Arteriogenesis of the Spinal Cord-The Network Challenge

[Ischemia-related compartment syndromes in vascular surgery]

Even after the endovascular revolution, acute compartment syndrome (CS) remains an important and frequently present differential diagnosis after many operations. Based on a qualitative review this article gives an overview of the most frequent forms of CS as well as some less frequent entities that require attention in the routine clinical practice. Additionally, the pathophysiology, diagnostics and treatment as well as current research topics for CS, especially concerning the lower leg, are dealt with in detail. In summary, nothing has essentially changed ever since the first description of CS in that the clinical estimation remains the gold standard. The detection and the adequate treatment especially of abdominal CS and CS of the lower leg remain a key competence of vascular surgeons.

Peptide OM-LV20 promotes arteriogenesis induced by femoral artery ligature via the miR-29b-3p/VEGFA axis

BACKGROUND AND AIMS

Therapeutic arteriogenesis is a promising direction for the treatment of ischemic disease caused by atherosclerosis. However, pharmacological or biological approaches to stimulate functional collateral vessels are not yet available. Identifying new drug targets to promote and explore the underlying mechanisms for therapeutic arteriogenesis is necessary.

METHODS

Peptide OM-LV20 (20 ng/kg) was administered for 7 consecutive days on rat hindlimb ischemia model, collateral vessel growth was assessed by H&E staining, liquid latex perfusion, and specific immunofluorescence. In vitro, we detected the effect of OM-LV20 on human umbilical vein endothelial cells (HUVEC) proliferation and migration. After transfection, we performed quantitative real-time polymerase chain reaction, in situ-hybridization and dual luciferase reporters to assessed effective miRNAs and target genes. The proteins related to downstream signaling pathways were detected by Western blot.

RESULTS

OM-LV20 significantly increased visible collateral vessels and endothelial nitric oxide synthase (eNOS), together with enhanced inflammation cytokine and monocytes/macrophage infiltration in collateral vessels. In vitro, we defined a novel microRNA (miR-29b-3p), and its inhibition enhanced proliferation and migration of HUVEC, as well as the expression of vascular endothelial growth factor A (VEGFA). OM-LV20 also promoted migration and proliferation of HUVEC, and VEGFA expression was mediated via inhibition of miR-29b-3p. Furthermore, OM-LV20 influenced the protein levels of VEGFR2 and phosphatidylinositol3-kinase (PI3K)/AKT and eNOS in vitro and invivo.

CONCLUSIONS

Our data indicated that OM-LV20 enhanced arteriogenesis via the miR-29b-3p/VEGFA/VEGFR2-PI3K/AKT/eNOS axis, and highlighte the application potential of exogenous peptide molecular probes through miRNA, which could promote effective therapeutic arteriogenesis in ischemic conditions.

Usefulness of Motor Evoked Potential Measurement and Analysis of Risk Factors for Spinal Cord Ischaemia from 300 Cases of Thoracic Endovascular Aortic Repair

OBJECTIVE

This study investigated the usefulness of motor evoked potentials (MEPs) for intra-operative monitoring to detect the risk of spinal cord ischaemia (SCI) during thoracic endovascular aortic repair (TEVAR). Risk factors for SCI in TEVAR were also analysed.

METHODS

Among 330 TEVARs performed from February 2009 to October 2018, 300 patients underwent intra-operative MEP monitoring. SCI risk groups were extracted based on MEP amplitude changes using a cutoff value of 50%. When the amplitude decreased to < 50% of the pre-operative value, intra-operative mean arterial pressure (MAP) was increased by about 20 mmHg using noradrenaline, whereas MAP was usually controlled to about 80 mmHg during surgery. Other efforts were also made to increase MEP amplitude by increasing cardiac output, correcting anaemia, and finishing the surgery promptly. Based on MEP amplitude data, SCI risk groups were extracted and risk factors for SCI in TEVAR were analysed.

RESULTS

A total of 283 non-SCI risk patients and 17 SCI risk patients by MEP monitoring were extracted; only 1.0% developed immediate paraplegia and none developed delayed paraplegia. Bivariable analysis showed significant differences in chronic kidney disease, haemodialysis, artery of Adamkiewicz closure, and stent graft (SG) covered length ≥ 8 vertebral bodies. Logistic regression analysis showed hyperlipidaemia (odds ratio [OR] 3.55, 95% confidence interval [CI] 1.08 - 11.67; p = .037), SG covered length ≥ 8 vertebral bodies (OR 1.35, 95% CI 1.02 - 1.78; p = .034), and haemodialysis (OR 27.78, 95% CI 6.02 - 128.22; p < .001) were the most influential risk factors for SCI in TEVAR.

CONCLUSION

MEPs might be a useful monitoring tool to predict SCI in TEVAR. In addition, hyperlipidaemia, SG covered length ≥ 8 vertebral bodies, and haemodialysis represent key risk factors for SCI during TEVAR.

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 for thoracoabdominal aortic aneurysm repair: from bench to bedside

This keynote lecture and corresponding presentation discuss the anatomy and pathophysiology surrounding spinal cord injury in aortic surgery. This article will discuss risk factors and mechanisms for spinal cord injury, including loss of direct and collateral spinal cord perfusion and ischemia-reperfusion injury. This review will examine these elements in both the laboratory and clinical setting, in addition to other neuroprotective strategies applied in clinical practice. Addressing spinal cord injury requires an integrated and considerate approach to simultaneously optimize spinal cord blood flow, promote collateralization and improve ischemic tolerance. Given the catastrophic clinical consequences for both the patient and their caregivers, continuing to investigate and examine spinal cord injury is of the utmost importance.

Fenestrated and Branched Stent-Grafts for the Treatment of Thoracoabdominal Aortic Aneurysms: A Systematic Review and Meta-Analysis

Purpose

To investigate the safety and efficacy of total endovascular repair for thoracoabdominal aortic aneurysms (TAAAs) with fenestrated and branched stent-grafts.

Methods

The MEDLINE, EMBASE, and Cochrane databases were searched between January 2001 and December 2021 to identify literature relevant to the use of fenestrated and branched endografts for the treatment of TAAAs. Studies with <4 cases and those on juxtarenal or pararenal aortic aneurysms were excluded. Meta-analyses were conducted to evaluate spinal cord ischemia (SCI), irreversible SCI, renal insufficiency, dialysis, endoleak, reintervention, target vessel patency, 30-day mortality and overall mortality. Fourteen studies comprising 1,114 patients (mean age 72.42 years, 847 men) were selected. The mean TAAA diameter was 67 mm. The Crawford TAAA classification was type I-III in 759 cases, type IV in 344 cases, and type V in 10 cases. Outcomes of the meta-analysis are reported as proportions and 95% confidence intervals (CIs).

Results

The pooled rates for 30-day mortality and overall mortality were 6% and 18%, respectively. The pooled rate for technical success was 94% (95% CI, 93–96%), for SCI was 8% (95% CI, 7–10%), for irreversible SCI was 6% (95% CI, 4–7%), for reversible SCI was 5% (95% CI, 4–6%), for reversible SCI was 2% (95% CI, 2–3%), for renal insufficiency was 7% (95% CI, 5–10%), for dialysis was 3% (95% CI, 2–4%), for target vessel patency was 98% (95% CI, 97–99%), and for reintervention was 15% (95% CI, 9–24%).

Conclusion

Fenestrated and branched endografts for the treatment of TAAAs are safe and effective with acceptable early results. Lifelong regular follow-up and additional prospective studies are necessary to substantiate whether this technique is valid.

Erythropoietin regulates signaling pathways associated with neuroprotective events

Erythropoietin is a cytokine that binds to the Erythropoietin receptor and regulates the formation of erythroid cells during erythropoiesis in the bone marrow. However, many other organs and tissues express Erythropoietin and its receptor, such as the Nervous System, which principally regulates tissue protection. In the Central Nervous System, Erythropoietin is principally expressed by astrocytes, while neurons mainly express Erythropoietin receptors. Moreover, Erythropoietin acts as a pleiotropic molecule with neuroprotective effects, and its mechanisms of signal transduction pathways are defined, and there is a growing interest in its therapeutic potential. This review focuses on the role of Erythropoietin and its relationship with HIF1, PI3/Akt, GSK3B, JAK/STAT, and MAPKs signaling pathways that leads to cell survival after injury in the Central Nervous System. Knowledge of these signaling systems comprehensively could better guide EPO treatment to restoring different SNC alterations mediated by different insults.

[Open thoracic and thoracoabdominal aortic repair vs. f/bTEVAR - complementary or competitive?]

The classical approach of open repair (OR) for thoracic and thoracoabdominal aortic pathologies, including aneurysms and dissection, has been outnumbered by the use of fenestrated/branched (thoracic) endovascular aortic repair (f/b[T]EVAR) in recent years. Providing OR for complex cases in an aortic service requires a dedicated surgical setup and a huge body of expertise in this particular field.In order to reduce specific complications, such as perioperative mortality, kidney failure, spinal cord ischemia, stroke or bowel ischemia, it is necessary to apply cerebrospinal-spinal fluid drainage, point-of-care coagulation therapy, distal and retrograde aortic perfusion and sequential clamping. Despite the predominance of endovascular solutions, the specific OR expertise is still needed for specific indications, such as young patients, connective tissue disorder or aortic graft infections.Currently, the short and mid term results for f/b(T)EVAR outweigh those for OR, including the shorter hospital stay and less invasive procedures. However, OR provides better long-term results for overall mortality, re-intervention rates and secondary complications.In conclusion, in our opinion OR is a service that is still necessary for dedicated aortic centres, but will most likely become more frequent again in the years to come.

Risk factors associated with post-operative neurological deterioration in patients with thoracic disc disorders with myelopathy

PURPOSE

Post-operative neurological deterioration (ND) is a severe complication. However, limited literature exists on the ND in thoracic disc disorders with myelopathy (TDM). This study describes the risk factors of neurological deterioration in TDM with instrumentation and fusion.

METHODS

A single-centre review of TDM with instrumentation and fusion during 2006-2019 was performed. Post-operative neurological deterioration was defined as the deterioration of pre-existing neurological function or the appearance of new neurological symptoms. Patients were then grouped into two groups depending on neurological deterioration (ND group) or not (non-ND group). Demographics, radiographic parameters, and surgical characteristics were compared between the two groups.

RESULTS

A total of 257 cases were included, and neurological deterioration occurred in 16 (6.23%) cases. Multivariate analysis revealed spinal canal occupancy ratio > 75%, U-shaped compressed spinal cord in axial MRI, calcified herniated disc, anterior approach, and intra-operative blood loss > 1500 mL were associated with ND. Ten patients (62.5%) had complete neurological recovery within six months, and four patients (25%) had progressive neurological function improvement and equal or better than pre-operation within nine months.

CONCLUSIONS

The rate of neurological deterioration is 6.23%, and a higher spinal canal occupancy ratio, U-shaped compressed spinal cord, calcified herniated disc, anterior approach, and massive intra-operative blood loss were associated with neurological deterioration. Long-term outcomes of neurological deterioration are favourable, and 62.5% of patients experienced complete neurological recovery within six months. Patients with TMD who undergo surgery should be properly informed of the potential risks of neurological deterioration, despite its usually transient nature in most patients.