Evaluation of collateral network near-infrared spectroscopy during and after segmental artery occlusion in a chronic large animal model

Near-Infrared Spectroscopy for Spinal Cord Monitoring-A Roadmap to Translational Research in Aortic Medicine

Extensive aortic aneurysms represent a unique challenge necessitating interdisciplinary efforts for safe and effective treatment. Despite various adjunctive neuroprotective strategies, ischemic spinal cord injury remains a devastating complication. This article describes the implementation of collateral network near-infrared spectroscopy as the first noninvasive spinal cord monitoring modality in the setting of extensive open and endovascular aortic repair, from early conceptualization to clinical utilization. Potential capabilities and remaining uncertainties based on current evidence are outlined and discussed.

Anesthetic Management for Open Thoracoabdominal and Abdominal Aortic Aneurysm Repair

Open thoracoabdominal and abdominal aortic aneurysm repairs are some of the most challenging cases for anesthesiologists because of the potential for rapid blood loss combined with clamping and reperfusion, potential use of left heart bypass, the potential need for lung isolation, and potential placement and management of a spinal drain. In addition, patients often present with other significant comorbidities and a detailed understanding of the disease process, the complex physiology throughout the case, and the intricacies of organ protection are critical.

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.

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.

Near-Infrared Spectroscopy (NIRS) for Cerebral and Tissue Oximetry: Analysis of Evolving Applications

THE USE OF NEAR-INFRARED SPECTROSCOPY (NIRS) has increased significantly worldwide in the past decade. This technology, first described more than 40 years ago, is based on the fact that near-infrared light is able to penetrate biologic tissue and can obtain real-time, noninvasive information on tissue oxygenation and metabolism. In the clinical setting, NIRS has been able to provide clinicians potentially valuable information in patients with impaired microcirculations (systemic and cerebral). Near-infrared spectroscopy has progressed beyond assessment of brain oxygenation to monitor local tissue and muscle oxygenation and perfusion. This review analyzes the published data and provides the clinician a comprehensive account of the perioperative utility of NIRS in cardiac, vascular and thoracic surgery, as well as its increasing role in tissue/muscle oxygenation monitoring.

When should a rare inherited connective tissue disorder be suspected in bicuspid aortic valve by primary-care internists and cardiologists? Proposal of a score

Size threshold for aortic surgery in bicuspid aortic valve (BAV) is debated. Connective tissue disorders (CTDs) are claimed as a clinical turning point, suggesting early surgery in BAV patients with CTD. Thus, we aimed at developing a score to detect high risk of carrying CTDs in consecutive BAVs from primary care. Ninety-eight BAVs without ectopia lentis or personal/family history of aortic dissection were studied at the Marfan syndrome Tuscany Referral Center. Findings were compared with those detected in 84 Marfan patients matched for sex and age. We selected traits with high statistical difference between MFS and BAV easily obtainable by cardiologists and primary-care internists: mitral valve prolapse, myopia ≥ 3DO, pectus carenatum, pes planus, wrist and thumb signs, and difference between aortic size at root and ascending aorta ≥ 4 mm. Clustering of ≥ 3 of these manifestations were more frequent in Marfan patients than in BAVs (71.4% vs 6.1%, p < 0.0001) resulting into an Odds Ratio to be affected by MFS of 38.3 (95% confidence intervals 14.8-99.3, p < 0.0001). We propose a score assembling simple clinical and echocardiographic variables resulting in an appropriate referral pattern of BAVs from a primary-care setting to a tertiary center to evaluate the presence of a potential, major CTD.

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.

Paraspinal muscle claudication after fenestrated-branched endovascular aortic repair of thoracoabdominal aortic aneurysms

Fenestrated-branched endovascular repair of thoracoabdominal aneurysms carries a risk of spinal cord ischemia owing to extensive coverage of intercostal arteries, but other consequences of decreased flow to the paraspinal muscles have not been delineated. We describe a 54-year-old woman treated by multibranched thoracoabdominal aneurysm repair who developed severe disabling exertional thoracic and lumbar back pain after the operation. Despite physical therapy, the patient remains with disabling symptoms at 2 years of follow-up. Transcutaneous oxygen pressures confirmed exercise-induced decrease in oxygen pressure, consistent with decreased muscle perfusion. We propose the term paraspinal muscle claudication to describe these symptoms.

Sizing and planning fenestrated and branched stent-grafts in patients with chronic post-dissection thoracoabdominal aortic aneurysms

Fenestrated-branched endovascular repair (FB-EVAR) has been widely applied to treat chronic post-dissection thoracoabdominal aortic aneurysms (TAAAs) with favorable outcomes. A recent multicenter experience indicates that outcomes of FB-EVAR for chronic post-dissection are comparable to degenerative TAAAs. Anatomical and technical pitfalls are different than degenerative aneurysms because of true lumen compression, separate target vessel origin from true or false lumen and possible extension of dissection flaps into the renal and mesenteric vessels. This article focuses on planning and sizing FB-EVAR in patients with chronic post-dissection TAAAs.