Development and Validation of Medical Decision Tools in Detection and Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a permanent dilatation of the infrarenal segment of the abdominal aorta which can be fatal if the aneurysm ruptures. Ruptured AAA is the second leading cause of global surgical mortality, and prophylactic AAA repair can decrease mortality by a tenfold if surgery is performed as an elective procedure. While screening and repair of AAA could potentially reduce AAA-related mortality, selecting patients that are likely to benefit from repair remains a complex medical decision process which has been compounded by an improved life expectancy of the general population, minimal invasive treatment methods and the increased prevalence of AAA in the elderly. The overall aim of this thesis was to improve detection and management of AAA and to develop a predictive decision tool that can assist in clinical management. This thesis has been conducted, to shed some light into issues highlighted above using New Zealand and international data. The format of this thesis was categorized into three main domains: First, the prevalence of AAA and the influence of aortic size on late survival was documented in a large cohort of individuals undergoing CT colonography for gastrointestinal symptoms in Canterbury, New Zealand; Second, a systematic review and meta-analysis of prognostic factors that might influence late survival following AAA repair were performed, and the national clinical and administrative AAA repair databases were interrogated to provide epidemiological and outcome data; Third, the factors identified from this review were applied into developing a discrete event-simulation model to predict survival following AAA repair. The model developed has been externally validated against existing national databases of patients undergoing AAA repair and it appears sufficiently accurate to predict five- year survival. The results and conclusions presented throughout this thesis fill some of the gap in AAA knowledge, and such predictive decision-making tools might help improve AAA management

The impact of COVID-19 pandemic on vascular registries and clinical trials.

Quality improvement programs and clinical trial research experienced disruption due to the coronavirus disease 2019 (COVID-19) pandemic. Vascular registries showed an immediate impact with significant declines in second-quarter vascular procedure volumes witnessed across Europe and the United States. To better understand the magnitude and impact of the pandemic, organizations and study groups sent grass roots surveys to vascular specialists for needs assessment. Several vascular registries responded quickly by insertion of COVID-19 variables into their data collection forms. More than 80% of clinical trials have been reported delayed or not started due to factors that included loss of enrollment from patient concerns or mandated institutional shutdowns, weighing the risk of trial participation on patient safety. Preliminary data of patients undergoing vascular surgery with active COVID-19 infection show inferior outcomes (morbidity) and increased mortality. Disease-specific vascular surgery study collaboratives about COVID-19 were created for the desire to study the disease in a more focused manner than possible through registry outcomes. This review describes the pandemic effect on multiple VASCUNET registries including Germany (GermanVasc), Sweden (SwedVasc), United Kingdom (UK National Vascular Registry), Australia and New Zealand (bi-national Australasian Vascular Audit), as well as the United States (Society for Vascular Surgery Vascular Quality Initiative). We will highlight the continued collaboration of VASCUNET with the Vascular Quality Initiative in the International Consortium of Vascular Registries as part of the Medical Device Epidemiology Network coordinated registry network. Vascular registries must remain flexible and responsive to new and future real-world problems affecting vascular patients

Editor's Choice - The Impact of Centralisation and Endovascular Aneurysm Repair on Treatment of Ruptured Abdominal Aortic Aneurysms Based on International Registries

Objectives: Current management of ruptured abdominal aortic aneurysms (RAAA) varies among centres and countries, particularly in the degree of implementation of endovascular aneurysm repair (EVAR) and levels of vascular surgery centralisation. This study assesses these variations and the impact they have on outcomes. Materials and methods: RAAA repairs from vascular surgical registries in 11 countries, 2010-2013, were investigated. Data were analysed overall, per country, per treatment modality (EVAR or open aortic repair [OAR]), centre volume (quintiles IV), and whether centres were predominantly EVAR (>= 50% of RAAA performed with EVAR [EVAR(p)]) or predominantly OAR [OAR(p)]. Primary outcome was peri-operative mortality. Data are presented as either mean values or percentages with 95% CI within parentheses, and compared with chi-square tests, as well as with adjusted OR. Results: There were 9273 patients included. Mean age was 74.7 (74.5-74.9) years, and 82.7% of patients were men (81.9-83.6). Mean AAA diameter at rupture was 7.6 cm (7.5-7.6). Of these aneurysms, 10.7% (10.0-11.4) were less than 5.5 cm. EVAR was performed in 23.1% (22.3-24.0). There were 6817 procedures performed in OAR(p) centres and 1217 performed in EVAR(p) centres. Overall peri-operative mortality was 28.8% (27.9-29.8). Peri-operative mortality for OAR was 32.1% (31.0-33.2) and for EVAR 17.9% (16.3-19.6), p 22 repairs per year), 23.3% (21.2-25.4) than in QII-V, 30.0% (28.9-31.1), p <.001. Peri-operative mortality after OAR was lower in high volume centres compared with the other centres, 25.3% (23.0-27.6) and 34.0% (32.7-35.4), respectively, p <.001. There was no significant difference in peri-operative mortality after EVAR between centres based on volume. Conclusions: Peri-operative mortality is lower in centres with a primary EVAR approach or with high case volume. Most repairs, however, are still performed in low volume centres and in centres with a primary OAR strategy. Reorganisation of acute vascular surgical services may improve outcomes of RAAA repair. (C) 2018 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Development and Validation of Medical Decision Tools in Detection and Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a permanent dilatation of the infrarenal segment of the abdominal aorta which can be fatal if the aneurysm ruptures. Ruptured AAA is the second leading cause of global surgical mortality, and prophylactic AAA repair can decrease mortality by a tenfold if surgery is performed as an elective procedure. While screening and repair of AAA could potentially reduce AAA-related mortality, selecting patients that are likely to benefit from repair remains a complex medical decision process which has been compounded by an improved life expectancy of the general population, minimal invasive treatment methods and the increased prevalence of AAA in the elderly. The overall aim of this thesis was to improve detection and management of AAA and to develop a predictive decision tool that can assist in clinical management. This thesis has been conducted, to shed some light into issues highlighted above using New Zealand and international data. The format of this thesis was categorized into three main domains: First, the prevalence of AAA and the influence of aortic size on late survival was documented in a large cohort of individuals undergoing CT colonography for gastrointestinal symptoms in Canterbury, New Zealand; Second, a systematic review and meta-analysis of prognostic factors that might influence late survival following AAA repair were performed, and the national clinical and administrative AAA repair databases were interrogated to provide epidemiological and outcome data; Third, the factors identified from this review were applied into developing a discrete event-simulation model to predict survival following AAA repair. The model developed has been externally validated against existing national databases of patients undergoing AAA repair and it appears sufficiently accurate to predict five- year survival. The results and conclusions presented throughout this thesis fill some of the gap in AAA knowledge, and such predictive decision-making tools might help improve AAA management

Aorto-cutaneous fistula of the ascending aorta : case report and a literature review of endovascular management

Aorto-cutaneous fistulas are an unusual and life-threatening complication after aortic surgery. We present the case of an endovascular intervention for an aorto-cutaneous fistula of the ascending aorta that was intended to be a bridge to definitive surgical treatment and report a literature review. A 56-year-old woman had a previous Bentall's procedure and mitral valve annuloplasty in 2016. Four years later she re-presented with an infective pseudoaneurysm of the distal anastomosis of the ascending aortic graft, with aorto-cutaneous fistulation. She was at high risk for a revision operation and required optimization before a major open surgery. A thoracic endovascular aortic repair stent graft (Valiant Navion; Medtronic Inc) was implanted to exclude the distal anastomotic pseudoaneurysm. Two months later she re-presented with a new infected pseudoaneurysm at the proximal end of the previously implanted stent graft, and a further thoracic endovascular aortic repair was undertaken

Definitive coverage of distal vein graft in a case of early skin necrosis following popliteal to dorsalis pedis bypass

Inframalleolar bypass is an effective intervention for chronic limb threatening ischemia. A successful outcome can be compromised by early pedal wound disruption with secondary bypass exposure. We describe the case of a 74-year-old man with a WIfI (wound, ischemia, foot infection) clinical stage 4 foot who underwent popliteal-dorsalis pedis bypass, complicated by early skin necrosis overlying the pedal anastomosis. This necessitated a multidisciplinary approach to obtain tissue coverage over the anastomosis. The wound healed within 28 days, and at 2 years, the patient was mobilizing independently. We outline the approach taken and discuss the management of this challenging limb salvage problem