Experimental near-infrared spectroscopy-guided minimally invasive segmental artery occlusion

OBJECTIVES

Minimally invasive staged segmental artery (SA) coil- and plug embolization is a new method for paraplegia prevention associated with extensive aortic procedures. Near-infrared spectroscopy of the paraspinal collateral network (cnNIRS) has emerged as a non-invasive method for spinal cord monitoring. The aim of this study was to evaluate cnNIRS to guide minimally invasive SA occlusion.

METHODS

In a chronic large animal experiment, 18 juvenile pigs underwent two-stage minimally invasive staged SA coil- and plug embolization for complete SA occlusion. Coil-embolization was performed either by SA main stem occlusion (characteristic of pig anatomy) or separately for the left- and right SA. Lumbar cnNIRS was recorded during and after the procedure. Neurological status was assessed up to 3 days after complete SA occlusion.

RESULTS

Mean time from SA coil embolization to minimum cnNIRS values was 11 ± 5 min with an average decrease from 101 ± 2% to 78 ± 8% of baseline (difference: -23 ± 9, P < 0.001). Lumbar cnNIRS demonstrated significant differences between left and right when SAs were occluded separately in all cases (-7 ± 4%, 1 min after first SA occlusion; P = 0.001). Permanent paraplegia occurred in 2 (11%) and any kind of neurological deficit-temporary or permanent-in 7 animals (39%). Association between lumbar cnNIRS and neurological outcome after minimally invasive staged SA coil- and plug embolization suggests positive correlation (R = 0.5, P = 0.052).

CONCLUSIONS

Lumbar cnNIRS independently reacts to unilateral SA occlusion. cnNIRS-guided SA occlusion is feasible and may become a useful adjunct facilitating adequate and complete vessel occlusion.

Narrative review on endovascular techniques for left subclavian artery revascularization during thoracic endovascular aortic repair and risk factors for postoperative stroke

OBJECTIVES

The aim of this study was to present a narrative review on endovascular techniques (ET) for revascularization of the left subclavian artery (LSA) during zone 2 thoracic endovascular aortic repair (TEVAR) and on risk factors for postoperative stroke following TEVAR procedures.

METHODS

Non-systematic search of the literature from the PubMed, Ovid and Scopus databases to identify relevant English-language articles fully published in the period 1 January 2010-1 August 2020.

RESULTS

Current general agreement is that LSA revascularization should be always attempted in the elective setting. Under urgent circumstances, it can be delayed but might be considered during the same session on a case-by-case basis. Three ET are currently available: (i) chimney/snorkels (also known as parallel grafts), (ii) fenestrations or branches and (iii) proximal scallops. The main issue with ET is the potential for increased peri-operative stroke risk owing to increased manipulation within the aortic arch. Also, they are relatively novel and further assessment of their long-term durability is needed. Intra-operative embolism and loss of left vertebral artery perfusion are hypothesized as the main causes of stroke in patients undergoing TEVAR.

CONCLUSIONS

The overall risk of stroke seems higher without LSA revascularization during zone 2 TEVAR. As LSA revascularization might have a direct effect in preventing posterior stroke, it should be routinely performed in elective cases, while a case-by-case evaluation can be made under urgent circumstances. While ET can provide effective options for LSA revascularization during zone 2 TEVAR, they are novel and need further durability assessment. Stroke after TEVAR is a multifactorial pathological process and preventing TEVAR-related cerebral injury remains a significant unmet clinical need.

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.

Short-term and Mid-term Outcomes after Use of the Native Infrarenal Aorta as Distal Landing Zone for Fenestrated-Branched Endovascular Aortic Repair

BACKGROUND

This study aimed to examine outcomes after use of the native infrarenal aorta as distal landing zone for fenestrated-branched endovascular aortic repair (F-BEVAR) of pararenal-thoracoabdominal aortic aneurysms (PRAA-TAAA).

METHODS

All F-BEVAR procedures for treatment of PRAA-TAAA (2011-2019) at 2 aortic centers were examined. The outcomes of interest were as follows: i) technical success, ii) perioperative morbidity, iii) preservation of lumbar arteries and the inferior mesenteric artery, iv) type IB endoleaks, v) reinterventions, vi) survival, vii) aneurysm sac behavior, and viii) infrarenal aortic changes.

RESULTS

Twenty consecutive patients with distal landing in the native infrarenal aorta were included (median age 71 years; 25% men). The median number of visible lumbar arteries at baseline was 7, and a patent inferior mesenteric artery (IMA) before the operation was present in 19 (95%) of the cases. There were no deaths within 30 days. One patient (5%), operated on with a 4-BEVAR for a type 2 TAAA, experienced spinal cord ischemia (permanent paraplegia). The median decrease in the number of visible lumbar arteries at the first postoperative scan was 3 from the baseline value, whereas a patent IMA was preserved in 12 out of 19 patients. Only in one case (5%), a type IB endoleak was noted for an overall technical success rate of 95%, which required a standard EVAR 20 months after the initial operation. The median follow-up duration for the study cohort was 491 days; all patients were alive at the longest available individual follow-up, and no instances of new-onset type IB endoleaks were observed. Another 3 late reinterventions (in addition to the one mentioned previously) were performed during midterm follow-up, all because of target vessel instability. In patients with ≥12 months of follow-up after the index procedure (n = 12, 60% of the entire cohort), no instances of aneurysm sac increase >5 mm were noted; the median largest aortic diameter was 51 mm with a median difference from baseline of -6 mm. The median distal landing zone diameter increase was 4 mm from baseline but never beyond the nominal stent-graft diameter, whereas the median aortic bifurcation diameter differed 1 mm from baseline.

CONCLUSIONS

This preliminary experience shows that the use of the native infrarenal aorta as a distal landing zone for F-BEVAR is safe in the short term and midterm in patients with suitable anatomy, allowing the sparing of collateral vessels. Longer follow-up is warranted to assess durability.

Use of Fenestrated Stent-Grafts for Preservation of Spinal Artery Flow During Endovascular Repair of Thoracoabdominal Aortic Disease

We illustrate the safety and feasibility of the application of fenestrated stent-grafts for the preservation of spinal artery flow during endovascular repair of thoracoabdominal aortic aneurysms (TAAA) in 2 patients deemed high-risk for spinal cord ischemia (SCI). In one case, an unstented fenestration was used in a 78-year-old male treated for distal stent-graft induced new entry tear. In the other case, a fenestration with a bridging stent-graft was used to revascularize a spinal artery in a 66-year-old female with Marfan disease and island patch aneurysm following open TAAA reconstruction. Both procedures were successful without any postoperative neurologic complication. The unstented fenestration led to a type III endoleak that required the relining of the aortic stent-graft 2 years later. The stented spinal fenestration was patent at a 5-year imaging follow-up.

Cerebrospinal Fluid Drainage During Endovascular Aortic Aneurysm Repair: A Systematic Review of the Literature and Treatment Recommendations

Introduction:

Spinal cord injury (SCI) is a known complication of aortic aneurysm repair. Previous reports indicate that cerebrospinal fluid drainage (CSFD) may reduce incidence of SCI during open aortic aneurysm repair but its utility in endovascular repair remains poorly understood. We performed a systematic review of the literature to examine the protocols and outcomes of CSFD in patients undergoing endovascular aortic aneurysm repair.

Methods:

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were utilized to conduct a systematic literature review. PubMed, Scopus, Ovid, Cochrane, and EMBASE were queried for articles published since 2016 using search terms “(cerebrospinal fluid diversion OR CSF diversion OR lumbar drain OR subarachnoid drain OR spinal) AND (aortic aneurysm AND thoracic AND endovascular OR TEVAR).” Ninety-two articles were identified and screened by 2 independent reviewers, and 23 studies met criteria for full-text review after initial screening.

Results:

A total of 8 studies met full inclusion criteria for final analysis. Six studies reported incidence of SCI in patients with CSFD and 2 compared SCI incidence between patients with and without CSFD. Protocols for drainage most commonly included draining to a target pressure intra- and postoperatively, between 8 and 12 mm Hg. Incidence of SCI ranged from 0% to 17% in patients with CSFD, and from 0% to 50% in those without CSFD. Rates of CSFD-related complications ranged from <1% to 28%.

Conclusion:

There may be a protective benefit of CSFD in preventing SCI, but there remains significant variation in drain placement protocols. Significant potential bias exists in the reviewed data. Higher quality studies on the role of CSFD in endovascular aortic aneurysm repair are needed.