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.

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

OBJECTIVE: Ischemic spinal cord injury remains the most devastating complication after open and endovascular aortic repair. Collateral network near-infrared spectroscopy has been introduced to noninvasively monitor real-time spinal cord oxygenation. In view of recent advancements in endovascular treatment and minimally invasive staged preconditioning before aortic repair, this study sought to evaluate collateral network near-infrared spectroscopy during and after segmental artery occlusion in a chronic porcine model. METHODS: Surgery for segmental artery occlusion was performed in 12 juvenile pigs, and bilateral lumbar collateral network near-infrared spectroscopy was recorded. Two intervention groups were designed: Group 1 received subtotal segmental artery occlusion (mimicking reimplantation of crucial segmental arteries with patent T12/T13, N = 5), and group 2 received total occlusion (T4-L5, N = 7). Pigs were monitored over 3 days. RESULTS: All animals were paraplegic during the first 24 hours. The subtotal occlusion group completely recovered, whereas 57% of the total occlusion group remained paraplegic (N = 4/7). After segmental artery occlusion, collateral network near-infrared spectroscopy decreased from 92.3% ± 8% of baseline to 69.3% ± 18% after 10 minutes in the subtotal group (P = .003-.017) and from 90.1% ± 4% to 58.2% ± 9% in the total group (P < .001-.008). Throughout the postoperative period, collateral network near-infrared spectroscopy in the total occlusion group remained lower compared with the subtotal group (<30% baseline threshold, P < .05). Lumbar collateral network near-infrared spectroscopy and neurologic outcome were significantly correlated (R = 0.7, P < .001). CONCLUSIONS: Lumbar collateral network near-infrared spectroscopy reacts to occlusion of segmental arteries and correlates with neurologic outcome. The preliminary data suggest that collateral network near-infrared spectroscopy may be a valuable noninvasive tool for detecting imminent spinal cord ischemia during and after aortic procedures involving segmental artery occlusion.