MRI-based Quantitative Aortic Blood Flow Analysis in a Rabbit Model During Ante- and Retrograde Extracorporeal Circulation

Background: Although extracorporeal circulation (ECC) is routinely used during cardiac surgery, the optimal ECC cannulation strategy is still under debate. Therefore, we used our previously published miniaturized magnetic resonance imaging (MRI)-compatible rabbit ECC model and conducted MRI measurements of blood flow during ante- (via ascending aorta) and retrograde (via abdominal aorta) ECC scenarios.

Methods: Sixteen New Zealand White rabbits underwent ECC by ante- (n = 7) or retrograde (n = 9) perfusion. MRI measurements were conducted in a 9.4 Tesla MR scanner (Bruker, Germany). 3D flow data were acquired by phase contrast velocity mapping using Bruker FLOWMAP sequences. High-resolution arterial blood flow profiles were assessed during ante- and retrograde perfusion with a special focus on cerebral and visceral perfusion. The arterial blood pressure and ECC flow rates were continuously measured. Every 30 minutes blood gas analyses were conducted. All data were analyzed in MATLAB (version R2021a).

Results: In both ECC scenarios, the inflow through the arterial cannula was similar (248.1 ± 18.41 (antegrade) vs. 252.5 ± 12.83 (retrograde) mL/min; p = 0.86). The blood flow in the ascending aorta, aortic arch and descending aorta was significantly higher during ante- versus retrograde perfusion (in mL/min; AoAsc: 241.7 ± 21.6 vs. 6.46 ± 1.46; Arch: 189.5 ± 20.93 vs. 47.93 ± 2.94; AoDesc: 179.2 ± 11.69 vs. 45.14 ± 12.63; for all: p < 0.0001) as well as significantly higher in the abdominal aorta during retro- compared to antegrade perfusion (in mL/min; 209.9 ± 16.53 vs. 29.27 ± 5.9, p < 0.0001). Interestingly, no differences could be seen for cerebral (in mL/min; brachiocephalic artery: 29.83 ± 3.31 vs. 26.33 ± 7.72, p = 0.78; left carotid artery: 14.18 ± 2.33 vs. 7.2 ± 2.63, p = 0.12; left subclavian artery: 12.71 ± 1.82 vs. 11.91 ± 2.65, p = 0.85) or visceral perfusion (in mL/min: celiac trunk: 23.64 ± 13.12 vs. 30.39 ± 4.74, p = 0.59; superior mesenteric artery: 36.0 ± 4.89 vs. 46.31 ± 4.3, p = 0.19; left renal artery: 2.22 ± 3.32 vs. 7.89 ± 4.07, p = 0.31; right renal artery: 14.81 ± 3.6 vs. 12.33 ± 3.22, p = 0.63).

Conclusion: To the best of our knowledge, this is the first in vivo study on aortic blood flow measurements during ECC. When compared to antegrade perfusion, retrograde ECC did not significantly change cerebral or visceral perfusion, despite lower blood flow in the ascending aorta, arch and descending aorta, and higher flow in the abdominal aortic segments.

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Artikel online veröffentlicht:
13. Februar 2024