Sean A. Crawford

Effects of Pulsatile Fatigue on In Situ Antegrade Fenestrated Polyester Stent Grafts Deployed in a Patient-Specific Phantom Model of Juxtarenal Aortic Aneurysm

PURPOSE To evaluate the effects of in situ fenestration on the fabric of stent grafts deployed in a patient-specific phantom of a juxtarenal abdominal aortic aneurysm. MATERIALS AND METHODS Four patient-specific juxtarenal abdominal aortic aneurysm polyurethane models were created, and bifurcated Zenith (Cook, Inc, Bloomington, Indiana) and Endurant (Medtronic, Minneapolis, Minneapolis) endografts were deployed into the models, covering the renal arteries. Antegrade in situ fenestration was carried out with radiofrequency puncture followed by balloon dilation with either conventional or cutting balloons. Renal covered stents were deployed and flared. Specimens were mounted onto an accelerated fatigue tester for 40M cycles (1 patient life-year), and evaluated with microscopy, caliper measurements, and fabric counts. RESULTS Cutting balloons resulted in more fabric fraying. None of the fenestrations grew beyond the targeted 6-mm diameter despite accelerated fatigue. Fluoroscopic images demonstrated a very prominent waist of the renal fenestration in the Cook device when a conventional balloon was used compared with a cutting balloon. The average fenestration diameter for the Cook device was only 3.1 mm with the conventional balloon compared with 4.8 mm with the cutting balloon. The average fenestration diameter for the Medtronic device was 3.8 mm with the conventional balloon compared with 5.1 mm with the cutting balloon. The fabric counts suggested crowding of yarns around the fenestrations with conventional balloons but less with cutting balloons. CONCLUSIONS This experimental work suggests that the size of in situ renal fenestrations does not expand beyond the target diameter despite cyclic fatigue. Although the small number of devices tested and selected aortorenal anatomy in this study may limit conclusions, textile analysis suggests that cutting balloons should be used for the Cook Zenith device, whereas conventional balloons should be used for the Medtronic Endurant device when performing in situ fenestration.

Analysis of Iliac Artery Geometric Properties in Fenestrated Aortic Stent Graft Rotation

Introduction: A complication of fenestrated endovascular aneurysm repair is the potential for stent graft rotation during deployment causing fenestration misalignment and branch artery occlusion. The objective of this study is to demonstrate that this rotation is caused by a buildup of rotational energy as the device is delivered through the iliac arteries and to quantify iliac artery geometric properties associated with device rotation. Methods: A retrospective clinical study was undertaken in which iliac artery geometric properties were assessed from preoperative imaging for 42 cases divided into 2 groups: 27 in the nonrotation group and 15 in the rotation group. Preoperative computed tomography scans were segmented, and the iliac artery centerlines were determined. Iliac artery tortuosity, curvature, torsion, and diameter were calculated from the centerline and the segmented vessel geometry. Results: The total iliac artery net torsion was found to be higher in the rotation group compared to the nonrotation group (23.5 ± 14.7 vs 14.6 ± 12.8 mm−1; P = .05). No statistically significant differences were found for the mean values of tortuosity, curvature, torsion, or diameter between the 2 groups. Conclusion: Stent graft rotation occurred in 36% of the cases considered in this study. Cases with high iliac artery total net torsion were found to be more likely to have stent graft rotation upon deployment. This retrospective study provides a framework for prospectively studying the influence of iliac artery geometric properties on fenestrated stent graft rotation.

Prediction of advanced endovascular stent graft rotation and its associated morbidity and mortality

Objective: Advanced endovascular aneurysm repair (EVAR) with fenestrated and branched stent grafts is increasingly being used to repair complex aortic aneurysms; however, these devices can rotate unpredictably during deployment, leading to device misalignment. The objectives of this study were to quantify the short‐term clinical outcomes in patients with intraoperative stent graft rotation and to identify quantitative anatomic markers of the arterial geometry that can predict stent graft rotation preoperatively. Methods: A prospective study evaluating all patients undergoing advanced EVAR was conducted at two university‐affiliated hospitals between November 2015 and December 2016. Stent graft rotation (defined as ≥10 degrees) was measured on intraoperative fluoroscopic video of the deployment sequence. Standard preoperative computed tomography angiography imaging was used to calculate the geometric properties of the arterial anatomy. Any in‐hospital and 30‐day complications were prospectively documented, and a composite outcome of any end‐organ ischemia or death was used as the primary end point. Results: Thirty‐nine patients undergoing advanced EVAR were enrolled in the study with a mean age of 75 years (interquartile range [IQR], 71‐80 years) and a mean aneurysm diameter of 64 mm (IQR, 59‐65 mm). The incidence of stent graft rotation was 37% (n = 14), with a mean rotation of 25 degrees (IQR, 21‐28 degrees). A nominal logistic regression model identified iliac artery torsion, volume of iliac artery calcification, and stent graft length as the primary predictive factors. The total net torsion and the total volume of calcific plaque were higher in patients with stent graft rotation, 8.9 ± 0.8 mm−1 vs 4.1 ± 0.5 mm−1 (P < .0001) and 1054 ± 144 mm3 vs 525 ± 83 mm3 (P < .01), respectively. The length of the implanted stent grafts was also higher in patients with intraoperative rotation, 172 ± 9 mm vs 156 ± 8 mm (P < .01). The composite outcome of any end‐organ ischemia or death was also substantially higher in patients with stent graft rotation (36% vs 0%; P = .004). In addition, patients with stent graft rotation had significantly higher combined rates of type Ib and type III endoleaks (43% vs 8%; P = .03). Conclusions: Patients with intraoperative stent graft rotation have a significantly higher rate of severe postoperative complications, and this is strongly associated with higher levels of iliac artery torsion, calcification, and stent graft length. These findings suggest that preoperative quantitative analysis of iliac artery torsion and calcification may improve risk stratification of patients before advanced EVAR.

The Influence of Surgical Technique on Device Rotation and Fenestration Alignment in Advanced Endovascular Aneurysm Repair

ICH, Intracranial hemorrhage; MI, myocardial infarction; N/A, not applicable. ICH and MI were significantly increased among patients who underwent CEA within 2 days of symptom onset (Fisher exact test, P 1⁄4 .05). Stroke rate was nonsignificantly increased in patients who received CEA within 2 days of symptoms (Fisher exact test, P 1⁄4 .32). Values are reported as number (%). Sean A. Crawford, MD, Matthew G. Doyle, PhD, Cristina H. Amon, ScD, MS, P Eng, Thomas L. Forbes, MD, FRCSC. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada

PC040 Analysis of Fenestrated Endovascular Aneurysm Repair Complication Frequency With Respect to Stent Graft Misalignment

Objectives: The objective of the current study is to evaluate the incidence of and clinical outcomes following fenestrated stent graft misalignment during complex endovascular aortic repairs. Methods: A retrospective record review was performed for all fenestrated endovascular aneurysm repairs (FEVAR) performed at our center between January 2008 and April 2015. Data were gathered from physician notes, radiology records, laboratory reports, and intraoperative imaging. Vertical stent graft misalignment was defined as

Publication outcomes for research presented at a Canadian surgical conference

4 mm and was calculated as the distance from the center of the fenestration markers to the center of the target vessel ostium on the intraoperative fluoroscopic images at the time of cannulation. Horizontal stent graft misalignment was defined as

‘In-stock’ fenestrated stent graft for the urgent repair of an abdominal aortic aneurysm

15 and was calculated as the difference between the native vessel angle and the intraoperative stent graft orientation. Native vessel angles were calculated using vessel centerlines generated using open source software (The Vascular Modeling Toolkit). Intraoperative stent graft orientation was determined from the angle of the image intensifier when the fenestration was profiled for cannulation. Data are presented as the mean and 95% confidence interval or standard error. Results: Eighty FEVAR procedures were performed with a mean patient age of 76 6 0.8 years, a mean aneurysm diameter of 64 6 0.9 mm, and an overall 30-day mortality rate of 5% (n 1⁄4 4). Fifteen patients were excluded due to a lack of sufficient quality medical imaging data, leaving 65 patients in the study cohort. A horizontal misalignment of >15 was identified in 47.5% of patients (n 1⁄4 26) and >30 in 9.2% of patients (n 1⁄4 6). A vertical misalignment of

Psychiatric Predictors of Surgery Non-completion Following Suitability Assessment for Bariatric Surgery

4 mm was identified in 32.3% of patients (n 1⁄4 21). The incidence of severe postoperative complications, defined as any in-hospital end organ ischemia and/or death, was significantly higher for patients with either horizontal misalignment or vertical misalignment, 34.6% (19%-54%) vs 7.7% (2%-12%) and 32% (16%-53%) vs 13% (5%-25%), respectively. There was a trend toward higher rates of target vessel cannulation failure in patients with stent graft misalignment 3% (n 1⁄4 99 fenestrations) vs 0% (n 1⁄4 76 fenestrations). The combined incidence of any intraoperative target vessel complication (ie, cannulation failure, vessel occlusion, dissection, and/ or perforation) was significantly higher in patients with misalignment, 8.1% (4%-15%) vs 1.3% (0%-8%). Conclusions: Intraoperative stent graft misalignment is associated with higher rates of both intraoperative target vessel complications and severe postoperative complications. Patients in which stent graft misalignment is identified should be considered high-risk for early postoperative complications.

Understanding disposition after referral for bariatric surgery: when and why patients referred do not undergo surgery.

Background The failure of investigators to publish research in peer-reviewed journals following acceptance at a national or international meeting can lead to significant publication biases in the literature. Our objective was to evaluate the abstract to manuscript conversion rate for abstracts presented at the Canadian Society for Vascular Surgery (CSVS) annual meeting and to evaluate the conversion rate for CSVS-awarded research grants. Methods We searched for authors of abstracts accepted at the CSVS Annual Meeting (2007–2013) and recipients of CSVS research awards (2005–2013) on Scopus and PubMed databases to identify related publications. Results We identified 84 publications from 188 research abstracts (45%) and 17 publications from 39 research grants (44%). The mean time to publication was 1.8 years and the mean impact factor was 2.7. Studies related to endovascular therapies demonstrated a trend toward a higher rate of publication relative to open surgical therapies (64 [56%] v. 37 [27%]). Additionally, we observed a similar trend in research grant topics related to endovascular therapies relative to open surgical therapies (9 [67%] v. 8 [38%]). Finally, CSVS research grant recipients who subsequently published had a significantly higher h-index at the time of receipt than those who had not published. Conclusion The CSVS annual meeting’s abstract to publication conversion rate is comparable to that of its Canadian peers as well as to other medical specialties; however, a substantial publication gap remains. We identified several potential areas that may help to improve the effectiveness of CSVS research grants.

Clinical outcomes and material properties of in situ fenestration of endovascular stent grafts

Endovascular aneurysm repair (EVAR) is a minimally invasive method for the treatment of abdominal aortic aneurysms; however, the implementation of this technique is often limited by the aortic pathology, especially in the urgent or emergent setting. An 82-year-old male with a 7.3 cm symptomatic juxtarenal aneurysm presented at our centre for assessment. He was diagnosed as a high-risk candidate for open repair and therefore, not suitable for a conventional EVAR. Fortunately, a custom two-vessel fenestrated stent graft, which was originally constructed for another patient, was available. This device was implanted with no complications and all branches remain unobstructed; clear of aneurysms at 1 year. We present the use of ‘in-stock’ fenestrated grafts as a potential option to be considered in the urgent or emergent repair of abdominal aortic aneurysms.