The collateral network concept: a reassessment of the anatomy of spinal cord perfusion

Physician-Modified Reversed Iliac Branch Device to Prevent Spinal Cord Ischemia in an Urgent Branched Endovascular Aortic Repair

PURPOSE

Repair of pararenal aneurysms poses a challenge, especially in an urgent setting. Despite the minimally invasive nature of the fenestrated/branched endovascular aortic repair, the technique may require extensive coverage of the aorta, increasing the risk of spinal cord ischemia.

TECHNIQUE

A 68-year-old man was admitted with a rapid enlargement of an asymptomatic juxtarenal aortic aneurysm. A minimally invasive treatment with an off-the-shelf branched endovascular graft was planned. Before completing the aneurysm exclusion, an angiography highlighted a large lumbar artery, potentially significant for the perfusion of the spinal cord collateral network. Owing to this finding and an unsuccessful placement of the cerebrospinal fluid drainage, the procedure was staged and completed 5 days later using a physician-modified iliac branch device (IBD) for the segmental artery. The device was shortened and reversely loaded to obtain a cranially-oriented branch. A balloon-expandable covered stent was used to connect the retrograde branch (8 mm) to the lumbar artery (4 mm). Pre-discharge computed tomography (CT)-angiography confirmed the vessel patency. No neurological symptoms occurred.

CONCLUSION

The use of a reversely-loaded IBD for segmental artery preservation appears feasible and safe.

CLINICAL IMPACT

Intraoperative modification of an iliac branch device during an urgent branched endovascular aortic repair enabled preservation of a potentially critical segmental artery, thus reducing the risk of spinal cord ischemia. This adaptive interventional technique may also offer a strategy for preserving other anatomically significant vessels, such as accessory renal arteries, during complex aortic reconstructions in urgent settings.

Posterior False Lumen and Paraplegia After FET Procedure in Acute Type A Aortic Dissection

BACKGROUND

Postoperative paraplegia is the major concern with the frozen elephant trunk (FET) procedure in patients with acute type A aortic dissection (ATAAD). It is crucial to identify patients with a high risk of paraplegia before implementing the FET procedure.

METHODS

From January 2013 to December 2018, 544 patients with ATAAD who underwent FET procedures were included in this study. The segment number of posterior false lumens (PFLs) between T9 and L2 levels was calculated. In-hospital outcomes and long-term survival were investigated on the basis of the number of PFLs.

RESULTS

The average age was 46.5 ± 9.9 years, and the proportion of female patients was 19.5% in this cohort. The incidence of postoperative paraplegia was significantly increased when PFL was present in 3 or more segments. Patients were divided into a high-PFL group (3-6 segments; n = 124) and a low-PFL group (0-2 segments; n = 420). The demographic characteristics were similar between the 2 groups. Involvement of the celiac trunk and the superior mesenteric artery was significantly lower in the high-PFL group (all P < .05). The other baseline characteristics and procedural information were statistically balanced. The incidence of postoperative paraplegia was significantly higher in the high-PHL group (7.3% vs 1.9;P = .006). Multivariable logistic analysis revealed that high PFL was independently associated with postoperative paraplegia after an FET procedure (odds ratio, 3.812; 95% CI, 1.378-10.550; P = .010). Additionally, the moderate nasopharyngeal temperature of hypothermic circulatory arrest (≧23.0 °C) was clarified as a protective factor for paraplegia (odds ratio, 0.112; 95% CI, 0.023-0.535; P = .006).

CONCLUSIONS

Patients with ATAAD who present with high PFL between T9 and L2 levels have a significantly high risk of postoperative paraplegia if they undergo an FET procedure.

Hemodynamic predictors of negative false lumen remodeling after frozen elephant trunk for acute aortic dissection

OBJECTIVE

We evaluated the blood flow within the downstream aortic false lumen after frozen elephant trunk repair for acute aortic dissection and identified hemodynamic predictors of false lumen expansion and negative false lumen remodeling using four-dimensional flow magnetic resonance imaging.

METHODS

Thirty-one patients (Stanford type A, n = 28; Stanford type B, n = 3) with patent false lumen who underwent frozen elephant trunk procedures for acute aortic dissection were included in this observational study. Each patient underwent computed tomography during the follow-up period and four-dimensional flow magnetic resonance imaging within 3 postoperative months. The false lumen volumetric expansion rate was calculated using computed tomography data. The direction and the rate of flow in the lower descending aortic false lumen were analyzed. Negative false lumen remodeling was defined as a volumetric increase of > 10% from the baseline volume.

RESULTS

Negative false lumen remodeling had developed in 6 of the 31 patients during the observation period. Most of the false lumen flows were biphasic during systole. The range between peak and nadir flow rates was associated with the false lumen volumetric expansion rate (β coefficient = 6.77; p < 0.01, R2 = 0.43).

CONCLUSIONS

The range between peak and nadir flow rates may serve as a hemodynamic predictor of negative false lumen remodeling, enabling further treatment for patients at risk of expansion in the downstream aorta.

Comparison of LED- and LASER-based fNIRS technologies to record the human peri‑spinal cord neurovascular response

Recently, functional Near-Infrared Spectroscopy (fNIRS) was applied to obtain, non-invasively, the human peri‑spinal Neuro-Vascular Response (NVR) under a non-noxious electrical stimulation of a peripheral nerve. This method allowed the measurements of changes in the concentration of oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) from the peri‑spinal vascular network. However, there is a lack of clarity about the potential differences in perispinal NVR recorded by the different fNIRS technologies currently available. In this work, the two main noninvasive fNIRS technologies were compared, i.e., LED and LASER-based. The recording of the human peri‑spinal NVR induced by non-noxious electrical stimulation of a peripheral nerve was recorded simultaneously at C7 and T10 vertebral levels. The amplitude, rise time, and full width at half maximum duration of the perispinal NVRs were characterized in healthy volunteers and compared between both systems. The main difference was that the LED-based system shows about one order of magnitude higher values of amplitude than the LASER-based system. No statistical differences were found for rise time and for duration parameters (at thoracic level). The comparison of point-to-point wave patterns did not show significant differences between both systems. In conclusion, the peri‑spinal NRV response obtained by different fNIRS technologies was reproducible, and only the amplitude showed differences, probably due to the power of the system which should be considered when assessing the human peri‑spinal vascular network.

Descending thoracic aortic mural ulceration is associated with postoperative spinal cord ischemia after branched endovascular aortic aneurysm repair

OBJECTIVE

Paraplegia is one of the most feared complications after thoracoabdominal aortic aneurysm repair. The purpose of this study is to determine whether aortic thrombus characteristics are associated with spinal cord ischemia (SCI) after branched endovascular aneurysm repair (BEVAR).

METHODS

From April 2011 to April 2020, 62 patients underwent elective BEVAR for thoracoabdominal aortic aneurysm and pararenal aortic aneurysms using a low-profile device and had a complete preoperative computed tomography angiography of the aorta from the sinotubular junction to the aortic bifurcation. Aortic thrombus was evaluated for thrombus thickness ≥5 mm, thrombus >2/3 of aortic circumference, and the presence of an ulcer-like thrombus. One point was assigned at each 5 mm axial image if all 3 criteria were met, resulting in a total "shaggy score" for the entire aorta. Data on demographics, procedural details, and outcomes were collected prospectively. All patients underwent a standard spinal cord protection protocol, including routine cerebrospinal fluid drainage. In July 2016, an insulin infusion protocol (IIP) was initiated to maintain postoperative blood glucose levels <120 mg/dL for 48 hours. The primary clinical end point was postoperative SCI.

RESULTS

10 (16%) patients developed postoperative SCI: 6 with transient paraparesis, 2 with persistent paraparesis, and 2 with persistent paraplegia. Patients with SCI were older, had higher shaggy scores, and were less likely to have been on an IIP. There were no significant differences in demographics, aneurysm type, or operative parameters. In a logistic multivariate regression model for SCI, age (odds ratio [OR]: 1.2 [1.1-1.4], P = .02) and shaggy score (OR: 1.2 [1.1-1.4], P = .02) were independently associated with increased risk of SCI, whereas treatment with the IIP was associated with lower risk of SCI (OR: 0.04 [0.006-0.50], P = .05). Of the individual components of the shaggy score, higher descending thoracic aortic ulcer scores were the most strongly associated with postoperative SCI (P = .009).

CONCLUSIONS

Preoperative characterization of aortic wall thrombus is an important adjunctive tool for individualized clinical decision-making and patient counseling about the risk of SCI after BEVAR.

Predictive value of preoperative platelet count and D-dimer levels for spinal cord injury following acute type a aortic dissection

BACKGROUND

This study aims to identify the risk factors contributing to spinal cord injury (SCI) following a type A acute aortic dissection (TA-AAD).

METHODS

This retrospective study was conducted at a single center and involved 481 patients who received frozen elephant trunk stent implantation for TA-AAD. Additionally, these patients underwent total arch replacement with deep hypothermic circulatory arrest. This study was performed at Fuwai Hospital between September 2016 and April 2020.

RESULTS

The resulting data of the multivariate logistic regression analysis demonstrated that preoperative platelet count (odds ratio [OR] = 0.774) and D-dimer levels (OR = 2.247) could serve as independent predictors for postoperative SCI in patients with TA-AAD.

CONCLUSION

The findings indicate that preoperative platelet count and D-dimer levels are independent risk factors for postoperative SCI in patients with TA-AAD. This study holds significant clinical implications regarding the prognosis and therapeutic responses for patients with TA-AAD.

Adjunctive hyperbaric oxygen therapy for spinal cord ischemia after complex aortic repair

OBJECTIVE

Spinal cord ischemia (SCI) with paraplegia or paraparesis is a devastating complication of complex aortic repair (CAR). Treatment includes cerebrospinal fluid drainage, maintenance of hemoglobin concentration (>10 g/L), and elevating mean arterial blood pressure. Animal and human case series have reported improvements in SCI outcomes with hyperbaric oxygen therapy (HBOT). We reviewed our center's experience with HBOT as a rescue treatment for spinal cord ischemia post-CAR in addition to standard treatment.

METHODS

A retrospective review of the University Health Network's Hyperbaric Medicine Unit treatment database identified HBOT sessions for patients with SCI post-CAR between January 2013 and June 2021. Mean estimates of overall motor function scores were determined for postoperative, pre-HBOT, post-HBOT (within 4 hours of the final HBOT session), and at the final assessment (last available in-hospital evaluation) using a linear mixed model. A subgroup analysis compared the mean estimates of overall motor function scores between improvement and non-improvement groups at given timepoints. Improvement of motor function was defined as either a ≥2 point increase in overall muscle function score in patients with paraparesis or an upward change in motor deficit categorization (para/monoplegia, paraparesis, and no deficit). Subgroup analysis was performed by stratifying by improvement or non-improvement of motor function from pre-HBOT to final evaluation.

RESULTS

Thirty patients were treated for SCI. Pre-HBOT, the motor deficit categorization was 10 paraplegia, three monoplegia, 16 paraparesis, and one unable to assess. At the final assessment, 14 patients demonstrated variable degrees of motor function improvement; eight patients demonstrated full motor function recovery. Seven of the 10 patients with paraplegia remained paraplegic despite HBOT. The estimated mean of overall muscle function score for pre-HBOT was 16.6 ± 2.9 (95% confidence interval [CI], 10.9-22.3) and for final assessment was 23.4 ± 2.9 (95% CI, 17.7-29.1). The estimated mean difference between pre-HBOT and final assessment overall muscle function score was 6.7 ± 3.1 (95% CI, 0.6-16.1). The estimated mean difference of the overall muscle function score between pre-HBOT and final assessment for the improved group was 16.6 ± 3.5 (95% CI, 7.5-25.7) vs -4.9 ± 4.2 (95% CI, -16.0 to 6.2) for the non-improved group.

CONCLUSIONS

HBOT, in addition to standard treatment, may potentially improve recovery in spinal cord function following SCI post-CAR. However, the potential benefits of HBOT are not equally distributed among subgroups.

Covering the intercostal artery branching of the Adamkiewicz artery during endovascular aortic repair increases the risk of spinal cord ischemia

Objectives

This study aimed to determine the relationship between covering the intercostal artery branching of the Adamkiewicz artery (ICA-AKA) and spinal cord ischemia (SCI) during thoracic endovascular aortic repair (TEVAR).

Methods

Patients who underwent TEVAR from 2008 to 2022 were enrolled. Stent grafts covered the ICA-AKA in 108 patients (covered AKA group) and stent grafts didn't cover the ICA-AKA in 114 patients (uncovered AKA group). The characteristics of 58 patients from each group were matched based on propensity scores.

Results

No significant differences in SCI rates were detected between the covered AKA (10%; 11/108) and uncovered AKA (3.5%; 4/114) groups (P = .061). Shaggy aorta (odds ratio [OR], 5.16; 95% confidence interval [CI], 1.74-15.3, P = .003), iliac artery access (OR, 6.81; 95% CI, 2.22-20.9, P = .001), and procedural time (OR, 1.01; 95% CI, 1.00-1.02, P = .003) were risk factors for SCI in the entire cohort. Although covering the ICA-AKA (OR, 2.60; 95% CI, 0.86-7.88, P = .058) was not a significant risk factor, shaggy aorta (OR, 8.15; 95% CI, 2.07-32.1, P = .003), iliac artery access (OR, 9.09; 95% CI, 2.22-37.2, P = .002), and procedural time (OR, 1.01; 95% CI, 1.01-1.02, P = .008) were risk factors for SCI in the covered AKA group. No significant risk factors were detected in the uncovered AKA group.

Conclusions

Covering the ICA-AKA was not an independent risk for SCI in TEVAR. However, covering the ICA-AKA was indirectly associated with the risk of SCI in patients with shaggy aorta, iliac access, and procedural time.

Risk Factors for Spinal Cord Injury during Endovascular Repair of Thoracoabdominal Aneurysm: Review of the Literature and Proposal of a Prognostic Score

Despite recent improvements, spinal cord ischemia remains the most feared and dramatic complication following extensive aortic repair. Although endovascular procedures are associated with a lower risk compared with open procedures, this risk is still significant and must be considered. A combined medical and surgical approach may help to optimize the tolerance of the spinal cord to ischemia. The aim of this review is to describe the underlying mechanism involved in spinal cord injury during extensive endovascular aortic repair, to describe the different techniques used to improve spinal cord tolerance to ischemia-including the prophylactic or curative use of spinal drainage-and to propose our algorithm for spinal cord protection and the rational use of spinal drainage.

Preparing the spinal cord - priming or preconditioning? A systematic review of experimental studies

Objectives. Paraplegia is devastating complication associated with thoracic and thoracoabdominal aortic aneurysm repair. Vast evidence has been gathered on pre-, peri- and postoperative protective adjuncts aiming to minimize spinal cord ischemia. This review focuses on the pretreatment phase of open surgical or endovascular aortic procedures and gathers the experimental data on the interventional preconditioning and priming methods that increase the spinal cord ischemic tolerance. Design. By the start of March 2021, a systematic review was performed in PubMed, Scopus and Web of Science core collection to identify the articles that reported (i) either an ischemic preconditioning, remote ischemic preconditioning or priming method prior to (ii) experimental spinal cord ischemia performed in endovascular or open surgical fashion mimicking either thoracic, abdominal or thoracoabdominal aortic aneurysm procedures. (iii) The outcomes were reported via neurological, motor-evoked potential, somatosensory-evoked potential, histopathological, immunohistochemical, physiological analysis, or in different combinations of these measurements. Results. The search yielded 7802 articles, and 57 articles were included in the systematic review. The articles were assessed by the evaluated species, the utilized pretreatment, the measured protective effects, and the suggested underlying mechanisms. Conclusions. The reviewed articles showed several possible mechanisms in ischemic and remote ischemic preconditioning for prevention of spinal cord ischemia. The main suggested method for priming was arteriogenetic stimulus. Future studies should confirm these hints of arteriogenetic stimulus with more precise quantification of the protective recruitment process.

Spinal cord protection in open and endovascular approaches to thoracoabdominal aortic aneurysms

Despite advancements in surgical and postoperative management, spinal cord injury has been a persistent complication of both open and endovascular repair of thoracoabdominal and descending thoracic aortic aneurysm. Spinal cord injury can be explained with an ischemia-infarction model which results in local edema of the spinal cord, damaging its structure and leading to reversible or irreversible loss of its function. Perfusion of the spinal cord during aortic procedures can be enhanced by several adjuncts which have been described with a broad variety of evidence in their support. These adjuncts include systemic hypothermia, cerebrospinal fluid drainage, extracorporeal circulation and distal aortic perfusion, segmental arteries reimplantation, left subclavian artery revascularization, and staged aortic repair. The Authors here reviewed and discussed the role of such adjuncts in preventing spinal cord injury from occurring, pinpointing current evidence and outlining future perspectives.

Necrostatin-1 Attenuates Delayed Paraplegia after Transient Spinal Cord Ischemia in Rabbits by Inhibiting the Upregulation of Receptor-Interacting Protein Kinase 1 and 3

BACKGROUND

Delayed-onset paraplegia is a disastrous complication after thoracoabdominal aortic open surgery and thoracic endovascular aortic repair. Studies have revealed that transient spinal cord ischemia caused by temporary occlusion of the aorta induces delayed motor neuron death owing to apoptosis and necroptosis. Recently, necrostatin-1 (Nec-1), a necroptosis inhibitor, has been reported to reduce cerebral and myocardial infarction in rats or pigs. In this study, we investigated the efficacy of Nec-1 in delayed paraplegia after transient spinal cord ischemia in rabbits and assessed the expression of necroptosis- and apoptosis-related proteins in motor neurons.

METHODS

This study used rabbit transient spinal cord ischemia models using a balloon catheter. They were divided into a vehicle-treated group (n = 24), Nec-1-treated group (n = 24), and sham-controls (n = 6). In the Nec-1-treated group, 1 mg/kg of Nec-1 was intravascularly administered immediately before ischemia induction. Neurological function was assessed using the modified Tarlov score, and the spinal cord was removed 8 hr and 1, 2, and 7 days after reperfusion. Morphological changes were examined using hematoxylin and eosin staining. The expression levels of necroptosis-related proteins (receptor-interacting protein kinase [RIP] 1 and 3) and apoptosis-related proteins (Bax and caspase-8) were assessed using western blotting and histochemical analysis. We also performed double-fluorescence immunohistochemical studies of RIP1, RIP3, Bax, and caspase-8.

RESULTS

Neurological function significantly improved in the Nec-1-treated group compared with that in the vehicle-treated group 7 days after reperfusion (median 3 and 0, P = 0.025). Motor neurons observed 7 days after reperfusion were significantly decreased in both groups compared with the sham group (vehicle-treated, P < 0.001; Nec-1-treated, P < 0.001). However, significantly more motor neurons survived in the Nec-1-treated group than in the vehicle-treated group (P < 0.001). Western blot analysis revealed RIP1, RIP3, Bax, and caspase-8 upregulation 8 hr after reperfusion in the vehicle-treated group (RIP1, P = 0.001; RIP3, P = 0.045; Bax, P = 0.042; caspase-8, P = 0.047). In the Nec-1-treated group, the upregulation of RIP1 and RIP3 was not observed at any time point, whereas that of Bax and caspase-8 was observed 8 hr after reperfusion (Bax, P = 0.029; caspase-8, P = 0.021). Immunohistochemical study revealed the immunoreactivity of these proteins in motor neurons. Double-fluorescence immunohistochemistry revealed the induction of RIP1 and RIP3, and that of Bax and caspase-8, in the same motor neurons.

CONCLUSIONS

These data suggest that Nec-1 reduces delayed motor neuron death and attenuates delayed paraplegia after transient spinal cord ischemia in rabbits by selectively inhibiting necroptosis of motor neurons with minimal effect on their apoptosis.

Rationale of the PAPAartis trial

Surgical and interventional repair of thoracoabdominal aortic aneurysms improve survival significantly compared to the natural history of the disease. However, both strategies are associated with a substantial risk of spinal cord ischemia, which has been reported to occur-even in contemporary series by expert centers-in up to 12% of patients, depending on the extent of the disease. Following improved neurological outcomes after staged approaches in extensive clinical and long-term large animal studies, and the description of the "collateral network", the concept of "Minimally Invasive Staged Segmental Artery Coil Embolization" (MIS2ACE) was introduced by Etz et al. This concept of priming the collateral network in order to improve spinal cord blood supply showed promising experimental and early clinical outcomes, and consequently led to the initiation of the randomized controlled multicenter PAPAartis trial (Paraplegia Prevention in Aortic Aneurysm Repair by Thoracoabdominal Staging). This Keynote Lecture describes the background and rationale for this trial and gives an update on the current status.

Minimally invasive staged segmental artery coil embolization (MIS2ACE) for spinal cord protection

Minimally invasive staged segmental artery coil embolization (MIS2ACE) is an emerging technology for priming of the paraspinous collateral network prior to open or endovascular thoracoabdominal aortic aneurysm (TAAA) repair. Its safety and efficacy have been previously proven in various experimental settings and confirmed in numerous multicentric pilot studies for open and endovascular repair. MIS2ACE is safe and has the potential to decisively reduce the risk of postoperative paraplegia, the most devastating complication of open and endovascular TAAA repair, still affecting up to 20% of patients. Up to now, MIS2ACE has been clinically implemented with excellent results, and is currently being investigated in the international, multicenter, randomized controlled trial PAPAartis, funded by the German Research foundation, and the European Union. MIS2ACE can be performed under local anesthesia, enabling continuous monitoring of neurological function, and in case of clinical signs of imminent ischemia, preemptive interruption of the procedure. A thorough evaluation of preoperative computed tomography (CT) imaging for identification of open and accessible segmental arteries (SAs) is critical. Segmental artery occlusion can be achieved with either micro coils, or vascular plugs. A maximum number of seven SAs is currently recommended to be occluded in the same session, and a minimum interval of 5 days should be awaited between either two MIS2ACE sessions or between MIS2ACE and the final repair. Adjuvant side-effects of MIS2ACE are the reduction in segmental back-bleeding during open repair leading to harmful steal phenomenon and the reduction of the incidence of type II endoleaks in endovascular repair. Current contraindications for MIS2ACE are emergency cases, hostile anatomy, and a shaggy aorta. Other neuroprotective adjuncts such as cerebrospinal fluid (CSF) drainage, permissive hypertension, motor-evoked potentials (MEP)/somato-sensory evoked potentials (SSEP) and monitoring of paraspinous muscle oxygenation by near-infrared spectroscopy should also be applied independent of prior MIS2ACE procedure.

Collateral network concept in 2023

Extensive thoracoabdominal aortic aneurysm repair can cause spinal cord ischemia which significantly impacts survival and quality of life. Although this complication is uncommon, it is important to recognize the pathophysiology and preventative measures. In the 1990s, Dr. Griepp and colleagues proposed the existence of an extensive collateral network that supports spinal cord perfusion, "the collateral network concept". This includes an interconnecting complex of vessels in the intraspinal, paraspinous, and epidural spaces, and in the paravertebral muscles, involving the intercostal and lumbar segmental arteries as well as the subclavian and hypogastric (iliac) arteries. In this concept, as opposed to the one major segmental input model such as the Adamkiewicz artery, recognition of the importance of multiple inputs to the spinal circulation is paramount to maintaining the spinal blood flow and preventing spinal cord ischemia. In this article, we review the current evidence of the collateral concept and its application in aortic surgery.

Impact of preoperative identification of the artery of Adamkiewicz on spinal cord injury after descending aortic and thoracoabdominal aortic repair

Background

Some recent reports have demonstrated that preoperative Adamkiewicz artery (AKA) identification and its targeted reconstruction has provided satisfactory outcomes with respect to spinal cord protection. This paper investigates the impact of preoperative identification of the AKA on reducing the incidence of spinal cord injury (SCI) in open repair (OR) and endovascular repair (EVR) of descending thoracic aortic (dTA) and thoracoabdominal aortic aneurysm (TAA) repair.

Methods

The clinical data of patients with dTA and TAA treated between 2011 and 2022 were investigated. A total of 256 patients comprising of 201 males and 55 females, with a mean age of 72.1±10.0 years, were included. OR was used in 102 patients and EVR in 154 patients whose distal landing zone was below T8, all of which needed preoperative identification of the AKA.

Results

The AKA was identified in 207 (80.9%) patients, and was located in the level between T8 and T12 in 81.2%. In OR, the responsible arteries, including the identified AKA, were promptly reconstructed in 66 (64.7%) patients. In EVR, 65 (42.2%) patients had the AKA covered by an endovascular prosthesis. Deaths prior to 30 days occurred in seven (2.7%, four in OR and three in EVR) patients. In OR, SCI occurred in six (5.9%) patients including three (2.9%) with paraplegia and three (2.9%) with paraparesis, whereas in EVR ten (6.5%) patients had SCI, including two (1.3%) with paraplegia and eight (5.2%) with paraparesis. The incidence of SCI was significantly higher in patients with the AKA covered than those without it covered [13.8% (9 of 65) vs. 1.1% (1 of 89); P=0.002], whereas no significant differences were found between patients with or without the AKA reconstructed.

Conclusions

Preoperative identification of the AKA was useful enough to determine treatment strategies with less likelihood of SCI in both OR and EVR for dTA and TAA pathologies.

The result of prospective evaluation of 3-dimensional printing-aided extensive thoracoabdominal aorta repair

OBJECTIVES

Paraplegia is a distressing complication after open thoracoabdominal aortic aneurysm (TAAA) repair, and revascularization of T8-L2-level segmental arteries is considered pivotal to prevent paraplegia. We employed 3-dimensional (3D) printing to efficiently revascularize segmental/visceral arteries and prospectively evaluated its safety and efficacy.

METHODS

From January 1, 2020, to June 30, 2022, we prospectively enrolled patients of extent I, II, or III TAAA repair. Guidance models were 3D-printed based on preoperative computed tomography, and multibranched aortic grafts were manually constructed upon this model before surgery. The composite outcome of operative mortality, permanent stroke, and permanent spinal cord deficit (SCD) was compared with the historical control group (n = 77, in 2015-2020), subjected to similar TAAA repair without 3D printing.

RESULTS

A total of 38 patients (58.6 ± 13.2 years) underwent open TAAA repair with the aid of 3D printing. Extent I, II, and III repairs were performed in 14 (36.8%), 17 (44.7%), and 7 (18.4%), respectively. Concomitant arch repair and bi-iliac reconstruction were performed in 7 (18.4%) and 6 patients (15.8%), respectively. Mean pump time was 107.7 ± 55.5 minutes. Operative mortality, permanent stroke, and permanent SCD each occurred in 1 patient (2.6%), and the incidence of the composite outcome was 7.9% (3/38). In the control group, mean pump time was 166.0 ± 83.9 minutes, significantly longer than the 3D-printing group (P < .001), and operative mortality, permanent stroke, permanent SCD, and the composite outcome occurred in 7 (9.1%), 9 (11.7%), 8 (10.4%), and 19 (24.7%), respectively.

CONCLUSIONS

Open repairs of extensive TAAA with 3D printing showed favorable safety and efficacy, which need further validation by larger studies.

The anesthesiologist's perspective on emergency aortic surgery: Preoperative optimization, intraoperative management, and postoperative surveillance

The management of emergencies related to the aorta requires a multidisciplinary approach involving various health care professionals. Despite technological advancements in treatment methods, the risks and mortality rates associated with surgery remain high. In the emergency department, definitive diagnosis is usually obtained through computed tomography angiography, and management focuses on controlling blood pressure and treating symptoms to prevent further deterioration. Preoperative resuscitation is the main focus, followed by intraoperative management aimed at stabilizing the patient's hemodynamics, controlling bleeding, and protecting vital organs. After the operation, factors such as organ protection, transfusion management, pain control, and overall patient care must be taken into account. Endovascular techniques are becoming more common in surgical treatment, but they also present new challenges in terms of complications and outcomes. It is recommended that patients with suspected ruptured abdominal aortic aneurysms be transferred to facilities with both open and endovascular treatment options and a track record of successful outcomes to ensure the best patient care and long-term results. To achieve optimal patient outcomes, close collaboration and regular case discussions between health care professionals are necessary, as well as participation in educational programs to promote a culture of teamwork and continuous improvement.

Mouse Model of Spinal Cord Hypoperfusion with Immediate Paralysis Caused by Endovascular Repair of Thoracic Aortic Aneurysm

BACKGROUND

A clinically relevant mouse model of thoracic endovascular aortic repair-induced ischemic spinal cord injury has been lacking since the procedure was first employed in 1991. The hypothesis was that ligation of mouse intercostal arteries would simulate thoracic endovascular aortic repair-induced ischemic spinal cord injury and behavioral deficit. The aim was to create a mouse model of thoracic endovascular aortic repair-induced spinal cord hypoperfusion by ligating five pairs of mouse intercostal vessels.

METHODS

Mice were divided into sham (n = 53) and ligation (n = 60) groups. The procedures called for double ligation of three pairs and single ligation of two pairs of thoracic intercostal arteries in adult C57BL/6 mice. A laser Doppler probe was used in vivo on the spinal cords and intercostal arteries to document the extent of arterial ligation and spinal cord hypoperfusion. The Basso Mouse Scale for Locomotion, histological studies, and electron microscopy demonstrated postligation locomotive and histopathological changes.

RESULTS

Ligation induced a significant and instantaneous drop in blood flow in the intercostal arteries (% change; mean = -63.81; 95% CI, -72.28 to -55.34) and the thoracic spinal cord (% change; mean = -68.55; 95% CI, -80.23 to -56.87). Paralysis onset was immediate and of varying degree, with behavioral deficit stratified into three groups: 9.4% exhibited severe paralysis, 37.5% moderate paralysis, and 53.1% mild paralysis at day 1 (n = 32; P < 0.001). Mild and moderate paralysis was transient, gradually improving over time. Severe paralysis showed no improvement and exhibited a higher mortality rate (83%; n = 15 of 18) compared to moderately (33%; n = 6 of 18) and mildly (24%; n = 6 of 25) paralyzed mice (P < 0.001). The overall ligation group survival rate (84%; n = 46 of 55) was significantly lower than the sham group (100%; n = 48 of 48) with P = 0.003.

CONCLUSIONS

The mouse model generates reproducible spinal cord hypoperfusion and accompanying histopathological ischemic spinal cord damage. The resulting anatomical changes and variable behavioral deficits mimic the variability in radiological and clinical findings in human patients.

EDITOR’S PERSPECTIVE

Near-infrared spectroscopy to monitor spinal cord oxygenation in οpen thoraco-abdominal aortic surgery. A case series

Objectives. We adopted the near-infrared spectroscopy (NIRS) technology to monitor the spinal oxygen supply through the paraspinous muscles oxygenation in agreement with the concept of “collateral network” circulation. We retrospectively investigated our database of subjects who underwent thoraco-abdominal aorta open repair assessing for the reliability of this monitoring to predict spinal cord injury. Methods. Consecutive patients who underwent elective thoraco-abdominal aorta open repair between March 2019 and September 2021. In addition to standard monitoring, patients received the monitoring of the paraspinous muscles oxygenation by NIRS. Results. In one patient a significant drop of the mean arterial pressure (49 mmHg) and the spinal-cord perfusion pressure (31 mmHg) occurred after the aortic clamping, with a contemporary lowering of the left-side oxygenation of paraspinous muscles (<40%). Both the blood pressure and the spinal cord perfusion pressure were restored within 10 minutes, but the oxygenation remained at an unsafe level (<55%) until the end of the surgery. This same patient experienced a lower-limb paralysis post-operatively. It did not happen in the other 11 cases of the sample. Conclusions. The main finding of our retrospective analysis indicates reliability of this technology to monitor the spinal cord oxygenation during open thoraco-abdominal aortic surgery and possibly predict spinal cord injury. Still, several questions need to be addressed about the suitability of this technology to the anatomic and pathophysiology of the spinal cord circulation

Laryngoscopy mediated stress response induces opposite effects on cerebral and paraspinal oxygen saturation

Background: Intraoperative sympathetic stimulation induces a cascade of metabolic and hormonal changes. It increases perfusion of vital organs, but also causes vasoconstriction of blood vessels supplying less vital organs, potentially leading to organ injury. To date, it is unknown how an endogenous stress reaction affects the spinal cord blood supply. Near-infrared spectroscopy (NIRS) can be applied paravertebrally to monitor the oxygenation of the collateral network, which contributes to the spinal cord blood supply. It has already been demonstrated that regional cerebral oxygen saturation (rScO2) increases following sympathetic stimulation. Objectives: We hypothesized that laryngoscopy would cause an increase in cerebral and paraspinal regional tissue saturations (rScO2 and rSpsO2, respectively). Design: Retrospective analysis of a previous conducted randomized trial. Setting: Laryngoscopy in the operating room. Methods: Data of 28 patients, scheduled for arterial dilation of the lower limb, were retrospectively analyzed. Before induction of anesthesia, standard monitoring, BIS and 8 NIRS sensors were applied (two on the forehead, six bilaterally on the back at T3-T4, T9-T10 and L1-L2). Sympathetic stimulation was induced by laryngoscopy. Main outcome measures: Changes in rStO2 following sympathetic stimulation induced by laryngoscopy. Results: Following laryngoscopy, rScO2 significantly increased and rSpsO2 significantly decreased at T9-T10 and L1-L2. The relative changes (regional tissue oxygen saturation (rStO2) after intubation-rStO2 before intubation)/ rStO2 before intubation), at cerebral level, T9-T10 and L1-L2 were 9%, -5% and -3%, respectively (p < 0.01). rSpsO2 at T3-T4 did not change significantly. Changes (Δ) in mean arterial pressure following laryngoscopy were weakly correlated with ΔrScO2 and moderately correlated with ΔrSpsO2 at T9-T10 and L1-L2. Conclusions: Intraoperative sympathetic stimulation may decrease the oxygen supply to the spinal cord. Trial registration: The trial was registered at ClinicalTrials.gov (NCT 03767296).

Early Repair of Aortic Wall Structural Defect by "Net" Endoprosthesis to Arrest the Aneurysm without Interference with Aortic Branch Vessel Perfusion

Current treatments of aortic aneurysm include surgical or endovascular, respectively, anatomical or functional, substitution of the aneurysm tract; however, with these methods, perfusion of at least some collateral branches cannot be fully restored, leading to the risk of paraplegia. We present a novel endovascular “net” prosthesis to strengthen the aortic wall while preserving perfusion of collateral branches. This consists of a polyester mesh “net”-layered conduit in a variable cylindrical shape, which is personalized based on patient computed tomography scan images, and is defined by circular crossing spirals of a thin nitinol wire. The prosthetic conduit, shrunk by compressing the nitinol spirals, can be inserted into the vascular lumen and expanded in situ. Then, the insertion control device can be fully removed. Thus, the, “net” prosthesis, positioned inside the aorta in stable contact with the intimal wall for 2 to 5 months, is colonized by neointima and spontaneously moved deeper into the aortic wall in contact with the media, thus being ideally able to stabilize aortic diameter without interference with collateral branch blood perfusion. This new, (ideally) paraplegia-free procedure is aimed at curing the aortic wall structural defect, thus arresting the aneurysm from further progression. This contrasts with current treatments, indicated by aneurysm dimensions for their implied complication risk, which are actually for prophylaxis of impending rupture or dissection rather than fortification of the natural aorta. Moreover, this new approach can be used alongside open surgical procedures (personalized external aortic root support) as well as a frozen “net” elephant trunk technique, for full aortic stabilization.

Neuroprotective Effects of Dexpanthenol on Rabbit Spinal Cord Ischemia/Reperfusion Injury Model

OBJECTIVE

Dexpanthenol (DXP) reportedly protects tissues against oxidative damage in various inflammation models. This study aimed to evaluate its effects on oxidative stress, inflammation, apoptosis, and neurological recovery in an experimental rabbit spinal cord ischemia/reperfusion injury (SCIRI) model.

METHODS

Rabbits were randomized into 5 groups of 8 animals each: group 1 (control), group 2 (ischemia), group 3 (vehicle), group 4 (methylprednisolone, 30 mg/kg), and group 5 (DXP, 500 mg/kg). The control group underwent laparotomy only, whereas other groups were subjected to spinal cord ischemia by aortic occlusion (just caudal to the 2 renal arteries) for 20 min. After 24 h, a modified Tarlov scale was employed to record neurological examination results. Malondialdehyde and caspase-3 levels and catalase and myeloperoxidase activities were analyzed in tissue and serum samples. Xanthine oxidase activity was measured in the serum. Histopathological and ultrastructural evaluations were also performed in the spinal cord.

RESULTS

After SCIRI, serum and tissue malondialdehyde and caspase-3 levels and myeloperoxidase and serum xanthine oxidase activities were increased (P < 0.05-0.001). However, serum and tissue catalase activity decreased significantly (P < 0.001). DXP treatment was associated with lower malondialdehyde and caspase-3 levels and reduced myeloperoxidase and xanthine oxidase activities but increased catalase activity (P < 0.05-0.001). Furthermore, DXP was associated with better histopathological, ultrastructural, and neurological outcome scores.

CONCLUSIONS

This study was the first to evaluate antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects of DXP on SCIRI. Further experimental and clinical investigations are warranted to confirm that DXP can be administered to treat SCIRI.

Prevention of Spinal Cord Injury during Thoracoabdominal Aortic Aneurysms Repair: What the Anaesthesiologist Should Know

Thoraco-abdominal aortic repair is a high-risk surgery for both mortality and morbidity. A major complication is paraplegia-paralysis due to spinal cord injury. Modern thoracic and abdominal aortic aneurysm repair techniques involve multiple strategies to reduce the risk of spinal cord ischemia during and after surgery. These include both surgical and anaesthesiologic approaches to optimize spinal cord perfusion by staging the procedure, guaranteeing perfusion of the distal aorta through various techniques (left atrium–left femoral artery by-pass) by pharmacological and monitoring interventions or by maximizing oxygen delivery and inducing spinal cord hypothermia. Lumbar CSF drainage alone or in combination with other techniques remains one of the most used and effective strategies. This narrative review overviews the current techniques to prevent or avoid spinal cord injury during thoracoabdominal aortic aneurysms repair.

Comprehensive review of hybrid aortic arch repair with focus on zone 0 TEVAR and our institutional experience

Even with increasing operator experience and a better understanding of the disease and the operation, intervention for aortic arch pathologies continues to struggle with relatively higher mortality, reintervention, and neurologic complications. The hybrid aortic arch repair was introduced to simplify the procedure and improve the outcome. With recent industry-driven advances, hybrid repairs are not only offered to poor surgical candidates but have become mainstream. This review discusses the evolution of hybrid repair, terminology pertinent to this technique, and results. In addition, we aim to provide a pervasive review of hybrid aortic arch repairs with reference to relevant literature for a detailed understanding. We have also discussed our institutional experience with hybrid repairs.

Priming protects the spinal cord in an experimental aortic occlusion model

OBJECTIVES

Paraplegia is a devastating complication in aortic aneurysm surgery. Modifying the spinal cord vasculature is a promising method in spinal cord protection. The aim of this study was to assess whether the spinal cord can be primed by occluding thoracic segmental arteries before simulated aneurysm repair in a porcine model.

METHODS

Twelve piglets were randomly assigned to the priming group (6) and the control group (6). Eight uppermost thoracic segmental arteries were occluded at 5-minute intervals in the priming group before a 25-minute aortic crossclamp. In the control group, the aorta was crossclamped for 25 minutes. During the first 5 minutes, 8 segmental arteries were occluded. After the aortic crossclamping, piglets were observed under anesthesia for 5 hours and followed up 5 days postoperatively. Near-infrared spectroscopy, motor-evoked potentials, blood samples, neurology with the modified Tarlov score, and histopathology of the spinal cord were assessed.

RESULTS

The median Tarlov score during the first postoperative day was higher in the priming group than in the control group (P = .001). At the end, 50% of the control animals had paraplegia compared with 0% of paraplegia in the priming group. The mean regional histopathologic score differed between the priming group and the control group (P = .02). The priming group had higher motor-evoked potentials during the operation at separate time points. The lactate levels were lower in the priming group compared with the control group (Pg = .001, Pg×t = .18).

CONCLUSIONS

Acute priming protects the spinal cord from ischemic injury in an experimental aortic crossclamp model.

Iliac branch device to treat type IB endoleak with a brachial access or an "up-and-over" transfemoral technique

PURPOSE

This study aimed to review the results of secondary IBD (iliac branch device) implantation in patients with type IB endoleak after prior fenestrated and/or branched or infrarenal endovascular aortic repair (F/B-EVAR or EVAR), using either brachial access or an "up-and-over" transfemoral technique.

METHODS

A retrospective single centre analysis was conducted between Jan 2016 and Oct 2021 including consecutive patients that underwent IBD to correct a type IB endoleak after prior EVAR or F/B-EVAR. Groups were defined by arterial access which was either brachial (group 1) or transfemoral (group 2). All IBD implanted were manufactured by Cook Medical (INC, Bloomington, IN, USA). Demographics, anatomical features, technical success, and 30-day major adverse events (MAE) were recorded according to the current SVS standards. Survival curves according to Kaplan-Meier were calculated. Branch instability was a composite endpoint of any IIA branch-related complication or reintervention indicated to treat endoleak, kink, disconnection, stenosis, occlusion or rupture.

RESULTS

Overall, 28 patients (93% male, median age 74 years) receiving 32 IBDs were included, with 14 patients in each group. Prior endovascular aortic repairs were 23 EVAR and 5 F/B-EVAR, with time from initial repair being 58 months [48, 70]. Median pre-IBD maximal aneurysm diameter was 63.5 mm [59.0, 78.0]. Patients' baseline characteristics were similar in both groups except for pulmonary status. All procedures were performed in a hybrid operative room. Median total operating time, fluoroscopy time and dose area product were 120 min [86, 167], 23 min [15, 32] and 54 Gy.cm2 [40, 62], respectively. Total operating time was shorter in group 2 (p=0.006). Technical success rate was 100% and no early death reported. One 30-day MAE occurred including a medically treated colonic ischemia (group 2). Aortic-related secondary interventions were required in 7 patients (5 in group 1 and 2 in group 2) including 3 surgical explantations. Median follow-up was 31 months [24, 42] and 6 months [3, 10] in group 1 and 2, respectively. In group 1, 2-year freedom from aortic-related secondary intervention and IIA branch instability were 84.6% [67.1-100] and 92.3% [78.9-100], respectively. In group 2, 6-month freedom from aortic-related secondary intervention and IIA branch instability were 87.5% [67.3-100] and 91.7% [77.3-100], respectively.

CONCLUSION

The secondary implantation of IBD to correct distal type I endoleak of previous aortic stent-graft is safe with a high technical success rate. The "up-and-over" technique could be considered as an alternative to the brachial access in patients with suitable anatomy.

Normothermic frozen elephant trunk: our experience and literature review

BACKGROUND AND OBJECTIVE

The frozen elephant trunk (FET) technique has undoubtable advantages in treating complex and extensive disease of the aortic arch and the thoracic descending aorta. Despite several improvements in cardiopulmonary bypass conduction and surgical strategy, operative times and the institution of systemic circulatory arrest remain the main determinants of early mortality, cerebral/spinal cord injury and visceral organs dysfunction. We have conducted this review to highlight the recent technical advances in arch and FET surgery aiming at the reduction/avoidance of systemic circulatory arrest, and their impact on early outcomes.

METHODS

A literature search (from origin to January 2022), limited to publications in English, was performed on online platforms and database (PubMed, Google, ResearchGate). After a further review of associated or similar papers, we found 4 experiences, described by 11 peer-reviewed published papers, which focused on minimising or avoiding systemic circulatory arrest during total arch replacement plus stenting of the descending thoracic aorta.

KEY CONTENT AND FINDINGS

Recent experiences reported the use of an antegrade endoaortic balloon, advanced and inflated into the stent graft, to provide an early systemic reperfusion soon after the deployment of the stented portion of the FET prosthesis and minimize the circulatory arrest time (down to a mean of 5 minutes), thus avoiding the need of moderate or deep hypothermia (mean systemic temperature 28-30 °C) while allowing a complete arch and FET repair. Our approach, based on off-pump retrograde vascular stent graft deployment in distal arch/descending thoracic aorta, and the use of a retrograde endoballoon, allows the repair of extensive aortic pathologies during uninterrupted normothermic cerebral and lower body perfusion.

CONCLUSIONS

The use of endoballoon occlusion has emerged in recent years as a safe and effective strategy to allow distal perfusion during FET repair. This technique minimizes or avoids the detrimental effects of hypothermia and systemic circulatory arrest and significantly reduces the operative times.

Simultaneous Endovascular Repair Is Not Associated With Increased Risk for Thoracic and Abdominal Aortic Pathologies: Early and Midterm Outcomes

Coexisting multilevel aortic pathologies were caused by atherosclerosis and hypertension and presented in a small subgroup of patients. Endovascular repair is a safe and effective treatment for a variety of aortic pathologies. However, fewer small series and cases were reported using simultaneous thoracic endovascular repair (TEVAR) and endovascular aneurysm repair (EVAR) for both aortic segments. To determine the outcomes of simultaneous and separately TEVAR and EVAR treating for multilevel aortic pathologies. Between 2010 and 2020, 31 patients and 22 patients were treated by one-staged and two-staged repair, respectively at a single center. All patients had the concomitant thoracic and abdominal aortic disease (aortic dissection, aneurysms, and penetrating aortic ulcers). Compared with the patients with two-staged aortic repair, the one-staged repair patients were older (mean age, 68 vs. 57 years; P < 0.001) and had a larger preoperative maximal aortic diameter (67.03 ± 10.65 vs. 57.45 ± 10.36 mm; p = 0.002). The intraoperative and postoperative outcomes show that the procedure times and length of hospital stay (LOS) were longer in the two-staged group. There is no significant difference in postoperative complications between the two groups. In the follow up, the freedom from re–intervention and the mean survival rate for the one-staged group were 100 vs. 100%, 92.4 vs. 95%, and 88 vs. 88% at one, two, and 5 years, respectively, whereas the mean survival rate for the two-staged group was 86.4 vs. 90.5%, 87 vs. 90.5%, and 76 vs. 84% at one, two, and 5 years, respectively, all with no statistical difference. Combined TEVAR and EVAR can be performed successfully with minimal morbidity and mortality. The one-staged repair was not associated with the increased risk for multilevel aortic pathologies treatment.

Staging Endovascular Thoracic and Thoracoabdominal Aortic Aneurysm Repairs and the Risk of Post-operative Spinal Cord Ischemia

OBJECTIVE

Staged aortic aneurysm repair is one method used to decrease the risk of spinal cord ischemia (SCI) following endovascular aortic intervention. Sequential sacrifice of arteries perfusing the spine may allow for improved spinal perfusion through the development of collateral networks over time. To evaluate the impact of staging endovascular aortic aneurysm repairs on SCI, we conducted a conservative analysis of Vascular Quality Initiative (VQI) data.

METHODS

De-identified VQI data were queried for cases of endovascular thoracic and thoracoabdominal aneurysm repairs from year 2014 to 2019. Cases were selected based on inclusion criteria: aneurysmal disease, no ruptures, no prior aortic surgeries, no retreatments, and only cases with complete data on aortic zones and SCI. Chi-square, Student's t-tests, and Mann-Whitney U tests were used for univariable analyses, as appropriate. Logistic regression analyses were used to identify independent predictors of outcome.

RESULTS

There were 116 staged aortic repairs (SARs) (8.2%) performed out of a total of 1421 endovascular aortic repairs that fit study criteria. The overall rate of SCI within the study cohort was 3.4% (n = 48). The distribution of SARs and SCI events according to aortic zone coverage are displayed in Table 1. Patients who underwent staged endovascular aortic repairs had higher rates of SCI, pre-op spinal drain placement, non-African-American race, COPD, smoking history, positive stress tests, aspirin and statin use, increased estimated blood loss, physician-modified endografts, number of aortic zones covered, lower pre-op hemoglobin levels, larger aneurysm sac size, fusiform aneurysms, and longer total procedure times, Table 2. After adjusting for factors associated with SCI, a priori, and factors with a P < 0.1 univariable analysis, SAR was not associated with SCI (odds ratio [OR] = 1.86, 95% confidence interval [CI] = 0.77-4.50, P = 0.17). Of the six factors associated with SCI on univariable analysis, only procedure time ≥6 hours (OR = 2.49, 95% CI = 1.09-5.70, P = 0.031) and the number of aortic zones covered (OR = 1.15, 95% CI = 1.00-1.32, P = 0.047) were predictive of SCI. Staged repairs had a lower proportion of permanent SCI (38%, 3 of 8 cases) compared with repairs that were not staged (68%, 27 of 40 cases), with a relative risk reduction of 44% for those who developed SCI, P = 0.21.

CONCLUSIONS

In a large national data set, SARs were performed for patients with more extensive aortic disease. SARs were only performed in about 8% of cases and the rate of SCI remained low. After adjusting for baseline comorbidities, extent of aortic disease, and other factors that may potentiate SCI, staged aortic aneurysm repair had a similar risk of SCI compared with non-staged repairs. However, there was a trend toward decreased permanent SCI risk in the SAR group.

Outcomes of Great Vessel Debranching to Facilitate Thoracic Endovascular Aortic Repair

OBJECTIVES

With the expanding application of endovascular technology, the need to deploy into zone 0 has been encountered on occasion. This study evaluates the outcomes of great vessel debranching (GVD) as a method of extending the proximal landing zone (PLZ) to facilitate thoracic endovascular aortic repair (TEVAR).

METHODS

A single-center retrospective review of all patients who underwent GVD followed by TEVAR between May 2013 and December 2020 was conducted. The primary outcome was primary patency of all targeted vessels, with all-cause perioperative mortality as a secondary outcome. Kaplan-Meier analysis was used to account for censoring the mortality and primary patency. The extent of hybrid aortic repairs was characterized into type I: GVD + TEVAR without ascending aorta or aortic arch reconstruction; type II: GVD + TEVAR with ascending aorta reconstruction; and type III: GVD + TEVAR with ascending aorta and aortic arch reconstruction with an elephant trunk (surgical or "frozen").

RESULTS

There were 42 patients (23 males [54.8%], mean age of 62.2 ± 11.2 years) who underwent GVD with 122 vessels revascularized (42 innominate, 42 left common carotid [LCCA], and 38 left subclavian [LSA] arteries). The indication for TEVAR was aneurysmal degeneration from aortic dissection in 32 (76.2%) patients, thoracic aneurysm in 9 (21.4%) patients, and perforated aortic ulcer in 1 (2.4%) patient. Median duration between GVD and TEVAR was 82 days. Mean follow-up was 25.7 ± 23.5 months. Type I repair was performed in 4, type II in 16, and type III in 22 patients. Perioperative mortality, stroke, and paraplegia rates were 9.5%, 7.1%, and 2.4%, respectively. Neither the extent of repair (p = 0.80) nor a prior history of aortic repair (p = 0.90) was associated with early mortality. Late deaths (>30 days) occurred in 6 of 38 patients who survived the perioperative period. At 36 months, the survival estimate was 68.6% (95% CI: 45.7% - 83.4%); the overall primary patency of the innominate artery, LCCA, and LSA was 100%, 89.5%, and 94.1%, respectively. The primary assisted patency rate was 100% for all vessels.

CONCLUSIONS

GVD is a safe and effective means of extending the PLZ into zone 0 with outstanding primary patency rates. Further studies are needed to confirm the safety and longer-term durability in these patients.

Neuromonitoring during descending aorta procedures

Thoraco-abdominal aneurysm (TAA) repair carries a significant risk of spinal cord infarction. The latter results from irreversible changes in the spinal cord arterial network, e.g., sacrifice of the segmental arteries. Intra-operative neurophysiology with somatosensory and especially motor evoked potential (SEP and MEP respectively) monitoring, has emerged as an effective tool to assess the efficiency of the collateral blood flow, detect reversible spinal cord ischemia and guide the peri-operative multidisciplinary management to prevent postoperative paraplegia. The main roles of such monitoring include diagnosis of spinal cord vs peripheral limb ischemia, titration of mean arterial pressure during aortic clamping, the guidance of selective re-implantation of critical segmental arteries, and management of hemodynamics in the immediate postoperative period. In addition, manipulation of the aortic arch and proximal descending aorta, adds the risk of cerebral infarction from both low flow state and/or thromboembolic events. As such, EEG monitoring may be a useful add-on for either assessment of the efficiency of cerebral cooling as a neuroprotective method and/or for detection and treatment of reversible cerebral ischemia. This chapter presents the multimodality approach to open TAA monitoring as a versatile tool for the prevention of devastating postoperative neurologic deficits.

Risk factors for spinal cord ischemia in frozen elephant trunk–induced upper spinal cord ischemia in patients with combination of degenerative arch aneurysms and peripheral artery diseases: a possible mechanism

Background

Degenerative aortic arch aneurysms are known to develop through a pathological process of arterial atherosclerosis, which could be accompanied by peripheral artery diseases and resultant development of intrapelvic collateral arteries to the ischemic lower limbs. The aim of this study was to investigate the relationship between peripheral collateral circulation and postoperative paraplegia after total arch repair with a frozen elephant trunk in patients with degenerative aortic arch aneurysms and peripheral artery diseases.

Methods

Between October 2014 and March 2020, 27 patients (20 men; 69.8 ± 7.7 years old) underwent total arch repair with a frozen elephant trunk. Two of the 27 patients developed paraplegia postoperatively. The patients were divided into two groups, spinal cord ischemia (SCI) group (2 patients) and no-SCI group (25 patients). The aortic shagginess score, arterial calcification (subclavian artery; hypogastric artery) score, and the number of hypogastric artery branches, assessed using preoperative contrast-enhanced computed tomography images, were compared between the two groups.

Results

The ankle brachial artery pressure index (i.e., lower side value each patient) was lower in the SCI group than that in the no-SCI group (0.64, 0.71, and 1.09±0.07, respectively). There was no difference between the two groups in the arterial calcification scores or the aortic shagginess score. The number of hypogastric artery branches was greater in the SCI group than in the no-SCI group (66, 66, and 30.7±7.5, respectively).

Conclusions

Enhanced collateral circulation to the ischemic lower limbs in patients with combination of degenerative aortic arch aneurysms and peripheral artery diseases may be involved in paraplegia the upper thoracic spinal cord injury after total arch repair with a frozen elephant trunk.

Morphology of the left subclavian artery: implications for single-branched endovascular aortic arch repair

OBJECTIVES

Our goal was to evaluate the morphology of the aortic arch, focusing on the left subclavian artery (LSA), and to anticipate implications for single-branched endovascular aortic arch repair.

METHODS

We performed a morphological analysis of computed tomography angiography scans of 322 patients between January 2002 and December 2018. Arch type and distance between arch vessels on the convexity were evaluated. We defined 3 morphological types: U-type distance between the left common carotid artery (LCCA) and LSA offspring >10 mm; V-type distance between the LCCA and LSA offspring <10 mm and W-type isolated left vertebral artery offspring from the aortic arch.

RESULTS

Most patients presented a type III arch [50% (n = 161)]. The median distance from the brachiocephalic trunk offspring to the LCCA offspring measured 2.5 mm (2.0-3.0 mm) and that between the LCCA offspring and the LSA offspring was 6.5 mm (4.0-11.0 mm). We observed no significant difference based on the morphological type (V versus U versus W) in the brachiocephalic trunk-LCCA distance, but there were significant differences in the LCCA-LSA distance between types V and U (P < 0.001) and between types V and W (P < 0.001). Interestingly, we found no significant difference in the LCCA-LSA distance between types U and W. We noted a significant difference in the median diameter of the LSA according to U, V and W types: V type versus U type, 12.5 vs 13.5 mm (P = 0.033) as well as U type versus W type, 13.5 vs 10.5 mm (P < 0.001) and V type versus W type, 12.5 vs 10.5 mm (P < 0.002). The distances between the LSA offspring and left vertebral artery offspring between types U and V did not differ significantly.

CONCLUSIONS

Our categorization of the U, V and W types of the LSA can help us anticipate shapes and distances and thereby function as an initial evaluation tool for predicting single branched endovascular aortic arch repair involving the LSA.

Multi-staged endovascular repair of thoracoabdominal aneurysms by fenestrated and branched endografts

AIM

To report outcomes of a multi-staged approach for endovascular repair of thoracoabdominal aortic aneurysms (TAAAs) by fenestrated/branched endografting (F/B-EVAR).

METHODS

Between 2010 and 2020 (June), patients undergoing F/B-EVAR for TAAAs were collected. Data of cases managed by a multi-staged approach, to reduce the incidence of spinal cord ischemia (SCI), were retrospectively analyzed and reported in a cohort study. Thirty-day mortality and SCI were assessed as study's outcomes.

RESULTS

One hundred and thirty-seven patients underwent TAAAs repair by F/B-EVAR. A multi-staged approach was applied in 73(53%) cases, more frequently for Crawford's extent I-III (60/78) compared with IV (13/59) (P: <.0001). A complete TAAAs exclusion was achieved in 2, 3 or 4 steps in 64(88%), 8(11%) and 1(1%) cases, respectively, within the same hospitalization in 68(93%) cases. The mean time between first and last step was 16±8days, with a mean hospital stay of 21±12days. In 3(4%) cases the complete TAAA repair was not achieved due to inter-steps mortality (2) or permanent paraplegia (1). There were no cases of aortic rupture or target visceral vessels occlusions between the different steps. Seven (10%) patients suffered postoperative SCI with 2(4%) cases of permanent paraplegia. In 5/7 cases SCI occurred after the first stage; in 3/5 cases TAAAs exclusion was successfully completed with total SCI recovery. The 30-day mortality was 4% (3/73).

CONCLUSION

A multi-staged endovascular repair with F/B-EVAR can be safely performed for TAAAs repair. The majority of cases can be treated within a single, long hospitalization. The cost/effectiveness of the prolonged in-hospital time should be evaluated.

Prior Infrarenal Aortic Surgery is Not Associated with Increased Risk of Spinal Cord Ischemia Following Thoracic Endovascular Aortic Repair and Complex Endovascular Aortic Repair

OBJECTIVES

Patients with prior infrarenal aortic intervention represent an increasing demographic of patients undergoing thoracic endovascular aortic repair (TEVAR) and/or complex EVAR. Studies have suggested that prior abdominal aortic surgery is a risk factor for spinal cord ischemia (SCI). However, these results are largely based on single-center experiences with limited multi-institutional and national data assessing clinical outcomes in these patients. The objective of this study was to evaluate the effect of prior infrarenal aortic surgery on SCI.

METHODS

The Society for Vascular Surgery Vascular Quality Initiative database was retrospectively reviewed to identify all patients ≥18 years old undergoing TEVAR/complex EVAR from January 2012 to June 2020. Patients with previous thoracic or suprarenal aortic repairs were excluded. Baseline and procedural characteristics and postoperative outcomes were compared by group: TEVAR/complex EVAR with or without previous infrarenal aortic repair. The primary outcome was postoperative SCI. Secondary outcomes included postoperative hospital length of stay (LOS), bowel ischemia, renal ischemia, and 30-day mortality. Multivariate regression was used to determine independent predictors of postoperative SCI. Additional analysis was performed for patients undergoing isolated TEVAR.

RESULTS

A total of 9506 patients met the inclusion criteria: 8691 (91.4%) had no history of infrarenal aortic repair and 815 (8.6%) had previous infrarenal aortic repair. Patients with previous infrarenal repair were older with an increased prevalence of chronic kidney disease (p=0.001) and cardiovascular risk factors including hypertension, chronic obstructive pulmonary disease, and smoking history (p<0.001). These patients presented with larger maximal aortic diameters (6.06±1.47 cm versus 5.15±1.76 cm; p<0.001) and required more stent grafts (p<0.001) with increased intraoperative blood transfusion requirements (p<0.001), and longer procedure times (p<0.001). Univariate analysis demonstrated no difference in postoperative SCI, postoperative hospital LOS, bowel ischemia, or renal ischemia between the two groups. Thirty-day mortality was significantly higher in patients with prior infrarenal repair (p=0.001). On multivariate regression, prior infrarenal aortic repair was not a predictor of postoperative SCI, while aortic dissection (odds ratio [OR] 1.65; 95% confidence interval [CI] 1.26-2.16, p<0.001), number of stent grafts deployed (OR 1.45; 95% CI 1.30-1.62, p<0.001), and units of packed red blood cells transfused intraoperatively (OR 1.33; 95% CI 1.03-1.73, p=0.032) were independent predictors of SCI.

CONCLUSIONS

Although TEVAR/complex EVAR patients with prior infrarenal aortic repair constituted a sicker cohort with higher 30-day mortality, the rate of SCI was comparable to patients without prior repair. Previous infrarenal repair was not associated with risk of SCI.

A Systematic Review of Spinal Cord Ischemia Prevention and Management After Open and Endovascular Aortic Repair

OBJECTIVE

Spinal cord ischemia (SCI) is one of the most devastating complications after descending thoracic aortic (DTA) and thoracoabdominal aortic (TAA) repairs. Patients who develop SCI have a poor prognosis with mortality rates reaching 75% within the first year after surgery. Many factors have been shown to increase the risk of this complication, including extent of TAA repair, length of aortic and collateral network coverage, embolization, and reduced spinal cord perfusion pressure. As a result, a variety of treatment strategies have evolved. We aimed to provide an up-to-date review of SCI rates with associated treatment algorithms from open and endovascular DTA and TAA repairs.

METHODS

Using PRISMA guidelines, a literature review with the Medical Subject Headings (MeSH) terms "spinal cord ischemia; spinal cord ischemia prevention and mitigation strategies; spinal cord ischemia rates; spinal cord infarction" was performed in the Cochrane and PubMed databases to seek all peer-reviewed studies of DTA and TAA repairs with SCI complications, limited to 2012-2021 and the English language. MeSH subheadings including diagnosis, complications, physiopathology, surgery, mortality, and therapy were used to further restrict the articles. Studies were excluded if they were not in humans, not pertaining to SCI in DTA/TAA operative repairs, and if the study primarily discussed neuromonitoring techniques. Additionally, studies with <40 patients or limited information regarding SCI protection strategies were excluded. Each study was individually reviewed by two researchers to assess for type and extent of aortic pathology, operative technique, SCI protection or mitigation strategies, rates of overall and permanent SCI symptoms, associations with SCI on multivariate analysis, and mortality.

RESULTS

Of 450 studies returned by the MeSH search strategy, 41 met inclusion criteria and were included in the final analysis. For endovascular DTA repair patients, overall SCI rates ranged from 0-10.6% with permanent SCI symptoms ranging from 0-5.1%. Endovascular and open TAA repairs had rates of overall SCI of 0-35%. Permanent SCI symptom rate was reported by only one open study at 1.1% while endovascular TAA repairs had between 2-20.5%.

CONCLUSION

This review provides an up-to-date review of current rates of SCI as well as prevention and mitigation strategies for DTA and TAA repairs. We find that a multimodal approach, including a bundled institutional protocol, staging of multiple repairs, preservation of collateral blood flow network, augmented spinal cord perfusion, selective cerebrospinal fluid drainage, and distal aortic perfusion in open TAA repairs, appears to be important in reducing the risk of SCI.

Anisotropic scaffolds for peripheral nerve and spinal cord regeneration

The treatment of long-gap (>10 mm) peripheral nerve injury (PNI) and spinal cord injury (SCI) remains a continuous challenge due to limited native tissue regeneration capabilities. The current clinical strategy of using autografts for PNI suffers from a source shortage, while the pharmacological treatment for SCI presents dissatisfactory results. Tissue engineering, as an alternative, is a promising approach for regenerating peripheral nerves and spinal cords. Through providing a beneficial environment, a scaffold is the primary element in tissue engineering. In particular, scaffolds with anisotropic structures resembling the native extracellular matrix (ECM) can effectively guide neural outgrowth and reconnection. In this review, the anatomy of peripheral nerves and spinal cords, as well as current clinical treatments for PNI and SCI, is first summarized. An overview of the critical components in peripheral nerve and spinal cord tissue engineering and the current status of regeneration approaches are also discussed. Recent advances in the fabrication of anisotropic surface patterns, aligned fibrous substrates, and 3D hydrogel scaffolds, as well as their in vitro and in vivo effects are highlighted. Finally, we summarize potential mechanisms underlying the anisotropic architectures in orienting axonal and glial cell growth, along with their challenges and prospects.

Feasibility and Preliminary Patency of Prophylactic Hypogastric Artery Stenting for Prevention of Spinal Cord Ischemia in Complex Endovascular Aortic Repair

BACKGROUND

To report early results of feasibility and patency of prophylactic hypogastric artery (HA) stenting during complex endovascular aortic repair.

METHODS

This is a single centre retrospective non comparative cohort study of all consecutive patients undergoing prophylactic HA stenting during fenestrated and/or branched EVAR (F/B EVAR) in order to prevent spinal cord ischemia (SCI). Endpoints included technical success and early outcomes in terms of morbidity, mortality and patency of the implanted stents.

RESULTS

Between May 2014 and June 2019 prophylactic HA stenting was performed in 36 consecutive patients with significant HA stenosis during F/B EVAR to prevent SCI. 69.4% of patients presented with asymptomatic, 25% with symptomatic and 5.6% with ruptured aortic aneurysms. 55.6% were treated for thoracoabdominal aortic aneurysms, 44.4% for pararenal abdominal aortic aneurysms. In 13.9% aortic coverage was limited to the abdominal aorta. In 86.1% the aortic coverage was in the thoracoabdominal aortic segment. Unilateral HA stenting was performed in 91.7%, whereas 8.3% underwent bilateral stenting. Technical success was 100%. The primary patency of the implanted stents after a median follow-up time of 9.5 months was 97.5%. One intraprocedural bleeding from an HA branch occurred and was successfully treated by coil embolization. No further procedure-related complications occurred. 11.1% of the patients developed SCI.

CONCLUSIONS

HA stenting is feasible and safe with high rates of technical success and short-term patency.