Spinal Ischemia in Thoracic Aortic Procedures: Impact of Radiculomedullary Artery Distribution

Abstract

Background: The aim of this study was to assess the influence of thoracic anterior radiculomedullary artery (tARMA) distribution on spinal cord perfusion in a thoracic aortic surgical model.

Methods: Twenty-six pigs (34 ± 3 kg; study group, n = 20; sham group, n = 6) underwent ligation of the left subclavian artery and thoracic segmental arteries. End points were spinal cord perfusion pressure (SCPP), regional spinal cord blood flow (SCBF), and neurologic outcome with an observation time of 3 hours. tARMA distribution patterns tested for an effect on end points included (1) maximum distance between any 2 tARMAs within the treated aortic segment (0 or 1 segment = small-distance group; >1 segment = large-distance group) and (2) distance between the end of the treated aortic segment and the first distal tARMA (at the level of the distal simulated stent-graft end = group 0; gap of 1 or more segments = group ≥1).

Results: The number of tARMA ranged from 3 to 13 (mean, 8). In the large-distance group, SCBF dropped from 0.48 ± 0.16 mL/g/min to 0.3 ± 0.08 mL/g/min (p < 0.001). We observed no detectable SCBF drop in the small-distance group: 0.2 ± 0.05 mL/g/min at baseline to 0.23 ± 0.05 mL/g/min immediately after clamping (p = 0.147). SCBF increased from 0.201 ± 0.055 mL/g/min at baseline to 0.443 ± 0.051 mL/g/min at 3 hours postoperatively (p < 0.001) only in the small-distance group.

Conclusions: We demonstrate experimental data showing that distribution patterns of tARMAs correlate with the degree of SCBF drop and insufficient reactive parenchymal hyperemia in aortic procedures. Individual ARMA distribution patterns along the treated aortic segment could help us predict the individual risk of spinal ischemia.