Retrospective Cohort Study on Vessel Deformation During Fenestrated or Branched Endovascular Aortic Repair; Traditional CTA Roadmaps Provide Insufficient and Inadequate Guidance During Target Vessel Cannulation

Abstract

Introduction: Optimal visualization of target vessels in three-dimensions (3D) plays a key role in complex endovascular procedures, such as fenestrated and branched endovascular aortic repair (EVAR). A popular imaging technique to enhance target vessel visualization is image fusion. Image fusion combines real-time fluoroscopy with static preprocedural anatomical images, typically computed tomography angiography (CTA) to create an arterial roadmap. However, the introduction of stiff endovascular devices cause the arteries to stretch, leading to a mismatch between the actual position of the (origin of the) artery and its representation on the image fusion roadmap. This retrospective study assesses vessel deformation of the aorta and its side branches due to the introduction of a stiff endovascular devices, during fenestrated and branched EVAR. Furthermore, the influence of vascular tortuosity on the extent of vessel deformation was analysed. Methods: Patients that underwent fenestrated or branched EVAR between January 2015 and January 2018 were retrospectively included in this study. Two imaging datasets were collected from each patient: 1) the preoperative CTA and 2) the intraoperative contrast-enhanced cone beam computed tomography (ce-CBCT), acquired after the insertion of the stiff guidewire and stent delivery device (Zenith® custom made, Cook, Bloomington IN, USA) . Manual registration of both datasets was performed, using the bony landmarks of the vertebrae. Subsequently, the ostium of the celiac artery (CA), superior mesenteric artery (SMA), left renal artery (LRA) and right renal artery (RRA) were marked in both the CTA and ce-CBCT reconstructions. The ostium displacement of the four target vessels was reported as a 3D vector as well as a 2D vector in the coronal plane (RRA and LRA) or sagittal plane (CA and SMA). The tortuosity index of the iliac and the abdominal aortic segment were calculated. The effect of the tortuosity index on the extent of vessel deformation was assessed using linear regression. Results: In total 77 target vessels from 20 patients were included in this study. The 3D mean displacement vector of the ostium of the CA, SMA, RRA and LRA were respectively 8.7±3.8mm, 7.4±2.7mm, 7.9±2.7mm and 7.6±4.4mm. The 2D mean displacement vector for the SMA and CA in the sagittal viewing plane was 4.9±2.9mm and 6.5±3.0mm respectively. The 2D mean displacement vector of the RRA and LRA in the coronal viewing plane was 7.0±2.8mm 6.2±4.3mm respectively. An example of the 2D displacement of the RRA in the coronal plane is shown in Figure 1. In total, 74% of the target vessels had a 2D vector displacement of more than 50% of the diameter of the vessel. The mean tortuosity index of the abdominal aortic segment and the iliac segment was 1.10 and 1.34 respectively. Linear regression showed no association between the extend of vessel displacement and the tortuosity index of the abdominal aortic segment (p=0.37), nor the iliac segment (p=0.11). Conclusion: There is significant vessel displacement of the ostium of the target vessels, during fenestrated and branched EVARs caused by the introduction of stiff endovascular devices. Consequently, preoperative CTA roadmaps are inadequate to guide target vessel cannulation during fenestrated or branched EVAR. Disclosure: Nothing to disclose