Assessing changes in aortic motion and hemodynamics after valve-sparing aortic root surgery in Marfan syndrome using four-dimensional balanced steady-state free precession and four-dimensional flow cardiovascular magnetic resonance.

BACKGROUND

Aortic root surgery in patients with Marfan syndrome (MFS) has significantly improved survival, allowing time for distal aortic complications such as type B aortic dissection (TBAD) to emerge. The implantation of a non-compliant synthetic graft may alter aortic biomechanics and hemodynamics, potentially contributing to these late complications. This proof-of-concept study aimed to assess changes in aortic motion and flow characteristics following aortic root surgery using advanced cardiovascular magnetic resonance (CMR) techniques.

METHODS

Three MFS patients (aged 26-37 years), two males, one female, undergoing valve-sparing aortic root surgery, were prospectively studied before and 6 months after surgery. All participants underwent non-contrast-enhanced four-dimensional (4D) balanced steady-state free precession and 4D flow CMR at 3T. A deep learning-based segmentation pipeline (nnU-Net) provided segmentations utilized for calculation of aortic displacement, distensibility, regional wall shear stress (WSS) and velocity, and global pulse wave velocity (PWV).

RESULTS

Postoperatively, all patients exhibited markedly decreased ascending aorta (AAo) volume. Three-dimensional distensibility (10⁻³ mmHg⁻¹) also decreased: patient 1, from 4.1 to 1.7; patient 2, from 3.4 to 1.2; and patient 3, from 2.9 to 1.5. Displacement in the AAo, especially at the sinotubular junction, was substantially reduced, consistent with the rigidity of the implanted graft. In the descending aorta (DAo), distensibility and displacement showed increases in two patients and a decrease in one. Peak systolic velocity and WSS increased in the AAo for all patients, whereas DAo values remained largely unchanged. PWV change varied between patients: decreasing slightly in patient 1, from 8.4 to 7.9 m/s, but increased in patients 2 and 3 (8.0 to 8.9 m/s and 6.2 to 9.8 m/s, respectively.

CONCLUSION

This study demonstrated that AAo biomechanics and hemodynamics change predictably following valve-sparing aortic root surgery in MFS, while changes in the DAo were not consistent between patients. Further research with larger sample sizes is required to identify which of these changes are linked to specific disease profiles and whether parameter combinations can indicate a predisposition to TBAD.