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ANZSVS Conference 2022
ANZSVS Conference 2022
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Session Program

3:30 pm

Purpose: The global burden of abdominal aortic aneurysms (AAA) has changed over the last 20 years but still considered to be a major cause of cardiovascular mortality worldwide. In the past two decades the introduction of endovascular aortic repair (EVAR) and improved peri-operative care has resulted in a steady improvement in both outcomes and long term survival. The objective of this study was to identify the burden of AAA disease by AAA events, AAA related deaths and describe how the vascular surgical workload has changed in the Aotearoa New Zealand (AoNZ) context over the last 20 years. Methodology: All AAA repairs performed in NZ between 2001 and 2019 were identified from the National Minimum Dataset (NMDS) of the NZ Ministry of Health. Operative data from 2010 onwards was cross referenced against the Australasian Vascular Audit (AVA). Data was analysed for patient characteristics including ethnicity and deprivation index, repair technique and outcomes. Mortality data was obtained from the NZ Mortality Collection dataset(MORT). Results: There were 18,220 patients with AAA identified with a median age of 76.5 years. There were 4,979 (27.3%) ruptured aneurysms. The incidence of AAA has decreased from 30 per 100,000 in 2001 compared to 13 per 100,000 in 2019. The incidence of intact AAA repair has overall increased until 2017 where a reduction in intact AAA repair was observed. EVAR has been increasingly used for intact AAA repair over the last 20 years; 17.1% in 2001 compared to 62.9% in 2019. The incidence of surgery for ruptured AAA (rAAA) did not significantly change. The 30 day mortality has decreased over time for intact AAA repair from 6.4% in 2001 to 1.8% in 2019. Conclusion: This study highlights the epidemiological trends and survival outcomes of AAA management in AoNZ over 20 years. Understanding the changing pattern of AAA burden is paramount to improve resource allocation and promote surgical quality improvement.

3:35 pm

Purpose Long terms outcomes after endovascular aneurysm repair (EVAR) versus open aneurysm repair (OAR) are controversial. Data from randomised trials summarised in meta-analysis indicate lower peri-operative mortality and morbidity with EVAR. At two years and beyond survival is similar in both methods and pre-existing co-morbidities appear to be the predominant factors influencing overall survival. The objective of this study was to compare the long term outcomes of EVAR versus OAR in NZ. Methodology All patients undergoing first-time abdominal aortic aneurysm (AAA) repair in New Zealand between January 1, 2001 and December 31, 2019 were identified from the National Minimum Dataset (NMDS) of the NZ Ministry of Health. Data from 2010 onwards was cross referenced against the Australasian Vascular Audit (AVA). Patients were divided into two groups based on the modality of AAA repair: EVAR and OAR. Primary long-term outcomes was all-cause mortality, rupture, and re-intervention. Results There was 18,220 patients identified who presented with a AAA. Of these 9,022 (49.5%) AAA’s had intervention; 5,854 (64.9%) of repairs were performed by open surgery and 3,168 (35.1%) were repaired endovascularly. Regarding intact AAA repair 2,856 (41.5%) underwent EVAR and 4,015 (58.4%) OAR. EVAR has been increasingly used for intact AAA repair over the last 20 years; 17.1% in 2001 compared to 62.9% in 2019. Open repair was associated with a higher 30 day mortality (5.1% OAR vs 1.3% EVAR). However, EVAR and OAR had similar survival rates at two and five years (87.% OAR vs 88.2% EVAR and 76% OAR vs 75% EVAR). Overall OAR was associated with a lower re-intervention and late aneurysm rupture rate. Conclusion EVAR has peri-operative benefits in terms of mortality but this benefit decreases overtime. Although EVAR remains a highly valuable treatment modality, especially in patients who are not candidates for open surgery, this study highlights the importance of careful patient selection and long term surveillance.

3:48 pm

Objective: The aim of this study was to assess whether aortic peak wall stress (PWS) and peak wall rupture index (PWRI) were associated with the risk of AAA rupture or repair (defined as AAA events) among participants with small abdominal aortic aneurysms (AAA). Methods: PWS and PWRI were estimated from computed tomography angiography (CTA) scans of 210 participants with small AAAs (≥30 and ≤50 mm) recruited between 2002 and 2014. Participants were followed for a median of 2.0 (inter-quartile range 1.9, 2.8) years to record the incidence of AAA events. The associations between PWS and PWRI with AAA events were assessed using Cox proportional hazard analyses. The ability of PWS and PWRI to reclassify the risk of AAA events compared to initial AAA diameter was examined using net reclassification index (NRI) and classification and regression tree (CART) analysis. Results: After adjusting for other risk factors, PWS (Hazard ratio, HR, 1.56, 95% Confidence intervals, CI 1.19, 2.06; p=0.001) and PWRI (HR 1.74, 95% CI 1.29, 2.34; p<0.001) were associated with a significantly higher risk of AAA events. According to CART analysis, PWRI was identified as the best single predictor of AAA events. PWRI, but not PWS, significantly improved the classification of risk of AAA events compared to initial AAA diameter alone. Conclusion: PWS and PWRI were independently predictive of AAA events. PWRI, but not PWS, improved the risk stratification compared to initial AAA diameter alone.

3:53 pm

Purpose: People with Abdominal Aortic aneurysms (AAA) suffer a high risk of adverse major vascular events (MVE) and peripheral vascular events (PVE). Although medical therapies such as lowering LDL-C are critical in preventing these events, people with AAA are often under treated. This study assessed the incidence of MVE and PVE in people with small AAA and modelled the theoretical benefits and costs of an intensified LDL-C lowering program in this cohort. Methods: 583 participants with AAAs measuring 30 to 54 mm were included in this study. The occurrence of MVE (myocardial infarction, stroke, cardiovascular death and coronary or non-coronary revascularisation) and PVE (non-coronary revascularisation, AAA repair and major amputation) were recorded prospectively and the incidence of these events was calculated using Kaplan Meier analysis. The relative risk reduction reported for these events in a previous RCTs were then applied to these figures to model ARR and NTT that could theoretically be achieved with a mean LDL-C lowering of 1mmol/L. The maximum allowable expense for a cost-effective intensive LDL-C lowering program was estimated using a cost utility analysis. Results: 28.5% of participants had an LDL-C of <1.8mmol/L and only 18.5% were prescribed a high potency statin. The 5-year incidence of MVE and PVE were 38.1% and 44.7% respectively. It was estimated that if the mean LDL-C of the cohort had been reduced by 1mmol/L, this could have reduced the absolute risk of MVE and PVE by 6.5% (95% CI 4.4, 8.7%; NNT 15) and 5.3% (1.4, 7.5%; NNT 19) respectively. It was estimated that the maximum allowable expense for a cost-effective LDL-C lowering program would be between $1,239 AUD and $1,582 AUD per person per annum over a 5-year period. Conclusions: People with small asymptomatic AAA are at high risk of MVE and PVE. This study provides evidence on the possible benefits and allowable expense for a cost-effective intensive LDL-C lowering program in this population.

4:06 pm

Persistent Type II endoleaks after EVAR’s can cause increase in aneurysmal sac size & subsequent rupture. Transcaval access to the aortic sac in a novel method of treating these endoleaks by using embolic agents to obliterate the nidus or individually embolize the feeding vessels. The technique involved & the outcomes are presented.

4:22 pm

An update on the results on the Western Australian IBE registry. Currently the largest non-industry sponsored registry of IBE's

4:38 pm

Time critical emergencies such as a ruptured abdominal aortic aneurysm instills a need for urgency into the vascular surgeon for definitive, life-saving intervention, but also into the emergency department who are usually the first to suggest the underlying diagnosis. With the advent and proven morbidity benefit for endovascular repair, a pre-operative CT angiogram, even in the setting of haemodynamic instability, as suggested by the 2019 European Society for Vascular Surgery aortic aneurysm management guidelines, is of growing importance. A review of all ruptured AAAs presenting to the Princess Alexandra Hospital over a 22 month period was performed. Clinical data in regards to arrival time to the emergency department, time to CT angiogram, haemodynamic observations (within the accepted parameters of permissive hypertension of a systolic blood pressure between 70 and 90 mmHg), and time to definitive intervention were all collated and compared. 27.3% (6 out of 22) of patients presenting to the emergency department were hypotensive below accepted parameters, whereby only one did not undergo a pre-operative CT angiogram. Of all presentations with a ruptured AAA, only 9% of patients did not have a pre-oeprative CT angiogram, of which all proceeded to an open operation. Of the 6 deaths within 30 days post-operatively, only one was profoundly hypotensive pre-operatively. 41% of emergent repairs were conducted endovascularly, with the remaining 59% performed in an open fashion. One patient’s operation was converted from endovascular to open due to intra-operative haemodynamic instability. This highlights the role and safety of a pre-operative CT angiogram in the setting of a ruptured AAA to allow appropriate surgical planning, including in the setting of haemodynamic instability. Whilst a larger sample size needs to be gathered to further elucidate the safe parameters permitted, the morbidity benefit of endovascular repair over open repair is one always worth considering.

4:48 pm

Purpose: Mesenteric angina is a rare condition with life-threatening implications. Surgical management can be challenging when endovascular intervention is not appropriate, particularly with bulky aortic plaque at the origin of visceral vessels. A unique challenge arises when the atheroma also compromises renal perfusion, contributing to the patient’s premorbid renal dysfunction. The potential renal insult from supra-renal clamping could commit these patients to lifelong dialysis.  We describe a case where trapdoor aortic endarterectomy was performed with an extracorporeal perfusion circuit utilised to provide temporary renal perfusion while clamped, followed by direct insertion of a renal artery stent. Methodology: A 78 year old female with a history of IHD and chronic kidney disease (eGFR 30) presented with classic symptoms of mesenteric angina. Revascularisation was recommended to treat her symptoms and prevent acute mesenteric ischaemia. Initially a perfusion circuit was established between the left axillary artery and the left femoral vein, attached to a 5-way manifold to provide a sideline to perfuse the renal arteries. The visceral aorta was then approached retroperitoneally via a left thoracoabdominal incision through the 11th rib space. A trapdoor endarterectomy was performed, with cannulation of the right renal artery to the perfusion circuit, and subsequent removal of the bulky, cauliflower-like atheroma from the aortic lumen at the origin of the visceral and renal vessels. Right renal artery stenosis was stented under direct vision.   Results: Patient made an uneventful recovery and was discharged to local rehabilitation unit on day 8 with improvement in food intake and renal function (eGFR 56) Conclusion: Surgical treatment of mesenteric angina in patients with renal impairment can be technically challenging. We describe a case where we incorporated techniques from other spheres of surgery to address this unique problem which could be refined and adapted to similar surgeries.

4:53 pm

COVID-19 has had an unprecedented effect on the global delivery of vascular surgical services. The international Vascular Surgery COVID-19 Collaborative (VASCC) registry prospectively recruited patients to evaluate the impact of surgical delay and subsequent natural history of patients awaiting scheduled aortic operations. VASCC has over 200 collaborators from over 30 different countries, and most US states. The VASCC registry identified 127 patients with aortic disease whose operations were postponed during the 2020 COVID-19 pandemic. This interim analysis was conducted approximately 10 months after commencement of the registry based on data from centres in the United States. Data was collected on 127 planned aortic cases with a mean age of 70.7 (SD 11.3) and 68.5% were male. The range of procedures delayed consisted of 100 (78.7%) for aneurysm repair, 7 (5.5%) acute aortic syndromes (penetrating aortic ulcer, intramural hematoma and subacute or chronic Type B dissection), and 18 (14.2%) endoleak procedures. As of this analysis, 89 (70%) of patients had completed surgeries with a mean delay of 82.7 days (SD 68.1) with one patient undergoing unsuccessful emergency repair for aneurysm rupture. 18 (14.2%) were still waiting for surgery at the time of completion of the case report form, consisting of 17 aneurysms and one endoleak. 13 patients (10.2%) had their procedure permanently cancelled. Including the aforementioned rupture, another 5 patients (3.9%) were reported as having died after postponement of their aneurysm surgery. Mortality amongst aneurysm patients alone was 6% during the 10-month analysis period. At the time of analysis, 70% of postponed aortic procedures were completed with a mean delay of 82.7 days. Overall mortality of 6 patients (4.7%) over 10 months from COVID-19 related health service disruption underscores the wider impacts of this pandemic, and the importance of resource and contingency planning for future epidemics and natural disasters.

4:58 pm

Purpose Visceral aneurysm surveillance is outlined by the Society of Vascular Surgery Clinical Practice Guidelines.(1) In practice, surveillance does not appear to follow a clear pattern and there may be an overuse of imaging. Our study aims to assess the frequency and adequacy of imaging episodes and compare this to published guidelines. Methodology Visceral aneurysms on surveillance under the care of The Auckland Regional Vascular Service were identified through radiology requests over a five-year period. Imaging frequency, size change over time and the need for intervention were collected. Results Total of 98 patients were identified to have visceral aneurysm(s). The majority were splenic (55%) and renal aneurysms (34%). The mean age was 68, females making up 70% of the sample population. All visceral aneurysms were identified incidentally by various imaging modalities. The median time between surveillance scans of splenic aneurysms was 1.96 years (range 22 days - 6.4 years) and 1.79 years for renal artery aneurysms (range 106 days – 8.38 years). A total of 15 patients had an intervention. Of these 12 true aneurysms met the size criteria on detection. One patient with a mycotic superior mesenteric artery (SMA) aneurysm had an intervention for increasing aneurysmal size. Two patients with pseudoaneurysms (hepatic and SMA) presented with aneurysmal rupture. Only five patients with true aneurysms were reported to have radiological increase in size, none of which went forward for intervention. Conclusion There is a large variation in the frequency of surveillance imaging of visceral aneurysms. A more standardised approach for the Auckland Regional Vascular Service would reduce unnecessary use of imaging. Further research to evaluate the frequency of surveillance scanning may allow for adjustment of current recommendations. Reference 1. The Society for Vascular Surgery clinical practice guidelines on the management of visceral aneurysms. J Vasc Surg 2020;72:3S-39S

5:03 pm

Introduction: Ruptured arterial aneurysms carry high mortality. Australia and New Zealand currently have no formal screening programme or surveillance and referral pathways. Aneurysms are often found incidentally but subsequent follow-up is variable. Method: A retrospective audit study was conducted in a New Zealand peripheral hospital to establish the proportion of arterial aneurysms on radiological studies that were then actioned. All radiological reports over a 5-month period (first cycle January-June 2021) were screened for keywords (“aneurysm” or “AAA”). Electronic medical records were reviewed and data was gathered regarding aneurysm characteristics and subsequent investigations or referrals initiated. Written correspondence was sent out to the General Practitioners of patients whose aneurysms were not followed up. These “missed cases” were re-audited one month later with telephone follow-up. This audit-intervention cycle was repeated three times. Results: The percentages of arterial aneurysms that received no follow-up were 34%,21% and 26% over the three 5-month periods. Mean patient age was 76.3 years. The main radiological modality identifying aneurysms was CT (%). The majority were abdominal aortic aneurysms (AAA). The mean percentage missed of AAA, thoracic aortic aneurysms, iliac aneurysms, splenic aneurysms and renal aneurysms over the three cycles were 16.2%,36%,55.5%,72.3% and 77.8%, respectively. Mean sizes of AAAs and thoracic aortic aneurysms found were 44.8mm and 46mm, respectively. At one-month 90.5% then 56% of General Practitioners had subsequently taken action. Conclusion: Significant numbers of aneurysms are not being followed up. Opportunities for risk factor management and elective treatment may be missed. These findings strongly suggest formalized surveillance and referral guidelines/pathways are required to reduce potentially significant patient morbidity and mortality, particularly for less common aneurysms.

5:16 pm

Other Suggested Sessions

Breakfast Session
22 October 2022 7:00 am
Grand Ballroom 2 & 3
Dr Cathy Thoo

Scientific Session
23 October 2022 1:30 pm
Grand Ballroom 2 & 3
Dr Cathy Thoo, Dr David Cottier