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Unresolved for over half a century now since the beginning of aortic surgery spinal cord injury (SCI) remains the most devastating complication after extensive open and endovascular thoracoabdominal aortic aneurysm (TAA/A) repair. Over the past decade extensive research on spinal cord perfusion lead to a better understanding of previously unknown physiologic mechanisms involved in the suspension of the cord's arterial supply and the consecutive development of SCI underscoring the need for new concepts in treatment strategy and monitoring methods during and after TAA/A repair. Based on this knowledge, new treatment strategies in particular the staged-repair were developed. The first-in-man translation of this idea has just been published introducing the new concept: minimally invasive selective segmental artery coil-embolization. Another approach to overcome the most critical initial period after segmental artery occlusion due to stent graft deployment in the descending or thoracoabdominal aorta is temporary aneurysm sac perfusion, which also has recently been clinically trialed. Furthermore, the new non-invasive real-time monitoring method to record spinal cord viability by means of near-infrared spectroscopy of the paraspinal collateral network by means of near-infrared spectroscopy has also been suggested and successfully introduced in a pilot series to a clinical setting. This review addresses problems, unsolved questions and future perspectives regarding these three new concepts.

Stent graft fixation in the vessel affects the success of endovascular aneurysm repair. Thereby the radial forces of the stent, which are dependent on several factors, play a significant role. In the presented work, a finite element sensitivity study was performed. The radial forces are 29% lower when using the hyperelastic approach for the vessel compared with linear elastic assumptions. Without the linear elastic modeled plaque, the difference increases to 35%. Modeling plaque with linear elastic material approach results in 8% higher forces than with a hyperelastic characteristic. The significant differences resulting from the investigated simplifications of the material lead to the conclusion that it is important to apply an anisotropic nonlinear approach for the vessel. The oversizing study shows that radial forces increase by 64% (0.54 N) when raising the oversize from 10 to 22%, and no further increase in force can be observed beyond these values (vessel diameter D=12 mm). Starting from an oversize of 24%, the radial force steadily decreases. The findings of the investigation show that besides the oversizing the material properties, the ring design and the vessel characteristics have an influence on radial forces., (Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to evaluate the feasibility of non-invasive monitoring of the paraspinous collateral network (CN) oxygenation prior to, during, and after thoracoabdominal aortic repair in a clinical series., Methods: Near-infrared spectroscopy optodes were positioned bilaterally-over the thoracic and lumbar paraspinous vasculature-to transcutaneously monitor muscle oxygenation of the CN in 20 patients (age: 66 ± 10 years; men = 11) between September 2010 and April 2012; 15 had open thoracoabdominal aortic repair (Crawford II and III), three had thoracic endovascular aortic repair (TEVAR; Crawford I), and two had a hybrid repair (Crawford II). CN oxygenation was continuously recorded until 48 hours postoperatively., Results: Hospital mortality was 5% (n = 1), 15% suffered ischemic spinal cord injury (SCI). Mean thoracic CN oxygenation saturation was 75.5 ± 8% prior to anesthesia (=baseline) without significant variations throughout the procedure (during non-pulsatile cooling on cardiopulmonary bypass and with aortic cross-clamping; range = 70.6-79.5%). Lumbar CN oxygenation (LbS) dropped significantly after proximal aortic cross-clamping to a minimum after 11.7 ± 4 minutes (74 ± 13% of baseline), but fully recovered after restoration of pulsatile flow to 98.5% of baseline. During TEVAR, stent-graft deployment did not significantly affect LbS. Three patients developed relevant SCI (paraplegia n = 1/paraparesis n = 2). In these patients LbS reduction after aortic cross-clamping was significantly lower compared with patients who did not experience SCI (p = .041)., Conclusions: Non-invasive monitoring of CN oxygenation prior to, during, and after thoracoabdominal aortic repair is feasible. Lumbar CN oxygenation levels directly respond to compromise of aortic blood circulation., (Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.)