In the short to moderate term, in situ fenestration appears to be a reasonable and effective method to extend the proximal landing zone for revascularization of the left subclavian artery. However, longer follow-up is needed to fully assess the long-term durability of this procedure. Based on studies of material properties, an energy-based fenestration technique (radiofrequency or laser) is recommended, along with the avoidance of cutting balloons for dilation of the fenestration.

Fenestrated endovascular aneurysm repair (FEVAR) is a minimally invasive method of abdominal aortic aneurysm (AAA) repair utilized in patients with complex vessel anatomies. Stent grafts (SG) used in this process contain fenestrations within the device that need to be aligned with the visceral arteries upon successful SG deployment. Proper alignment is crucial to maintain blood flow to these arteries and avoid surgical complications. During fenestrated SG deployment, rotation of the SG can occur during the unsheathing process. This leads to misalignment of the vessels, and the fenestrations and is associated with poor clinical outcomes. The aim of this study was to develop a computational model of the FEVAR process to predict SG rotation. Six patient-specific cases are presented and compared with surgical case data. Realistic material properties, frictional effects, deployment methods, and boundary conditions are included in the model. A mean simulation error of 2 deg (range 1-4 deg) was observed. This model was then used to conduct a parameter study of frictional properties to see if rotation could be minimized. This study showed that increasing or decreasing the coefficients of friction (COF) between the sheath and the vessel walls would decrease the amount of rotation observed. Our model accurately predicts the amount of SG rotation observed during FEVAR and can be used as a preoperative planning tool within the surgical workflow.

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.

Background: Abdominal aortic aneurysm (AAA) rupture has an associated mortality of 90%. AAAs are repaired when they meet size criteria, become symptomatic, or rupture. Use of aortic diameter as the primary criterion in the decision to intervene fails to take into consideration that AAAs rupture at sizes below operative thresholds or reach extreme size without rupture. We have previously shown that AAAs rupture at sites of low wall shear stress (WSS) where flow recirculation and intraluminal thrombus (ILT) tend to be more abundant. This study examined the fate of ILT deposition in AAA growth. We hypothesized that AAA expansion would be associated with increasing ILT deposition in sites of flow recirculation.Methods: A total of six patients with serial images of AAA growth over three time points were studied. Aortic measurements and sites of ILT deposition were recorded. Three-dimensional AAA geometry was generated from computed tomography angiography images. Predicted aortic blood flow velocity, localized pressure variation, and WSS profiles were correlated with AAA growth and ILT deposition. This study was carried out with biomedical ethics approval.Results: AAA growth was associated with increasing ILT deposition in most cases. The site of maximal ILT deposition strongly correlated with regions of flow recirculation and low WSS but did not correlate with the region of maximal aortic expansion. Interestingly, in some cases, the recirculation zone changed location with AAA growth, and this was associated with similar change in location of ILT deposition.Conclusions: This study has shown that ILT increases with increasing AAA size in most aneurysms and that deposition of ILT occurs at sites with low WSS and flow recirculation. An understanding of the alterations in WSS in pulsatile flow and its effect on vascular endothelium will lead to a better understanding of AAA development and growth and may ultimately lead to better prediction of AAA rupture potential.

this contributes to publication bias in vascular surgery. Emphasis should be placed on publication of nonpositive findings and of abstracts that have a higher place on the hierarchy of evidence.