Optimal occlusion pattern for minimally invasive staged segmental artery coil embolization in a chronic porcine model

OBJECTIVES: Minimally invasive staged segmental artery coil- and plug embolization (MIS(2)ACE) has been introduced for spinal cord injury prevention prior to open or endovascular thoraco-abdominal aortic aneurysm repair. To date, no optimal pattern has been developed. The aim of this study was to identify the optimal MIS(2)ACE occlusion pattern. METHODS: Twenty-five juvenile pigs were randomly assigned to 3 MIS(2)ACE occlusion patterns (2 stages) and a control group [single-stage segmental artery (SA) occlusion, N = 7]. The first pattern started with occlusion of all lumbar segmental arteries in the first stage and the remaining thoracic arteries in the second stage (regional pattern, N = 6). In group 2, an alternating approach with occlusion of every other SA in the first stage and the remainder in the second stage was used (alternating pattern, N = 6). The third pattern started with occluding the watershed area between thoracic level 12 and lumbar level 2 in the first stage and the remaining arteries in the second stage (watershed pattern, N = 6). Neurological assessment at 6-h intervals and spinal cord tissue perfusion measurements via microspheres at 6 time points were performed. At the end of the experiments, the spinal cord was histopathologically examined. RESULTS: An average of 6 +/- 2 coils were used per SA. In the control group a total of 57% (N = 4) of animals experienced permanent paraplegia, 1 animal (16%) of the alternating and watershed intervention group suffered from permanent paraplegia. Animals from the staged regional pattern did not experience permanent paraplegia. Furthermore, no evidence of significant tissue damage was observed (P < 0.05 vs control). Tissue perfusion of the lumbar spinal cord in the regional pattern group recovered within 3 days after the second stage to 89.2 +/- 47 percent-of-baseline (P = 0.393), whereas mean perfusion of the other 2 intervention groups and the control remained significantly lower compared to the baseline (35.7 +/- 16%, 30.2 +/- 11% and 63.2 +/- 19, P < 0.05). CONCLUSIONS: This study provides evidence that MIS(2)ACE (minimally invasive staging) may result in less ischaemic spinal cord injury and favourable neurological outcomes compared to complete (1 stage) SA occlusion. A regional-based occlusion pattern (starting with the lumbar segmental arteries) seems to be the best 2-stage approach.