The Retrograde Approach: Recent Episodes
Dr Sam Farah and Dr Yogeesan Sivakumaran
The Retrograde Approach is a vascular surgery podcast made by two Australian vascular surgeons, that explores our speciality in detail. We discuss current issues, themes and topics in vascular surgery and its related fields including interventional radiology, angiography, medicine and surgery.
Supported by the Australian and New Zealand Society of Vascular Surgery (www.anzsvs.org.au)
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 Stenting
The 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 available
The 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
Indications
- Aneurysmal disease (>5.5cm) - true degenerative aneurysms vs. post dissection aneurysms vs. mycotic vs. pseudo aneurysms (Zone 2)
- Complicated acute aortic syndromes
- Blunt thoracic aortic injury
- Evolving techniques - management of dissection aneurysms in Zone 0/1
Approved Devices
- Gore TAG Conformable Thoracic Stent Graft
- Medtronic Valiant Thoracic Stent Graft with Captivia Delivery System
- Cook Zenith Alpha
- Endospan Nexus and Bolton
- Terumo Aortic Relay Device
Pre-operative Considerations
How do we do it?
- General consideration -
- vascular access, iliac vessel diameters
- For suitable iliac and femoral access vessels are required
- Small 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 a
- Proximal 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
- Imaging
- CTA with fine slices
- Sizing
- Overzealous 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 especially in areas of tortuosity and angulation
- Neck diameters between the proximal and distal sealing zones can vary
- A 10 to 20% oversizing at the proximal landing zone is recommended; less for dissection
- Adjunctive Measures for Neuroprotection
- Patients with long segment descending thoracic aortic coverage (>150mm), antecedent or concomitant abdominal aortic repair or bilateral internal iliac artery occlusions are at particularly high risk of spinal cord ischaemia
- Staging procedures
- Selective segmental artery coil embolisation
- Intra-operative monitorings - Near infra-red spectroscopy monitoring, transcranial doppler and EEG
- Identifying a threshold value with NIRS that correlates to cerebral ischaemia has been poor and it only gives information regarding the status of the frontal lobes
- Spinal Drain
- Elevated Blood Pressure, MAP > 90mmHg —. Can increase to 100mmHg if neurologic deficits are noted
- Hb > 100
- Oxygen supplementation
Procedure
- Percutaneous femoral artery access
- Typically up the right for the graft
- Small access on the contralateral side for insertion of a diagnostic pigtail catheter
- After access is established, a stiff guide wire is advanced into the ascending aorta; curved 260cm Lunderquist Wire and positioned such that the apex of the curve rests against the aortic valve
- The end of the wire should be marked and efforts made to ensure that the wire stays in this position
- Arch aortogram is performed via a pigtail catheter with a LAO of 30 to 60 degrees - the angle should be determined based on the pre-operative CTA
- Air is then flushed from the system - ensure no air in the line; can be done by winding back into the pump or under water
- Induction of temporary apnoea necessary
- The endograft is introduced and advanced under fluoroscopic guidance
- Typically the endograft is advanced past the proximal landing zone and drawn back to eliminated stored energy
- Steady integrate pressure on the wire keeps the device positioned against the outer aortic wall for accurate deployment - stent grafts conform to the outer curvature of the thoracic aorta which can cause the graft to jump distally
- Forward pressure on the Lunderquist wire will help push the wire against the outer curvature to better approximate the true path of the stent graft during deployment
- The pressure can also help the apposition of the graft to the vessel wall, avoiding the “bird-beaking” effect
- Acute angles in the descending thoracic aorta may render device tracking difficult - put the graft at risk of Type 1 endoleak and bird bearing
- “Body flossing” - brachiofemoral access wires can help straighten the most angulated of vessels
- When more than one TEVAR device is required, the smallest diameter device should be deployed first; for large proximal aortic aneurysms, with distal thoracic aortic tortuosity deploying the distal endograft first is preferable as it stabilises the proximal endograft and improves deployment accuracy
- Proximal TEVAR deployments benefit from temporary reduction of mean arterial pressure which minimises the windsock effect and potential endograft migration
- Strategies - administration of vasodilators, adenosine induced cardiac asystole, rapid cardiac pacing, sustained Valsalva manoeuvre, IVC balloon occlusion
- Ongoing aortic blood flow can become trapped in the deploying graft graft and displace the stent distally, in a phenomenon known as the “windsock” effect
- Graft molding is generally avoided in the setting of treatment for aortic dissection due to the risk of causing retrograde dissection - in aneurysmal disease, a non-compliant balloon can be used k
- Completion angiogram
Complications
- Mortality - early experience with first and second generation endografts in high risk individuals was associated with a high clearly mortality (9 to 12%); trials with third generation devices reported a 30 day mortality of 1 to 2.2% which is significantly lower than the 7% mortality associated with open surgical repair
- Stroke - 3 to 8%
- Presence of mobile atheroma, prior stroke, deployment of TEVAR proximal to the left CCA, air or plaque embolisation
- Paraplegia
- Peripheral Vascular Complications - embolism, thrombosis and vascular trauma
- Vascular access complications due to large bore sheaths placed in atherosclerotic arteries were relatively high in the early trials but lower in follow up trials (~6%)
- Aortic dissection
- Aneurysm Sac Enlargement
- Stent graft migration or fracture
- Late migration < 0.7 to 3.9% - can occur at either end; predisposing factors for device migration include excessive endograft oversizing, tortuous seal zone anatomy and aortic elongation
- Endoleak
Reasons for Spinal Drain
- Length of coverage > 20cm
- Coverage in the region of the artery of Adamweikz
- Previous infrarenal aortic repair
- Bilateral internal iliac artery atherosclerotic
- Coverage of the left subclavian artery
However spinal drains are not without complications - that can arise during and/or after CSF drain insertion including catheter fracture, post dural puncture headache, neuroaxial haematoma, intracranial haemorrhage and meningitis
Complications associated with left subclavian artery coverage during TEVAR
- Stroke - students have demonstrated a high overall stroke rate and posterior circulation stroke with intentional coverage of the left subclavian artery compared with left subclavian artery revascularisation
- Spinal cord ischaemia / long term - chronic symptoms (claudication)
- Left upper extremity ischaemia
Reasons for left subclavian artery revascularisation
- Patent left arm arteriovenous shunt for dialysis
- Presence of a patent left internal mammary to coronary artery bypass graft
- Absent, atretic or occluded right vertebral artery
- A dominant left vertebral artery is present in > 60% of patients; intuitively these anatomic findings place patients at increased risk for posterior circulation infarction if covered
- Termination of the left vertebral artery into the posterior inferior cerebellar artery
- Prior infrarenal aortic operation with previously ligated lumbar and middle sacral arteries
- Planned extensive (>20cm) coverage of the descending thoracic aorta
- Hypogastric artery occlusion
- Presence of early aneurysmal disease where future therapy involving the distal thoracic aorta may be necessary
- Anomalous origin of the left vertebral artery from the aortic arch
Anatomy of the Spinal Cord Circulation
- Arterial supply
- Anterior spinal artery which arises off the vertebral arteries
- Prior to becoming the basilar artery, the vertebral arteries give off branches that become the anterior spinal artery which then passes down the anterior sulcus of the vertebral column
- Posterior spinal arteries which arise off the posterior inferior cerebellar arteries and travel down caudally
- Mid cervical cord receives blood supply via the segmental spinal arteries directly off the vertebral arteries
- The lower cervical and upper thoracic cord receives blood supply via the radiculomedullary branches arising from the cervicothoracic trunk
- Intercostal artery branches which give off segmental spinal arteries which supply the mid thoracic segment
- The largest segmental spinal artery branch being the Artery of Adamkiewicz which arises from T8 to L2
- Branches of the internal iliac artery supply the lumbosacral segment
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 disease
Oxford Vascular Study Enrolled 2354 consecutive patients including 207 with 50 to 99% carotid stenosis The 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 Study In 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 progression
Prevalence of ACAS Four 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% respectively Moderate stenosis > 50% found in 4.8% of men and 2.2% of women younger than 70 years The percentage increase to 12.5% in men and 6.9% in women if patients older than 70 years are considered
Severe asymptomatic stenosis (>70%) indicate that its prevalence ranges from 0% to 3.1% of general population Seminal Trials Seminal 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)
ACAS 1662 patients with asymptomatic >60% carotid stenosis were randomised to medical therapy versus CEA plus medical therapy Across the United States and Canada The study was stopped early, after a median follow up of 2.7 years Patients 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-1 3120 patients with asymptomatic >60% carotid stenosis were randomised to either immediate CEA or deferred CEA Asymptomatic patients were considered those without neurological symptoms during the 6 months preceding enrolment Patients in the immediate CEA group had a significantly reduced five year and 10 year risk of any stroke and peri-operative stroke/death than the deferred CEA group (5 year, 6.9% vs. 10.9%, 10 year 13.4% vs. 17.9%) An absolute risk reduction of 5.4% was seen in the rate of any stroke and...
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.
This episode of The Retrograde Approach is proudly supported by The Australian and New Zealand Society for Vascular Surgery (anzsvs.org). We are excited to welcome Dr Nedal Katib (http://www.specialistvascular.com.au/dr-nedal-Katib/ (http://www.specialistvascular.com.au/dr-nedal-Katib/)). Dr Katib completed his Vascular Surgery Training through the Royal Australasian College of Surgeons, which took him to South Australia, New Zealand and New South Wales. He also completed a further fellowship in Belgium in advanced Endovascular and Minimally Invasive Surgery. Originally born in Melbourne, his career path has taken him all over the world including Dubai UAE and graduating from the Royal College of Surgeons in Dublin Ireland before returning to Australia to continue his surgical career. During his training he completed his masters in surgical anatomy at Sydney University and his United States Medical Licensing Exams (ECFMG licence). Dr Katib is also the chair of communications for the ANZSVS.
Absorbed dose, effective dose, equivalent dose, air kerma and Marie Curie. In this episode, we dive into radiation safety.
In this special episode, we are joined by Adelaide vascular surgeon Dr Edwards Travers to discuss the sometimes daunting and confusing area of hyperhidrosis management.
In this very special episode, we are joined by Professor Ramon Varcoe to discuss his updated meta-analysis on the mortality rates after paclitaxel coated device use in patients with occlusive femoropopliteal disease. Found in the Journal of Endovascular Therapy: https://pubmed.ncbi.nlm.nih.gov/34106028/ (https://pubmed.ncbi.nlm.nih.gov/34106028/)
In this weeks episode we are joined by Dr Kalpa Perera, a final year vascular surgery trainee who recently successfully completed the Royal Australasian College of Surgeon Fellowship Examination in Vascular Surgery in Melbourne. He reflects on his time as a vascular surgery trainee, and shares insights and advice about the strategies he used to succeed in the exam.
In this episode of The Retrograde Approach, Yogi and Sam delve into the world of acute limb ischaemia.
In this weeks episode of The Retrograde Approach, we are joined by Mr Iman Bayat. Mr Bayat is the Head of vascular surgery at Northern Health and Head of complex venous disorders at Northern Health. In this episode he shares with us a wealth of knowledge when it comes to managing all things iliofemoral. Buckle up, this is a good one!
In this episode we discuss our decision making and thought processes when it comes to managing tibial vessel disease, including open reconstruction and endovascular procedures.
In this episode of The Retrograde Approach, we are joined by Dr Tom Lovelock, a first year vascular surgery trainee to talk about his strategy and approach for success in the selection process for vascular surgery training, and unpack his strategy to conquer the selection interview.
In this episode Yogi and Sam discuss their management, work up and assessment of ruptured abdominal aortic aneurysms. Link to Journal of Vascular Surgery article https://www.jvascsurg.org/article/S0741-5214(20)32132-7/fulltext
In this episode of The Retrograde Approach, Yogi and Sam discuss open infrainguinal bypass and reconstruction.
In this episode Yogi and Sam discuss their approach to the assessment and management of patients presenting with popliteal artery aneurysms. Including both acute and elective presentations.
In this episode Dr Yogi Sivakumaran and Dr Sam Farah discuss how they prepare, plan and perform an endovascular aneurysm repair (EVAR). General Principles Quality of the CT Scan 1mm slices If initial scan – scan thoracic, abdomen and lower limbs; allows for exclusion of aneurysmal disease elsewhere as well as if baseline status of the aortia prior to intervention Also allows planning if a fenestrated repair required Centerline – images are not cross-sectional and end up with cross-sectional diameters Narrow diameter of the elliptical cross-section more in keeping with the true diameter Draw a diagram and compare with the rep and consultant’s plan – appreciation of the complexity of the case Date of the index scan Documentation calcification, dissection, thrombus and stenotic disease Site of the lowest renal artery Clock face of the renal arteries origin as well as the origin of the internal iliac arteries Angulation of the aortic neck Type of neck Straight, angulated (plan according to IFU), tapered (oversize on the basis of the diameter below the renal arteries), reverse tapered (careful to avoid oversizing), bulge and short Access vessels Diameters and lengths (which will be discussed) Grafts chosen Talk to the reps re: planning books
Pre-operative consideration In the era of an endovascular repair, a durable repair is desired Patient’s age Patient’s co-morbidities Renal function, cardiac and respiratory history Life expectancy Fitness for GA vs. LA and Sedation The patient better of with an open or endovascular management strategy Suitability for endovascular Complex vs. Standard EVAR
Imaging Renal artery position Lowest renal artery; accessory renal arteries
Diameters Infrarenal aortic neck diameter (assess for infrarenal thrombus; aim < 25% of the circumference and <2mm thickness) – multiple across the length of the neck Aneurysm sac diameter Aortic bifurcation diameter CIA proximal, mid and distal
Lengths Aortic neck length Length from lowest renal to aortic bifurcation (to ensure sure that there is enough length for the contralateral limb) Length from aortic bifurcation to iliac bifurcation
Angles Renal arteries origin off the aortic Internal iliac arteries origin off the bifurcation Supra and infrarenal angulation if appropriate
Access vessels Femoral/Iliac artery diameter Tortuosity of the iliac arteries
Large lumbar vessels or inferior mesenteric artery >3mm
In this episode, Yogi and Sam discuss the management of blunt thoracic injury and discuss difficult and challenging operative decisions.
In our third and final part in our review of the vascular exam in vascular surgery we discuss the clinical decision making viva, as well as the long case and the short cases.
In our second episode, Yogi and Sam take a deeper look into the fellowship exam looking specifically at the operative and imaging vivas. They reflect on the strategies and approaches they used to successfully navigate these challenging aspects of the examination.
In our first episode of The Retrograde Approach, Dr Yogi Sivakumaran and Mr Sam Farah embark on part one of a three part series discussing their recent reflections on completing the fellowship exam in vascular surgery in a year like no other.