Made available in DSpace on 2014-06-11T19:23:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-16Bitstream added on 2014-06-13T19:50:42Z : No. of bitstreams: 1 rafael_la_me_botfmvz.pdf: 598677 bytes, checksum: 9244a6bf719ef84e48cb12aef3188a32 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os processos sépticos são complicações frequentes nas estruturas sinoviais e demais tecidos da porção distal dos membros de equinos. A perfusão regional intravenosa é uma opção terapêutica, que objetiva aumentar significativamente a concentração de antimicrobiano na porção distal ao posicionamento do torniquete. No entanto, alguns pontos ainda não estão totalmente esclarecidos e algumas complicações, como trombose venosa, podem ocorrer. Objetivou-se com este estudo avaliar o potencial trombogênico da perfusão regional de gentamicina, na dose de 2,2 mg/kg na veia cefálica de equinos. Utilizou-se 15 equinos hígidos, divididos em três grupos de cinco animais. Grupo 1, somente torniquete (GT), grupo 2, torniquete e 40 ml de solução fisiológica (GSF), grupo 3, torniquete e gentamicina na dose de 2,2 mg/kg e solução fisiológica até completar um volume de 40 ml (GSG). Um membro torácico de cada animal foi escolhido aleatoriamente para o tratamento e torniquete aplicado no terço médio proximal do rádio. Ultrassonografia Doppler foi realizada no membro testado imediatamente antes, 30 minutos, 2, 3, 4, 6, 12, 24, 48, 72 e 96 horas após o tratamento na veia cefálica e artéria mediana. A artéria mediana também foi avaliada aproximadamente 15 minutos após posicionamento do torniquete. A termografia foi realizada em ambos os membros em todos os momentos. Os dados foram avaliados por análise de variância com medidas repetidas, teste de Tukey de comparações múltiplas de médias para comparar os grupos e ajustado para Dunnett para comparar os momentos em relação ao momento M0. Significância foi aceito p <0,05. Todos os grupos apresentaram escore trombótico zero, não houve diferença significativa entre os grupos quanto à temperatura do membro e diâmetro médio da veia. A perfusão regional intravenosa com... / Septic processes are common in synovial structures and tissues of the distal limbs in horses. Regional intravenous perfusion is a therapeutic option that aims to significantly increase the antibiotic concentration in the limb, distal to the tourniquet. Nevertheless, some critical points remains unclear, and complication such as thrombosis may occur along this procedure. The purpose of this work was to assess the thrombogenic potential of regional intravenous perfusion after administration of gentamicin in the cephalic vein. Fifteen healthy horses were assigned to three groups of 5 animals. Group 1, tourniquet group (TG), group 2, tourniquet and 40 mL of physiologic saline solution (SPG) and group 3, tourniquet and 2.2 mg/kg gentamicin completed to 40 mL by addition of physiologic saline solution (ASG). One forelimb of each animal was randomly chosen for treatment and tourniquet applied at the proximal end of the radius. Doppler ultrasonography was performed in the treated limb immediately before and 30 minutes, 2, 3, 4, 6, 12, 24, 48, 72 and 96 hours after treatment in the cephalic vein and artery median. The median artery was also evaluated approximately 15 minutes after placement of the tourniquet. Thermography was performed in both limbs at all the moments. Data were assessed by analysis of variance with repeated measures, Tukey's multiple mean comparison test to compare the groups and Dunnett's multiple mean comparison test to compare the moments regarding M0. Significance was accepted at p <0.05. Thrombotic score was zero for the three groups; no difference was found between groups regarding temperature and mean vein diameter of the treated limb. Regional intravenous perfusion using a single dose... (Complete abstract click electronic access below)

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No. of bitstreams: 1 brandao_gms_dr_bot.pdf: 2703945 bytes, checksum: d9034b6210add676a4f9b7cbf4c31ad3 (MD5) Previous issue date: 2016-05-25 / Pentasaccharides para o tratamento da trombose venosa profunda Questão da revisão: Os novos anticoagulantes da classe dos pentasaccharides podem ser uma alternativa eficaz e segura aos anticoagulantes convencionais utilizados na terapia padrão do tratamento da trombose venosa profunda? Visão geral: Trombose venosa profunda (TVP) é uma doença grave e potencialmente fatal que se caracteriza pela formação aguda de um coágulo de sangue nas veias profundas. Sua incidência aumenta exponencialmente com a idade e estima-se que na população geral, sua incidência seja de 5 casos em 10,000 habitantes. O tratamento padrão se faz por meio de medicamentos anticoagulantes, inicialmente pela administração de medicamentos injetáveis, as heparinas, por 5 a 7 dias e em seguida pelo uso prolongado de medicamentos de uso oral, os antagonistas da vitamina K. Entretanto, o alto risco de sangramento e a necessidade de um rigoroso controle laboratorial, permanecem como importantes limitações à terapia padrão. Os pentasaccharides são anticoagulantes sintéticos que podem apresentar vantagens em relação ao tratamento convencional como um efeito mais previsível, um regime de dosagem mais conveniente, a ausência da necessidade de controle laboratorial, ausência de interações com medicamentos e/ou alimentos, ausência da temida diminuição das plaquetas induzida pela heparina e em muitos casos melhor custo-benefício. Características chaves e resultados: Nossas buscas, realizadas até julho de 2015, identificaram 20 entre 730 registros que representavam 5 estudos elegíveis, compreendendo um total de 6981 pacientes. Os estudos compararam os pentasaccharides fondaparinux, idraparinux e idrabiotaparinux com a terapia padrão (heparina seguida por antagonista da vitamina K). O principal resultado de eficácia foi feito pela avaliação da incidência de qualquer episódio tromboembolismo venoso (novo episódio de TVP ou embolia pulmonar) durante o tratamento. E o principal resultado de danos foi incidência de sangramento. Esta revisão mostrou que os pentasaccharides (fondaparinux, e a dose de 2.5 mg de idraparinux e a dose equivalente de 3.0 mg de idrabiotaparinux) podem ser uma alternativa eficaz e segura a anticoagulação convencional para o tratamento da TVP. Qualidade da evidência: A qualidade da evidência foi considerada moderada a alta. Um único estudo incluído (Persist) poderia ser julgado potencialmente falho devido ao relevante número de pacientes que foram perdidos ou descontinuaram prematuramente o tratamento após a randomização. De forma geral, os estudos incluídos responderam diretamente as perguntas e foram considerados de boa qualidade. Os resultados dos estudos foram consistentes e os efeitos estimados foram precisos. Nós acreditamos que seja improvável que a maioria dos nossos principais resultados de eficácia e danos possam ser modificados por estudos adicionais. Entretanto, estudos futuros com os pentasaccharides de meia vida prolongada (idraparinux e idrabiotaparinux) em baixas doses podem confirmar nossas estimativas com relação a sua não inferioridade em comparação à terapia padrão. / Background: Deep vein thrombosis (DVT) is a severe disorder caused by acute formation of a clot or thrombus in the deep vein system. The incidence of DVT increases with age: from 2 to 3/10,000 in adults aged 30 to 49 years to 20/10,000 in adults aged 70 to 79 years. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Standard treatment is based on antithrombotic therapy, initially with parenteral administration of unfractionated heparin or low molecular weight heparins (LMWH) for five to seven days, then subsequent long-term oral vitamin K antagonists (e.g. warfarin) therapy. However, hemorrhagic complications are a major concern associated with warfarin treatment. Indeed, the hemorrhagic risk of warfarin and the required laboratory control remain the Achilles’ heel of vitamin K antagonist management. The pentasaccharides have characteristics that may be favourable over conventional treatment, including a predictable effect, lack of frequent monitoring or re-dosing and few known drug interactions and absence of heparin-induced thrombocytopenia. To date, no systematic review has measured the effectiveness and safety of these drugs in the treatment of DVT. Objectives: To assess the efficacy and harms of pentasaccharides for the treatment of deep venous thrombosis. Search strategy: 1 The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched July 2015) and the Cochrane Register of Studies (last searched July 2015). We searched clinical trials databases for details of ongoing or unpublished studies and the reference lists of relevant articles retrieved by electronic searches for additional citations. Selection criteria: We included randomised controlled trials in which people with a DVTconfirmed by standard imaging techniques, were allocated to receive a pentasaccharide (fondaparinux, idraparinux or idrabiotaparinux) for the treatment of DVT. Data collection and analysis: Three review authors (GB, DJ and MS) independently extracted the data and assessed the risk of bias in the trials. Any disagreements were resolved by discussion. We performed meta-analyses when we considered heterogeneity low. The two primary outcomes were recurrent VTE and major (and clinically non-major) bleeding. Other outcomes included all-cause mortality, recurrent DVT, PE, thrombocytopenia, heparin-induced thrombocytopenia syndrome and all other adverse effects induced by the treatments . We calculated all outcomes using a relative risk (RR) with a 95% confidence interval (CI). Main results: We included 5 randomised controlled trials of 6981 participants. Two studies tested fondaparinux, while three tested idraparinux (being one tested idrabiotaparinux). We deemed all included studies to be of high methodological quality and generally low risk of bias. The quality of the evidence was generally graded as high as the outcomes were direct and effect estimates were consistent and precise, as reflected in the narrow CIs around the RRs. Meta-analysis of two studies (2658 participants) comparing fondaparinux with standard anticoagulation groups showed no difference in the risk of recurrent VTE (RR 0.88, 95% CI 0.60 to 1.29). The RR of bleeding in the initial period of treatment (RR 0.94, 95% CI 0.73 to 1.22) and three months of follow up (RR 0.61, 95% CI 0.36 to 1.01) were similar comparing both interventions. Two studies comparing idraparinux with standard therapy showed no difference in the risk of recurrent VTE during three months (RR 1.51; 95% CI 0.26, 8.90) and (RR 0.79; 95% CI 0.21; 2.91). The treatment with idraparinux clearly showed a bleeding risk with a pattern dose-response. However, at a dose of 2.5 mg idraparinux, there was no significant difference in the risk of bleeding in patients receiving idrapaparinux in comparison to standard therapy during six months of follow up (RR 0.92, 95% CI 0.69 to 1.22). One study contributed with data for the analysis (n=741 participants) that there was no significant difference in the risk of recurrent VTE during six months follow-up between idrabiotaparinux compared with idraparinux (RR 0.71, 95% CI 0.30 to 1.66). The risk of bleeding was also similar comparing the two interventions (RR 0.71, 95% CI 0.49 to 1.04). Authors' conclusions: The pentasaccharides (fondaparinux, the dose of 2.5 mg idraparinux and equimolar dose of 3.0 mg idrabiotaparinux) may be an effective and safe alternative to conventional anticoagulation treatment for acute DVT.

Orientador: Celso Antônio Rodrigues / Banca: Carlos Alberto Hussni / Banca: Luis Cláudio Lopes Correia da Silva / Resumo: Os processos sépticos são complicações frequentes nas estruturas sinoviais e demais tecidos da porção distal dos membros de equinos. A perfusão regional intravenosa é uma opção terapêutica, que objetiva aumentar significativamente a concentração de antimicrobiano na porção distal ao posicionamento do torniquete. No entanto, alguns pontos ainda não estão totalmente esclarecidos e algumas complicações, como trombose venosa, podem ocorrer. Objetivou-se com este estudo avaliar o potencial trombogênico da perfusão regional de gentamicina, na dose de 2,2 mg/kg na veia cefálica de equinos. Utilizou-se 15 equinos hígidos, divididos em três grupos de cinco animais. Grupo 1, somente torniquete (GT), grupo 2, torniquete e 40 ml de solução fisiológica (GSF), grupo 3, torniquete e gentamicina na dose de 2,2 mg/kg e solução fisiológica até completar um volume de 40 ml (GSG). Um membro torácico de cada animal foi escolhido aleatoriamente para o tratamento e torniquete aplicado no terço médio proximal do rádio. Ultrassonografia Doppler foi realizada no membro testado imediatamente antes, 30 minutos, 2, 3, 4, 6, 12, 24, 48, 72 e 96 horas após o tratamento na veia cefálica e artéria mediana. A artéria mediana também foi avaliada aproximadamente 15 minutos após posicionamento do torniquete. A termografia foi realizada em ambos os membros em todos os momentos. Os dados foram avaliados por análise de variância com medidas repetidas, teste de Tukey de comparações múltiplas de médias para comparar os grupos e ajustado para Dunnett para comparar os momentos em relação ao momento M0. Significância foi aceito p <0,05. Todos os grupos apresentaram escore trombótico zero, não houve diferença significativa entre os grupos quanto à temperatura do membro e diâmetro médio da veia. A perfusão regional intravenosa com... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Septic processes are common in synovial structures and tissues of the distal limbs in horses. Regional intravenous perfusion is a therapeutic option that aims to significantly increase the antibiotic concentration in the limb, distal to the tourniquet. Nevertheless, some critical points remains unclear, and complication such as thrombosis may occur along this procedure. The purpose of this work was to assess the thrombogenic potential of regional intravenous perfusion after administration of gentamicin in the cephalic vein. Fifteen healthy horses were assigned to three groups of 5 animals. Group 1, tourniquet group (TG), group 2, tourniquet and 40 mL of physiologic saline solution (SPG) and group 3, tourniquet and 2.2 mg/kg gentamicin completed to 40 mL by addition of physiologic saline solution (ASG). One forelimb of each animal was randomly chosen for treatment and tourniquet applied at the proximal end of the radius. Doppler ultrasonography was performed in the treated limb immediately before and 30 minutes, 2, 3, 4, 6, 12, 24, 48, 72 and 96 hours after treatment in the cephalic vein and artery median. The median artery was also evaluated approximately 15 minutes after placement of the tourniquet. Thermography was performed in both limbs at all the moments. Data were assessed by analysis of variance with repeated measures, Tukey's multiple mean comparison test to compare the groups and Dunnett's multiple mean comparison test to compare the moments regarding M0. Significance was accepted at p <0.05. Thrombotic score was zero for the three groups; no difference was found between groups regarding temperature and mean vein diameter of the treated limb. Regional intravenous perfusion using a single dose... (Complete abstract click electronic access below) / Mestre

Superficial venous thrombosis (SVT) is a common inflammatory and thrombotic pathology occurring within a superficial vein. SVT can result in distressing symptoms of redness and pain in the affected area and exposes patients to a risk of developing deep vein thrombosis (DVT) and pulmonary embolism (PE). Various therapeutic options are available to patients including anti-inflammatories, anti-coagulation and surgical procedures, however which of these therapies is the best first line treatment remains unknown. Several randomized controlled trials have been conducted addressing this question, yet methodological and design flaws have limited the translation of their results into a change of clinical practice. The following thesis consists of a multi-step process of reviewing the evidence to date followed by a process of engaging with clinician stakeholders with the goal of designing a randomized control trial that would provide a meaningful answer to patients and their clinicians. In the first step of this process, a systematic review of the literature was performed, including a meta-analysis to estimate pooled risk of developing symptomatic venous thromboembolic (VTE) complications in patients with isolated SVT following various treatments. These results were then presented to expert Canadian clinicians in a series of surveys using a Delphi process to determine the clinical trial design that would have the greatest impact on changing clinical practice. An additional survey of expert clinicians was conducted to determine current practice variation in the diagnosis, management, and follow up of patients with SVT, in order to design a clinical trial that best reflected current standard Canadian clinical practice. Our systematic review identified 15 articles and including 5775 patients. Quality and assessment of risk of bias was moderate for most included studies. The findings of our meta-analysis identified that Fondaparinux, at prophylactic dose, to had the lowest event rate of 2.0 events per 100 patient years of follow-up (95% CI 0.4 to 4.7, I2=33%) for the primary outcome of deep vein thrombosis (DVT) or pulmonary embolism (PE) during follow-up. Pooled event rates ranged from 8.6-16.6 events per 100 patient-years across other treatment categories, including placebo/observation only, with an event rate of 10.5 events per 100-patient years (95% CI 3.0 to 22.0). Heterogeneity was moderate to high for most pooled estimates, limiting the interpretation of these findings. Our survey of practice variation among expert Canadian clinicians revealed wide practice variation in in diagnosis and therapeutic management including sub-groups (e.g. cancer). There was agreement that clinical equipoise exists for the optimal treatment of SVT (77% of respondents), supporting the need for further research. Two rounds of surveys were performed using Delphi process methods, resulting in consensus for the design of a future randomized control trial (RCT). The agreed on design was for a randomized control trial comparing a direct oral anticoagulant (DOAC) such as Rivaroxaban, to Non-Steroidal Anti-Inflammatories (NSAIDs), using a non-inferiority RCT design with a non-inferiority margin of 3%. Future direction of this research will be to continue stakeholder engagement by engaging patients in the clinical trial design, followed by development of a pilot RCT protocol and application for peer-reviewed funding.

An underlying myeloproliferative disorder (MPD), especially polycythemia vera (PV) or essential thrombocythemia (ET), is a risk factor for thrombosis. Considering large selected studies, prevalence rates for major thrombosis, at time of diagnosis, range from ∼34 to 39% for PV and 10 to 29% for ET; the corresponding figures for thrombosis at follow-up are ∼8 to 19% for PV and 8 to 31% for ET. In all instances, arterial events were more frequent than venous events. In both PV and ET, advanced age and history of thrombosis are independent predictors of recurrent thrombosis. In addition, leukocytosis, but not thrombocytosis, has been identified as a potential risk factor for thrombosis in both diseases. The particular observation is consistent with the laboratory demonstration, in these disorders, of increased number of activated granulocytes and granulocyte-platelet aggregates, upregulation of platelet P-selectin and tissue factor expression by granulocytes, and the antithrombotic value of hydroxyurea therapy. Most recently, a JAK2 gain-of-function mutation (JAK2V617F) was described in virtually all patients with PV and ∼50% of those with ET. Whether the presence of this specific mutation or its allele burden modifies the risk of thrombosis in patients with MPDs currently is under investigation.

A research report submitted to the University of Witwatersrand, Johannesburg in fulfilment for the requirements of the degree of Master of Medicine 4 June 2019 Descriptive study of Venous Thromboembolic Disease in the adult population admitted to Tshepong Hospital comparing the proportion of HIV and non-HIV infected patients / Background HIV and TB independently incur increased risk for venous thromboembolic disease (VTE): deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Data from high HIV and TB burden settings describing VTE is scarce. The Wells’ DVT and PE scores are widely used but their utility in these settings has not been reported on extensively. We therefore report clinical and treatment aspects of in-patients with newly diagnosed VTE to assess HIV and TB prevalence, and their Wells’ score. Setting Tshepong Hospital in the North West Province of South Africa. Methods A prospective cohort of adult in-patients with radiologically confirmed VTE were recruited. Demographics, presence of TB, HIV status, duration of treatment, CD4 count, viral load, VTE risk factors, and parameters to calculate the Wells’ score were collected. Results One hundred patients were recruited, of whom 59 were HIV-infected; 39 had TB disease and 32 were HIV/TB co-infected. Eighty -three patients had a DVT only; 11 patients had a PE, and six had both a DVT and PE. Eighteen of 42 patients on antiretroviral treatment (ART) were on treatment for less than six months. Twenty patients of 39 were on TB treatment for less than one month. The median DVT and PE Wells’ score in all sub-groups was 3.0 (IQR: 1.0-4.0) and 3.0 (IQR: 2.5-4.5), respectively. There were nine deaths. Conclusion HIV /TB co-infection appear to confer a risk for VTE, especially early after ART and/or TB treatment, and therefore require careful monitoring for VTE and early initiation of thrombo-prophylaxis. / E.K. 2019

BACKGROUND: Though direct oral anticoagulants (DOACs) have become a standard of care in the treatment of acute deep vein thrombosis (DVT), it is our observation that physicians tend to initiate heparin or low-molecular-weight heparin, hereafter called “heparin”, for the treatment of extensive DVT or phlegmasia cerulea dolens (PCD). This might be due to a perception that heparin might relieve DVT-related symptoms more quickly than DOACs. Whether these assumptions are true has not been evaluated. METHODS: We conducted a survey of thrombosis specialists in North America to explore the practical management of anticoagulant therapy in patients with extensive DVT, and the underlying reasons for the selection of heparin over DOACs. A cross-sectional, web-based survey was distributed to thrombosis specialists who are members of four thrombosis societies. RESULTS: Eighty-nine respondents provided consent. Most respondents selected DOACs over heparin in a case scenario representing mild DVT-related symptoms and limited thrombus involvement (81% vs. 19%). Most respondents selected heparin over DOACs in a case scenario representing early stage PCD (84% vs.16.3%) or a patient with high bodyweight (72% vs. 28%). In a case scenario representing extensive DVT, 57.4% of the respondents selected heparin, whereas, 42.6% selected DOACs. In the respondents who selected heparin over DOACs, the major reason was that heparin might relieve DVT-related symptoms more quickly because of its anti-inflammatory effects. DISCUSSION: Severity of DVT-related symptoms, thrombus extent, and bodyweight play a role in the selection of anticoagulant therapy. Despite a lack of evidence to support the hypothesis with respect to which anticoagulant is superior, most thrombosis specialists selected heparin over DOACs in patients with severe DVT-related symptoms and extensive thrombus involvement. Observation of variations in the selection of anticoagulant therapy for the treatment of extensive DVT also indicates that clinical trials in this patient population are needed. / Thesis / Master of Science (MSc)

Thrombotic disorders include myocardial infarction (MI), acute ischemic stroke (AIS) and venous thromboembolism (VTE), which encompasses pulmonary embolism (PE), and deep vein thrombosis (DVT). To prevent further complications or mortality in patients with MI and AIS, rapid restoration of blood flow is needed to minimize organ damage. Such treatment also is needed in patients with massive PE. Blood flow can be restored mechanically via percutaneous coronary intervention with stent implantation for MI and by thrombectomy in patients with AIS or PE. Alternatively, pharmacological reperfusion can be achieved by systemic administration of plasminogen activators (PAs). PAs convert plasminogen to the fibrinolytic enzyme, plasmin. Plasmin then degrades the clot into soluble fragments. Streptokinase (SK) and urokinase (UK) were the first therapeutic clot dissolving drugs but both lead to excessive bleeding complications because of non-specific effects. Current therapy focuses on clot specific agents such as recombinant tissue-PA (rt-PA) or tenecteplase (TNK), a rt-PA variant. However, there is a risk of intracranial bleeding in at least 1% of patients, which can be fatal or disabling. Thus, a need exists for new strategies to enable safer reperfusion that are not associated with potentially fatal side effects. This study focuses on the therapeutic role of alpha2-antiplasmin (α2AP). α2AP is the primary inhibitor of plasmin. One approach to thrombolysis is to attenuate α2AP with an inhibitory antibody (A2AP IgG). Inhibition of α2AP would enable clot lysis with lower doses of PAs, thereby reducing the risk of bleeding and serving as a safer approach to thrombolytic therapy. We aimed to characterize A2AP IgG and evaluate its effect on fibrinolysis in vitro and in vivo. A2AP IgG1 was selected and developed using phage display and an antibody gene library with human and rabbit α2AP as the antigen. Affinity maturation was performed and the Fc portion of the A2AP IgG1 was subsequently changed to the IgG4 isotype which yielded A2AP IgG4. A2AP IgG4 binds α2AP with 63-fold higher affinity than A2AP IgG1 as determined using surface plasmon resonance (SPR). SDS-PAGE and western blot analysis reveals that both antibodies bind to the plasmin-α2AP (PAP) complex, fibrinogen, and fragment X but not to α2AP; results confirmed by ELISA. In functional studies, A2AP IgG1 significantly reduced plasmin inhibition by α2AP by 5.5-fold. Both A2AP IgG1 and A2AP IgG4 shortened tissue-PA (t-PA)-mediated clot lysis in a concentration dependent manner. A2AP IgG4 was 2.2-fold more potent than A2AP IgG1 in human plasma and 1.4-fold more potent in rabbit plasma. Compared with t-PA or TNK alone, addition of either antibody enhanced the lysis of preformed plasma clots. Combining A2AP IgG4 with 10% of the highest t-PA or TNK dose produced more clot lysis than the highest dose of t-PA or TNK alone. In a rabbit jugular vein thrombosis model, A2AP IgG4 alone produced 20% lysis. When combined with a low dose of TNK, 40% clot lysis resulted, which was significantly greater than the 30% clot lysis observed with a higher dose of TNK. A2AP IgG4 alone or in combination with a lower dose of TNK did not cause significantly more bleeding than the higher dose of TNK alone and did not degrade circulating fibrinogen. Thus, we have shown that by inactivating α2AP, A2AP IgG attenuates α2AP activity, and accelerates clot lysis in vitro and in vivo. This demonstrates that antibody-mediated inhibition of α2AP, enhances thrombolysis and enables use of lower doses of PAs. / Thesis / Master of Science in Medical Sciences (MSMS)

Femoral artery pseudoaneurysm (FAP) is a common complication associated with left heart cardiac catheterization. FAP is a pulsatile encapsulated mass usually formed three to seven days after removal of the arterial sheath post cardiac catheterization. Usually, FAP is asymptomatic. Groin pain and swelling are the most common complaints in symptomatic patients. It can be associated with multiple different complications including rupture, bleeding, and vascular compression leading to venous thrombosis, limb ischemia, and neuropathy. Deep vein thrombosis (DVT) resulting from FAP is an unusual complication with very few cases reported in the literature. We present a case of right-sided DVT secondary to the compression of femoral vein resulting in venous outflow obstruction due to iatrogenic FAP post cardiac catheterization that was successfully managed conservatively.

The demonstration of antithrombotic efficacy in man is challenging. Most techniques evaluate specific plasma or cellular components under static conditions in vitro. In contrast, in vivo thrombus initiation and growth occur in whole blood, under conditions of continuous flow and in the presence of vascular injury. An in vivo model for use in clinical studies presents significant safety issues and does not currently exist. The Badimon chamber is an ex vivo model of thrombosis that is suitable for use in clinical studies and has previously been used to assess novel antithrombotic regimens. Although well-established, previous characterisation studies were performed in a porcine system and using methodology that has since been superceded. In addition, it has a number of disadvantages that limit its broader applicability and has not previously been used to assess fibrinolysis. Having established The Badimon Chamber within my own institution, I developed the methodology and performed careful validation and characterisation studies with a particular emphasis on reproducibility. These developments allowed more efficient data analysis and the accurate addition of compounds to the extracorporeal circuit, both of which broaden the applicability of the technique. In subsequent studies, using a series of double-blind randomised controlled crossover studies in healthy volunteer cohorts, I utilised the updated methodology to address questions in separate but overlapping areas of cardiovascular medicine. The dynamic regulation of intravascular thrombus formation by the endogenous fibrinolytic system is central to the pathogenesis of acute atherosclerotic events, particularly within the coronary circulation. Previous work within our institution has provided novel insights into the role of endogenous fibrinolysis. Despite a growing body of evidence, a key limitation of studies to date is that the effects of acute endogenous t-PA release on in situ thrombus formation have not been demonstrated. Is endogenous endothelial t-PA released under agonist stimulation functionally active and able to enhance fibrinolysis of in situ thrombus? Firstly, I demonstrated that the addition of exogenous t-PA into the extracorporeal circuit of The Badimon Chamber results in a dose dependent increase in plasma D-dimer associated with a dose dependent reduction in thrombus formation, consistent with enhanced fibrinolysis. Having validated the model, I proceeded to investigate whether freshly released endogenous t-PA would have similar effects to exogenous t-PA. By combining intraarterial infusion of bradykinin into the human forearm in order to stimulate acute release of endogenous t-PA with an assessment of thrombus formation in the Badimon Chamber, I demonstrated that endogenous t-PA released acutely from the human vascular endothelium enhances fibrinolysis and limits in situ thrombus formation. These data validate the forearm model as a relevant model with which to assess acute fibrinolytic capacity, confirm the functional significance of t-PA released during agonist stimulation and suggest that further studies to explore its therapeutic manipulation are warranted. I went on to evaluate a promising small molecule PAI-1 inhibitor, PAI-749, using assessments of ex vivo thrombosis complimented by extensive in vitro studies. Interestingly, in contrast to the promising results seen with this compound in preclinical models, we were unable to demonstrate efficacy in any of the clinical models used, highlighting the potential pitfalls of relying solely on in vitro and preclinical models during early compound development. In the final phase of this work, I used the chamber to explore the prothrombotic effects of exposure to air pollution. A plethora of observational data exist to suggest that acute exposure to particulate air pollution can trigger vascular events including myocardial infarction although the underlying mechanisms are only partly understood. Using a unique human exposure facility, we demonstrated that inhalation of diesel exhaust causes platelet activation and enhances thrombus formation. These data provide a plausible mechanism linking exposure to particulate air pollution with acute cardiovascular events including myocardial infarction. Furthermore, in a separate study we were able to demonstrate that reducing the particulate component of the exposure using a commercially available particle trap prevents the detrimental effects on ex vivo thrombosis and endothelial function. These data support calls for the application of particle traps to diesel-powered vehicles in order to limit a range of adverse cardiovascular effects that result from exposure to traffic-derived air pollution.