Flow Rate in Pressure-Controlled, Selective Hypothermic Intercostal Artery Perfusion and Temperature Changes in Cerebrospinal Fluid during Thoracoabdominal Aortic Aneurysm Repair

Objectives: We have performed selective hypothermic intercostal artery perfusion (HIAP) during thoracoabdominal aortic aneurysm repair since 2011. The flow rate of individual HIAP and temperature change in the cerebrospinal fluid (CSF) were monitored. We have observed variability in the flow rate and temperature changes in the CSF. The objective of this study was to characterize the flow rate during HIAP and temperature changes in the CSF in terms of intraoperative confirmation of perfusion into the critical intercostal artery (ICA).

Methods: From January 2011 to July 2019, 113 cases underwent TAAA repair using HIAP technique in our institute. A sequence of HIAP technique is as follows. Prior to surgery, a spinal drainage catheter incorporated with a thermometer was placed in the intrathecal cavity by lumbar puncture. After an aneurysm was opened, a 10 mm prosthetic graft was anastomosed to the periphery of the ostium of the preoperatively identified critical ICA connected to the Adamkiewicz artery (AKA). The critical ICA was then perfused with 15 blood through a 12-Fr balloon catheter while monitoring its perfusion pressure. Some of the neighboring ICAs were also perfused in the same fashion when necessary. We recorded the individual flow rate, CSF temperature. We defined temperature decrease γ 1.0 in 5 minutes as significant change. We decided which ICA to be reconstructed by taking these data into account.

Results: Hospital death was observed in three patients due to stroke, lung torsion, and retrograde aortic dissection in each. Spinal cord injury (SCI) was encountered in 8 (7.1%) patients (paraplegia in six patients and paraparesis in two). Preoperatively, a critical ICA-AKA or major collateral artery was identified in 105 cases (92.9%). Average flow rate was higher in the critical ICA-AKA than the other ICA (57.0 ± 6.2 vs. 49.9 ± 5.6 mL/min, p < 0.05). In the SCI cases, flow rate into the preoperatively diagnosed critical ICA-AKA was significantly lower than in the non-SCI cases (33.0 ± 22.6 vs. 59.8 ± 6.3; p < 0.05), and the reconstructed critical ICA-AKA was found to be patent in five cases, occluded in one and undermined in two. With regard to CSF temperature changes, significant temperature change was observed in 86 out of 113 patients, but not in 19 cases and undetermined in 8 case.

Conclusion: These results suggest that when the flow rate into the preoperatively diagnosed critical ICA-AKA was low, a wrong ICA was reconstructed, or the reconstructed ICA occluded. Another possibility was the preoperative identification was not accurate.