Endovascular coil embolization of segmental arteries prevents paraplegia after subsequent thoracoabdominal aneurysm repair: an experimental model

A direct aorta to segmental artery bypass for prevention of spinal cord ischemia after endovascular aortic repair

Spinal cord ischemia remains a persistent challenge after endovascular aortic aneurysm repair. We present a novel direct aorta to segmental artery bypass before aneurysm repair in a 64-year-old woman presenting with an enlarging aneurysm following dissection. Through an eighth intercostal incision, a polyester graft was sewn into the aorta using pledgeted sutures. An entry needle was used to directly access the previously treated aortic segment, and the opening was stented and angioplasty was performed to create inflow. Anastomoses were performed to a prominent left T10 segmental artery with a harvested saphenous vein. The patient remained neurologically intact postoperatively and the 1-month follow-up angiography demonstrated bypass patency.

Endovascular occlusion of segmental arteries feeding the anterior spinal artery to stage endovascular thoracoabdominal aortic repair

Objective

Minimally invasive segmental artery coil embolization was introduced to prevent spinal cord ischemia after endovascular repair of thoracoabdominal aortic aneurysms. There is no consensus on whether the endovascular occlusion of segmental arteries feeding directly the anterior radiculomedullary artery and anterior spinal artery can be safely performed without causing spinal cord ischemia. Our aim was to investigate the feasibility and clinical impact of endovascular occlusion of segmental arteries supplying the anterior spinal artery during minimally invasive segmental artery coil embolization in patients with thoracoabdominal aortic aneurysms.

Methods

Between January 2018 and July 2020, 54 patients (36 male; mean age, 71.1 ± 9.3 years) underwent direct embolization of segmental arteries feeding the anterior radiculomedullary artery before endovascular repair of thoracoabdominal aortic aneurysms. End points included technical success of minimally invasive segmental artery coil embolization of segmental arteries, anterior radiculomedullary artery, neurological complications, and in-hospital mortality after minimally invasive segmental artery coil embolization and endovascular repair of thoracoabdominal aortic aneurysms.

Results

The thoracoabdominal aortic aneurysm classification was type I (n = 8), type II (n = 24), type III (n = 11), and type IV (n = 11). During minimally invasive segmental artery coil embolization, 388 segmental arteries were occluded, each patient having 7.2 ± 3.1 coiled segmental arteries occluding 64.5% (25-100%) of open segmental arteries within the treated aortic segment. Altogether, 66 anterior radiculomedullary arteries were seen originating between Th8 and L3 levels from 85 (21.9%) segmental arteries. In 10 patients (18.5%), 2 large anterior radiculomedullary arteries were identified, and 1 patient (1.9%) showed 3 anterior radiculomedullary arteries on the spinal arteriography. No spinal cord ischemia or procedure-related complications occurred after minimally invasive segmental artery coil embolization. After 47.9 ± 39.4 days, all patients received endovascular repair of their thoracoabdominal aortic aneurysms. There was no in-hospital mortality. One male patient developed incomplete temporary spinal cord ischemia after endovascular repair.

Conclusions

Minimally invasive segmental artery coil embolization of segmental arteries feeding the anterior spinal artery in patients with thoracoabdominal aortic aneurysms to prevent spinal cord ischemia after endovascular repair is feasible and clinically safe.

Thoracoabdominal Aortic Aneurysm Repair Using Fenestrated and Branched Endovascular Grafts for High-Risk Patients: Evolving yet Safe

PURPOSE

The purpose was to investigate outcomes of high-risk patients undergoing thoracoabdominal aortic aneurysm (TAAA) repair using fenestrated or branched endovascular aneurysm repair (F/BEVAR) devices at a single center in Canada.

MATERIALS AND METHODS

A retrospective review of all patients undergoing endovascular TAAA repair with F/BEVAR from June 2007 to July 2020. Imaging and clinical endpoints of interest including death, reintervention, and target vessel patency were reported.

RESULTS

Ninety-five consecutive patients underwent endovascular TAAA repair using F/BEVAR stent grafts (63 males, median age 74 [interquartile range 70, 78] years). Repairs included 81 elective and 14 urgent/emergent cases (6 ruptures and 8 symptomatic). Graft deployment was 100% successful. Intraoperative target vessel revascularization was successful in 336/355 (94.6%) vessels with the celiac having the lowest success rate 72/82 (87.8%). In-hospital mortality was 9.5% (7.4% elective and 21.4% urgent/emergent, p=0.125) and permanent paraplegia was 4.2% (3.7% elective and 7.1% urgent/emergent, p=0.458). In-hospital complications included stroke in 5.3%, acute myocardial infarction in 8.4%, and bowel ischemia in 5.3%. No patients required permanent dialysis or tracheostomy during their hospital stay. However, 22 (23.2%) patients required additional unplanned procedures for various indications (branch occlusion, endoleaks, realignment) during their hospital stay. Patients were followed up for a mean of 3.6 ± 3.0 years. Clinical follow-up was 100%, with 80/86 (93%) having surveillance imaging. On follow-up imaging, 43 (50%) patients had at least 1 endoleak identified and 337/341 (98.8%) of the target vessels were found to be patent. At 5 years, cumulative probability of reintervention was 46.3% (95% confidence interval [CI], 36.1-56.4). Survival at 5 and 8 years was 50.1% (95% CI, 38.4-65.4) and 34.4% (95% CI, 22.5-52.8), respectively. Progression of aneurysmal disease leading to rupture on follow-up was confirmed in 1 patient at 10 years.

CONCLUSION

Endovascular TAAA repair provides a safe treatment option with a high technical success rate and low pulmonary and renal complications. Long-term survival is similar to previous literature; however, high rates of secondary reintervention reaffirm the need for ongoing patient follow-up and further technical improvements.

CLINICAL IMPACT

This study demonstrates that endovascular repair of TAAAs can be performed in a high-risk elderly population with acceptable rates of mortality, TALE and SCI, using evolving technology. The incidences of post-operative respiratory failure and renal dysfunction were lower in patients who underwent endovascular repair compared with open repair. Future technical and procedural refinements in addition to increasing surgical experience are expected to lead to further improvements in short- and long-term outcomes exceeding those of open repair.

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.

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.

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.

The Associative Pattern Between Segmental Arterial Damage and Complete Neurological Disorder After Spinal Cord Injury: A Case-Control Study

INTRODUCTION

The prevalence of vascular trauma surrounding the thoracic spine following Spinal Cord Injury (SCI) is unknown. The potential for neurologic recovery is uncertain in many cases; in some cases, neurologic assessment is not possible, for example, in severe head injury or early intubation, and detection of segmental artery injury may help as a predictive factor.

OBJECTIVE

To assess the prevalence of segmental vessel disruption in two groups, with and without neurologic deficit.

MATERIAL AND METHODS

This is a retrospective cohort study, with a group SCI American Spinal Injury Association (ASIA) E and a group SCI ASIA A. All patients had a high-energy thoracic or thoracolumbar fracture from T1 to L1. Patients were matched 1:1 (one ASIA A matched with one ASIA E) according to the fracture type, age, and level. The primary variable was the assessment of the presence/disruption of the segmental arteries, bilaterally, around the fracture. Analysis was performed twice by two independent surgeons in a blinded fashion.

RESULTS

Both groups had 2 type A, 8 type B, and 4 type C fractures. The right segmental artery was detected in 14/14 (100%) of the patients with ASIA E and in 3/14 (21%) or 2/14 (14%) of the patients with ASIA A, according to the observers, p=0.001. The left segmental artery was detectable in 13/14 (93%) or 14/14 (100%) of the patients ASIA E and in 3/14 (21%) of the patients ASIA A for both observers. All in all, 13/14 of the patients with ASIA A had at least one segmental artery undetectable. The sensibility varied between 78%to 92%, and the specificity from 82% to 100%. The Kappa Score varied between 0.55 and 0.78.

CONCLUSION

Segmental arteries disruption was common in the group ASIA A. This may help to predict the neurological status of patients with no complete neurological assessment or potential for recovery post-injury.

Angio Cone-Beam CT (Angio-CBCT) and 3D Road-Mapping for the Detection of Spinal Cord Vascularization in Patients Requiring Treatment for a Thoracic Aortic Lesion: A Feasibility Study

BACKGROUND

Spinal cord ischemia is a major complication of treatment for descending thoracic aorta (DTA) disease. Our objectives were (1) to describe the value of angiographic cone-beam CT (angio-CBCT) and 3D road-mapping to visualize the Adamkiewicz artery (AA) and its feeding artery and (2) to evaluate the impact of AA localization on the patient surgical strategy.

METHODS

Between 2018 and 2020, all patients referred to our institution for a surgical DTA disorder underwent a dedicated AA evaluation by angio-CBCT. If the AA feeding artery was not depicted on angio-CBCT, selective artery catheterization was performed, guided by 3D road-mapping. Intervention modifications, based on AA location and one month of neurologic follow-up after surgery, were recorded.

RESULTS

Twenty-one patients were enrolled. AA was assessable in 100% of patients and in 15 (71%) with angio-CBCT alone. Among them, 10 patients needed 3D road-mapping-guided DSA angiography to visualize the AA feeding artery. The amount of contrast media, irradiation dose, and intervention length were not significantly different whether the AA was assessable or not by angio-CBCT. AA feeding artery localization led to surgical sketch modification for 11 patients.

CONCLUSIONS

Angio-CBCT is an efficient method for AA localization in the surgical planning of DTA disorders.

Ultra-Hybrid Repair: Open Thoracoabdominal Completion After Descending Stent Grafting

To characterize patient risk profiles and outcomes associated with staged ultra-hybrid repair of extensive aortic disease, in which open thoracoabdominal completion was performed after thoracic stent grafting. From 1/2006 to 1/2021, 92 patients underwent open thoracoabdominal repair of chronic dissection (n=58, 63%), degenerative aneurysm (n=28, 30%), endoleak (n=4, 4.3%), or symptomatic acute type B dissection (n=2, 2.2%) after descending thoracic stent grafting (69, 75%), frozen elephant trunk (5, 5%), or both (18, 20%). The surgical graft was sewn to the distal endovascular device in situ, reducing the extent of the open procedure and eliminating the need for hypothermic circulatory arrest. Mean age was 58±13 years, 89 (97%) were hypertensive, 38 (43%) had chronic obstructive pulmonary disease, 63 (72%) were smokers, 20 (24%) had a prior stroke, and 33 (36%) had a suspected or confirmed heritable aortic condition. Hospital mortality was 7.6% (n=7). Complications included dialysis (16, 20%), tracheostomy (8, 8.7%), stroke (5, 5.7%), and permanent paralysis (6, 6.9%). Survival at 1, 3, and 5 years was 80%, 71%, and 66%, respectively. Mortality was associated with higher blood urea nitrogen and longer distance between the distal endograft edge and proximal patent visceral vessel (P=0.004 and .01, respectively). Patients with extensive aortic disease undergoing open aortic repair after thoracic stent grafting are often young with chronic dissection, multiple comorbidities, or a heritable aortic condition. Success of staged ultra-hybrid operations demonstrates open and endovascular repair strategies are complementary, even when performed in a high-risk patient population.

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.

Minimally Invasive Segmental Artery Coil Embolization (MISACE) Prior to Endovascular Thoracoabdominal Aortic Aneurysm Repair

PURPOSE

Minimally Invasive Segmental Artery Coil Embolization (MISACE) is a novel approach to reduce paraplegia risk in Thoracoabdominal aortic aneurysm (TAAA) repair with limited data. We report our experience with MISACE as a method of spinal cord pre-conditioning to prevent spinal cord ischemia following endovascular repair of TAAA.

MATERIAL AND METHODS

A retrospective analysis of 17 patients who had an attempted MISACE prior to endovascular TAAA repair with mean follow-up of 350 days (2017-2020). Baseline patient and aneurysm characteristics along with procedural technique and outcomes were analyzed.

RESULTS

Mean age of 69 years and 76.5% were males. TAAA Crawford classification were II, n = 6 (35.3%), III, n = 4 (23.5%) and IV, n = 5 (29.4%). The mean aortic diameter was 70.6 ± 10.9 mm. Staged repair was performed on 9 patients. Technically successful embolization occurred in 14 patients (82.4%) and was unsuccessful in 3 patients. The median number of embolized arteries was 3 and 71% of the target arteries were between T9 and T12. Mean fluoroscopy time was 51.5 ± 22.5 min and mean contrast volume used was 132.8 ± 56.1 mL. Average number of catheters used was 4.6 and 3.5 wires. No complications related to the procedure. Mean interval between embolization to endovascular TAAA repair was 51.2 days (5-110 days). All patients received spinal drainage at the time of repair. Postoperatively, 2/14 of patients developed paraparesis in the MISACE successful group and 1/3 patients developed paraplegia in the unsuccessful group.

CONCLUSIONS

MISACE is a promising strategy to prevent SCI. This data demonstrates the technique is feasible and safe but anatomic challenges remain.

Systematic review and meta-analysis of association of prophylactic cerebrospinal fluid drainage in preventing spinal cord ischemia after thoracic endovascular aortic repair

OBJECTIVE

We conducted a systemic review and meta-analysis to compare the association between prophylactic cerebrospinal fluid drainage (CSFD) vs non-CSFD in preventing spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR) for aneurysm and dissection.

METHODS

The MEDLINE, Embase, and Cochrane databases were systematically searched to identify all relevant studies reported before April 1, 2020. A systematic review and meta-analysis were performed. We assessed the association between CSFD strategies, including routine CSFD vs selective CSFD or no CSFD, and the SCI rates after TEVAR for patients with aortic dissection (AD), solitary thoracic aortic aneurysm (TAA), or thoracoabdominal aortic aneurysm (TAAA). Subgroup analyses were conducted to assess the association between different aortic pathologies, including AD and thoracic aneurysms, and SCI rates after TEVAR with and without prophylactic CSFD. The data are presented as the pooled event rates (ERs) and 95% confidence intervals (CIs).

RESULTS

A total of 34 studies of 3561 patients (2671 with TAA or TAAA and 890 with type B AD) were included in the present analysis. The data are presented as the pooled ERs and 95% CIs. The overall SCI rate for patients who had undergone TEVAR with prophylactic CSFD for AD (ER, 1.80%; 95% CI, 0.88%-2.72%) was significantly lower than that for the aortic aneurysm group (ER, 5.73%; 95% CI, 4.20%-7.27%; P < .0001). The SCI rate after TEVAR with prophylactic CSFD was not significantly different from that without CSFD for AD (P = .51). No association was found between the rates of SCI after TEVAR with routine prophylactic CSFD vs selective prophylactic CSFD for aortic aneurysms (P = .76) and AD (P = .70). The SCI rate after TEVAR without CSFD for aortic aneurysms, including isolated TAA and TAAA (ER, 3.49%; 95% CI, 0.23%-6.76%) was not significantly different from that for AD (ER, 3.20%; 95% CI, 0.00%-7.20%; P = .91). For the patients with TAAAs, the rate of SCI after TEVAR with routine prophylactic CSFD was significantly lower than that with selective prophylactic CSFD (P = .04).

CONCLUSIONS

Our systematic review and meta-analysis has shown that SCI occurs more often after TEVAR for aortic aneurysms than for AD. Routine prophylactic CSFD, compared with selective CSFD, was associated with a lower rate of postoperative SCI after TEVAR for TAAAs. No significant association was found between the SCI rate and routine prophylactic CSFD for patients undergoing TEVAR for isolated TAA or AD.

Adverse Outcomes after Advanced EVAR in Patients with Sarcopaenia

PURPOSE

To determine whether low total psoas muscle area (tPMA), as a surrogate for sarcopaenia, is a predictor of adverse outcomes in patients undergoing advanced EVAR.

MATERIALS AND METHODS

A retrospective review of medical records was performed for 257 patients who underwent advanced EVAR (fenestrated or branched technique) in a single tertiary centre from 1 January 2008 to 1 September 2019. The study cohort was divided into tertiles based on tPMA measurement performed independently by two observers from a peri-procedural CT scan at the level of mid-L3 vertebral body. The low tertile was considered sarcopaenic. Logistic regression analysis was used to assess the association of tPMA with 30-day mortality and post-procedural complications. Univariable analysis and adjusted multivariable Cox regression were used to assess the association of tPMA with all-cause mortality.

RESULTS

A total of 257 patients comprised 193 males and 64 females with the mean age of 75.4 years (± 6.8) were included. Adjusted multivariable Cox regression revealed an 8% reduction in all-cause mortality for every 1 cm² increase in tPMA, P < 0.05. TPMA was associated with 30-day mortality (OR 0.85, 95% CI 0.75-0.96, P < 0.05) and spinal cord ischaemia (SCI) (OR 0.89, 95% CI 0.82-0.97, P < 0.05). For remaining post-procedural complications, tPMA was not a useful predictive tool. TPMA correlated negatively with hospital stay length (r_s-0.26, P < 0.001). Patients with lower tPMA were more likely to be discharged to a rehabilitation center (OR 0.93, 95% CI 0.87-0.98 , P < 0.05).

CONCLUSION

Measurement of tPMA can be a useful predictive tool for adverse outcomes after advanced EVAR.

LEVEL OF EVIDENCE

Level 3, Retrospective cohort study.

Intercostal artery embolization to induce false lumen thrombosis in type B aortic dissection

Persistent false lumen flow is common after thoracic endovascular aortic repair of type B aortic dissection and may contribute to continued aortic aneurysmal degeneration. We report an innovative technique of intercostal artery embolization within the false lumen for a patient who had incomplete false lumen thrombosis and progressive aortic enlargement after thoracic endovascular aortic repair of chronic type B aortic dissection. Technical success was facilitated by use of on-table cone beam computed tomography angiography, virtual vessel marking, and modern endovascular tools. The patient had no complications from the procedure. Postoperative imaging demonstrated complete thoracic false lumen thrombosis and favorable aortic remodeling with reduction in maximal aortic diameter.

Arteriogenesis of the Spinal Cord-The Network Challenge

Spinal cord ischemia (SCI) is a clinical complication following aortic repair that significantly impairs the quality and expectancy of life. Despite some strategies, like cerebrospinal fluid drainage, the occurrence of neurological symptoms, such as paraplegia and paraparesis, remains unpredictable. Beside the major blood supply through conduit arteries, a huge collateral network protects the central nervous system from ischemia—the paraspinous and the intraspinal compartment. The intraspinal arcades maintain perfusion pressure following a sudden inflow interruption, whereas the paraspinal system first needs to undergo arteriogenesis to ensure sufficient blood supply after an acute ischemic insult. The so-called steal phenomenon can even worsen the postoperative situation by causing the hypoperfusion of the spine when, shortly after thoracoabdominal aortic aneurysm (TAAA) surgery, muscles connected with the network divert blood and cause additional stress. Vessels are a conglomeration of different cell types involved in adapting to stress, like endothelial cells, smooth muscle cells, and pericytes. This adaption to stress is subdivided in three phases—initiation, growth, and the maturation phase. In fields of endovascular aortic aneurysm repair, pre-operative selective segmental artery occlusion may enable the development of a sufficient collateral network by stimulating collateral vessel growth, which, again, may prevent spinal cord ischemia. Among others, the major signaling pathways include the phosphoinositide 3 kinase (PI3K) pathway/the antiapoptotic kinase (AKT) pathway/the endothelial nitric oxide synthase (eNOS) pathway, the Erk1, the delta-like ligand (DII), the jagged (Jag)/NOTCH pathway, and the midkine regulatory cytokine signaling pathways.

Paraplegia prevention in aortic aneurysm repair by thoracoabdominal staging with 'minimally invasive staged segmental artery coil embolisation' (MIS²ACE): trial protocol for a randomised controlled multicentre trial

INTRODUCTION

Spinal cord injury (SCI) including permanent paraplegia constitutes a common complication after repair of thoracoabdominal aortic aneurysms. The staged-repair concept promises to provide protection by inducing arteriogenesis so that the collateral network can provide a robust blood supply to the spinal cord after intervention. Minimally invasive staged segmental artery coil embolisation (MIS²ACE) has been proved recently to be a feasible enhanced approach to staged repair.

METHODS AND ANALYSIS

This randomised controlled trial uses a multicentre, multinational, parallel group design, where 500 patients will be randomised in a 1:1 ratio to standard aneurysm repair or to MIS²ACE in 1-3 sessions followed by repair. Before randomisation, physicians document whether open or endovascular repair is planned. The primary endpoint is successful aneurysm repair without substantial SCI 30 days after aneurysm repair. Secondary endpoints include any form of SCI, mortality (up to 1 year), length of stay in the intensive care unit, costs and quality-adjusted life years. A generalised linear mixed model will be used with the logit link function and randomisation arm, mode of repair (open or endovascular repair), the Crawford type and the European System for Cardiac Operative Risk Evaluation (euroSCORE) II as fixed effects and the centre as a random effect. Safety endpoints include kidney failure, respiratory failure and embolic events (also from debris). A qualitative study will explore patient perceptions.

ETHICS AND DISSEMINATION

This trial has been approved by the lead Ethics Committee from the University of Leipzig (435/17-ek) and will be reviewed by each of the Ethics Committees at the trial sites. A dedicated project is coordinating communication and dissemination of the trial.

TRIAL REGISTRATION NUMBER

NCT03434314.

Staged procedures for prevention of spinal cord ischemia in endovascular aortic surgery

Background

Spinal cord ischemia with development of paraplegia is the most relevant complication of thoracoabdominal aortic surgery caused by compromising the segmental arteries. To prevent this devastating complication in endovascular aortic surgery, staging procedures have been developed to reinforce collateral blood flood to the spinal cord.

Results

In patients with a medium to high risk for spinal cord ischemia, staged aortic repair is recommended. The classical staged repair is the two-step repair with delayed implantation of the aortic stent grafts. Additionally, more recent methods for short-term salvage of segmental artery perfusion by leaving an endoleak have been developed. Perfusion branches, delayed bridging stents as well as the open branch technique are among these methods. The latest option of staged repair is minimally invasive segmental artery embolization.

Conclusion

Besides the nonsurgical options for monitoring and therapy of spinal cord ischemia, various staging procedures are available, which can be implemented depending on the patient and the aortic anatomy. Evidence that underlines staged repair for endovascular treatment of thoracoabdominal aortic pathologies is mostly based on retrospective studies.

Onyx Migration Into the Anterior Spinal Artery During Lumbar Artery Embolisation: an Adverse Event

Introduction

The impact of sequential lumbar and intercostal artery occlusion on the risk of spinal cord ischaemia was evaluated; however, an adverse event (paraplegia) was encountered, which resulted in study interruption. Investigations were carried out to understand the reasons for the paraplegia.

Report

To develop a porcine model of spinal cord ischaemic preconditioning prior to extensive thoraco-abdominal aneurysm endovascular aortic repair, the lumbar arteries were selectively embolised with Onyx 5 days prior to an extended thoracic aortic stent graft. Six pigs were used in this preliminary work. Four cases of paraplegia secondary to accidental migration of Onyx to the anterior spinal artery from the lumbar arteries are reported. Histological analysis confirmed severe spinal ischaemic injury and the presence of Onyx particles in the anterior spinal artery.

Discussion

Onyx is used for lumbar artery embolisation in type II endoleak treatment after endovascular aortic repair, and while migration in lumbar arteries is frequent, the risk of spinal cord ischaemia has never been described. The current study demonstrates the risk of paraplegia following Onyx migration to the anterior spinal artery from the lumbar artery in an experimental model. Thus, Onyx treatment for type II endoleaks from lumbar arteries should be used cautiously.

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Accidental Onyx migration to anterior spinal artery from lumbar artery is described.

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Onyx migration in the anterior spinal artery leads to paraplegia.

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The risk of spinal cord ischaemia after onyx migration has never been described.

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Onyx is used for lumbar artery embolisation in type II endoleak treatment.

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Onyx treatment for type II endoleaks from lumbar arteries should be used cautiously.

Changes in Pressure, Hemodynamics, and Metabolism within the Spinal Cord during the First 7 Days after Injury Using a Porcine Model

Traumatic spinal cord injury (SCI) triggers many perturbations within the injured cord, such as decreased perfusion, reduced tissue oxygenation, increased hydrostatic pressure, and disrupted bioenergetics. While much attention is directed to neuroprotective interventions that might alleviate these early pathophysiologic responses to traumatic injury, the temporo-spatial characteristics of these responses within the injured cord are not well documented. In this study, we utilized our Yucatan mini-pig model of traumatic SCI to characterize intraparenchymal hemodynamic and metabolic changes within the spinal cord for 1 week post-injury. Animals were subjected to a contusion/compression SCI at T10. Prior to injury, probes for microdialysis and the measurement of spinal cord blood flow (SCBF), oxygenation (in partial pressure of oxygen; PaPO₂), and hydrostatic pressure were inserted into the spinal cord 0.2 and 2.2 cm from the injury site. Measurements occurred under anesthesia for 4 h post-injury, after which the animals were recovered and measurements continued for 7 days. Close to the lesion (0.2 cm), SCBF levels decreased immediately after SCI, followed by an increase in the subsequent days. Similarly, PaPO₂ plummeted, where levels remained diminished for up to 7 days post-injury. Lactate/pyruvate (L/P) ratio increased within minutes. Further away from the injury site (2.2 cm), L/P ratio also gradually increased. Hydrostatic pressure remained consistently elevated for days and negatively correlated with changes in SCBF. An imbalance between SCBF and tissue metabolism also was observed, resulting in metabolic stress and insufficient oxygen levels. Taken together, traumatic SCI resulted in an expanding area of ischemia/hypoxia, with ongoing physiological perturbations sustained out to 7 days post-injury. This suggests that our clinical practice of hemodynamically supporting patients out to 7 days post-injury may fail to address persistent ischemia within the injured cord. A detailed understanding of these pathophysiological mechanisms after SCI is essential to promote best practices for acute SCI patients.

Perioperative cerebrospinal fluid drainage for the prevention of spinal ischemia after endovascular aortic repair

Endovascular treatment of thoracic and thoracoabdominal aortic diseases is accompanied by a risk of spinal ischemia in 1-19% of patients, depending on the entity and extent of the disease. The use of perioperative drainage of cerebrospinal fluid is one of the invasive measures to reduce the occurrence of this severe complication. This article reviews the incidence of spinal ischemia, its risk factors, the evidence for carrying out cerebrospinal fluid drainage and its modern use by means of an automated, pressure controlled system (LiquoGuard®7).

Strategies to prevent TEVAR-related spinal cord ischemia

Spinal cord ischemia remains the Achilles’ heel of thoracic and thoracoabdominal diseases management. Great improvements in morbidity and mortality have been obtained with the endovascular approach TEVAR (Thoracic Endovascular Aortic Repair) but this devastating complication continues to severely affect the quality of life, even if the primary success of the procedure – dissection/aneurysm exclusion – has been achieved.

Several strategies to deal with this complication have been published in the literature over the time. Knowledge and technology have been evolving from identification of the risk factors associated with spinal cord ischemia, including lessons learned from open surgery, and from developments in the collateral network concept for spinal cord perfusion.

In this comprehensive review, the authors cover several topics from the traditional measures comprising haemodynamic control, cerebrospinal drainage and neuroprotective drugs, to the staged-procedures approach, the emerging MISACE (minimally invasive selective segmental artery coil-embolization) and innovative neurologic monitoring such as NIRS (near-infrared spectroscopy) of the collateral network.

The neuroprotective mechanism of puerarin in the treatment of acute spinal ischemia-reperfusion injury is linked to cyclin-dependent kinase 5

Puerarin is shown to exert a variety of pharmacological effects including neuroprotective properties. However, mechanisms of the action are not fully understood. This study was designed to explore the mechanism of puerarin in treatment of acute spinal ischemia-reperfusion injury in rats. Acute spinal ischemia-reperfusion injury was conducted by aortic occlusion in twenty-eight male Sprague-Dawley rats, weighting 230-250 g. The animals were randomly divided into four groups. In the animals with puerarin treatment, 50 mg/kg of puerarin was injected intraperitoneally after reperfusion, and followed by the same dose of injection every 24h for 2 days. In the animals with roscovitine pre-treatment, 30 mg/kg roscovitine was intravenously administrated 60 min before spinal ischemia started. After spinal ischemia for 60 min followed by 48 h of reperfusion, the motor function, spinal infarction volume, apoptosis indices and the activities of Cdk5 and p25 were examined. Acute spinal ischemia-reperfusion resulted in an injury of the spines associated with motor deficit, elevation of Cdk5 and p25 activities, and increase in the spinal apoptosis number and spinal infarction volume. Puerarin improved motor function associated with the decreased apoptosis number, spinal infarction volume, and Cdk5 and p25 activities. The present study indicated that reduction of spinal injury was associated with inhibition of Cdk5 and p25, and that inhibition of Cdk5 and p25 was one of the neuroprotective mechanisms in the puerarin treatment of acute ischemia/reperfusion-induced spinal injury in rats.