Evolution of Risk for Neurologic Deficit After Descending and Thoracoabdominal Aortic Repair

Midterm outcomes of open repair versus endovascular descending thoracic aortic aneurysm repair

Objective

The study objective was to evaluate the midterm outcome of thoracic endovascular aortic repair compared with open repair in patients with descending thoracic aortic aneurysm.

Methods

From August 1993 to February 2023, 499 patients with descending thoracic aortic aneurysms underwent open repair (n = 221) or thoracic endovascular aortic repair (n = 278). Of these, 120 matched pairs were identified using propensity score matching based on age, sex, chronic lung disease, stroke, coronary artery disease, diabetes, ejection fraction, dialysis, peripheral vascular disease, prior cardiac surgery, connective tissue disease, and chronic dissection. Primary outcomes were postoperative paralysis, operative mortality, reoperation, and midterm survival.

Results

After matching, the preoperative demographics and comorbidities were balanced in both groups. Intraoperatively, open repair had a lower temperature (18 °C vs 36 °C) and more patients required blood products (66% vs 8%), P < .001. Postoperatively, patients undergoing thoracic endovascular aortic repair had fewer strokes (2.5% vs 9.2%; P = .03), less dialysis (0% vs 3.3%; P = .04), and shorter length of stay (5 days vs 12 days, P < .001), but similar lower-extremity paralysis (2.5% vs 2.5%, P = 1.00) compared with open repair. Furthermore, thoracic endovascular aortic repair had higher 7-year incidence of first reoperation (16.1% vs 3.6%, P < .001) but similar operative mortality (0.8% vs 4.2%; P = .10) and 10-year survival outcome (56%; 95% CI, 43-72 vs 58%; 95% CI, 49-68; P = .55) compared with open aortic repair. The hazard ratio was 0.93 (P = .78) for thoracic endovascular aortic repair for midterm mortality and 6.87 (P < .001) for reoperation.

Conclusions

Open repair could be the first option for patients with descending thoracic aortic aneurysms who were surgical candidates.

Practice of neuromonitoring in open and endovascular thoracoabdominal aortic repair-an international expert-based modified Delphi consensus study

OBJECTIVES

Spinal cord injury is detrimental for patients undergoing open or endovascular thoracoabdominal aortic aneurysm (TAAA) repair. The aim of this survey and of the modified Delphi consensus was to gather information on current practices and standards in neuroprotection in patients undergoing open and endovascular TAAA.

METHODS

The Aortic Association conducted an international online survey on neuromonitoring in open and endovascular TAAA repair. In a first round an expert panel put together a survey on different aspects of neuromonitoring. Based on the answers from the first round of the survey, 18 Delphi consensus questions were formulated.

RESULTS

A total of 56 physicians completed the survey. Of these, 45 perform open and endovascular TAAA repair, 3 do open TAAA repair and 8 do endovascular TAAA repair. At least 1 neuromonitoring or protection modality is utilized during open TAAA surgery. Cerebrospinal fluid (CSF) drainage was used in 97.9%, near infrared spectroscopy in 70.8% and motor evoked potentials or somatosensory evoked potentials in 60.4%. Three of 53 centres do not utilize any form of neuromonitoring or protection during endovascular TAAA repair: 92.5% use CSF drainage; 35.8%, cerebral or paravertebral near infrared spectroscopy; and 24.5% motor evoked potentials or somatosensory evoked potentials. The utilization of CSF drainage and neuromonitoring varies depending on the extent of the TAAA repair.

CONCLUSIONS

The results of this survey and of the Delphi consensus show that there is broad consensus on the importance of protecting the spinal cord to avoid spinal cord injury in patients undergoing open TAAA repair. Those measures are less frequently utilized in patients undergoing endovascular TAAA repair but should be considered, especially in patients who require extensive coverage of the thoracoabdominal aorta.

Hypothermic circulatory arrest versus aortic clamping in thoracic and thoracoabdominal aortic aneurysm repair

BACKGROUND

To compare perioperative and midterm outcomes in thoracic and thoraco-abdominal aortic aneurysm (TAA and TAAA) repair using hypothermic circulatory arrest (HCA) or aortic clamping (AC) with mild hypothermia.

METHODS

From 2012 to 2021 there were 180 open repairs of a TAA or TAAA, of which 90 (50%) were done with HCA and 90 (50%) with aortic clamping with mild hypothermia. The indications for HCA were arch aneurysm, TAA from chronic aortic dissection, and inability to clamp the aorta for proximal anastomosis.

RESULTS

Compared to AC, the HCA group had less prior descending aorta replacement/repair (9.1% vs. 32%, p = 0.0001). Intraoperatively, the HCA group had more TAAs (70% vs. 20%, p < 0.0001) while the AC group had more TAAAs (80% vs. 30%, p < 0.0001). HCA group had longer cardiopulmonary bypass times (242 vs. 181 min, p < 0.0001) but shorter cross-clamp time (39 vs. 120 min, p < 0.0001) and lower temperatures (18°C vs. 34°C, p < 0.0001). Postoperatively, the HCA group had longer intubation times (31 vs. 26 h, p = 0.002), but all other postoperative outcomes including paralysis (2.2% vs. 8.9%, p = 0.08), and operative mortality (4.4% vs. 2.2%, p = 0.68) were similar between HCA and AC groups. Patient age was an independent risk factor for postoperative paralysis (OR 1.07, p = 0.03) while HCA was not significant (OR 0.37, p = 0.21). Five-year survival was similar between HCA and AC groups (85% vs. 80%, p = 0.36).

CONCLUSIONS

Postoperative outcomes and midterm survival were acceptable in thoracic and thoracoabdominal aneurysm patients after HCA or AC. Both HCA and AC with mild hypothermia were valid approaches in TAA/A repair.

The application of modular multifunctional left heart bypass circuit system integrated with ultrafiltration in thoracoabdominal aortic aneurysm repair

Open thoracoabdominal aortic aneurysm (TAAA) repair is a complex and challenging operation with a high incidence of serious complications, and high perioperative mortality and morbidity. Left heart bypass (LHB) is a circulatory support system used to perfuse the distal aorta during TAAA operation, and the advantages of LHB include guaranteeing distal perfusion, reducing the use of heparin, and diminishing the risk of bleeding and postoperative neurological deficits. In China, the circuit for TAAA repair is deficient, and far from the perfusion requirements. We designed a modular multifunctional LHB circuit for TAAA repair. The modular circuit consisted of cannulation pipelines, functional consumables connection pipelines, and accessory pipelines. The accessory pipelines make up lines for selective visceral perfusion and kidney perfusion, suckers and rapid infusion. The circuit can be assembled according to surgical requirements. The ultrafilter and heat exchanger are integrated into the circuit to fulfill the basic demands of LHB. The LHB circuit also has pipelines for selective visceral perfusion to the celiac artery and superior mesenteric artery and renal perfusion pipelines. Meanwhile, the reserved pipelines facilitate the quick switch from LHB to conventional cardiopulmonary bypass (CPB). The reserved pipelines reduce the time of reassembling the CPB circuit. Moreover, the rapid infusion was integrated into the LHB circuit, which can rapid infusion when massive hemorrhage during the open procedures such as exposure and reconstruction of the aorta. The ultrafiltration can diminish the consequent hemodilution of hemorrhage and rapid infusion. A hemoperfusion cartridge also can be added to reduce the systemic inflammatory during operation. The circuit can meet the needs of LHB and quickly switch to conventional CPB. No oxygenator was required during LHB, which reduce the use of heparin and reduce the risk of bleeding. The heat exchanger contributes to temperature regulation; ultrafiltration, arterial filter, and rapid-infusion facilitated the blood volume management and are useful to maintain hemodynamic stability. This circuit made the assembly of the LHB circuit more easily, and more efficient, which may contribute to the TAAA repair operation performed in lower volume centers easily. 26 patients who received TAAA repair under the modular multifunctional LHB from January 2018-March 2022 were analyzed, and we achieved acceptable clinical outcomes. The in-hospital mortality and 30-day postoperative mortality were 15.4%, and the postoperative incidences of paraparesis (4%), stroke (4%), and AKI need hemodialysis (12%) were not particularly high, based on the limited patients sample size in short research period duration.

Surgical Thoracoabdominal Aortic Aneurysm Repair in a Non-High-Volume Institution

BACKGROUND

Surgical thoracoabdominal aortic aneurysm (TAAA) repair remains challenging. Apart from mortality, spinal cord injury (SCI) is a dreaded complication. We analyzed our experience to identify predictors for SCI in a nonhigh-volume institution.

PATIENTS AND METHODS

All patients who underwent TAAA repair between February 1996 and November 2016 (n = 182) were enrolled. Most were male (n = 121; 66.4%), median age was 68 years (range: 21-84). Elective operations were performed in 153 instances (84.1%). Our approach to minimize SCI includes distal aortic perfusion, mild hypothermia, identification of the Adamkiewicz artery, and sequential aortic clamping. Cerebrospinal fluid drainage was introduced in 2001 and liberal use of selective visceral perfusion in 2006.

RESULTS

Early mortality was 12.1%; it was 8.5% after elective procedures. Reduced left ventricular function, nonelective setting, older age, and longer bypass time were identified as independent predictors for mortality in multivariable logistic regression model. Permanent SCI was observed in nine patients (4.9%), of whom seven (3.8%) developed paraplegia. In a multivariable logistic regression model for paraplegia, peripheral arterial disease (PAD), Crawford type II repair, smaller body surface area, and era before 2001 were identified as independent predictors, whereas only PAD was significant for SCI. The incidence of paraplegia was 13.8% in extensive repair out of the first 91 cases, whereas it was improved up to 2.7% thereafter.

CONCLUSION

Using an integrated approach, acceptable outcome of TAAA repair can be achieved, even in a nonhigh-volume center. PAD and extensive involvement of the aorta are strong independent predictors for spinal cord deficit after TAAA repair.

Therapeutic hypothermia attenuates paraplegia and neuronal damage in the lumbar spinal cord in a rat model of asphyxial cardiac arrest

Spinal cord ischemia can result from cardiac arrest. It is an important cause of severe spinal cord injury that can lead to serious spinal cord disorders such as paraplegia. Hypothermia is widely acknowledged as an effective neuroprotective intervention following cardiac arrest injury. However, studies on effects of hypothermia on spinal cord injury following asphyxial cardiac arrest and cardiopulmonary resuscitation (CA/CPR) are insufficient. The objective of this study was to examine effects of hypothermia on motor deficit of hind limbs of rats and vulnerability of their spinal cords following asphyxial CA/CPR. Experimental groups included a sham group, a group subjected to CA/CPR, and a therapeutic hypothermia group. Severe motor deficit of hind limbs was observed in the control group at 1 day after asphyxial CA/CPR. In the hypothermia group, motor deficit of hind limbs was significantly attenuated compared to that in the control group. Damage/death of motor neurons in the lumbar spinal cord was detected in the ventral horn at 1 day after asphyxial CA/CPR. Neuronal damage was significantly attenuated in the hypothermia group compared to that in the control group. These results indicated that therapeutic hypothermia after asphyxial CA/CPR significantly reduced hind limb motor dysfunction and motoneuronal damage/death in the ventral horn of the lumbar spinal cord following asphyxial CA/CPR. Thus, hypothermia might be a therapeutic strategy to decrease motor dysfunction by attenuating damage/death of spinal motor neurons following asphyxial CA/CPR.

Lessons learned and learning curve of fenestrated and branched endografts

Fenestrated and branched endovascular repair (F-BEVAR) has been increasingly used to treat patients with complex aortic aneurysms involving the renal-mesenteric arteries. As with any new procedure, there is a learning curve associated with mastering the technique. However, proficiency with deployment is only one aspect of the learning process, and ultimately, this curve is defined not by one quality parameter, but by patient selection, the performance of the entire team, the surgeon's ability to adapt to unexpected events, and the durability of the repair. This article reviews the importance of novel training paradigms, learning curve, and factors affecting outcomes of complex endovascular aneurysm repair.

State-of the-art review on the renal and visceral protection during open thoracoabdominal aortic aneurysm repair

During open thoracoabdominal aortic aneurysm repair (OTAAAR), there is an inevitable organ ischemic period that occurs when the abdominal arteries are being reattached to the aortic graft. Despite various protective techniques, the incidence of renal and visceral complications remains substantial. This state-of-the-art review gives an overview of the current and most evidence-based organ protection methods during OTAAAR, based on the most recent publications and personal experience. An electronic search was performed in four medical databases, using the following MeSH terms: thoracoabdominal aneurysm, TAAAR, visceral protection, renal protection, kidney, perfusion, and intestines. Every publication type was considered. The literature search was ended on August 31st, 2017. The left heart bypass (LHB) is currently the most frequent adjunct to provide distal aortic perfusion (DAP) during aortic clamping. Together with systemic hypothermia, it forms the cornerstone in organ protection during aortic clamping. Further renal protection can be obtained by selective renal perfusion (SRP) with cold blood or cold crystalloid solution, the latter enriched with mannitol. The perfusion should be administered in a volume- and pressure-controlled way and, if possible, by use of a pulsatile pump. Selective visceral perfusion (SVP) is not routinely used, as it does not provide adequate blood flow for visceral protection. The best way to protect the intestines is by minimizing the ischemic time. The preservation of renal and visceral function after OTAAAR can only be obtained with specific strategies before, during, and after the operation. This involves a series of measures, including selective digestive decontamination (SDD), avoidance of nephrotoxic drugs, minimizing the renal and intestinal ischemic time, systemic cooling, avoidance of hemodynamic instability, and regional protective perfusion of the kidneys. Future innovations in catheters, cardiac bypass flow types, mechanical components, hybrid vascular grafts, and pharmaceutical protection measures will hopefully further reduce organ complications.

Spinal cord injury as a complication of thoracic endovascular aneurysm repair

OBJECTIVE

Spinal cord ischemia (SCI) is a devastating complication of thoracic aortic aneurysm repair in the era of thoracic endovascular aneurysm repair (TEVAR). This review aims to clarify the causes of SCI during TEVAR and to propose ways that it may be prevented.

METHODS AND RESULTS

We performed an extensive literature search of SCI during TEVAR. Based on the existing literature, we examined the anatomy of the anterior spinal cord artery, which supplies blood to the anterior aspect of the spinal cord, and discuss reported effective ways to prevent SCI during TEVAR, including augmentation of arterial blood pressure and drainage of cerebrospinal fluid.

CONCLUSION

After reviewing the mechanism of SCI during TEVAR, we evaluated promising preventative measures.

The efficacy and risk of cerebrospinal fluid drainage for thoracoabdominal aortic aneurysm repair: a retrospective observational comparison between drainage and non-drainage

Objectives

We reviewed our experiences with thoracoabdominal aortic aneurysm (TAAA) repair to assess the efficacy of cerebrospinal fluid drainage (CSFD) to prevent the neurological deficits and complications associated with CSFD.

Methods

Between 2002 and 2015, 118 patients underwent TAAA repair. Seventy-eight patients underwent CSFD for 2.7 ± 1.1 days after surgery. CSFD was not performed for the other 40 patients due to an urgent situation, chronic disseminated intravascular coagulation or anatomical difficulties.

Results

There were 5 in-hospital deaths (4.2%). The neurological complications included paraplegia ( n  = 14, 11.9%), paraparesis ( n  = 3, 2.5%), cerebral infarction ( n  = 11, 9.3%) and intracranial haemorrhage ( n  = 1, 0.85%), none related to CSFD. The complications related to CSFD included headaches ( n  = 13, 11.0%), subdural haematoma (which was treated conservatively) ( n  = 1, 0.85%), a neurological symptom of the bilateral thighs ( n  = 1, 0.85%), pale haemorrhagic discharge ( n  = 2, 1.7%) and a fractured catheter ( n  = 1, 0.85%). Eight patients had paraplegia and 1 patient had paraparesis among the 78 patients who underwent CSFD (9/78, 11.5%); among the 40 patients who did not undergo CSFD, 6 had paraplegia and 2 had paraparesis (8/40, 20.0%). A multivariate analysis demonstrated that CSFD had a significant protective effect for the spinal cord (odds ratio = 0.045, P  = 0.007).

Conclusions

CSFD effectively prevented spinal cord dysfunction in TAAA repair. However, some serious complications occurred, including subdural haematoma and a fractured catheter. It is therefore important to recognize both the efficacy and the risks of CSFD in TAAA repair.

Decision to Interrupt Second-Stage Side-Branch Completion in Thoracoabdominal Branched Aortic Stent Grafting to Prevent Spinal Cord Ischemia

BACKGROUND

Spinal cord ischemia (SCI) is a severe complication of extended endovascular repair of thoracoabdominal aneurysms. We describe voluntary interruption of side-branch completion in staged branched endovascular aneurysm treatment due to uncertainty regarding SCI possible onset, based on intraoperative angiography findings.

METHODS

We report a case of a staged endovascular treatment of thoracoabdominal aortic aneurysm in a 64-year-old patient using a branched endograft with an additional side branch that allows temporary sac perfusion to prevent SCI. The third operative step was intended to occlude the side branch. Intraoperative angiography through the side branch demonstrated circulating aneurysm sac, with patent inferior intercostal and superior lumbar arteries giving direct blood supply to a clearly visible anterior spinal artery. The procedure was stopped.

RESULTS

One month later, sac thrombosis occurred spontaneously and was clinically responsible for neurogenic claudication that resolved during follow-up.

CONCLUSION

Interrupting side-branch completion seems to have allowed additional ischemic conditioning of the spinal cord as the spontaneous sac thrombosis induced mild neurological event.

The use of lumbar drains in preventing spinal cord injury following thoracoabdominal aortic aneurysm repair: an updated systematic review and meta-analysis

OBJECTIVE Paraplegia and paraparesis following aortic aneurysm repair occur at a substantially high rate and are often catastrophic to patients, their families, and the overall health care system. Spinal cord injury (SCI) following open thoracoabdominal aortic aneurysm (TAAA) repair is reported to be as high as 20% in historical controls. The goal of this study was to determine the impact of CSF drainage (CSFD) on SCI following TAAA repair. METHODS In August 2015 a systematic literature search was performed using clinicaltrials.gov , the Cochrane Library, PubMed/MEDLINE, and Scopus that identified 3478 articles. Of these articles, 10 met inclusion criteria. Random and fixed-effect meta-analyses were performed using both pooled and subset analyses based on study type. RESULTS The meta-analysis demonstrated that CSFD decreased SCI by nearly half (relative risk 0.42, 95% confidence interval 0.25-0.70; p = 0.0009) in the pooled analysis. This effect remained in the subgroup analysis of early SCI but did not remain significant in late SCI. CONCLUSIONS This meta-analysis showed that CSFD could be an effective strategy in preventing SCI following aortic aneurysm repair. Care should be taken to prevent complications related to overdrainage. No firm conclusions can be drawn about the newer endovascular procedures at the current time.

Thoracoabdominal aortic aneurysm (extent II) repair in a patient with systemic vasculitis

Conventional open repair is a gold standard for treating thoracoabdominal aortic aneurysm (TAAA) in patients with connective tissue disorders or systemic vasculitis. In a 42-year-old male patient with systemic vasculitis, TAAA extent II open repair was performed at our hospital. Here, we present the case with a video clip and technical tips.

Extended Motor Evoked Potentials Monitoring Helps Prevent Delayed Paraplegia After Aortic Surgery

OBJECTIVE

Motor evoked potentials (MEPs) monitoring can promptly detect spinal cord ischemia (SCI) from aortic clamping during open thoracoabdominal aneurysm repair (OTAAR) with distal aortic perfusion (DAP) and thus help decrease the risk of immediate postoperative SCI (IP-SCI). However, neither stable MEPs during aortic clamp interval (ACI) nor absence of IP-SCI eliminate the possibility of delayed postoperative SCI (DP-SCI). We hypothesized that extension of MEPs monitoring beyond ACI can also help decrease the risk of DP-SCI.

METHODS

We identified 150 consecutive patients at our institution between April 2005 and October 2014 who underwent OTAAR with DAP and MEPs monitoring and had no IP-SCI. Using logistic regression analysis, we studied the independent effect of extended MEPs monitoring on the risk of developing DP-SCI. We used a propensity score analysis to adjust for potential confounders, such as poorly controlled hypertension, previous aneurysm surgery, splenectomy, acute aortic dissection, aneurysm type, older age, and history of diabetes and smoking.

RESULTS

From the 150 patients, 129 (86%) remained neurologically intact whereas 21 (14%) developed DP-SCI. Nineteen of these twenty-one patients (90%) had no extended monitoring. Fifty-seven of fifty-nine (97%) patients who benefited from extended monitoring had no DP-SCI (p = 0.003). Extended MEPs monitoring was independently associated with decreased risk of DP-SCI (odds ratio = 0.14; 95% confidence interval: 0.03, 0.65; p = 0.01).

INTERPRETATION

MEPs detect the lowest systemic blood pressure that ensures appropriate spinal cord perfusion in the postoperative period. Thus, they inform the hemodynamic management of patients post-OTAAR, particularly in the absence of a reliable neurological exam.

Neuromonitoring, Cerebrospinal Fluid Drainage, and Selective Use of Iliofemoral Conduits to Minimize Risk of Spinal Cord Injury During Complex Endovascular Aortic Repair

Purpose: To review outcomes of continuous motor/somatosensory-evoked potential (MEP/SSEP) monitoring, cerebrospinal fluid drainage, and selective use of iliofemoral conduits in patients undergoing endovascular repair of descending thoracic aneurysm (DTA) and thoracoabdominal aortic aneurysms (TAAAs). Methods: The clinical data of 49 patients (mean age 75±8 years; 38 men) who underwent endovascular repair of DTA and TAAAs (2011–2014) were reviewed. All patients had cerebrospinal fluid drainage, permissive hypertension (mean arterial pressure ≥80 mm Hg), and MEP/SSEP monitoring. There were 44 (90%) patients with TAAAs and 5 (10%) with DTA. Types I and II TAAAs were repaired in staged procedures. Iliofemoral conduits were used for small iliac arteries and to minimize time of lower extremity ischemia in patients with difficult anatomy. In patients with changes in MEP/SSEPs, a standardized protocol was employed to optimize spinal cord perfusion and restore lower extremity blood flow. Endpoints were mortality, spinal cord injury (SCI), and lower extremity ischemic complications. Results: Sixteen (33%) patients had staged TAAA repair. A total of 163 visceral arteries were targeted by fenestrations and branches (mean 3.7±1.0 vessels/patient). Temporary iliofemoral conduits were used in 16 limbs/14 patients. A stable MEP/SSEP was achieved in all patients. Thirty-one (63%) patients had a ≥75% decrease in MEP/SSEP amplitude in 50 limbs starting on average 75±28 minutes after obtaining vascular access. MEP/SSEP amplitude improved with maneuvers in 12 (39%) patients and returned to baseline with restoration of lower extremity flow in all except 1 patient who developed immediate SCI. Thirty-day mortality was 4%. Three (6%) patients had SCI, 2 permanent and 1 temporary at 14 days. There were no lower extremity ischemic complications. Conclusion: Neuromonitoring predicted immediate SCI and allowed use of a protocol to optimize spinal cord and lower extremity perfusion during complex endovascular aortic repair. Larger clinical experience is needed to evaluate the efficacy of neuromonitoring to prevent SCI.

Management of Recurrent Delayed Neurologic Deficit After Thoracoabdominal Aortic Operation

Delayed neurologic deficit (DND) is a devastating adverse event after thoracoabdominal aortic aneurysm repair. Multiple adjuncts have been devised to counteract the development of DND, most notably cerebrospinal fluid (CSF) drainage. We report a case of a 63-year-old woman in whom DND developed four times during the first 10 days after her thoracoabdominal aortic operation. This necessitated lumbar drain "weaning" to allow for a slowly rising CSF pressure and preservation of lower extremity motor function.

Management of acute aortic dissection

A new appraisal of the management of acute aortic dissection is timely because of recent developments in diagnostic strategies (including biomarkers and imaging), endograft design, and surgical treatment, which have led to a better understanding of the epidemiology, risk factors, and molecular nature of aortic dissection. Although open surgery is the main treatment for proximal aortic repair, use of endovascular management is now established for complicated distal dissection and distal arch repair, and has recently been discussed as a pre-emptive measure to avoid late complications by inducing aortic remodelling.

Early and late management of type B aortic dissection

The management of type B aortic dissection is undergoing profound changes with timely TEVAR accepted as first-line strategy in the setting of complicated dissection; with recent technological advances and in experienced hands this intervention is considered safe and life-saving. With the ability to remodel the dissected aorta as a result of scaffolding even pre-emptive endovascular treatment is being considered and supported by long-term stability and often prevention of aneurysmal expansion. This insight and a growing number of silent risk conditions (resistant hypertension, partial false lumen thrombosis) may lower the threshold for TEVAR in asymptomatic patients in the subacute phase. In the chronic phase of a type B dissection patients are usually free of symptoms, however, with the expanding false lumen at risk of rupture. Advanced TEVAR options (including branches and fenestrations) are likely to be used more often than open surgical replacement of such aneurysmatic segment of the dissected aorta in that chronic phase. All dissection patients should be offered lifelong surveillance.

Role of the TLR4 pathway in blood-spinal cord barrier dysfunction during the bimodal stage after ischemia/reperfusion injury in rats

Background

Spinal cord ischemia-reperfusion (I/R) involves two-phase injury, including an initial acute ischemic insult and subsequent inflammatory reperfusion injury, resulting in blood-spinal cord barrier (BSCB) dysfunction involving the TLR₄ pathway. However, the correlation between TLR₄/MyD₈₈-dependent and TLR₄/TRIF-dependent pathways in BSCB dysfunction is not fully understood. The aim of this study is to characterize inflammatory responses in spinal cord I/R and the events that define its clinical progression with delayed neurological deficits, supporting a bimodal mechanism of injury.

Methods

Rats were intrathecally pretreated with TAK-242, MyD₈₈ inhibitory peptide, or Resveratrol at a 12 h interval for 3 days before undergoing 14-minute occlusion of aortic arch. Evan’s Blue (EB) extravasation and water content were detected at 6, 12, 18, 24, 36, 48, and 72 h after reperfusion. EB extravasation, water content, and NF-κB activation were increased with time after reperfusion, suggesting a bimodal distribution, as maximal increasing were detected at both 12 and 48 h after reperfusion. The changes were directly proportional to TLR₄ levels determined by Western blot. Double-labeled immunohistochemical analysis was also used to detect the relationship between different cell types of BSCB with TLR₄. Furthermore, NF-κB and IL-1β were analyzed at 12 and 48 h to identify the correlation between MyD₈₈-dependent and TRIF-dependent pathways.

Results

Rats without functional TLR₄ and MyD₈₈ attenuated BSCB leakage and inflammatory responses at 12 h, suggesting the ischemic event was largely mediated by MyD₈₈-dependent pathway. Similar protective effects observed in rats with depleted TLR₄, MyD₈₈, and TRIF receptor at 48 h infer that the ongoing inflammation which occurred in late phase was mainly initiated by TRIF-dependent pathway and such inflammatory response could be further amplified by MyD₈₈-dependent pathway. Additionally, microglia appeared to play a major role in early phase of inflammation after I/R injury, while in late responding phase both microglia and astrocytes were necessary.

Conclusions

These findings indicate the relevance of TLR₄/MyD₈₈-dependent and TLR₄/TRIF-dependent pathways in bimodal phases of inflammatory responses after I/R injury, corresponding with the clinical progression of injury and delayed onset of symptoms. The clinical usage of TLR₄ signaling inhibitors at different phases may be a therapeutic option for the prevention of delayed injury.

Setting up and utilizing a service for measuring perioperative transcranial motor evoked potentials during thoracoabdominal aortic surgery and thoracic endovascular repair

OBJECTIVES

Paraplegia is a complication that may occur following surgery or endovascular stenting of thoracic and thoracoabdominal aortic pathology. Measuring transcranial motor evoked potentials (tcMEPs) has been shown to provide a reliable measure of spinal cord function during such procedures allowing interventions to protect cord function. In the spirit of sharing experience and eliminating the learning curve for others, this manuscript describes our experience of setting up a service for tcMEP monitoring as well as the documents and algorithms for measuring, recording and acting on the patient data, the so-called 'MEP Pathway'.

METHODS

Recording and interpretation of tcMEP during thoracoabdominal aortic intervention requires training of staff and close team working in the operating theatre and postoperative intensive care unit. Providing consistent, reliable, specific and sensitive information on spinal cord function and its safe and effective use to alter patient outcomes requires a protocol. The MEP pathway was developed by medical and paramedical staff at our institution based on clinical experience and literature reviews over a 1-year period (2012-2013).

RESULTS

The tcMEP pathway comprises six documents that guide staff in: (a) assessing suitability of patients, (b) setting up hardware, (c) preparing algorithms for management, (d) documenting intervention (left heart bypass, cardiopulmonary bypass or endovascular stenting) as well as (e) documenting postoperative intensive care processes.

CONCLUSIONS

The tcMEP pathway acts as a guide for safe introduction and use of tcMEPs in thoracoabdominal aortic interventions. tcMEP-led guidance of intraoperative and postoperative management in thoracic aortic surgery is an important adjunct in caring for this patient group.

The evolution of chemokine release supports a bimodal mechanism of spinal cord ischemia and reperfusion injury

BACKGROUND

Paraplegia remains a devastating complication of thoracic aortic surgery. The mechanism of the antecedent spinal cord ischemia and reperfusion injury (IR) remains poorly described. IR involves 2 injuries, an initial ischemic insult and subsequent inflammatory amplification of the injury. This mechanism is consistent with the clinical phenomenon of delayed onset paraplegia. This study sought to characterize the inflammatory response in the spinal cord after IR and hypothesized that this would support a bimodal mechanism of injury.

METHODS AND RESULTS

Male C57Bl/6 mice were subjected to 5 minutes of aortic arch and left subclavian occlusion with subsequent reperfusion to generate spinal cord ischemia. Functional outcomes were scored at 12-hour intervals. Spinal cords were harvested after 0, 6, 12, 18, 24, 36, and 48 hours of reperfusion. Cytokine levels were analyzed using a mouse magnetic bead-based multiplex immunoassay. Inflammatory chemokine concentrations (interleukin [IL]-1β, IL-6, keratinocyte-derived cytokine, macrophage inflammatory protein-1α, monocyte chemotactic protein-1, RANTES, and tumor necrosis factor-α) peaked at 6 hours and 36 to 48 hours after reperfusion. Functional scores reflected initial gain in function with subsequent decline, inversely proportional to cytokine levels. Immunofluorescent staining demonstrated microglia activation at 12 and 48 hours.

CONCLUSIONS

Spinal cord ischemia and reperfusion injury occurs in 2 phases, correlating to increases in inflammatory chemokines release and microglial activation. These observations chronologically parallel the too-common clinical syndrome of delayed-onset paraplegia. Understanding the molecular pathogenesis of this injury may allow future intervention to prevent this devastating complication.

Endovascular repair of thoracic aortic aneurysms

Degenerative aneurysms of the thoracic aorta are increasing in prevalence; open repair of descending thoracic aortic aneurysms is associated with high rates of morbidity and mortality. Repair of isolated descending thoracic aortic aneurysms using stent grafts was introduced in 1995, and in an anatomically suitable subgroup of patients with thoracic aortic aneurysm, repair with endovascular stent graft provides favorable outcomes, with decreased perioperative morbidity and mortality relative to open repair. The cornerstones of successful thoracic endovascular aneurysm repair are appropriate patient selection, thorough preprocedural planning, and cautious procedural execution, the elements of which are discussed here.

Effects of minocycline on hind-limb motor function and gray and white matter injury after spinal cord ischemia in rats

STUDY DESIGN

A prospective, randomized laboratory investigation.

OBJECTIVE

To investigate whether administration of minocycline attenuates hind-limb motor dysfunction and gray and white matter injury after spinal cord ischemia.

SUMMARY OF BACKGROUND DATA

Minocycline, a semisynthetic tetracycline antibiotic, has been shown to have neuroprotective effects in models of focal and global cerebral ischemia. However, there have been no data available regarding the effects of minocycline in a model of spinal cord ischemia.

METHODS

Thirty-six rats were randomly allocated to one of three groups; control (C) group (n = 11), minocycline (M) group (n = 13), or sham group (n = 12). Minocycline or saline was intraperitoneally administered for 3 days beginning at 12 hours before 10 minutes of spinal cord ischemia or sham operation. Spinal cord ischemia was induced with intraaortic balloon catheter and blood withdrawal. Seventy-two hours after reperfusion, hind-limb motor functions were assessed using Basso, Beattie, Bresnahan (BBB) Scale (0 = paraplegia, 21 = normal). For histologic assessments, the gray and white matter injury was evaluated using the number of normal neurons and the extents of vacuolations in the white matter, respectively. Activated microglia was also evaluated using Iba-1 immunohistochemistry.

RESULTS

BBB scores and the numbers of normal neurons in the M group were significantly higher than those in the C group. The percentage areas of vacuolations in the white matter and the number of Iba-1 positive cells were significantly lower in the M group compared with those in the C group.

CONCLUSION

The results indicated that minocycline administration improved hind-limb motor function and attenuated gray and white matter injury and microglial activation after spinal cord ischemia in rats.

Management of acute aortic syndromes

Acute aortic syndrome (AAS) is a modern term to describe interrelated emergency aortic conditions with similar clinical characteristics and challenges. These conditions include aortic dissection, intramural haematoma (IMH), and penetrating atherosclerotic ulcer (PAU and aortic rupture); trauma to the aorta with intimal laceration may also be considered. The common denominator of AAS is disruption of the media layer of the aorta with bleeding within IMH, along the aortic media resulting in separation of the layers of the aorta (dissection), or transmurally through the wall in the case of ruptured PAU or trauma. Population-based studies suggest that the incidence of acute dissection ranges from 2 to 3.5 cases per 100 000 person-years; hypertension and a variety of genetic disorders with altered connective tissues are the most prevalent risk conditions. Patients with AAS often present in a similar fashion, regardless of the underlying condition of dissection, IMH, PAU, or contained aortic rupture. Pain is the most commonly presenting symptom of acute aortic dissection and should prompt immediate attention including diagnostic imaging modalities (such as multislice computed tomography, transoesophageal ultrasound, or magnetic resonance imaging). Prognosis is clearly related to undelayed diagnosis and appropriate surgical repair in the case of proximal involvement of the aorta; affection of distal segments of the aorta may call for individualized therapeutic approaches favouring endovascular in the presence of malperfusion or imminent rupture, or medical management.

Continued favorable results with open surgical repair of type IV thoracoabdominal aortic aneurysms

OBJECTIVES

Type IV thoracoabdominal aortic aneurysm (TAAA) repair, despite low risk of spinal cord ischemia (SCI), is reported to have significant morbidity and mortality. This has led some to apply adjuncts (eg, extracorporeal circulation) used in more extensive TAAA repair or to consider alternative approaches, such as hybrid operations. We have used a consistent, simplified surgical approach to type IV TAAA, and the goal of the present study is to review experience over 2 decades with such treatment and to identify correlates of surgical morbidity.

METHODS

All type IV repairs at Massachusetts General Hospital from January 1989 through September 2009 were evaluated for clinical features, technical operative details, and 30-day outcomes. Logistic regression identified predictors of morbidity. Survival was assessed using Kaplan-Meier analysis.

RESULTS

A total of 179 patients underwent type IV repair, with elective repair in 156 (87%) and urgent in 23 (13%). The clamp-and-sew technique was used for all operations, with routine hypothermic renal perfusion. Clinical features were age 73 ± 8 years, coronary artery disease in 89 (50%), and creatinine level >1.8 mg/dL defining chronic renal insufficiency (CRI) in 32 (18%). Operative reconstruction in 166 (93%) consisted of one beveled proximal anastomosis incorporating the descending thoracic aorta, celiac, superior mesenteric artery, and right renal arteries origins (mean visceral clamp time, 36 ± 12 minutes) and a side-arm graft to the left renal artery. Technical details included previous abdominal aortic aneurysm (AAA) repair in 52 (29%), operative time of 290 ± 90 min, estimated blood loss of 2.7 ± 1.4 L, and splenectomy in 57 (32%). The 30-day outcomes were death in 5 (2.8%), myocardial infarction in 6 (3.4%), hemodialysis in 5 (2.8%), and any degree of SCI in 4 (2.2%). Regression analysis identified a history of CRI as an independent predictor of postoperative complication or death (odds ratio, 3.4; 95% confidence interval, 1.4-8). Survival rates at 1, 5, and 10 years were 89% ± 2%, 62% ± 4%, and 36% ± 5%, respectively.

CONCLUSIONS

A simplified operative approach for type IV TAAA repair is associated with favorable perioperative results. These data refute the need for surgical adjuncts commonly applied in more extensive TAAA and indicate that the hybrid operation is an illogical posture. CRI should figure prominently in clinical decision making. Long-term survival equates that observed after routine AAA repair.