of prothrombotic material (such as tissue factor), platelet aggregation, and platelet adhesion to the vascular wall. The initially labile platelet plaque is then stabilized by insoluble fibrin produced upon activation of the coagulation cascade. Inherited genetic factors (gene polymorphisms) and acquired predisposing conditions (such as the concentration and activity of clotting factors) can influence both the composition and the size of an arterial thrombus. Further research is needed to elucidate the functions of blood coagulation proteins and cellular elements that are critical to the pathogenesis of arterial thrombosis. This Review explains mechanisms of pathological arterial thrombus formation and discusses genetic and acquired risk factors of atherothrombosis.

Postoperative acquired coagulopathy: a pilot study to determine the impact on clinical and economic outcomes

STUDY OBJECTIVE

To characterize the clinical factors associated with postoperative acquired coagulopathy, and to estimate the economic impact of resources used to treat postoperative patients with this coagulopathy compared with postoperative patients who did not develop the coagulopathy.

DESIGN

Case-control study.

SETTING

Academically affiliated public hospital and level I trauma referral center.

PATIENTS

Twenty-six patients (mean age 53.9 yrs) who experienced acquired coagulopathy after undergoing an index surgery (cases), and 26 patients (mean age 50.8 yrs) matched to these case patients by index surgery, age, and sex (controls).

MEASUREMENTS AND MAIN RESULTS

Data were collected from a database of 5367 adult surgical admissions over 6 months during 2008, corresponding inpatient electronic health records, billing data, and Medicare Resource-Based Relative Value Scale payments. Case patients had a minimum of two postoperative consecutively drawn episodes of prothrombin time (PT) or activated partial thromboplastin time (aPTT) elevated to greater than 20% above the upper limit of normal. Patients with inherited clotting disorders or other identifiable causes of coagulopathy were excluded. Case patients underwent the following surgeries: 12 orthopedic (46%), six cardiovascular (23%), four gastrointestinal (15%), and four neurosurgical (15%). Mean values of the first elevated PT and aPTT were 19.7 and 50.8 seconds, respectively. Mean postoperative stay was 31.5 days for cases versus 9.8 days for controls (p<0.05). Mean cost (2008 U.S. dollars) of resources used was $112,280 for cases versus $38,357 for controls (p<0.001). Costs incurred between the onset of coagulopathy and discharge constituted 67% of postoperative costs. Physician reimbursement expenditures were minimal.

CONCLUSION

Postoperative acquired coagulopathy was associated with stays that were 3 times longer and resource use costs that were 3 times higher than those of controls. This type of coagulopathy may be an under-recognized and underappreciated event. The case-control design is limited to exploring associations and does not establish causality. Prospective studies need to be conducted to establish the causes of acquired coagulopathy and methods for screening and diagnosing this condition.

Descriptive epidemiology of hemophilia and other coagulation disorders in mansoura, egypt: retrospective analysis

Hemophilia represent the most severe inherited bleeding disorder (INB), it's thought to affect inviduals from all geographical areas in equal frequency. In Egypt which has a population of approximately (80million) consanguineous marriage are frequent, therefore autosomal recessive coagulation disorders reach a higher prevalence than in many other countries.The primary aim of this study was to describe the epidemiological situation of hemophilia in Mansoura, Egypt, as based on retrospective analysis of clinical records Mansoura University Children Hospital between years 2000 and 2008. The second aim was to assess the orthopedic complications and occurrence of hepatitis C in those patients and relate this status to the type of replacement therapy received prior to the study.The study included 72 children with hematological disorders registered from 2000 to 2008 in MUCH. The hemophilic patient was defined as a person with physician-diagnosed hemophilia A or B and a measured factor VIII or IX activity level of 30% or less. Persons with acquired inhibitors of FVIII or FIX excluded. Severity level was categorized as mild if the factor activity level was 6-30%, moderate if 1-5% and severe if <1% of normal.The severe presentation represents the majority in 76.7% followed by moderate severity in 17.2%. The commonest IBDs was hemophilia A affecting 44 patients, followed by Hemophilia B affecting 15 patients. The rare types were Factor XI deficiency, Factor V deficiency, Factor VII deficiency and combined FVIII, FIX and FX deficiency. The commonest orthopedic manifestation needing therapy was found among hemophilia A representing 8.3%. Hepatitis C viremia detected by PCR was found in 11.1% of patients. The bleeding complications as hematoma or hemarthrosis were the common complications. Nevertheless, 44.4% of patients had no complications, From this study we can conclude that the most common IBDs in our locality is hemophilia A followed by hemophilia B. The common presenting symptom was bleeding following male circumcision. Hepatitis C infection and arthropathy represented the main complications. The discovery of IBDs in young age children with proper supportive therapy could prevent arthropathy. Proper screening of blood and blood products reduce the risk of viral hepatitis and HIV acquisition.

Laboratory assessment and perioperative management of patients on antiplatelet therapy: from the bench to the bedside

The contribution of platelets in the pathophysiology of thromboses has established antiplatelet therapy as a cornerstone for prevention or treatment of these disorders. However, patients on antiplatelet drugs undergoing surgery face the life-threatening dilemma between the risk of perioperative thrombosis by ceasing therapy and restoring platelet function versus the risk of surgical bleeding by its continuation. According to their mechanism of action, antiplatelet drugs can be conventionally classified as agents that inhibit cyclooxygenase, block the platelet adenosine diphosphate P2Y12 receptor, inhibit phosphodiesterase, or block platelet glycoprotein IIb/IIIa. Although several tests have been developed to assess platelet inhibition by most of these compounds, studies to date have not been able to reliably evaluate the diagnostic efficiency of these tests to predict hemorrhage and/or blood loss, and accordingly perioperative assessment of drug-induced platelet inhibition cannot be recommended as yet. Although several management options are available to counteract the hemorrhagic risk of surgical patients using antiplatelet agents, perioperative discontinuation of these drugs is the preferable choice wherever possible. The use of platelet transfusions should be limited where necessary to the treatment of major, life-threatening bleeding. The contribution of newer hemostatic agents, such as desmopressin and recombinant activated factor VII, is yet to be fully determined, and there remain many challenges and unresolved issues in the clinical care of these patients.

The spectrum of inherited bleeding disorders in pediatrics

Inherited bleeding disorders (IBDs) are caused by quantitative and qualitative alterations of either platelets or plasma proteins involved in coagulation and fibrinolysis. Hemophilias are the most frequent IBDs; however, accumulated data from various studies reported that von Willebrand disease (VWD) is the most common cause of IBD, with an increased incidence of platelet function defects, mostly due to the increased rate of consanguinity in some communities. VWD is an inherited disorder of homeostasis due to quantitative or qualitative defect of von Willebrand factor. Data on its epidemiology and impact in developing countries are limited. The objective of this study was to assess the local prevalence of some IBD and establish the clinical and historical variables that are predictive for those bleeding disorders in pediatrics. The study involved 43 children with various bleeding manifestations and 15 age- and sex-matched controls, recruited from the Pediatrics Hematology Clinic at the National Research Centre, Sausan Mubarek children's hospital in Cairo, Egypt and the King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia. Hematological profile included platelet counts and function, prothrombin time, partial thromboplastin time, factor VIII antigen and its activity, factor IX antigen and its activity, von Willebrand factor and its activity assayed with multimeric analysis. A total of 12 (27.9%) children had VWD, 11 (25.5%) had hemophilia A, three (7%) had hemophilia B, seven (16.3%) had platelet dysfunction and 10 (23.3%) had bleeding with undiagnosed cause. Two of the VWD cases had type I, three had type II, four had type III and one case appeared to have type IIM and another to have IIB VWD. Bruising and epistaxis were the main symptoms in all children with VWD The majority of platelet dysfunction disorders were diagnosed as Glanzmann's thrombasthenia. VWD and Glanzmann's thrombasthenia should be considered not uncommon causes of IBDs in children in Egypt and Kingdom of Saudi Arabia. Routine hematological screening should be mandatory in children with positive family history of bruising and bleeding as a predictor for IBD.

Eosinophilia and first-line coagulation testing

Although eosinophilia (eosinophil count >0.60 x 10(9)/l), is a prothrombotic condition, little is known on the association between eosinophil count in blood and first-line coagulations tests, including fibrinogen, activated partial thromboplastin time (APTT), prothrombin time (PT) and platelet count. Cumulative results of APTT, PT, fibrinogen, platelet and eosinophil counts were retrieved from 6,944 outpatients >15 years old referred to our laboratory for routine blood testing over the previous 3 years. The median value and the percentage of patients with abnormal values of platelet count and fibrinogen but not APTT and PT, were significantly higher in patients with eosinophilia. This epidemiological association in a large subset of patients provides an additional potential mechanism to explain the link between eosinophilia and thrombosis and is consistent with the hypothesis that platelet count and fibrinogen might be worthwhile assessing in the presence of an abnormal eosinophil count.

Factor IX gene haplotypes and its relevance for the indirect genetic analysis of haemophilia B in its Indian perspective

In developing countries, especially in those with limited facilities and low budget resources, a reliable approach to carrier detection and prenatal diagnosis of haemophilia B might be based on indirect diagnostic strategies. As, the cost-effectiveness of indirect genetic analysis of haemophilia B has been little investigated so far, we here report our experience in India. Polymerase chain reaction analysis of DdeI/intron1, XmnI/intron 3 and HhaI/3' flanking region of the gene for factor IX (F9) was investigated in 68 individuals (23 haemophilia patients, 18 obligate carriers, 27 probable carriers) from 23 families of haemophilia B. Linkage disequilibrium analysis was done and haplotypes were generated employing the expectation-maximization algorithm. DdeI (+) and (-) allele frequencies were found to be 0.522 and 0.478, respectively, with the highest observed heterozygosity of 46.6% as compared to XmnI (24.4%) and HhaI (42.2%). The frequencies of haplotype III and VI, that is DdeI (+)-XmnI (-)-HhaI (-) and DdeI (-)-XmnI (-)-HhaI (-) were observed to be 0.363 and 0.257, respectively. Haplotype III was found to be the most heterogeneous that suggests its efficacy in the indirect genetic analysis of F9 gene. Linkage disequilibrium analysis revealed no association between DdeI/HhaI (D' = 0.092); however, significant but incomplete linkage disequilibrium was observed in XmnI/HhaI and DdeI/XmnI (D' = 0709, 0.515, respectively). The overall cumulative polymorphism information content of these three markers increased from about 0.33 to 0.72, which suggested the efficiency of haplotyping of these markers over individual gene analysis in the direction of carrier assessment of haemophilia B in India.

Prevalence and type of pre-analytical problems for inpatients samples in coagulation laboratory

RATIONALE, AIMS AND OBJECTIVES

Total quality in coagulation testing is a necessary requisite to achieve clinically reliable results. Evidence was provided that poor standardization in the extra-analytical phases of the testing process has the greatest influence on test results, though little information is available so far on prevalence and type of pre-analytical variability in coagulation testing.

METHODS

The present study was designed to describe all pre-analytical problems on inpatients routine and stat samples recorded in our coagulation laboratory over a 2-year period and clustered according to their source (hospital departments).

RESULTS

Overall, pre-analytic problems were identified in 5.5% of the specimens. Although the highest frequency was observed for paediatric departments, in no case was the comparison of the prevalence among the different hospital departments statistically significant. The more frequent problems could be referred to samples not received in the laboratory following a doctor's order (49.3%), haemolysis (19.5%), clotting (14.2%) and inappropriate volume (13.7%). Specimens not received prevailed in the intensive care unit, surgical and clinical departments, whereas clotted and haemolysed specimens were those most frequently recorded from paediatric and emergency departments, respectively. The present investigation demonstrates a high prevalence of pre-analytical problems affecting samples for coagulation testing.

CONCLUSIONS

Full implementation of a total quality system, encompassing a systematic error tracking system, is a valuable tool to achieve meaningful information on the local pre-analytic processes most susceptible to errors, enabling considerations on specific responsibilities and providing the ideal basis for an efficient feedback within the hospital departments.

Is the activated partial thromboplastin time suitable to screen for von Willebrand factor deficiencies?

The diagnostic approach to von Willebrand factor deficiencies is challenging and requires discretionary use of laboratory resources. Although extensive preoperative testing is not recommended, the activated partial thromboplastin time may be useful, especially in selected categories of patients. To establish the diagnostic sensitivity of this test to identify isolate von Willebrand factor deficiencies, 204 consecutive patients underwent a routine preoperative screening consisting of activated partial thromboplastin time, von Willebrand factor antigen, intrinsic pathway clotting factors activity, lupus anticoagulants and thrombin time. Thirty-seven patients were diagnosed with haemostasis disturbances other than von Willebrand factor deficiencies and were excluded from the evaluation. Isolated von Willebrand factor deficiency was diagnosed in 11 of the remaining 167 patients. A significant correlation was observed between von Willebrand factor antigen and activated partial thromboplastin time. Receiver operating characteristic curve analysis showed an area under the curve of 0.982 (95% confidence interval: 0.972-0.992; P < 0.001). At the 1.17 upper limit of the activated partial thromboplastin time, sensitivity and specificity were 100 and 85%, respectively, with negative and positive predictive values of 100 and 31%, respectively. These results demonstrate that activated partial thromboplastin time has an excellent diagnostic sensitivity and a satisfactory specificity for identifying isolated von Willebrand factor deficiencies.