Abstract 12157: 4d Flow Mri Demonstrates Hemodynamic Normalization After Coarctation Repair in Pediatric Patients

Abstract

Background: Coarctation of the aorta (COA) is a focal aortic narrowing, and intervention is required for patients with severe hemodynamic impairment. Following intervention, patients remain at risk for long-term re-coarctation. We used 4D flow MRI to assess aortic hemodynamics pre- and post- COA repair in children compared to age matched healthy controls. Methods: Aortic 4D flow MRI was performed in 5 pediatric COA patients (baseline age 6-14 yrs, 1F) pre- and post COA repair (4 native COA, 1 re-intervention) and 5 age-matched controls (ages 9-17 yrs, 2 female). Peak systolic velocities were quantified with velocity maximum intensity projections (MIP) ROIs in the ascending aorta (AAo), aortic arch, distal to the coarctation, and descending aorta (DAo) (Figure 1A). For flow quantification, nine 2D planes were placed along the aorta. Regional net flow was determined by averaging the 2D plane flows by region. The ratio between DAo to AAo (DAo/AAo) net flow was used to assess collateral flow. Results: Velocities were generally higher and more consistent across the aorta following surgery (Figure 1A). Plots highlighting changes in DAo/AAo flow ratio are shown in Figure 1B. Compared to controls, DAo/AAo flow ratio was significantly lower prior to COA repair (0.38±0.11 vs 0.61±0.05, p = 0.0004), indicating flow obstruction at the COA and presence of substantial collateral flow. Post COA repair DAo/AAo flow ratio was similar compared to age matched controls (0.59±0.06 vs 0.61±0.05, p = 0.51), indicating normalization of aortic flow. Patient 2, who underwent COA repair via stent placement showed the greatest improvement and normalization of flow consistency (DAo/AAo) across the aorta after intervention. Conclusion: A ortic 4D flow MRI shows normalization of aortic flow velocities, decreased collateral flow following COA repair, and has potential for long term surveillance and quantification of pre- and post-COA repair hemodynamic changes in children.