Spinal cord protection in surgical and endovascular repair of thoracoabdominal aortic disease

How We Would Treat Our Own Thoracoabdominal Aortic Aneurysm

This manuscript is intended to provide a comprehensive review of the current state of knowledge on endovascular repair of thoracoabdominal aortic aneurysms (TAAAs). The management of these complex aneurysms requires an interdisciplinary and patient-specific approach in high-volume centers. An index case is used to discuss the diagnosis and treatment of a patient undergoing fenestrated-branched endovascular aneurysm repair for a TAAA.

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.

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.

Spinal Cord Ischemia Following Endovascular Abdominal Aortic Aneurysm Repair: An Unpredictable Catastrophe

Spinal cord ischemia (SCI) following endovascular abdominal aortic aneurysm (AAA) repair (EVAR) is a rare yet catastrophic complication. The underlying pathophysiological mechanism remains incompletely understood. We present the case of a 75-year-old man with a difficult left common iliac artery (CIA) anatomy that necessitated the coiling of his left internal iliac artery (IIA) to ensure proper sealing of his aortic stent graft. The patient complained of bilateral lower extremity weakness immediately following the procedure. The patient was diagnosed with SCI, which was later confirmed by magnetic resonance imaging (MRI). He was treated with cerebrospinal fluid drainage. The patient's neurological status mildly improved on follow-up one year later.

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.

Hemodynamic Patterns of Spinal Cord Perfusion in Thoracoabdominal Aortic Aneurysm Repair

Paraplegia in aortic surgery is due to its impact on spinal cord perfusion whose hemodynamic patterns (SCPHP) are not clearly defined. Detailed morphological analysis of vascular network and collateral network modifications within Monro-Kellie postulate due to the fixed theca confines was performed to identify SCPHP. SCPHP may begin with intraspinal "backflow" (I-BF), that is, hemorrhage from anterior and posterior spinal arteries, backward via the connected anterior and posterior radicular medullary arteries, through the increasing diameter and decreasing resistance of segmental arteries (SAs), off their aortic orifices outside vascular network at 0 operative field pressure. The I-BF blood bypasses both intra- and extraspinal capillary networks and causes depressurization (0 diastolic pressure) and full ischemia of dependent spinal cord. When the occlusion of those SAs orifices arrests I-BF, the hemodynamic pattern of intraspinal "steal" (I-S) may take place. The formerly I-BF blood, in fact, is now variably shared between the fraction maintained in its physiological intraspinal network and that keeping flowing as I-S through the extraspinal capillary network. I-S is, however, counteracted by the extraspinal "steal" from the connected mammary/paraspinous-independent extraspinal feeders, all physically competing for the same room left by the missed physiological SA direct aortic blood inflow. Steal phenomenon evolves within the 120-hour time frame of CNm, whose intraspinal anatomical changes may offer the physical basis within the Monro-Kelly postulate, respectively of the intraoperative and postoperative paraplegia. The current procedures could not prevent the unphysiological SCPHP but awareness of details of their various features may offer the basis for improvements tailored, to the adopted intra- and postoperative procedures.

Splanchnic occlusive disease predicts for spinal cord injury after open descending thoracic and thoracoabdominal aneurysm repair

OBJECTIVE

In the present study, we sought to discern the effects of splanchnic occlusive disease (SOD; renal, superior mesenteric, and/or celiac axis arteries) on spinal cord injury (SCI; paraparesis or paraplegia) and major adverse events (MAE) after descending thoracic aneurysm (DTA) and thoracoabdominal aortic aneurysm (TAAA) open repair.

METHODS

Patients who had undergone DTA/TAAA repair at our institution were dichotomized according to the presence of SOD, which was investigated as a predictive factor of our primary (SCI) and secondary (operative mortality, myocardial infarction, stroke, tracheostomy, de novo dialysis, MAE, survival) endpoints. Risk adjustment used both propensity score matching and multivariable logistic regression.

RESULTS

From July 1997 to October 2019, 888 patients had undergone DTA/TAAA repair, of whom 19 were excluded from our analysis for missing data. SOD was absent in 712 patients and present in 157 patients. The patients with SOD had presented with a greater incidence of preoperative renal impairment (61 [38.9%] vs 175 [24.6%]; P < .01) and peripheral arterial disease (60 [38.2%] vs 162 [22.8%]; P < .01] and decreased left ventricular ejection fraction (45%; interquartile range, 10%; vs 50%; interquartile range, 4%; P < .01). The etiology of aortic disease was more frequently dissection in the SOD group (56.1% vs 43.7%) and more frequently nondissecting aneurysm in the non-SOD group (56.3% vs 43.9%; P < .01). Patients without SOD had presented with aneurysms more cranially located (DTA, 34.0% vs 7.6%; extent I TAAA, 44.0% vs 7.6%). In contrast, patients with SOD had presented with aneurysms more caudally located (extent II TAAA, 36.9% vs 8.6%; extent III TAAA, 30.6% vs 11.0%; extent IV TAAA, 17.2% vs 2.5%; P < .01). Propensity score matching led to 144 pairs, with SOD significantly associated with SCI (10 [6.9%] vs 2 [1.4%]; P = .03) and MAE (47 [32.6%] vs 26 [15%]; P < .01). Ten-year survival was reduced in those with SOD (31.5% vs 45.2%; P < .01). Conditional multivariable regression confirmed SOD to be a predictor of SCI in the matched sample (odds ratio, 6.60; P = .02).

CONCLUSIONS

Our results have shown that SOD is a significant predictor of SCI in patients undergoing open DTA/TAAA repair. The investigation of measures to prolong neuronal ischemia tolerance (eg, hypothermia) is warranted for such patients.

Staged total arch replacement, followed by fenestrated-branched endovascular aortic repair, for patients with mega aortic syndrome

OBJECTIVE

The aim of the present study was to review the clinical outcomes of a staged approach using total arch replacement (TAR) with an elephant trunk or a frozen elephant trunk, followed by fenestrated-branched endovascular aortic repair (F-BEVAR) for patients with mega aortic syndrome.

METHODS

We reviewed the clinical data and outcomes of 11 consecutive patients (8 men; mean age, 71 ± 7 years) treated by staged TAR and F-BEVAR from January 2014 to December 2018. The F-BEVAR procedures were performed under a prospective, nonrandomized, physician-sponsored investigational device exemption protocol. All patients had had mega aortic syndrome, defined by an ascending aorta, arch, and extent I-II thoracoabdominal aortic aneurysm. The endpoints were 30-day mortality, major adverse events (MAE), patient survival, freedom from reintervention, and freedom from target vessel instability.

RESULTS

Of the 11 patients, 6 had developed chronic postdissection aneurysms after previous Stanford A (three A₁₁, two A₁₀, one A₉) dissection repair and 5 had had degenerative aneurysms with no suitable landing zone in the aortic arch. The thoracoabdominal aortic aneurysms were classified as extent I in four patients and extent II in seven. One patient had died within 30 days after TAR (9.0%). However, none of the remaining 10 patients who had undergone F-BEVAR had died. First-stage TAR resulted in MAE in three patients (27%), including one spinal cord injury. The mean length of stay was 12 ± 6 days. The mean interval between TAR and F-BEVAR was 245 ± 138 days with no aneurysm rupture during the interval. Second-stage F-BEVAR was associated with MAE in two patients (20%), including spinal cord injury in one patient from spinal hematoma due to placement of a cerebrospinal fluid drain. The mean follow-up period was 14 ± 10 months. At 2 years postoperatively, patient survival, primary patency, secondary patency, and freedom from renal-mesenteric target vessel instability was 80% ± 9%, 94% ± 6%, 100%, and 86% ± 8%, respectively. No aortic-related deaths occurred during the follow-up period. Four patients had required reintervention, all performed using an endovascular approach.

CONCLUSIONS

A staged approach to treatment of mega aortic syndrome using TAR and F-BEVAR is a feasible alternative for selected high-risk patients. Larger clinical experience and longer follow-up are needed.

Complications and Management of the Thoracic Endovascular Aortic Repair

Endovascular treatment in thoracic aortic diseases has increased in use exponentially since Dake and colleagues first described the use of a home-made transluminal endovascular graft on 13 patients with descending thoracic aortic aneurysm at Stanford University in the early 1990s. Thoracic endovascular aneurysm repair (TEVAR) was initially developed for therapy in patients deemed unfit for open surgery. Innovations in endograft engineering design and popularization of endovascular techniques have transformed TEVAR to the predominant treatment choice in elective thoracic aortic repair. The number of TEVARs performed in the United States increased by 600% from 1998 to 2007, while the total number of thoracic aortic repairs increased by 60%. As larger multicenter trials and meta-analysis studies in the 2000s demonstrate the significant decrease in perioperative morbidity and mortality of TEVAR over open repair, TEVAR became incorporated into standard guidelines. The 2010 American consensus guidelines recommend TEVAR to be “strongly considered” when feasible for patients with degenerative or traumatic aneurysms of the descending thoracic aorta exceeding 5.5 cm, saccular aneurysms, or postoperative pseudoaneurysms. Nowadays, TEVAR is the predominant treatment for degenerative and traumatic descending thoracic aortic aneurysm repair. Although TEVAR has been shown to have decreased early morbidity and mortality compared with open surgical repair, endovascular manipulation of a diseased aorta with endovascular devices continues to have significant risks. Despite continued advancement in endovascular technique and devices since the first prospective trial examined the complications associated with TEVAR, common complications, two decades later, still include stroke, spinal cord ischemia, device failure, unintentional great vessel coverage, access site complications, and renal injury. In this article, we review common TEVAR complications with some corresponding radiographic imaging and their management.

Extravascular risk factors in the prognostic evaluation for spinal cord injury during thoraco-abdominal aortic aneurysm exclusion: a case report

Background

The etiology of delayed-onset spinal cord injury (SCI) following endovascular repair of thoraco-abdominal aortic aneurysms (TAAA) is still unclear and may be related to multiple factors. Extravascular factors, such as lumbar spinal stenosis (LSS), may play a significant role in the selection of patient at risk of SCI. In this report we describe a case of paraplegia following thoracic endovascular aortic repair (TEVAR) in a patient suffering from severe and symptomatic LSS and undergoing staged endovascular repair of a TAAA.

Case presentation

A 70-year-old man was admitted to our department with an asymptomatic type III TAAA in previous open repair for abdominal aortic aneurysm. The patient complained of buttock and thigh claudication in the absence of defects in the pelvic perfusion; a spinal magnetic resonance angiography (MRA) showed a severe narrowing of the lumbar canal.. After 24 h from first-step procedure (TEVAR) paraplegia was detected. A cerebrospinal fluid (CSF) drainage was then placed with incomplete recovery.

Conclusions

Stenotic damage to the spinal cord is thought to be the result of direct compression of the neural elements and ischemic disruption of arterial and venous structures surrounding the spinal cord. This comorbidity may constitute an additional anatomic risk factor in those patients currently recognized as prognostically associated to the development of SCI.

The Safety Profile of Intentional or Iatrogenic Sacrifice of the Artery of Adamkiewciz and Its Vicinity's Spinal Segmental Arteries: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

There is paucity of consensus on whether (1) the artery of Adamkiewicz (AoA) and (2) the number of contiguous segmental spinal arteries (SSAs) that can be safely ligated without causing spinal cord ischemia. The objective of this review is to determine the risk of motor neurological deficits from iatrogenic sacrifice of the (1) AoA and (2) its vicinity's SSAs.

METHODS

Systematic review of the spine and vascular surgery was carried out in accordance to PRISMA guidelines. Outcomes in terms of risk of postoperative motor neurological deficit with occlusion of the AoA, bilateral contiguous SSAs, or unilateral contiguous SSAs were analyzed.

RESULTS

Ten articles, all retrospective case series, were included. Three studies (total N = 50) demonstrated a postoperative neurological deficit risk of 4.0% when the AoA is occluded. When 1 to 6 pairs of SSAs (without knowledge of AoA location) were ligated, the postoperative neurological deficit risk was 0.6%, as compared with 5.4% when more than 6 bilateral pairs of SSAs were ligated (relative risk [RR] = 0.105, 95% CI 0.013-0.841, P = .0337). For unilateral ligation of SSAs of two to nine levels, the risk of postoperative neurological deficit does not exceed 1.3%.

CONCLUSION

The current best evidence indicates that (1) occlusion of the AoA and (2) occlusion of up to 6 pairs of SSAs is associated with a low risk of postoperative neurological deficit. This limited number of low quality studies restrict the ability to draw definitive conclusions. Ligation of AoA and SSAs should only be undertaken when absolutely required to mitigate the small but devastating risk of paralysis.

Endoscopic-assisted aortic replacement of the descending aorta through the 8th intercostal space to preserve collateral vessels: a case report

We present the case of a 75-year-old man with repeated lower limb hematoma caused by consumptive coagulopathy from a type B chronic aortic dissection. His abdominal aorta was replaced with a Y-shaped graft 30 years prior to admission. As his previous aortic stent graft treatment failed, he underwent open surgical prosthetic graft replacement of the descending aorta under deep hypothermia. To reduce intra- and postoperative bleeding, we avoided cutting the ribs and intercostal arteries. The aneurysm was approached only through the 8th intercostal space; however, as the proximal descending aorta was inaccessible from this site, total endoscopic or endoscopic-assisted procedure was performed to approach the proximal descending aorta. All intercostal arterial orifices were securely closed by suture. The postoperative course was uneventful, and he was discharged home on postoperative day 11. The endoscopic surgery reduced impairment of collateral vessels during surgery and might have reduced the risk of paraplegia.

Perioperative and Anesthetic Management of Coarctation of the Aorta

Isolated coarctation of the aorta is a relatively common form of congenital heart disease that is characterized by variable degrees of obstruction to aortic outflow. The clinical presentation varies from asymptomatic arterial hypertension to cardiogenic shock. The treatment options include surgical repair or interventional therapy with aortic balloon dilation and stent placement. This article will summarize the pathophysiology as well as describe the surgical and interventional procedures. The anesthetic management for those interventions will be reviewed.

Spinal cord protection in aortic endovascular surgery

A persistent neurological deficit, such as paraplegia or paraparesis, secondary to spinal cord injury remains one of the most feared complications of surgery on the descending thoracic or abdominal aorta. This is despite sophisticated advances in imaging and the use of less invasive endovascular procedures. Extensive fenestrated endovascular aortic graft prostheses still carry a risk of spinal cord injury of up to 10%; thus, this risk should be identified and strategies implemented to protect the spinal cord and maintain perfusion. The patients at highest risk are those undergoing extensive thoracic aortic stenting including thoracic, abdominal, and pelvic vessels. Although many techniques are available, lumbar cerebrospinal fluid drainage remains the most frequent intervention, along with maintenance of perfusion pressure and possibly staged procedures to allow collateral vessel stabilization. Many questions remain regarding other technical aspects, spinal cord monitoring and cooling, pharmacological protection, and the optimal duration of interventions into the postoperative period.

Spinal cord injury after thoracic endovascular aortic aneurysm repair

PURPOSE

Thoracic endovascular aortic aneurysm repair (TEVAR) has become a mainstay of therapy for aneurysms and other disorders of the thoracic aorta. The purpose of this narrative review article is to summarize the current literature on the risk factors for and pathophysiology of spinal cord injury (SCI) following TEVAR, and to discuss various intraoperative monitoring and treatment strategies.

SOURCE

The articles considered in this review were identified through PubMed using the following search terms: thoracic aortic aneurysm, TEVAR, paralysis+TEVAR, risk factors+TEVAR, spinal cord ischemia+TEVAR, neuromonitoring+thoracic aortic aneurysm, spinal drain, cerebrospinal fluid drainage, treatment of spinal cord ischemia.

PRINCIPAL FINDINGS

Spinal cord injury continues to be a challenging complication after TEVAR. Its incidence after TEVAR is not significantly reduced when compared with open thoracoabdominal aortic aneurysm repair. Nevertheless, compared with open procedures, delayed paralysis/paresis is the predominant presentation of SCI after TEVAR. The pathophysiology of SCI is complex and not fully understood, though the evolving concept of the importance of the spinal cord's collateral blood supply network and its imbalance after TEVAR is emerging as a leading factor in the development of SCI. Cerebrospinal fluid drainage, optimal blood pressure management, and newer surgical techniques are important components of the most up-to-date strategies for spinal cord protection.

CONCLUSION

Further experimental and clinical research is needed to aid in the discovery of novel neuroprotective strategies for the protection and treatment of SCI following TEVAR.

Spinal Ischemia in Thoracic Aortic Procedures: Impact of Radiculomedullary Artery Distribution

BACKGROUND

The aim of this study was to assess the influence of thoracic anterior radiculomedullary artery (tARMA) distribution on spinal cord perfusion in a thoracic aortic surgical model.

METHODS

Twenty-six pigs (34 ± 3 kg; study group, n = 20; sham group, n = 6) underwent ligation of the left subclavian artery and thoracic segmental arteries. End points were spinal cord perfusion pressure (SCPP), regional spinal cord blood flow (SCBF), and neurologic outcome with an observation time of 3 hours. tARMA distribution patterns tested for an effect on end points included (1) maximum distance between any 2 tARMAs within the treated aortic segment (0 or 1 segment = small-distance group; >1 segment = large-distance group) and (2) distance between the end of the treated aortic segment and the first distal tARMA (at the level of the distal simulated stent-graft end = group 0; gap of 1 or more segments = group ≥1).

RESULTS

The number of tARMA ranged from 3 to 13 (mean, 8). In the large-distance group, SCBF dropped from 0.48 ± 0.16 mL/g/min to 0.3 ± 0.08 mL/g/min (p < 0.001). We observed no detectable SCBF drop in the small-distance group: 0.2 ± 0.05 mL/g/min at baseline to 0.23 ± 0.05 mL/g/min immediately after clamping (p = 0.147). SCBF increased from 0.201 ± 0.055 mL/g/min at baseline to 0.443 ± 0.051 mL/g/min at 3 hours postoperatively (p < 0.001) only in the small-distance group.

CONCLUSIONS

We demonstrate experimental data showing that distribution patterns of tARMAs correlate with the degree of SCBF drop and insufficient reactive parenchymal hyperemia in aortic procedures. Individual ARMA distribution patterns along the treated aortic segment could help us predict the individual risk of spinal ischemia.

Transesophageal versus transcranial motor evoked potentials to monitor spinal cord ischemia

OBJECTIVES

We have previously reported that transesophageal motor evoked potential is feasible and more stable than transcranial motor evoked potential. This study aimed to investigate the efficacy of transesophageal motor evoked potential to monitor spinal cord ischemia.

METHODS

Transesophageal and transcranial motor evoked potentials were recorded in 13 anesthetized dogs at the bilateral forelimbs, anal sphincters, and hindlimbs. Spinal cord ischemia was induced by aortic balloon occlusion at the 8th to 10th thoracic vertebra level. In the 12 animals with motor evoked potential disappearance, occlusion was maintained for 10 minutes (n = 6) or 40 minutes (n = 6) after motor evoked potential disappearance. Neurologic function was evaluated by Tarlov score at 24 and 48 hours postoperatively.

RESULTS

Time to disappearance of bilateral motor evoked potentials was quicker in transesophageal motor evoked potentials than in transcranial motor evoked potentials at anal sphincters (6.9 ± 3.1 minutes vs 8.3 ± 3.4 minutes, P = .02) and hindlimbs (5.7 ± 1.9 minutes vs 7.1 ± 2.7 minutes, P = .008). Hindlimb function was normal in all dogs in the 10-minute occlusion group, and motor evoked potentials recovery (>75% on both sides) after reperfusion was quicker in transesophageal motor evoked potentials than transcranial motor evoked potentials at hindlimbs (14.8 ± 5.6 minutes vs 24.7 ± 8.2 minutes, P = .001). At anal sphincters, transesophageal motor evoked potentials always reappeared (>25%), but transcranial motor evoked potentials did not in 3 of 6 dogs. In the 40-minute occlusion group, hindlimb motor evoked potentials did not reappear in 4 dogs with paraplegia. Among the 2 remaining dogs, 1 with paraparesis (Tarlov 3) showed delayed recovery (>75%) of hindlimb motor evoked potentials without reappearance of anal sphincter motor evoked potentials. In another dog with spastic paraplegia, transesophageal motor evoked potentials from the hindlimbs remained less than 20%, whereas transcranial motor evoked potentials showed recovery (>75%).

CONCLUSIONS

Transesophageal motor evoked potentials may be superior to transcranial motor evoked potentials in terms of quicker response to spinal cord ischemia and better prognostic value.