Experimental Two-Stage Simulated Repair of Extensive Thoracoabdominal Aneurysms Reduces Paraplegia Risk

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.

Outcomes of Complex Endovascular Treatment of Post-Dissection Aneurysms

OBJECTIVE

Reports of endovascular treatment of chronic post-dissection aneurysms are limited to high volumes centres, posing questions about generalisability.

METHODS

All endovascular repairs of intact pararenal and thoraco-abdominal aneurysms in the Vascular Quality Initiative from 2014 to 2021 were studied, and peri-operative and long term outcomes were compared between repairs of degenerative and post-dissection aneurysms. Peri-operative outcomes were compared using mixed effects logistic regression, and long term outcomes using Medicare linkage.

RESULTS

There were 123 patients who completed treatment for post-dissection aneurysms and 3 635 for degenerative aneurysms, with 36% of post-dissection repairs and 6.7% of degenerative repairs performed in a staged fashion (p < .001). The majority (84%) of post-dissection aneurysms were extensive thoraco-abdominal aneurysms (TAAAs: Crawford Type 1, 2, 3, 5), compared with 22% of degenerative aneurysms (p < .001). Physician modified endografts were the primary repair type for post-dissection (73%), while commercially available fenestrated grafts were the dominant repair for degenerative (48%). The first stage of staged procedures was associated with a 2.8% peri-operative mortality rate, 5.1% spinal cord ischaemia, and 8.9% thoraco-abdominal life altering events (the composite of peri-operative death, stroke, permanent spinal cord ischaemia, and dialysis). Th final stage procedure and fluoroscopy times were similar, but technical success was lower in post-dissection repairs (75% vs. 83%, p = .018), both due to issues with the main endograft or bridging vessels (11% vs. 6.6%, p = .055), and types 1and 3 endoleak at completion (17% vs. 10%, p = .035). In addition, high volume surgeons had two fold higher odds of technical success than their low volume counterparts. Adjusted peri-operative outcomes were similar between pathology types, including when comparisons were restricted to extensive TAAAs. Crude and adjusted three year survival were similar, but three year re-interventions were significantly higher following post-dissection repairs (p < .001).

CONCLUSION

Complex endovascular repair of chronic post-dissection aneurysms is feasible but is associated with high rates of re-interventions and non-trivial rates of lack of technical success. More data are needed to evaluate the long term durability of these procedures, and the utility of centralising these complex procedures.

Comparison of single- and multistage strategies during fenestrated-branched endovascular aortic repair of thoracoabdominal aortic aneurysms

OBJECTIVE

The aim of this study was to compare outcomes of single or multistage approach during fenestrated-branched endovascular aortic repair (FB-EVAR) of extensive thoracoabdominal aortic aneurysms (TAAAs).

METHODS

We reviewed the clinical data of consecutive patients treated by FB-EVAR for extent I to III TAAAs in 24 centers (2006-2021). All patients received a single brand manufactured patient-specific or off-the-shelf fenestrated-branched stent grafts. Staging strategies included proximal thoracic aortic repair, minimally invasive segmental artery coil embolization, temporary aneurysm sac perfusion and combinations of these techniques. Endpoints were analyzed for elective repair in patients who had a single- or multistage approach before and after propensity score adjustment for baseline differences, including the composite 30-day/in-hospital mortality and/or permanent paraplegia, major adverse event, patient survival, and freedom from aortic-related mortality.

RESULTS

A total of 1947 patients (65% male; mean age, 71 ± 8 years) underwent FB-EVAR of 155 extent I (10%), 729 extent II (46%), and 713 extent III TAAAs (44%). A single-stage approach was used in 939 patients (48%) and a multistage approach in 1008 patients (52%). A multistage approach was more frequently used in patients undergoing elective compared with non-elective repair (55% vs 35%; P < .001). Staging strategies were proximal thoracic aortic repair in 743 patients (74%), temporary aneurysm sac perfusion in 128 (13%), minimally invasive segmental artery coil embolization in 10 (1%), and combinations in 127 (12%). Among patients undergoing elective repair (n = 1597), the composite endpoint of 30-day/in-hospital mortality and/or permanent paraplegia rate occurred in 14% of single-stage and 6% of multistage approach patients (P < .001). After adjustment with a propensity score, multistage approach was associated with lower rates of 30-day/in-hospital mortality and/or permanent paraplegia (odds ratio, 0.466; 95% confidence interval, 0.271-0.801; P = .006) and higher patient survival at 1 year (86.9±1.3% vs 79.6±1.7%) and 3 years (72.7±2.1% vs 64.2±2.3%; adjusted hazard ratio, 0.714; 95% confidence interval, 0.528-0.966; P = .029), compared with a single stage approach.

CONCLUSION

Staging elective FB-EVAR of extent I to III TAAAs was associated with decreased risk of mortality and/or permanent paraplegia at 30 days or within hospital stay, and with higher patient survival at 1 and 3 years.

"There is nothing better than participating in this study": Living the PAPAartis cardiovascular randomised controlled trial

Qualitative research can bring new dimensions of understanding decision-making process in clinical trials. Participating in a randomized clinical trial requires patients to accept complex information and make decisions in a context of uncertainty. It becomes especially complicated in the case of serious diseases in which the treatment itself implies unknown risks. This study examines these issues in the context of the PAPAartis randomized clinical trial, which aims to prevent spinal cord injuries that can occur as an adverse event following complex surgical repair of thoracoabdominal aneurysm. In this study, we accessed a group of 16 patients participating in the trial and, through in-depth interviews, sought to understand the decision-making process when taking part in the trial and their experience of it. Our results showed that patients participated for different reasons: due to trust in doctors, the hope of having a better treatment or for altruistic and collaborative reasons with science. Many patients felt they did not fully understand the extraneous information provided about the study and the complex nature of the procedure. Avoidance of paraplegia played a fundamental role in the decision to participate in this trial. Family support and the socioeconomic conditions of the patients influenced the recovery process after surgery.

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.

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.

Spinal cord protection in thoracoabdominal aortic aneurysm surgery: a multimodal approach

Spinal cord injury (SCI) is one major complication of open and endovascular thoracic and thoracoabdominal aortic aneurysm repair. Despite numerous neuroprotective adjuncts, the incidence of SCI remains high. This review article discusses established and novel adjuncts for spinal cord protection, including priming and preconditioning of the paraspinal collateral network, intraoperative systemic hypothermia, distal aortic perfusion, motor- and somatosensory evoked potentials and noninvasive cnNIRS monitoring as well as peri- and postoperative drainage of cerebrospinal fluid. Regardless of the positive influence of many of these strategies on neurologic outcome, to date no strategy assures definitive preservation of spinal cord integrity during and after aortic aneurysm repair.

Staged hybrid repair of type II thoracoabdominal aneurysms

BACKGROUND

Open repair of type II thoracoabdominal aortic aneurysms (TAAAs) remains a challenging procedure. Staged procedures could decrease the incidence and severity of complications after complex aortic repair. In the present report, we have described a strategy using thoracic endovascular aortic repair (TEVAR) for proximal repair, followed by distal open repair.

METHODS

From 2014 to 2018, 14 patients had undergone TEVAR, followed by distal open repair, for type II TAAAs. All patients should have a suitable proximal landing zone according to the current guidelines. In cases of chronic dissection, false lumen embolization was performed to achieve total exclusion.

RESULTS

The mean patient age was 48 ± 15 years. Of the 14 patients, 5 had had Marfan syndrome (36%) and 6 had undergone previous aortic arch repair (43%). Ten patients had had a chronic dissection. The maximal aortic diameter was 73 ± 12 mm. The TEVAR technical success rate was 100%. The aortic length coverage was 211 ± 63 mm. The number of covered segmental arteries was 6 (range, 4-13). Two endoleaks were observed, one type Ib and one type II. The delay between TEVAR and open repair was 12 ± 8 weeks. Cerebrospinal fluid drainage was used in 13 patients. Six patients had undergone segmental artery reattachment during surgery. No spinal cord ischemic event was observed. One patient had died 5 weeks after open repair of multiple organ failure. During the 32 months of follow-up, no aortic-related deaths had occurred. No new aortic procedure was needed. The type Ib endoleak had resolved during open repair, and the type II TAAA had resolved spontaneously. The mean maximal thoracic aortic diameter had significantly decreased to 49 ± 8 mm (P < .0001). Aneurysmal shrinkage of ≥5 mm was observed in 13 patients (93%).

CONCLUSIONS

Staged hybrid repair of type II TAAAs appears to be efficient, with low morbidity and mortality rates. This technique could improve postoperative outcomes after open repair, and TEVAR might have a role in ischemic preconditioning to protect against spinal cord ischemia.

A Modified Proximal Stent-Graft for Spinal Cord Preconditioning During Staged Endovascular Repair of Thoracoabdominal Aortic Aneurysms

Purpose: To describe a new custom-made thoracic device able to seal against the aortic wall and occlude intercostal arteries for spinal cord preconditioning during the first thoracic stage of a thoracoabdominal endovascular repair. Technique: The custom-made device, based on the Zenith Alpha stent-graft, combines different features from 2 previously described devices: the outer part is designed with a bell-bottom configuration similar to the “Embo” stent-graft, while the inner part mimics the “2 in 1” design. The outer stent-graft is designed to span the entire length of the thoracic aorta and cover as many intercostal arteries as possible during the first stage to effectively precondition the spinal cord. The sutured inner component is customizable in diameter and 20 to 40 mm shorter than the outer stent-graft. The technique has been used in 5 patients. Conclusion: The use of this new custom-made thoracic stent-graft might represent an additional tool for effectively preconditioning the spinal cord during fenestrated and branched staged procedures whenever a proximal thoracic proximal component is needed.

Lentiviral Vector Induced Modeling of High-Grade Spinal Cord Glioma in Minipigs

BACKGROUND

Prior studies have applied driver mutations targeting the RTK/RAS/PI3K and p53 pathways to induce the formation of high-grade gliomas in rodent models. In the present study, we report the production of a high-grade spinal cord glioma model in pigs using lentiviral gene transfer.

METHODS

Six Gottingen Minipigs received thoracolumbar (T14-L1) lateral white matter injections of a combination of lentiviral vectors, expressing platelet-derived growth factor beta (PDGF-B), constitutive HRAS, and shRNA-p53 respectively. All animals received injection of control vectors into the contralateral cord. Animals underwent baseline and endpoint magnetic resonance imaging (MRI) and were evaluated daily for clinical deficits. Hematoxylin and eosin (H&E) and immunohistochemical analysis was conducted. Data are presented using descriptive statistics including relative frequencies, mean, standard deviation, and range.

RESULTS

100% of animals (n = 6/6) developed clinical motor deficits ipsilateral to the oncogenic lentiviral injections by a three-week endpoint. MRI scans at endpoint demonstrated contrast enhancing mass lesions at the site of oncogenic lentiviral injection and not at the site of control injections. Immunohistochemistry demonstrated positive staining for GFAP, Olig2, and a high Ki-67 proliferative index. Histopathologic features demonstrate consistent and reproducible growth of a high-grade glioma in all animals.

CONCLUSIONS

Lentiviral gene transfer represents a feasible pathway to glioma modeling in higher order species. The present model is the first lentiviral vector induced pig model of high-grade spinal cord glioma and may potentially be used in preclinical therapeutic development programs.

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.

New Technique for Preconditioning of the Spinal Cord Before Endovascular Repair of Descending Thoracic and Thoracoabdominal Aortic Aneurysms

Purpose: To propose a new simplified technique to occlude multiple segmental arteries for staging and preconditioning of the spinal cord to decrease the potential for spinal cord ischemia after thoracic and thoracoabdominal aortic aneurysm repair. Technique: A thoracic stent-graft that flares out to a maximum of 51 mm is deployed in a standard fashion covering all segmental arteries where graft-wall apposition occurs in the first ~20 cm of the aneurysm. The segmental arteries are always closed at their ostia in contrast to selective coil embolization, where there is a risk of more peripheral closure. Follow-up imaging shows thrombus lining the stent-graft-covered portion of the aneurysm and secondary proximal segmental artery occlusion. Conclusion: A new and fast way of staging and preconditioning the spinal cord using a modified stent-graft prior to definitive repair might be an alternative to segmental artery embolization.

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.

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.

Multibranched Stent-Grafts for the Treatment of Thoracoabdominal Aortic Aneurysms

Purpose: To evaluate the available literature on endovascular repair of thoracoabdominal (TAAA) and pararenal aortic aneurysms (PRAA) using multibranched stent-grafts. Methods: MEDLINE, EMBASE, and Cochrane databases were searched between January 2001 and June 2015 to identify articles related to the use of multibranched stent-grafts for the treatment of TAAA and PRAA. Articles with <4 cases and those on juxtarenal aortic aneurysms were excluded. Meta-analyses were conducted to evaluate 30-day mortality, all-cause mortality, spinal cord ischemia, renal insufficiency, endoleak, target vessel patency, and reintervention. Of 370 articles screened, only 4 articles encompassing 185 patients (mean age 71.1 years; 137 men) were aligned with the inclusion criteria. There were 23 PRAAs; the mean aneurysm diameter was 64.5 mm. The Crawford TAAA classification was 10 type I, 47 type II, 37 type III, 58 type IV, and 9 type V; there was 1 Stanford type B dissection in association with a large TAAA. Results of the meta-analyses are reported as proportions and 95% confidence interval (CI). Results: Pooled analysis indicated a technical success rate of 98.9%. As study heterogeneity was significant, random effects models were used for meta-analysis. The rate for 30-day mortality was 9% (95% CI 3% to 19%), for all-cause mortality 27% (95% CI 17% to 38%), endoleaks 10% (95% CI 1% to 25%), target vessel patency 98% (95% CI 95% to 99%), SCI 17% (95% CI 1% to 26%), irreversible SCI 6% (95% CI 3% to 10%), renal insufficiency 15% (95% CI 0.8% to 41%), and reinterventions 21% (95% CI 4% to 47%). Conclusion: Use of multibranched stent-grafts in the treatment of TAAAs and PRAAs appears to be feasible and safe based on satisfactory early outcomes in the limited literature available to date. Long-term surveillance and further studies are essential to determine the durability of this technique.

Neuroprotective Strategies Can Prevent Permanent Paraplegia in the Majority of Patients Who Develop Spinal Cord Ischaemia After Endovascular Repair of Thoracoabdominal Aortic Aneurysms

OBJECTIVES

Spinal cord ischaemia (SCI) following endovascular thoracoabdominal aortic aneurysm (TAAA) repair is a devastating and unpredictable complication. This study describes a single unit's experience of SCI in patients who have had endovascular TAAA repair.

METHODS

A prospectively maintained database of patients having endovascular TAAA repair using branched and fenestrated stent grafts between 2008 and 2014 at a single high volume centre was reviewed. Patients who developed neurological symptoms and signs related to SCI were identified and factors associated with onset and recovery of neurology were analysed.

RESULTS

Sixty-nine patients (median age 73 years, 52 male; Crawford classification type I [n = 4], type II [n = 11], type III [n = 33], type IV [n = 14], type V [n = 7]) underwent endovascular TAAA repair. Twelve patients developed neurological symptoms/signs related to SCI but this was successfully reversed in eight patients, leaving four (5.8%) with permanent paraplegia. The median length of aorta covered was not significantly different in the 12 patients who developed SCI compared with the cohort that did not. Eleven of the patients who developed SCI had an intraoperative mean arterial pressure (MAP) below 80 mmHg. Cutaneous atheroemboli were noted in half of the patients in the SCI group compared with 11% of the non-SCI group (p < .05). Strategies used to reverse SCI included raising MAP, cerebrospinal fluid drainage, angioplasty of stenosed internal iliac arteries, and restoring perfusion to the aneurysm sac.

CONCLUSIONS

This series highlights some of the risk factors associated with the development of SCI after endovascular repair of TAAAs. It also illustrates the importance of a dedicated institutional protocol aimed at ensuring the early diagnosis of SCI and prompt intervention to reverse permanent paraplegia in the majority of cases.

Minimally Invasive Segmental Artery Coil Embolization for Preconditioning of the Spinal Cord Collateral Network before One-Stage Descending and Thoracoabdominal Aneurysm Repair

Objective

Paraplegia remains the most devastating complication after thoracic and thoracoabdominal aortic aneurysm (TAA/A) repair. The collateral network (CN) concept of spinal cord perfusion suggests segmental artery (SA) occlusion to mobilize redundant intraspinal and paraspinal arterial sources and ultimately trigger arteriogenesis, leading to spinal cord blood flow restoration within 96 to 120 hours. This principle is used by the two-staged approach to TAA/A-repair—which has lead to an elimination of paraplegia in an experimental model. However, the clinical implementation of a two-staged surgical procedure is challenging, particularly in the absence of an appropriate vascular segment for a “staged” open anastomosis or an appropriate endovascular landing zone. Selective, transfemoral minimally invasive SA coil embolization (MISACE) could provide the solution for one-stage repair of extensive aortic pathologies by triggering arteriogenic CN preconditioning and thereby allowing for recruitment of otherwise redundant arterial collaterals to the spinal cord.

Methods

The feasibility of MISACE was explored in a single animal using an established piglet model. A 6F sheet was introduced via the femoral artery, and a 4F standard Judkins catheter was used for selective angiography and coil insertion. All thoracic and lumbar aortic SAs (15 pairs; Th4–L5) were successfully identified by dye injection. Pediatric platinum endovascular coils (Trufill Pushable Coils, 3 × 20 mm; Cordis, Waterloo, Belgium) were deployed to serially occlude the SA mimicking a CN preconditioning procedure.

Results

All intercostal (thoracic) and lumbar aortic SAs (Th4–L5) were successfully identified and occluded by coil embolization. Successful SA coil embolization was verified intraoperatively by selective dye injection on angiography. No intraoperative coil dislodgement occurred. Autopsy revealed complete occlusion of all embolized SAs enhanced by early local thrombus formation. Thrombotic material was found only distally to the coils. No SA dissection was observed at the aortic SA origins.

Conclusions

The MIS ACE technique allows for rapid serial endovascular occlusion of all thoracic and lumbar SAs. This new innovative approach bares the potential to CN preconditioning at the respective level of aortic pathology—to allow for adequate perioperative spinal cord blood supply—before conventional open or endovascular surgery. Selective, transarterial MISACE might lead to a dramatic reduction of ischemic spinal cord injury after open and endovascular TAA/A repair in the future.

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

OBJECTIVES

To test a strategy for minimizing ischemic spinal cord injury after extensive thoracoabdominal aneurysm (TAAA) repair, we occluded a small number of segmental arteries (SAs) endovascularly 1 week before simulated aneurysm repair in an experimental model.

METHODS

Thirty juvenile Yorkshire pigs (25.2 ± 1.7 kg) were randomized into 3 groups. All SAs, both intercostal and lumbar, were killed by a combination of surgical ligation of the lumbar SAs and occlusion of intercostal SAs with thoracic endovascular stent grafting. Seven to 10 days before this simulated TAAA replacement, SAs in the lower thoracic/upper lumbar region were occluded using embolization coils: 1.5 ± 0.5 SAs in group 1 (T13/L1), and 4.5 ± 0.5 SAs in group 2 (T11-L3). No SAs were coiled in the controls. Hind limb function was evaluated blindly from daily videotapes using a modified Tarlov score (0 = paraplegia, 9 = full recovery). After death, each segment of spinal cord was graded histologically using the 9-point Kleinman score (0 = normal, 8 = complete necrosis).

RESULTS

Hind limb function remained normal after coil embolization. After simulated TAAA repair, paraplegia occurred in 6 of 10 control pigs, but in only 2 of 10 pigs in group 1; no pigs in group 2 had a spinal cord injury. Tarlov scores were significantly better in group 2 (control vs group 1, P = .06; control vs group 2, P = .0002; group 1 vs group 2, P = .05). A dramatic reduction in histologic damage, most prominently in the coiled region, was seen when SAs were embolized before simulated TAAA repair.

CONCLUSIONS

Endovascular coiling of 2 to 4 SAs prevented paraplegia in an experimental model of extensive hybrid TAAA repair, and helped protect the spinal cord from ischemic histopathologic injury. A clinical trial in a selected patient population at high risk for postoperative spinal cord injury may be appropriate.

A novel porcine model of traumatic thoracic spinal cord injury

Spinal cord injury (SCI) researchers have predominately utilized rodents and mice for in vivo SCI modeling and experimentation. From these small animal models have come many insights into the biology of SCI, and a growing number of novel treatments that promote behavioral recovery. It has, however, been difficult to demonstrate the efficacy of such treatments in human clinical trials. A large animal SCI model that is an intermediary between rodent and human SCI may be a valuable translational research resource for pre-clinically evaluating novel therapies, prior to embarking upon lengthy and expensive clinical trials. Here, we describe the development of such a large animal model. A thoracic spinal cord injury at T10/11 was induced in Yucatan miniature pigs (20-25 kg) using a weight drop device. Varying degrees of injury severity were induced by altering the height of the weight drop (5, 10, 20, 30, 40, and 50 cm). Behavioral recovery over 12 weeks was measured using a newly developed Porcine Thoracic Injury Behavior Scale (PTIBS). This scale distinguished locomotor recovery among animals of different injury severities, with strong intra-observer and inter-observer reliability. Histological analysis of the spinal cords 12 weeks post-injury revealed that animals with the more biomechanically severe injuries had less spared white matter and gray matter and less neurofilament immunoreactivity. Additionally, the PTIBS scores correlated strongly with the extent of tissue sparing through the epicenter of injury. This large animal model of SCI may represent a useful intermediary in the testing of novel pharmacological treatments and cell transplantation strategies.

Imaging of vascular remodeling after simulated thoracoabdominal aneurysm repair

OBJECTIVE

A better understanding of the response of the spinal cord blood supply to segmental artery (SA) sacrifice should help minimize the risk of paraplegia after both open and endovascular repair of thoracoabdominal aortic (TAA) aneurysms.

METHODS

Twelve female juvenile Yorkshire pigs were randomized into 3 groups and perfused with a barium-latex solution. Pigs in group 1 (control) had infusion without previous intervention. Pigs in group 2 were infused 48 hours after ligation of all SAs (T4-L5) and those in group 3 at 120 hours after ligation. Postmortem computed tomographic scanning of the entire pig enabled overall comparisons and measurement of vessel diameters in the spinal cord circulation.

RESULTS

We ligated 14.5 ± 0.8 SAs: all filled retrograde to the ligature. Paraplegia occurred in 38% of operated pigs. A significant increase in the mean diameter of the anterior spinal artery (ASA) was evident after SA sacrifice (P < .0001 for 48 hours and 120 hours). The internal thoracic and intercostal arteries also increased in diameter. Quantitative assessment showed an increase in vessel density 48 hours after ligation of SAs, reflected by an obvious increase in small collateral vessels seen on 3-dimensional reconstructions of computed tomographic scans at 120 hours.

CONCLUSIONS

Remodeling of the spinal cord blood supply--including dilatation of the ASA and proliferation of small collateral vessels--is evident at 48 and 120 hours after extensive SA sacrifice. It is likely that exploitation of this process will prove valuable in the quest to eliminate paraplegia after TAA aneurysm repair.

Staged hybrid approach using proximal thoracic endovascular aneurysm repair and distal open repair for the treatment of extensive thoracoabdominal aortic aneurysms

OBJECTIVE

Repair of patients with extent I and II thoracoabdominal aortic aneurysms (TAAAs) is associated with significant morbidity and mortality, whereas repair of more distal extent III and IV TAAAs has a lower risk of paraplegia and death. Therefore, we describe an approach using thoracic endovascular aneurysm repair (TEVAR) as the index operation to convert extent I and II TAAAs to extent III and IV TAAAs amenable to subsequent open aortic repair to minimize patient risk.

METHODS

Between July 2007 and March 2012, 10 staged hybrid operations were performed to treat one extent I and nine extent II TAAAs. Aortic aneurysm pathology included five chronic type B dissections, three acute type B dissections, and two penetrating aortic ulcers. Initially, the proximal descending thoracic aorta was repaired with TEVAR for coverage of the most proximal fenestration or penetrating ulcer, with seven elective and three emergent repairs. Interval open distal aortic replacement was performed in a short-term planned setting or for progressive dilation of the distal aortic segment. In the open repair, the proximal end of the graft was sewn directly to the distal end of the TEVAR and outer wall of the aorta.

RESULTS

Average patient age was 48 years, and 60% were men. Risk factors included hypertension (80%), current tobacco use (50%), and Marfan syndrome (30%). Complications after TEVAR included type IA (n=1) and type II (n=3) endoleaks, pleural effusions (n=3), and acute kidney injury (n=1). Three patients required endovascular reinterventions. In patients with dissection, persistent filling of the false lumen was common and associated with distal thoracic aortic dilation. Complications of open repair included acute kidney injury in two patients, but no cardiac, pulmonary, or neurologic morbidity. Median time between TEVAR and open repair was 14 weeks. Most importantly, no deaths or neurologic deficits occurred after either procedure during a median follow-up of 35 weeks.

CONCLUSIONS

A staged hybrid approach to extensive TAAAs combining proximal TEVAR, followed by interval open distal TAAA repair, is safe and appears to be an effective alternative to traditional open repair. This approach may decrease the significant morbidity associated with single-stage open extent I and II TAAA repairs and may be applicable to multiple TAAA etiologies.

Open, hybrid, and endovascular treatment for aortic coarctation and postrepair aneurysm in adolescents and adults

BACKGROUND

Open, hybrid, and endovascular procedures are used for grown-up patients with aortic coarctation and complications after repair, an expanding population. We sought to characterize patients and procedures, assess early and late outcomes, and describe indications to guide treatment of these complex patients.

METHODS

Between May 1999 and January 2011, 110 patients underwent open (n=40), hybrid (n=11), or endovascular (n=59) repair of coarctation (n=43), recurrent aortic coarctation (n=42), or postrepair aneurysm (n=25). Mean age was 38±14 years. Sixty-eight had previous repairs (median 27 years earlier; range, 1 to 50). Twenty-two had prior cardiovascular operations other than coarctation and 50% had bicuspid valve. Fifty-nine concomitant procedures were performed in 45 patients (40%). Data were from the prospective database, chart review, and Social Security Death Index.

RESULTS

Technical success was achieved in 100%, with no hospital deaths, no strokes, and no paraplegia. Complications were uncommon and included respiratory failure (n=2, 1.8%), and temporary renal failure (n=2, 1.8%). Twenty-two patients required reinterventions, but half of those were planned. There was no difference in occurrence of unplanned reintervention between approaches (endovascular 12%, hybrid 18%, open 12.5%). Length of stay was 4.8±4.8 days. Transcoarct gradient fell from 37.6±18 mm Hg preoperatively to 7.0±6.9 mm Hg in coarctation patients. Postrepair aneurysm patients had no late ruptures, and maximum diameter shrunk from 5.9±1.3 cm preoperatively to 4.8±1.3 cm. Estimated survival at 1, 5, and 8 years was 95%, 95%, and 90%, respectively.

CONCLUSIONS

Coarctation, recurrent coarctation, and postrepair aneurysm/pseudoaneurysm in adolescent and adult patients can be safely and effectively managed with open, hybrid, or endovascular techniques. Optimal results are achievable in this complex population of patients with a multimodality approach tailored to surgical indication and anatomy. All survivors of coarctation repair require lifelong surveillance.