Epsilon-Aminocaproic acid therapy for dental extractions in haemophilia and Christmas disease: a double blind controlled trial

Use of crushed tranexamic acid tablets in water for paediatric patients with bleeding disorders

BACKGROUND

Ε-Aminocaproic acid oral solution (EACA OS) is the only commercially available antifibrinolytic for patients who cannot swallow tablets. Insurance denials and high costs remain barriers to its use.

OBJECTIVES

To determine the safety and efficacy of crushed tranexamic acid tablets in water (cTXAw) for children with bleeding disorders.

METHODS

We retrospectively reviewed records of children (<10 years) with bleeding disorders who received cTXAw or EACA OS from 1 December 2018, through 31 July 2022, at Mayo Clinic (Rochester, Minnesota). Bleeding outcomes were defined according to ISTH criteria.

RESULTS

Thirty-two patients were included (median age, 3 years; male, n = 23). Diagnoses were VWD (n = 17), haemophilia (n = 5), FVII deficiency (n = 3), inherited platelet disorder (n = 4), ITP (n = 2), and combined FV and FVII deficiencies (n = 1). Thirty-two courses of cTXAw (monotherapy 24/32; mean duration 6 days) and fifteen courses of EACA (monotherapy 12/15; mean duration 5 days) were administered. No surgical procedures (n = 28) were complicated by bleeding. Of the 19 bleeding events, 16 had effective haemostasis, two had no reported outcome, and one had no response. cTXAw and EACA were equally effective in preventing and treating bleeding (p value > .1). No patients had adverse effects. Eight of 19 patients (42%) who were initially prescribed EACA OS did not receive it because of cost or insurance denial. The estimated average wholesale price of one treatment was $94 for cTXAw and $905 for EACA OS.

CONCLUSIONS

CTXAw appears to be an effective, safe, and low-cost alternative option to EACA OS for young children with bleeding disorders.

Dentistry for patients with haemophilia: Trialling a safe and economical change in management

INTRODUCTION

While the dental management of patients with haemophilia has changed considerably in the last decade, haemophiliacs in Western Australia have continued to receive pre-operative factor support for dentistry regardless of the type of dental procedure.

AIM

To review the efficacy and safety of established dental protocols that reduce factor use in the dental management of patients with haemophilia and to estimate cost savings.

METHODS

Records of 11 patients with haemophilia that were seen in the pilot programme period were reviewed. These were cross-referenced with previous dental and haematology notes that stated the amount and type of pre-operative factor used. Cost savings were estimated using the Australian National Blood Authority's Product List.

RESULTS

All study participants were male, and included those with haemophilia A (n = 9), and B (n = 2). Mean age was 45 years (range 22-80). A variety of dental treatments were undertaken, and no pre-operative factor was used. Patients on prophylaxis (n = 6) received dental treatment the same day as their regular factor administration. It was estimated AUD$26,314 was saved by not using pre-operative factor. One patient had bleeding post-extraction and was seen the following day to achieve haemostasis using local measures. The remaining patients had no complaints of post-operative bleeding, and did not require any further haemostatic measures.

CONCLUSION

This pilot programme supports data that haemophiliacs can safely receive a variety of dental treatments without the need for pre-operative factor, and the significant cost savings of doing so. Further data is required to support this protocol for invasive dental procedures.

Low dose prophylaxis and antifibrinolytics: Options to consider with proven benefits for persons with haemophilia

INTRODUCTION

Prophylaxis has become standard of care for persons with severe phenotype haemophilia (PWsH). However, 'standard prophylaxis' with either factor or non-factor therapies (emicizumab) is prohibitively expensive for much of the world. We sought to evaluate whether haemophilia care can be provided at a lower cost yet achieve good results using Lower dose/Lower frequency prophylaxis (LDP) and with increasing use of antifibrinolytics (Tranexamic acid and Epsilon amino caproic acid).

METHODS

We identified 12 studies that collectively included 335 PWsH using LDP. Additionally, we undertook a literature search regarding the benefits of antifibrinolytics in haemophilia care.

RESULTS

Identified studies show that LDP is far superior to no prophylaxis (On demand [OD] therapy) resulting in significant patient benefits. Patients on LDP showed (in comparison to patients OD) on average: 72% less total bleeds; 75% less joint bleeds; 91% less days lost from school; 77% less hospital admission days; and improved quality of life measures. These benefits come at similar or only slightly higher (< 2-fold greater) costs than OD therapy. Antifibrinolytics are effective adjunctive agents in managing bleeds (oral, nasal, intracranial, possibly other) and providing haemostasis for surgeries (particularly oral surgeries). Antifibrinolytics can substitute for more expensive factor concentrates or can reduce the use of such concentrates. There is evidence to show that antifibrinolytics may be used in conjunction with factor concentrates/emicizumab for more effective/less costly prophylaxis.

CONCLUSIONS

The use of LDP along with appropriate and increased use of antifibrinolytics offers less resourced countries good options for managing patients with haemophilia.

An Update on the Dental Management of Children with Haemophilia

Children with haemophilia present a bleeding risk and a challenge for dentists. Guidelines on the dental management of haemophilia patients are largely based on expert consensus. Many existing guidelines also provide generic guidance mainly for adult patients, which have been adapted for children. However, children have unique needs that require additional considerations. With limited evidence available, it is important that dentists have an understanding of the principles of both medical and dental management and have a close collaboration with the haematologist at all times. Therefore, this paper provides some key principles related to various aspects of dental management of children with haemophilia. Furthermore, there has been a recent update to the World Federation of Haemophilia (WFH) Guidelines for the Management of Haemophilia,¹ with references to novel medical therapies for haemophilia. Hence, this paper also aims to inform dentists with the standard and newer medical therapies for haemophilia, including a specific focus on the novel agent Emicizumab and the associated dental considerations.

Surgical management of patients with von Willebrand disease: summary of 2 systematic reviews of the literature

von Willebrand disease (VWD) is the most common inherited bleeding disorder. The management of patients with VWD who are undergoing surgeries is crucial to prevent bleeding complications. We systematically summarized the evidence on the management of patients with VWD who are undergoing major and minor surgeries to support the development of practice guidelines. We searched Medline and EMBASE from inception through October 2019 for randomized clinical trials (RCTs), comparative observational studies, and case series that compared maintaining factor VIII (FVIII) levels or von Willebrand factor (VWF) levels at >0.50 IU/mL for at least 3 days in patients undergoing major surgery, and those with options for perioperative management of patients undergoing minor surgery. Two authors screened and abstracted data and assessed the risk of bias. We conducted meta-analyses when possible. We evaluated the certainty of the evidence using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. We included 7 case series for major surgeries and 2 RCTs and 12 case series for minor surgeries. Very-low-certainty evidence showed that maintaining FVIII levels or VWF levels of >0.50 IU/mL for at least 3 consecutive days showed excellent hemostatic efficacy (as labeled by the researchers) after 74% to 100% of major surgeries. Low- to very-low-certainty evidence showed that prescribing tranexamic acid and increasing VWF levels to 0.50 IU/mL resulted in fewer bleeding complications after minor procedures compared with increasing VWF levels to 0.50 IU/mL alone. Given the low-quality evidence for guiding management decisions, a shared-decision model leading to individualized therapy plans will be important in patients with VWD who are undergoing surgical and invasive procedures.

Is Antifibrinolytic Therapy Effective for Preventing Hemorrhage in Patients with Hemophilia Undergoing Dental Extractions? A Systematic Review and Meta-Analysis

Objectives

This systematic review aims to analyze the systemic administration of antifibrinolytics (tranexamic acid and aminocaproic acid) to prevent postoperative bleeding in patients with hemophilia.

Methods

This systematic review was conducted adhering to PRISMA guidelines. Only randomized controlled trials that assessed human subjects of any age or gender with any severity of hemophilia undergoing dental extractions, and systemically administered antifibrinolytic therapy compared to placebo were included. Post-operative bleeding episodes and adverse events were presented. PubMed, Cochrane, Embase, CINAHL, Web of Science, and Scopus were searched through April 15, 2022. The risk ratio (RR) and odds ratio (OR) applying 95% confidence intervals (CI) were computed using RevMan 5.4.1 (Cochrane).

Results

Two randomized, placebo-controlled trials pooling in a total of 59 patients were pooled in this analysis. Among patients administered antifibrinolytic therapy, 84% reduced risk of post-operative bleeding was reported (RR = 0.16, 95% CI = 0.05–0.47, P = 0.0009). The chances of post-operative bleeding were reduced by 95% among the antifibrotics group (OR = 0.05, 95% CI = 0.01–0.22, P < 0.0001).

Conclusion

This review finds favorable outcomes for the routine use of antifibrinolytic therapy for dental extractions in hemophiliacs. Further trials are required to rationalize existing evidence.

ASH ISTH NHF WFH 2021 guidelines on the management of von Willebrand disease

BACKGROUND

von Willebrand disease (VWD) is a common inherited bleeding disorder. Significant variability exists in management options offered to patients.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH), the International Society on Thrombosis and Haemostasis (ISTH), the National Hemophilia Foundation (NHF), and the World Federation of Hemophilia (WFH) are intended to support patients, clinicians, and health care professionals in their decisions about management of VWD.

METHODS

ASH, ISTH, NHF, and WFH formed a multidisciplinary guideline panel. Three patient representatives were included. The panel was balanced to minimize potential bias from conflicts of interest. The University of Kansas Outcomes and Implementation Research Unit and the McMaster Grading of Recommendations Assessment, Development and Evaluation (GRADE) Centre supported the guideline development process, including performing and updating systematic evidence reviews (through November 2019). The panel prioritized clinical questions and outcomes according to their importance to clinicians and patients. The panel used the GRADE approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 12 recommendations and outlined future research priorities.

CONCLUSIONS

These guidelines make key recommendations regarding prophylaxis for frequent recurrent bleeding, desmopressin trials to determine therapy, use of antiplatelet agents and anticoagulant therapy, target VWF and factor VIII activity levels for major surgery, strategies to reduce bleeding during minor surgery or invasive procedures, management options for heavy menstrual bleeding, management of VWD in the context of neuraxial anesthesia during labor and delivery, and management in the postpartum setting.

Current state of play regarding dental extractions in patients with haemophilia: Consensus or evidence-based practice? A review of the literature

Due to the global prevalence of oral disease, tooth extraction is the most common surgical procedure required in general population thus likely to be similarly common in patients with haemophilia, especially those in older age and those living in countries with restricted resources. There are little or no consensus about optimal level and duration of factor replacement (FRP) therapy required to prevent bleeding complication following surgery and low levels of evidence to inform protocols and guidelines. The goal of this article was to review the literature regarding haematological treatment protocols and to assess their effectiveness in prevention of bleeding complications during and after tooth extractions in people with haemophilia. A total number of 29 articles were identified. Only two of the studies were randomized controlled trials, and meta-analysis was not possible. Significant heterogeneity regarding haematological regimes, dental surgical procedures, disease severity and sample size of published studies which are unable to reliably inform the provision of safe dental surgery was noted. Based on the haematological regimens, all studies were classified into one of three groups: pre- and postoperative FRP or DDAVP, single preoperative FRP or DDAVP, and no FRP treatment. The overall reported bleeding rate in case of both pre- and postoperative FRP and single dose FRP preoperative is similar, 11.9% and 11.4%, respectively, indicating that minimizing the use of clotting factor concentrate is possible if proper local haemostatic measures are provided. Strictly designed prospective studies with higher number of patients are necessary to get firm conclusions about optimal FRP treatment required to prevent bleeding complications during and after oral surgery in patients with haemophilia.

Absence of functional compensation between coagulation factor VIII and plasminogen in double-knockout mice

Plasminogen deficiency is associated with severely compromised fibrinolysis and extravascular deposition of fibrin. In contrast, coagulation factor VIII (FVIII) deficiency leads to prolonged and excessive bleeding. Based on opposing biological functions of plasminogen and FVIII deficiencies, we hypothesized that genetic elimination of FVIII would alleviate the systemic formation of fibrin deposits associated with plasminogen deficiency and, in turn, elimination of plasminogen would limit bleeding symptoms associated with FVIII deficiency. Mice with single and combined deficiencies of FVIII (F8^-/-) and plasminogen (Plg^-/-) were evaluated for phenotypic characteristics of plasminogen deficiency, including wasting disease, shortened lifespan, rectal prolapse, and multiorgan fibrin deposition. Conversely, to specifically examine the role of plasmin-mediated fibrinolysis on bleeding caused by FVIII deficiency, F8^-/- and F8^-/-/Plg^-/- mice were subjected to a bleeding challenge. Mice with a combined deficiency in FVIII and plasminogen displayed no phenotypic differences relative to mice with single FVIII or plasminogen deficiency. Plg^-/- and F8^-/-/Plg^-/- mice exhibited the same penetrance and severity of wasting disease, rectal prolapse, extravascular fibrin deposits, and reduced viability. Furthermore, following a tail vein-bleeding challenge, no significant differences in bleeding times or total blood loss could be detected between F8^-/- and F8^-/-/Plg^-/- mice. Moreover, F8^-/- and F8^-/-/Plg^-/- mice responded similarly to recombinant FVIII (rFVIII) therapy. In summary, the pathological phenotype of Plg^-/- mice developed independently of FVIII-dependent coagulation, and elimination of plasmin-driven fibrinolysis did not play a significant role in a nonmucosal bleeding model in hemophilia A mice.

Antifibrinolytic therapy for preventing oral bleeding in patients with haemophilia or Von Willebrand disease undergoing minor oral surgery or dental extractions

BACKGROUND

Minor oral surgery or dental extractions (oral or dental procedures) are widely performed and can be complicated by hazardous oral bleeding, especially in people with an inherited bleeding disorder such as haemophilia or Von Willebrand disease (VWD). The amount and severity of singular bleedings depend on disease-related factors, such as the severity of the haemophilia, both local and systemic patient factors (such as periodontal inflammation, vasculopathy or platelet dysfunction) and intervention-related factors (such as the type and number of teeth extracted or the dimension of the wound surface). Similar to local haemostatic measures and suturing, antifibrinolytic therapy is a cheap, safe and potentially effective treatment to prevent bleeding complications in individuals with bleeding disorders undergoing oral or dental procedures. However, a systematic review of trials reporting outcomes after oral surgery or a dental procedure in people with an inherited bleeding disorder, with or without, the use of antifibrinolytic agents has not been performed to date. This is an update of a previously published Cochrane Review.

OBJECTIVES

Primarily, we aim to assess the efficacy of antifibrinolytic agents to prevent bleeding complications in people with haemophilia or VWD undergoing oral or dental procedures.Secondary objectives are to assess if antifibrinolytic agents can replace or reduce the need for clotting factor concentrate therapy in people with haemophilia or VWD and to establish the effects of these agents on bleeding in oral or dental procedures for each of these patient populations.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches of the Cochrane Central Register of Controlled Trials (CENTRAL), of MEDLINE and from handsearching of journals and conference abstract books. We additionally searched the reference lists of relevant articles and reviews. We searched PubMed, Embase, Cinahl and the Cochrane Library. Additional searches were performed in ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP).Date of last search of the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 01 March 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in people with haemophilia or VWD undergoing oral or dental procedures using antifibrinolytic agents (tranexamic acid or epsilon aminocaproic acid (EACA)) to prevent perioperative bleeding compared to no intervention or usual care with or without placebo.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the titles and abstracts of all identified articles. Full texts were obtained for potentially relevant abstracts and two authors independently assessed these for inclusion based on the selection criteria. A third author verified trial eligibility. Two authors independently performed data extraction and risk of bias assessments using standardised forms.

MAIN RESULTS

While there were no eligible trials in people with VWD identified, two randomised, double-blind, placebo-controlled trials (total of 59 participants) in people with haemophilia undergoing dental extraction were included. One trial of tranexamic acid published in 1972 included 28 participants with mild, moderate or severe haemophilia A and B and one of EACA published in 1971 included 31 people with haemophilia with factor VIII or factor IX levels less than 15%. Overall, the two included trials showed a beneficial effect of tranexamic acid and EACA, administered systemically, in reducing the number of bleedings, the amount of blood loss and the need for therapeutic clotting factor concentrates. Regarding postoperative bleeding, the tranexamic acid trial showed a risk difference (RD) of -0.64 (95% confidence interval (CI) -0.93 to - 0.36) and the EACA trial a RD of -0.50 (95% CI 0.77 to -0.22). The combined RD of both trials was -0.57 (95% CI -0.76 to -0.37), with the quality of the evidence (GRADE) for this outcome is rated as moderate. Side effects occurred once and required stopping EACA (combined RD of -0.03 (95% CI -0.08 to 0.13). There was heterogeneity between the two trials regarding the proportion of people with severe haemophilia included, the concomitant standard therapy and fibrinolytic agent treatment regimens used. We cannot exclude that a selection bias has occurred in the EACA trial, but overall the risk of bias appeared to be low for both trials.

AUTHORS' CONCLUSIONS

Despite the discovery of a beneficial effect of systemically administered tranexamic acid and EACA in preventing postoperative bleeding in people with haemophilia undergoing dental extraction, the limited number of randomised controlled trials identified, in combination with the small sample sizes and heterogeneity regarding standard therapy and treatment regimens between the two trials, do not allow us to conclude definite efficacy of antifibrinolytic therapy in oral or dental procedures in people with haemophilia. No trials were identified in people with VWD.

Abrogating fibrinolysis does not improve bleeding or rFVIIa/rFVIII treatment in a non-mucosal venous injury model in haemophilic rodents

Essentials The efficacy of systemic antifibrinolytics for hemophilic non-mucosal bleeding is undetermined. The effect of systemically inhibiting fibrinolysis in hemophilic mice and rats was explored. Neither bleeding nor the response to factor treatment was improved after inhibiting fibrinolysis. The non-mucosal bleeding phenotype in hemophilia A appears largely unaffected by fibrinolysis.

SUMMARY

Background Fibrinolysis may exacerbate bleeding in patients with hemophilia A (HA). Accordingly, antifibrinolytics have been used to help maintain hemostatic control. Although antifibrinolytic drugs have been proven to be effective in the treatment of mucosal bleeds in the oral cavity, their efficacy in non-mucosal tissues remain an open question of significant clinical interest. Objective To determine whether inhibiting fibrinolysis improves the outcome in non-mucosal hemophilic tail vein transection (TVT) bleeding models, and to determine whether a standard ex vivo clotting/fibrinolysis assay can be used as a predictive surrogate for in vivo efficacy. Methods A highly sensitive TVT model was employed in hemophilic rodents with a suppressed fibrinolytic system to examine the effect of inhibiting fibrinolysis on bleeding in non-mucosal tissue. In mice, induced and congenital hemophilia models were combined with fibrinolytic attenuation achieved either genetically or pharmacologically (tranexamic acid [TXA]). In hemophilic rats, tail bleeding was followed by whole blood rotational thromboelastometry evaluation of the same animals to gauge the predictive value of such assays. Results The beneficial effect of systemic TXA therapy observed ex vivo could not be confirmed in vivo in hemophilic rats. Furthermore, neither intravenously administered TXA nor congenital knockout of the fibrinolytic genes encoding plasminogen or tissue-type plasminogen activator markedly improved the TVT bleeding phenotype or response to factor therapy in hemophilic mice. Conclusions The findings here suggest that inhibition of fibrinolysis is not effective in limiting the TVT bleeding phenotype of HA rodents in non-mucosal tissues.

Preventing perioperative bleeding in patients with inherited bleeding disorders

Data sourcesCochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, a regularly updated database informed by trials identified within electronic databases including MEDLINE. Further defined searches were undertaken in PubMed, Embase, The Cochrane Library, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform. Additional hand searching of relevant journals and books of conference proceedings was undertaken.Study selectionRandomised and quasi-randomised controlled trials in people of all ages with haemophilia or VWD undergoing oral or dental procedures using antifibrinolytic agents (tranexamic acid (TXA) or epsilon aminocaproic acid (EACA)) to prevent perioperative bleeding compared to no intervention with or without placebo.Data extraction and synthesisTwo authors independently assessed identified publications for inclusion based on defined selection criteria. The two authors performed data extraction and risk of bias assessments using standardised forms and the Cochrane risk of bias tools. A third author, deemed to have particular subject expertise, verified eligibility of inclusion.ResultsOne randomised, double-blinded placebo controlled trial and one quasi-randomised trial were included. A total of 59 participants with haemophilia undergoing dental extraction were involved. Both trials evidenced a notable reduction in post-operative bleeding following dental extraction when either TXA or EACA were used, in addition to routine preoperative factor replacement, when compared to placebo. The number of post-operative bleeds, amount of blood loss and the need for additional clotting factors were reduced in the groups receiving antifibrinolytic therapy. No eligible trials in people with VWD were identified.ConclusionsLow quality evidence exists to support the use of adjuvant antifibrinolytic therapy to reduce perioperative bleeding in patients with haemophilia undergoing dental extraction. The limited number of trials identified (N=2), minimal sample size (N=28, N=31) and historic nature of the studies, originating from the 1970s, in addition to study heterogeneity and subsequent selection bias results in a low quality evidence grade for recommending adjuvant antifibrinolytic therapy. There is no clear indication to alter current practice utilising antifibrinolytic therapy to manage patients with haemophilia undergoing dental surgery in accordance with internationally accepted guidelines. However, further research with standardised study deigns would be welcomed in order to enhance the evidence base in the management of people with haemophilia and VWD.

Antifibrinolytic therapy for preventing oral bleeding in patients with haemophilia or Von Willebrand disease undergoing minor oral surgery or dental extractions

BACKGROUND

Minor oral surgery or dental extractions (oral or dental procedures) are widely performed and can be complicated by hazardous oral bleeding, especially in people with an inherited bleeding disorder such as haemophilia or Von Willebrand disease. The amount and severity of singular bleedings depend on disease-related factors, such as the severity of the haemophilia, both local and systemic patient factors (such as periodontal inflammation, vasculopathy or platelet dysfunction) and intervention-related factors (such as the type and number of teeth extracted or the dimension of the wound surface). Similar to local haemostatic measures and suturing, antifibrinolytic therapy is a cheap, safe and potentially effective treatment to prevent bleeding complications in individuals with bleeding disorders undergoing oral or dental procedures. However, a systematic review of trials reporting outcomes after oral surgery or a dental procedure in people with an inherited bleeding disorder, with or without, the use of antifibrinolytic agents has not been performed to date.

OBJECTIVES

The primary objective was to assess the efficacy of local or systemic use of antifibrinolytic agents to prevent bleeding complications in people with haemophilia or Von Willebrand disease undergoing oral or dental procedures. Secondary objectives were to assess if antifibrinolytic agents can replace or reduce the need for clotting factor concentrate therapy in people with haemophilia or Von Willebrand disease and to further establish the effects of these agents on bleeding in oral or dental procedures for each of these populations.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches of the Cochrane Central Register of Controlled Trials (CENTRAL), of MEDLINE and from handsearching of journals and conference abstract books. We additionally searched the reference lists of relevant articles and reviews. We searched PubMed, Embase and The Cochrane Library. Additional searches were performed in ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP).Date of last search of the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 14 December 2015.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in people with haemophilia or Von Willebrand disease undergoing oral or dental procedures using antifibrinolytic agents (tranexamic acid or epsilon aminocaproic acid) to prevent perioperative bleeding compared to no intervention or usual care with or without placebo.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the titles and abstracts of all identified articles. Full texts were obtained for potentially relevant abstracts and two authors independently assessed these for inclusion based on the selection criteria. A third author verified trial eligibility. Two authors independently performed data extraction and risk of bias assessments using standardized forms.

MAIN RESULTS

While there were no eligible trials in people with Von Willebrand disease identified, two randomised, double-blind, placebo-controlled trials (total of 59 participants) in people with haemophilia undergoing dental extraction were included. One trial of tranexamic acid published in 1972 included 28 participants with mild, moderate or severe haemophilia A and B and one of epsilon aminocaproic acid published in 1971 included 31 people with haemophilia with factor VIII or factor IX levels less than 15%. Overall, the two included trials showed a beneficial effect of tranexamic acid and EACA, administered systemically, in reducing the number of bleedings, the amount of blood loss and the need for therapeutic clotting factor concentrates. Regarding postoperative bleeding, the tranexamic acid trial showed a risk difference of -0.64 (95% confidence interval -0.93 to - 0.36) and the EACA trial a risk difference of -0.50 (95% confidence interval 0.77 to -0.22). The combined risk difference of both trials was -0.57 (95% confidence interval -0.76 to -0.37), with the quality of the evidence (GRADE) for this outcome is rated as moderate. Side effects occurred once and required stopping epsilon aminocaproic acid (combined risk difference of -0.03 (95% CI -0.08 to 0.13). There was heterogeneity between the two trials regarding the proportion of people with severe haemophilia included, the concomitant standard therapy and fibrinolytic agent treatment regimens used. We cannot exclude that a selection bias has occurred in the epsilon aminocaproic acid trial, but overall the risk of bias appeared to be low for both trials.

AUTHORS' CONCLUSIONS

Despite the discovery of a beneficial effect of systemically administered tranexamic acid and epsilon aminocaproic acid in preventing postoperative bleeding in people with haemophilia undergoing dental extraction, the limited number of randomised controlled trials identified, in combination with the small sample sizes and heterogeneity regarding standard therapy and treatment regimens between the two trials, do not allow us to conclude definite efficacy of antifibrinolytic therapy in oral or dental procedures in people with haemophilia. No trials were identified in people with Von Willebrand disease.

Treatment for preventing bleeding in people with haemophilia or other congenital bleeding disorders undergoing surgery

BACKGROUND

In people with haemophilia or other congenital bleeding disorders undergoing surgical interventions, haemostatic treatment is needed in order to correct the underlying coagulation abnormalities and minimise the bleeding risk. This treatment varies according to the specific haemostatic defect, its severity and the type of surgical procedure. The aim of treatment is to ensure adequate haemostatic coverage for as long as the bleeding risk persists and until wound healing is complete.

OBJECTIVES

To assess the effectiveness and safety of different haemostatic regimens (type, dose and duration, modality of administration and target haemostatic levels) administered in people with haemophilia or other congenital bleeding disorders for preventing bleeding complications during and after surgical procedures.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews.Date of the last search: 20 November 2014.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing any hemostatic treatment regimen to no treatment or to another active regimen in children and adults with haemophilia or other congenital bleeding disorders undergoing any surgical intervention.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials (eligibility and risks of bias) and extracted data. Meta-analyses were performed on available and relevant data.

MAIN RESULTS

Of the 16 identified trials, four (112 participants) were eligible for inclusion.Two trials evaluated 59 people with haemophilia A and B undergoing 63 dental extractions. Trials compared the use of a different type (tranexamic acid or epsilon-aminocaproic acid) and regimen of antifibrinolytic agents as haemostatic support to the initial replacement treatment. Neither trial specifically addressed mortality (one of this review's primary outcomes); however, in the frame of safety assessments, no fatal adverse events were reported. The second primary outcome of blood loss was assessed after surgery and these trials showed the reduction of blood loss and requirement of post-operative replacement treatment in people receiving antifibrinolytic agents compared with placebo. The remaining primary outcome of need for re-intervention was not reported by either trial.Two trials reported on 53 people with haemophilia A and B with inhibitors treated with different regimens of recombinant activated factor VII (rFVIIa) for haemostatic coverage of 33 major and 20 minor surgical interventions. Neither of the included trials specifically addressed any of the review's primary outcomes (mortality, blood loss and need for re-intervention). In one trial a high-dose rFVIIa regimen (90 μg/kg) was compared with a low-dose regimen (35 μg/kg); the higher dose showed increased haemostatic efficacy, in particular in major surgery, with shorter duration of treatment, similar total dose of rFVIIa administered and similar safety levels. In the second trial, bolus infusion and continuous infusion of rFVIIa were compared, showing similar haemostatic efficacy, duration of treatment and safety.

AUTHORS' CONCLUSIONS

There is insufficient evidence from randomised controlled trials to assess the most effective and safe haemostatic treatment to prevent bleeding in people with haemophilia or other congenital bleeding disorders undergoing surgical procedures. Ideally large, adequately powered, and well-designed randomised controlled trials would be needed, in particular to address the cost-effectiveness of such demanding treatments in the light of the increasing present economic constraints, and to explore the new challenge of ageing patients with haemophilia or other congenital bleeding disorders. However, performing such trials is always a complex task in this setting and presently does not appear to be a clinical and research priority. Indeed, major and minor surgeries are effectively and safely performed in these individuals in clinical practice, with the numerous national and international recommendations and guidelines providing regimens for treatment in this setting mainly based on data from observational, uncontrolled studies.

Thrombin activatable fibrinolysis inhibitor: at the nexus of fibrinolysis and inflammation

TAFI (thrombin activatable fibrinolysis inhibitor) is the precursor of a basic carboxypeptidase (TAFIa) with strong antifibrinolytic and anti-inflammatory activity. Compelling evidence indicates that thrombin, either alone or in complex with thrombomodulin, is the main physiological activator of TAFI. For this reason derangements of thrombin formation, whatever the cause, may influence the fibrinolytic process too. Experimental models of thrombosis suggest that TAFI may participate in thrombus development and persistence under certain circumstances. In several models of pharmacological thrombolysis, the administration of TAFI inhibitors along with the fibrinolytic agent leads to a marked improvement of thrombus lysis, underscoring the potential of TAFI inhibitors as adjuvants for thrombolytic therapy. The role of TAFI in inflammatory diseases is more complex as it may serve as a defense mechanism, exacerbate the disease, or have no influence, depending on the nature of the model and the role played by the mediators controlled by TAFIa. Finally, the numerous clinical studies in patients with thrombotic disease support the idea that increased levels of TAFI and/or the enhancement of TAFI activation may represent a new risk factor for venous and arterial thrombosis.

Structure of activated thrombin-activatable fibrinolysis inhibitor, a molecular link between coagulation and fibrinolysis

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a metallocarboxypeptidase (MCP) that links blood coagulation and fibrinolysis. TAFI hampers fibrin-clot lysis and is a pharmacological target for the treatment of thrombotic conditions. TAFI is transformed through removal of its prodomain by thrombin-thrombomodulin into TAFIa, which is intrinsically unstable and has a short half-life in vivo. Here we show that purified bovine TAFI activated in the presence of a proteinaceous inhibitor renders a stable enzyme-inhibitor complex. Its crystal structure reveals that TAFIa conforms to the alpha/beta-hydrolase fold of MCPs and displays two unique flexible loops on the molecular surface, accounting for structural instability and susceptibility to proteolysis. In addition, point mutations reported to enhance protein stability in vivo are mainly located in the first loop and in another surface region, which is a potential heparin-binding site. The protein inhibitor contacts both the TAFIa active site and an exosite, thus contributing to high inhibitory efficiency.

Reducing the risk of ICH enlargement

Intracerebral hemorrhage (ICH) comprises 15% of all strokes, and carries the highest risk of mortality and poor long-term outcome. ICH has long been recognized as the least treatable form of stroke, and hematoma volume as the strongest single predictor of mortality and outcome. CT-based studies have found that early substantial hematoma expansion occurs in 18-38% of patients initially scanned within 3 h of symptom onset. This finding is associated with early neurological deterioration and an increased risk of poor outcome. Ultra-early hemostatic therapy might be beneficial in preventing hematoma growth, resulting in improved mortality and neurological function. Recombinant activated factor VII (rFVIIa) promotes local hemostasis in the presence or absence of coagulopathy at sites of vascular injury, and is a promising treatment for arresting active bleeding in ICH. The safety and feasibility of this approach was confirmed in a phase IIb randomized, double-blind, placebo-controlled, dose-ranging trial of 399 patients with non-coagulopathic ICH. Administration of rFVIIa within 4 h of ICH onset resulted in a significant reduction of hematoma expansion at 24 h, and reduced mortality and improved functional outcome at 90 days. A confirmatory phase III trial (The FAST Trial) to confirm these results will complete enrollment in the end of 2006.

Regulation of fibrinolysis by thrombin activatable fibrinolysis inhibitor, an unstable carboxypeptidase B that unites the pathways of coagulation and fibrinolysis

The coagulation and fibrinolytic systems safeguard the patency of the vasculature and surrounding tissue. Cross regulation of coagulation and fibrinolysis plays an important role in preserving a balanced hemostatic process. Identification of Thrombin Activatable Fibrinolysis Inhibitor (TAFI) as an inhibitor of fibrinolysis and one of the main intermediates between coagulation and fibrinolysis, greatly improved our understanding of cross regulation of coagulation and fibrinolysis. As TAFI is an enzyme that is activated by thrombin generated by the coagulation system, its activation is sensitive to the dynamics of the coagulation system. Defects in coagulation, such as in thrombosis or hemophilia, resonate in TAFI-mediated regulation of fibrinolysis and imply that clinical symptoms of coagulation defects are amplified by unbalanced fibrinolysis. Thrombomodulin promotes the generation of both antithrombotic activated protein C (APC) and prothrombotic (antifibrinolytic) activated TAFI, illustrating the paradoxical effects of thrombomodulin on the regulation of coagulation and fibrinolysis. This review will discuss the role of TAFI in the regulation of fibrinolysis and detail its regulation of activation and its potential therapeutic applications in thrombotic disease and bleeding disorders.

Thrombin activatable fibrinolysis inhibitor (TAFI)--how does thrombin regulate fibrinolysis?

The thrombin-catalysed conversion of plasma fibrinogen into fibrin and the development of an insoluble fibrin clot are the final steps of the coagulation cascade during haemostasis. A delicate balance between coagulation and fibrinolysis determines the stability of the fibrin clot. Thrombin plays a central role in this process, it not only forms the clot but it is also involved in stabilizing the clot by activating thrombin activatable fibrinolysis inhibitor (TAFI). Activated TAFI protects the fibrin clot against lysis. Here we will discuss the mechanisms for regulation of fibrinolysis by thrombin. The role of the coagulation system for the generation of thrombin and for the activation of TAFI implies that defects in thrombin generation will directly affect the protection of clots against lysis. Thus, defects in activation of TAFI might contribute to the severity of bleeding disorders. Vice versa an increased activation of TAFI due to an increased rate of thrombin generation might lead to thrombotic disorders. Specific inhibitors of activated TAFI or inhibitors that interfere with the generation of thrombin might provide novel therapeutic strategies for thrombolytic therapy. Besides having a role in the regulation of fibrinolysis, TAFI may also have an important function in the regulation of inflammation, wound healing and blood pressure.

Ultra-early Hemostatic Therapy for Acute Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the least treatable form of stroke, and causes high mortality, severe disability, and a staggering economic burden. ICH accounts for 15% of stroke cases in the United States and Europe, and up to 30% in Asian populations. Computed tomography-based studies suggest that ICH growth within the first few hours of onset is common, and the principal cause of early neurological deterioration. Hematoma volume is also a well-established predictor of 30-day mortality. Intervention with ultra-early hemostatic therapy could minimize or prevent this early dynamic bleeding process, and might improve outcome. Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) is approved for the treatment of bleeding in patients with hemophilia and inhibitors, but it may also promote hemostasis in patients with normal coagulation by acting locally at the bleeding site without activation of systemic coagulation. In a randomized, double-blind, placebo-controlled trial of 399 ICH patients treated with a single dose of 40, 80, or 160 microg/kg of rFVIIa or placebo within 4 hours of onset, subsequent hematoma growth was reduced by approximately 50% with rFVIIa. This was associated with a significant reduction (38%) in mortality, and improved functional outcomes among survivors. A phase III trial comparing 20 and 80 microg/kg rFVIIa with placebo is now in progress to confirm these results.

Diagnosis and treatment of von Willebrand disease

Von Willebrand disease (VWD) is the most common bleeding disorder; it is believed to occur in approximately 1% to 2% of the population. Mucocutaneous and surgical hemorrhage in affected individuals is caused by quantitative and qualitative defects in von Willebrand factor (VWF), a large, multimeric protein that supports platelet adhesion and aggregation in the initiation of hemostasis at the time of vascular injury and functions as a carrier protein for factor VIII in the circulation. Advances in cellular and molecular biology have led to improved understanding of the pathophysiology of the disorder and development of a classification scheme that is based on quantitative and qualitative defects. Effective treatment is dependent on an accurate diagnosis using specific assays of VWF that define the various defects.

The role of recombinant factor VIIa (FVIIa) in fibrin structure in the absence of FVIII/FIX

Patients with hemophilia have an impaired thrombin generation and therefore form loose fibrin hemostatic plugs that are easily dissolved by fibrinolysis. This prevents maintained hemostasis in these patients, resulting in a severe bleeding disorder. Recombinant (F)VIIa has been shown to enhance thrombin generation on already thrombin-activated platelets in the absence of FVIII and FIX. An efficacy rate of 80-90% has been found in hemophilia patients with inhibitors against FVIII or FIX both in association with major surgery and in the treatment of serious bleedings. In a model measuring fibrin clot permeability in a platelet-containing system described by Blombäck et al. (1994) this was demonstrated to be dependent on the concentration of FVIII and FIX. The addition of rFVIIa in concentrations of 1.9, 4.8 and 9.6 microg mL(-1) normalized fibrin clot permeability. The concentration of 1.9 microg mL(-1) of rFVIIa normalized clot permeability in this system and the higher concentrations of rFVIIa added only slightly to the effect. No further decrease in clot permeability was found when rFVIIa in a concentration of 1.9 microg mL(-1) was added to a sample with a normal concentration (100%) of FVIII or FIX. Higher concentrations of rFVIIa added to the plasma containing 100% of FVIII or FIX induced only a slight further decrease of fibrin permeability constant, arguing against any unwanted effect of extra rFVIIa on clot permeability in the case of a normal hemostasis. Furthermore, the fibrin network was studied with 3D microscopy and the loose network found in the absence of FVIII or FIX increased in density with increasing FVIII or FIX concentrations. The addition of rFVIIa to FVIII- or FIX-deficient systems altered the network structure, making the fibers thinner and more tightly packed.

Ultra-early hemostatic therapy for intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) causes higher morbidity and mortality than other forms of stroke and has no proven effective treatment. Hematoma volume is a powerful predictor of outcome after ICH.

SUMMARY OF REVIEW

Historically, ICH bleeding was considered to be a monophasic event that stopped quickly as a result of clotting and tamponade by surrounding brain tissue. More recently, prospective and retrospective CT-based studies have demonstrated that hematoma growth occurs in up to 38% of patients initially scanned within 3 hours of onset and in 16% scanned between 3 and 6 hours, even in the absence of coagulopathy. Progressive bleeding of this type has been associated with contrast extravasation on CT angiography and poor outcome after early (<4 hours) surgical clot evacuation. On the basis of these observations, it is plausible that ultra-early hemostatic therapy given in the emergency setting might reduce ICH volume in some patients and improve outcome. Among candidate agents for this indication, the most promising is recombinant activated factor VIIa, which promotes local hemostasis at sites of vascular injury in both coagulopathic and normal patients.

CONCLUSIONS

Ultra-early hemostatic therapy, given within 3 to 4 hours of onset, may potentially arrest ongoing bleeding and minimize hematoma growth after ICH. Given the current lack of effective therapy for ICH, clinical trials testing this treatment approach are justified.

Blood Coagulation in Hemophilia A and Hemophilia C

Tissue factor (TF)-induced coagulation was compared in contact pathway suppressed human blood from normal, factor VIII-deficient, and factor XI-deficient donors. The progress of the reaction was analyzed in quenched samples by immunoassay and immunoblotting for fibrinopeptide A (FPA), thrombin-antithrombin (TAT), factor V activation, and osteonectin. In hemophilia A blood (factor VIII:C <1%) treated with 25 pmol/L TF, clotting was significantly delayed versus normal, whereas replacement with recombinant factor VIII (1 U/mL) restored the clot time near normal values. Fibrinopeptide A release was slower over the course of the experiment than in normal blood or hemophilic blood with factor VIII replaced, but significant release was observed by the end of the experiment. Factor V activation was significantly impaired, with both the heavy and light chains presenting more slowly than in the normal or replacement cases. Differences in platelet activation (osteonectin release) between normal and factor VIII-deficient blood were small, with the midpoint of the profiles observed within 1 minute of each other. Thrombin generation during the propagation phase (subsequent to clotting) was greatly impaired in factor VIII deficiency, being depressed to less than 1/29 (<1.9 nmol TAT/L/min) the rate in normal blood (55 nmol TAT/L/min). Replacement with recombinant factor VIII normalized the rate of TAT generation. Thus, coagulation in hemophilia A blood at 25 pmol/L TF is impaired, with significantly slower thrombin generation than normal during the propagation phase; this reduced thrombin appears to affect FPA production and factor V activation more profoundly than platelet activation. At the same level of TF in factor XI-deficient blood (XI:C <2%), only minor differences in clotting or product formation (FPA, osteonectin, and factor Va) were observed. Using reduced levels of initiator (5 pmol/L TF), the reaction was more strongly influenced by factor XI deficiency. Clot formation was delayed from 11.1 to 15.7 minutes, which shortened to 9.7 minutes with factor XI replacement. The maximum thrombin generation rate observed (∼37 nmol TAT/L/min) was approximately one third that for normal (110 nmol/L TAT/min) or with factor XI replacement (119 nmol TAT/L/min). FPA release, factor V activation, and release of platelet osteonectin were slower in factor XI-deficient blood than in normal blood. The data demonstrate that factor XI deficiency results in significantly delayed clot formation only at sufficiently low TF concentrations. However, even at these low TF concentrations, significant thrombin is generated in the propagation phase after formation of the initial clot in hemophilia C blood.

Blood Coagulation in Hemophilia A and Hemophilia C

Tissue factor (TF)-induced coagulation was compared in contact pathway suppressed human blood from normal, factor VIII-deficient, and factor XI-deficient donors. The progress of the reaction was analyzed in quenched samples by immunoassay and immunoblotting for fibrinopeptide A (FPA), thrombin-antithrombin (TAT), factor V activation, and osteonectin. In hemophilia A blood (factor VIII:C &lt;1%) treated with 25 pmol/L TF, clotting was significantly delayed versus normal, whereas replacement with recombinant factor VIII (1 U/mL) restored the clot time near normal values. Fibrinopeptide A release was slower over the course of the experiment than in normal blood or hemophilic blood with factor VIII replaced, but significant release was observed by the end of the experiment. Factor V activation was significantly impaired, with both the heavy and light chains presenting more slowly than in the normal or replacement cases. Differences in platelet activation (osteonectin release) between normal and factor VIII-deficient blood were small, with the midpoint of the profiles observed within 1 minute of each other. Thrombin generation during the propagation phase (subsequent to clotting) was greatly impaired in factor VIII deficiency, being depressed to less than 1/29 (&lt;1.9 nmol TAT/L/min) the rate in normal blood (55 nmol TAT/L/min). Replacement with recombinant factor VIII normalized the rate of TAT generation. Thus, coagulation in hemophilia A blood at 25 pmol/L TF is impaired, with significantly slower thrombin generation than normal during the propagation phase; this reduced thrombin appears to affect FPA production and factor V activation more profoundly than platelet activation. At the same level of TF in factor XI-deficient blood (XI:C &lt;2%), only minor differences in clotting or product formation (FPA, osteonectin, and factor Va) were observed. Using reduced levels of initiator (5 pmol/L TF), the reaction was more strongly influenced by factor XI deficiency. Clot formation was delayed from 11.1 to 15.7 minutes, which shortened to 9.7 minutes with factor XI replacement. The maximum thrombin generation rate observed (∼37 nmol TAT/L/min) was approximately one third that for normal (110 nmol/L TAT/min) or with factor XI replacement (119 nmol TAT/L/min). FPA release, factor V activation, and release of platelet osteonectin were slower in factor XI-deficient blood than in normal blood. The data demonstrate that factor XI deficiency results in significantly delayed clot formation only at sufficiently low TF concentrations. However, even at these low TF concentrations, significant thrombin is generated in the propagation phase after formation of the initial clot in hemophilia C blood.

Mild hemophilia in children: prevalence, complications, and treatment

PURPOSE

To review the natural history of mild hemophilia (factor VIII or IX level >5% and <50%), including presentation and diagnosis, characteristics of bleeding episodes, and therapy, at two hemophilia treatment centers.

METHODS

Inpatient and outpatient records of 55 patients <17 years old with factor VIII or IX levels of 5 to 50% were reviewed and bleeding episodes for which medical attention was sought were analyzed.

RESULTS

Five of the 55 patients were girls. Girls and patients with no family history of hemophilia were diagnosed at 5.5 and 5.3 years of age, respectively, compared to 2.8 years overall. Thirty-five patients were diagnosed because of a positive family history. No bleeding occurred in 18 patients; 190 bleeding episodes occurred in 37 patients. Most bleeding occurred in muscle/soft tissue (101 episodes) or joints (57 episodes) and were associated with trauma (174 episodes).

CONCLUSIONS

Mild hemophilia may affect females more often than is appreciated. Delays in diagnosis and treatment may occur unless the variability in presentation is recognized.

Dental considerations for a Glanzmann's thrombasthenia patient: case report

Glanzmann's thrombasthenia is a qualitative platelet disorder characterized by a deficiency in the platelet membrane glycoproteins (GP) IIb-IIIa. It belongs to a group of hereditary platelet disorders typified by normal platelet numbers and a prolonged bleeding time. The bleeding seen in Glanzmann's thrombasthenia usually includes bruising, epistaxis, gingival hemorrhage, and menorrhagia. Spontaneous, unprovoked bleeding is unusual. The severity of bleeding is unpredictable in thrombasthenia and does not correlate with the severity of the platelet GP IIb-IIIa abnormality. The present case report describes the dental treatment of a patient with Glanzmann's thrombasthenia. A 39-year-old female with a history of Glanzmann's thrombasthenia presented for periodontal therapy for spontaneous gingival hemorrhage. The patient had been sporadically seen in the past and had a record of only returning for appointments on an "emergency" basis. The periodontal findings revealed a diagnosis of moderate to advanced adult periodontitis in all quadrants. After all dental options had been discussed, the treatment of choice was determined to be extraction of the remaining dentition and fabrication of immediate dentures. The patient received a loading dose of 5 grams of aminocaproic acid (EACA) intravenously 3 hours prior to the surgery. At the beginning of the extractions 1 gram of EACA per hour continuous infusion and a 6 pack of platelets was administered. The patient tolerated the extractions well. All sites healed normally. The patient has had no difficulty in adjusting to the dentures. The case report discusses a possible treatment option in a noncompliant patient having Glanzmann's thrombasthenia and briefly discusses other hereditary bleeding disorders with similar presentations.

Some complications of the therapy of hemorrhagic disorders

The principal mode for treating disorders of hemostasis is correction of the patient's functional defect by transfusions of appropriate fractions of normal plasma or transfusions of platelets. Two major complications of such therapy are the transmission of infectious diseases, particularly hepatitis and the acquired immune deficiency syndrome (AIDS), and the development of antibodies against clotting factors that are deficient in the patient's plasma. Measures that reduce the occurrence of infection include careful selection of donors, fractionation of plasma with the help of monoclonal antibodies, and treatment of plasma or its fractions with heat or with virus-inactivating organic solvents. No technique of preparing or administering blood or its components can prevent the emergence of antibodies against clotting factors. Desensitization by repeated infusions of antigen, for example, antihemophilic factor, however, appears to result in remission in some patients.

Case report: successful use of antifibrinolytic therapy in acquired factor VIII deficiency

Acquired factor VIII deficiency is a rare immunologic disorder characterized by severe bleeding due to an antibody inhibitor directed against factor VIII. Treatment of this coagulopathy often is ineffective and costly. The authors report a case of acquired factor VIII deficiency in a patient who developed severe recurrent epistaxis. Antifibrinolytic therapy with epsilon aminocaproic acid (EACA) was used to control the epistaxis with excellent results. To the authors' knowledge, this is the first report of the efficacy of EACA therapy in acquired factor VIII deficiency. Use of antifibrinolytic therapy may represent a relatively safe, effective, and inexpensive approach to treating factor VIII inhibitors.

Factor XI deficiency in Ashkenazi Jews in Israel

BACKGROUND AND METHODS

Severe factor XI deficiency, which is relatively common among Ashkenazi Jews, is associated with injury-related bleeding of considerable severity. Three point mutations--a splice-junction abnormality (Type I), Glu117----Stop (Type II), and Phe283----Leu (Type III)--have been described in six patients with factor XI deficiency. Clinical correlations with these mutations have not been carried out. We determined the relative frequency of the mutations and their association with plasma levels of factor XI clotting activity and bleeding, analyzing the mutations with the polymerase chain reaction and restriction-enzyme digestion.

RESULTS

The Type II and Type III mutations had similar frequencies among 43 Ashkenazi Jewish probands with severe factor XI deficiency; these two mutations accounted for 49 percent and 47 percent, respectively, of a total of 86 analyzed alleles. Among 40 of the probands and 12 of their relatives with severe factor XI deficiency, patients homozygous for Type III mutation had a significantly higher level of factor XI clotting activity (mean [+/- SD] percentage of normal values, 9.7 +/- 3.8 percent; n = 13) than those homozygous for Type II mutation (1.2 +/- 0.5 percent, n = 16) or compound heterozygotes with Type II/III mutation (3.3 +/- 1.6 percent, n = 23), as well as significantly fewer episodes of injury-related bleeding. Each of these three groups had a similarly increased proportion of episodes of bleeding complications after surgery at sites with enhanced local fibrinolysis, such as the urinary tract, or during tooth extraction.

CONCLUSIONS

Type II and Type III mutations are the predominant causes of factor XI deficiency among Ashkenazi Jews. Genotypic analysis, assay for factor XI, and consideration of the type and location of surgery can be helpful in planning operations in patients with this disorder.

Inherited bleeding disorders

Congenital bleeding disorders comprise a heterogeneous group of diseases that reflect abnormalities of blood vessels, coagulation proteins and platelets. Studies of these diseases, many of which are rare and several of which result in a mild bleeding diathesis only, have significantly increased our understanding of normal haemostasis. Two lessons have been learned. First, quantitative abnormalities of coagulation proteins and platelets are an important, but not the only, cause of significant haemorrhage; some cases of inherited bleeding disorders reflect synthesis of a dysfunctional coagulation protein or production of abnormal platelets. Diagnostic tests that reflect qualitative abnormalities are therefore important in the evaluation of selected patients with inherited bleeding disorders. Second, in occasional patients the inherited disorder is complex and reflects combined abnormalities of coagulation proteins alone or in association with platelet disorders. In clinical practice it is useful to distinguish disorders that cause significant clinical bleeding from those that cause few or no symptoms. Examples of the former include severe deficiencies of factors VIII and IX, and the homozygous forms of factor II, V, VII, X, XI, XIII, fibrinogen and von Willebrand factor. Comparable platelet disorders include the inherited thrombocytopenias with platelet counts less than 20 x 10(9) litre-1 and the homozygous forms of Bernard-Soulier syndrome and Glanzmann's thrombasthenia. The most frequently encountered mild haemostatic abnormalities include type I von Willebrand's disease, the platelet storage pool deficiency syndromes and the mild and moderate forms of haemophilia A and B; occasionally heterozygous or homozygous forms of the rarer coagulation disorders, e.g. factor XI deficiency, may present with a mild bleeding diathesis. Finally, some disorders are entirely asymptomatic, e.g. factor XII deficiency and deficiencies of other contact coagulation factors. Management of patients with inherited bleeding disorders should reflect knowledge of the specific disorder to be treated plus careful consideration of the clinical circumstance for which therapy is proposed. In all cases, once a decision to treat has been made, the safest efficacious therapy should be given (for example DDAVP in the treatment of patients with mild haemophilia A or type I von Willebrand's disease). Although blood products are now much safer and the risk of blood transmitted viral infections is low, there still remains a risk that transfusion of any blood product may be associated with serious side-effects. As a result, therapy should be given only after careful consideration of the risk: benefit ratio and not merely to treat an abnormal laboratory result.(ABSTRACT TRUNCATED AT 400 WORDS)

When a patient with a bleeding disorder needs dental work. How you can work with the dentist to prevent a crisis

Patients with bleeding disorders need close cooperation between their physician and their dental practitioner to receive safe, comprehensive dental care. When indicated, physicians must advise a compromised treatment plan to avoid deep injections or surgical procedures that may initiate a bleeding crisis in patients at risk. The conditions most commonly seen that require special consideration are long-term use of antithrombotic agents, platelet dysfunction caused by chronic renal failure, and congenital clotting factor deficiencies. Even these patients may undergo a high-risk procedure, such as periodontal surgery, with adequate precautions and preparation.

Oral surgery in patients with hereditary bleeding disorders. A survey of treatment in the Stockholm area (1974-1985)

The results on the oral surgical management of patients with coagulation disorders at the Karolinska Hospital, Stockholm, during the period 1974-1985 have been compiled and compared with those obtained during the period 1965-1973. The present study included 380 tooth extractions performed in 250 treatment sessions in 107 patients. The incidence of postoperative bleeding and duration of hospitalization were reduced during the period of investigation.

Convulsions induced by aminocaproic acid infusion

Aminocaproic acid is a widely used antifibrinolytic agent. Serious adverse effects associated with its use are rare, but we report on a patient with liver disease and cirrhosis who experienced a grand mal seizure during the intravenous administration of aminocaproic acid. Clinicians should be alert to the occurrence of this adverse effect in patients with no previous neurological problems.

Mild hemophilia A as a cause of bleeding in dermatologic surgery

A 63-year-old male had major postoperative bleeding complications following the excision of a basal cell carcinoma. The patient denied a prior history of bleeding complications and had normal coagulation screening studies. After coagulation evaluation, he was found to have mild hemophilia A with 23% of normal Factor VIII C. We discuss an approach to the evaluation of coagulation in patients with perioperative and postoperative bleeding. Also, we outline treatment alternatives for patients with hemophilia A who need cutaneous surgery.

Effects of EACA on thrombin generation as measured by the chromagen S2238

In the presence of epsilon aminocaproic acid (EACA) thrombin generation in recalcified platelet rich plasma (PRP) was markedly stimulated, as measured by the cleavage of the synthetic substrate S2238. However, thrombin activity remaining after 30 minutes incubation was reduced when compared with control values. The residual activity was shown to be hirudin insensitive and to be associated with a species of higher molecular weight than free thrombin. These results suggested an inhibition of thrombin binding to the antithrombin, alpha 2-macroglobulin (alpha 2M). Preincubation of PRP with EACA reduced the concentration at which EACA elicited its dual effects. Similar results were obtained with the alpha 2M inhibitor, hydrazine. These experiments indicated that alpha 2M may play a more important role in regulating thrombin generation than has been previously recognized.

Effect of local antifibrinolytic treatment with tranexamic acid in hemophiliacs undergoing oral surgery

The objectives of the present clinical investigation were to examine the effects in hemophiliacs of local antifibrinolytic treatment with tranexamic acid on the incidence of postoperative bleeding after oral surgery and on the amount of replacement therapy needed to control bleeding. The study compared three groups of patients. The patients in group A received high doses of factor concentrate and systemic antifibrinolytic treatment with tranexamic acid. In group B local antifibrinolytic treatment with tranexamic acid was added to the treatment received by group A. Group C received replacement therapy to raise factor levels to approximately 10% of the normal value perioperatively, combined with systemic and local antifibrinolytic treatment (mouth rinse) with tranexamic acid. The study demonstrated that local antifibrinolytic therapy with tranexamic acid as a supplement to the currently used systemic therapy significantly reduces the incidence of postoperative bleeding. The results of the study further suggest that replacement therapy can be reduced during oral surgery in the hemophilic patient provided that local and systemic inhibition of fibrinolysis is instituted.