Analysis of Spinal Cord Blood Supply Combining Vascular Corrosion Casting and Fluorescence Microsphere Technique: A Feasibility Study in an Aortic Surgical Large Animal Model

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Abstract

Spinal cord ischemia after cardiovascular interventions continues to be a devastating problem in modern surgery. The role of intraspinal vascular networks and anterior radiculomedullary arteries (ARMA) in preventing spinal cord ischemia is poorly understood. We are the first to combine the fluorescence microsphere technique and vascular corrosion cast to investigate spinal cord blood supply in a large animal model. Landrace pigs (n= 30, 35.1 ± 3.9 kg) underwent a lateral thoracotomy. Fluorescent microspheres were injected into the left atrium and a reference sample was aspirated from the descending aorta. Repeated measurements of spinal cord and renal cortical blood flow from the left and right kidneys with three different microsphere colors in 5 pigs were taken to validate reproducibility. Spinal cord blood flow to the upper thoracic (T1-T4), mid-thoracic (T5-T8), lower thoracic (T9-T13), and lumbar (L1-L3) levels were determined. After euthanasia, we carried out selective vascular corrosion cast and counted the left and right ARMAs from levels T1-T13. We observed no alterations in blood flow analysis and fluorescence background noise when using vascular corrosion casting in the same tissue. Repeated measurements of cortical renal blood flow and spinal cord blood flow were reproducible. Blood flow analysis of the left and right kidneys revealed a strong correlation (r = 0.94, p<0.001). We detected more left than right ARMAs, with the highest prevalence at T4 (p<0.05). The mean number of ARMAs was 8 ± 2. Their number in the upper thoracic region ranged from 2 to 7 (mean of 5 ± 1), while in the lower thoracic region they ranged from 0 to 5 (mean of 3 ± 1 (p<0.001)). This study shows that combining fluorescence microsphere technique and vascular corrosion cast is well suited for assessing the blood flow and visualizing the arteries at the same time.