Episode 21: Arteriovenous Fistula - The Basics

In our first non technical episode we discuss changes in life from going from trainee surgeon, to surgeon.

In this episode, Yogi and Sam delve into discussing thoracic aortic stenting. Podcast 26 - Thoracic Aortic StentingThe first endovascular thoracic aneurysm repair was performed by Dale in 1994 - with the use of custom designed graft with a combination go Gianturco Z-stents and polyester fabric. It was not till 2005 that a commercially available thoracic graft became availableThe introduction of TEVAR has added further dimensions to open surgery by creating treatment options not previously available in treating aortic dissection, thoracic and thoracoabdominal aneurysm and traumatic injury.In elderly patients, TEVAR has replaced open surgery and medical management for problems confined to the descending thoracic aorta IndicationsAneurysmal disease (>5.5cm) - true degenerative aneurysms vs. post dissection aneurysms vs. mycotic vs. pseudo aneurysms (Zone 2)Complicated acute aortic syndromesBlunt thoracic aortic injury Evolving techniques - management of dissection aneurysms in Zone 0/1Approved Devices Gore TAG Conformable Thoracic Stent GraftMedtronic Valiant Thoracic Stent Graft with Captivia Delivery System  Cook Zenith AlphaEndospan Nexus and BoltonTerumo Aortic Relay Device  Pre-operative ConsiderationsHow do we do it?General consideration - vascular access, iliac vessel diametersFor suitable iliac and femoral access vessels are requiredSmall diameters <7mm, existing calcification and vessel tortuosity have a profound impact on the procedure especially if present in combination The right femoral artery is typically favoured for device insertion, whereas the contralateral femoral artery is reserved for diagnostic imaging An ideal access vessel should be >7mm in diameter to accommodate a 22Fr sheath and >8mm for a 24 Fr sheath Alternate options - iliac conduits or endo-paving Landing zone General role >20mm of normal appearing aorta for an adequate seal zone - proximal and distal Longer seal zones is considered adequate for most cases, longer seal zones are preferable in angulated aortic segments to decrease the occurrence of Type 1 end-leaks and device migrations Anatomical boundaries include the left subclavian artery and the coeliac artery should be considered aProximal and distal aortic diameters Ishimaru’s Classification of Landing Zone Coverage of the left subclavian artery is generally well tolerated because of a rich collateral network - however routine exclusion should be discouraged because experimental and clinical evidence suggest that not all patients tolerate the occlusion safely The left subclavian artery is vital for perfusion of both the spinal cord and the brain via the left vertebral artery through the internal management and anterior intercostal branches When left subclavian coverage is considered, pre-operative CTA imaging should assess latency of the right vertebral artery, connections to the Basilian artery and the COW in order to identify patients that may not tolerate left SCA occlusion As we approach Zone 0,1 or sometimes in 2 supra-aortic debranching may be necessary Open CTS vs. CCA-CCA-SCA, CCA- SCA, chimney stents ImagingCTA with fine slicesSizingOverzealous device sizing is associated with graft infolding, gutter formation and aortic neck degeneration due to excessive radial force \Aortic diameters are measured with orthogonal reconstructions...

In this episode, Yogi and Sam unpack and explore the highly anticipated Surgery or Endovascular Therapy for Chronic Limb-Threatening Ischemia (Best CLI) publication. This study has sought to clarify questions that had been raised in regards to the optimal treatment of chronic limb threatening ischaemia in the era of modern endovascular treatment. https://www.nejm.org/doi/full/10.1056/NEJMoa2207899

In this episode we discuss the recent sitting of the vascular surgery fellowship exam with Dr Vikram Iyer. He shares his experiences and reflections on getting through the final hurdle before becoming a fully qualified vascular surgeon.

In this episode of The Retrograde Approach, Sam and Yogi take an introductory look at peripheral arterial disease.

In this weeks episode, we are joined by Dr Leonard Shan. A vascular surgeon working at St Vincent's hospital in Melbourne. Dr Shan is currently completing a PhD through the University of Melbourne, and joins us to talk today about balancing his busy research career, with his professional career and his home life. Dr Shan is an academic vascular surgeon and honorary senior fellow in the Department of Surgery at The University of Melbourne. He received his medical education at The University of Melbourne where he graduated with honours. Following vascular surgical training at multiple centres in Melbourne and Auckland, he joined the vascular staff at St. Vincent’s Hospital in 2020.His academic interest is in outcomes research where he has helped to improve the understanding of patient- reported outcomes after intervention. He serves on the editorial board of the Annals of Vascular Surgery and is a regular reviewer for the European Journal of Vascular and Endovascular Surgery and the Journal of Vascular Surgery. Leonard is currently undertaking a PhD on the patient-reported outcomes and economic evaluation of arterial surgery with Professor Peter Choong at The University of Melbourne, where he is the recipient of an Australian Government Research Training Program scholarship.

In this episode, we aim to give a basic overview to arteriovenous fistula's for dialysis access. Although, we could spend hours discussing AVFs - we have attempted to provide a general overview for those new to the concepts.

In this episode, Yogi and Sam provide an overview into foot disorders within diabetic patients.

In this episode we delve into the interesting world of carotid artery disease and discuss our management of patients who are asymptomatic. See Yogi's (amazing) crib notes below:Why do we care about asymptomatic carotid artery disease?About 10 to 15% of all first ever stroke patients will experience an unheralded ischaemic, carotid territory stroke following thromboembolism from a previously untreated asymptomatic significant carotid diseaseOxford Vascular StudyEnrolled 2354 consecutive patients including 207 with 50 to 99% carotid stenosisThe ipsilateral stroke rate at 5 years for the patients with 70% to 99% was 14.6% compared with 0% for 50 to < 70%For patients with 80 to 99% carotid stenosis, the ipsilateral stroke was significantly greater than that for those with 50% to <80% stenosis ACSRS StudyIn ACAS and risk of stroke, there was an S-shaped relationship between the severity of stenosis and the incidence of ipsilateral TIA or stroke, such that the event rate for 50 to 69% stenosis were 8.2%, for 70 to 89% were 10.7% and for 90 to 99% were 19.3%Progression of carotid stenosis is associated with an increased risk of stroke - patients with progression of carotid stenosis had two times the rate of ipsilateral stroke compared to patients without progressionPrevalence of ACASFour Population Based Cohort Studies (Malmo Diet and Cancer Study, Tromso Study, Carotid Atherosclerosis Progression Study and Cardiovascular Health Study)Prevalence of asymptomatic moderate (>50%) and severe (>70%) stenoses in a population of 23,706 people (mean age of 61 years, 46% male) was 2.0% and 0.5% respectivelyModerate stenosis > 50% found in 4.8% of men and 2.2% of women younger than 70 yearsThe percentage increase to 12.5% in men and 6.9% in women if patients older than 70 years are consideredSevere asymptomatic stenosis (>70%) indicate that its prevalence ranges from 0% to 3.1% of general populationSeminal TrialsSeminal trials have demonstrated a marginal but definitive benefit for CEA in reducing the risk of stroke after 5 and 10 years when compared with “best medical therapy” alone. However, these studies conducted in the late 1980s and in the 1990s, and since their completion, progress in the medical management of cardiovascular diseases has led to a progressive decrease in the yearly risk of stroke in patients with asymptomatic carotid artery stenosis managed with medical treatment alone.Veterans Affairs Cooperative Study (VACS) [1983 and 1987]440 men with asymptomatic >50% carotid stenosis were randomised to CEA plus medical management versus medical management only CEA significantly reduced the combined incidence of ipsilateral neurologic events (stroke or TIA) compared to medical group (8.0% vs. 20.6% respectively)ACAS1662 patients with asymptomatic >60% carotid stenosis were randomised to medical therapy versus CEA plus medical therapyAcross the United States and CanadaThe study was stopped early, after a median follow up of 2.7 yearsPatients in the surgical arm had a 5.1% risk of ipsilateral stroke and preoperative stroke/death over 5 years versus 11.0% risk of ipsilateral stroke in the medical arm for a relative risk reduction of 53%; absolute risk reduction of 5.9%Recommended CEA for patients aged < 80 years as long as the expected combined stroke and mortality rate for the individual surgeon as not > 3% ACST-13120 patients with asymptomatic >60% carotid stenosis were randomised to either immediate CEA or deferred

In this exciting episode we are joined by Dr Gert Frahm-Jensen, who is an Australian trained Vascular and Endovascular Surgeon working in the Australian Capital Territory. After attaining his medical degree from the Australian National University he completed specialist training in vascular surgery throughout Victoria, Queensland and the ACT.  He has a special interest in the management of thoracic outlet syndrome, and we are very appreciative of his expertise that he shares with us in this episode.