Different Hemodynamics after the Ross Procedure in Stenosis and Regurgitation: Innovative Insights from 4D Flow MRI

Background: The Ross procedure appears to offer optimal outcomes for non-elderly adults with aortic valve disease, with echocardiographic analyses showing low gradients across the aortic valve, indicating physiological hemodynamics. However, there is limited knowledge on hemodynamic changes across the valve and in the ascending aorta post-procedure, and the effect of the underlying disease. This study aimed to assess aortic flow patterns in patients with aortic regurgitation (AR) and stenosis (AS) before and after the Ross procedure using 4D flow MRI.

Methods: A total of 12 Ross patients underwent magnetic resonance imaging (MRI) at 3 Tesla pre- and postoperatively, with imaging occurring between 3 and 12 months following surgery. Subgroup analysis was performed according to the predominant indication for surgery. The predominant indication for surgery was classified as either predominant aortic regurgitation (n = 5) or predominant aortic stenosis (n = 7). The analysis planes were positioned at the level of the annulus, sinutubular junction (STJ), mid-ascending aorta (midAAo), and proximal arch (proxAA). The flow displacement (FD) was estimated as a measure of flow eccentricity, and the wall shear stress (WSS) was also calculated.

Results: Mean age at the time of procedure was similar in both groups (AR: 36.0 ± 8.0 versus AS: 39.1 ± 8.8; p = 0.543). The flow displacement decreased significantly postoperatively at all levels: STJ (0.27 ± 0.12 versus 0.12 ± 0.10; p = 0.003), proxAA (0.36 ± 0.07 versus 0.25 ± 0.12; p = 0.019), and midAAo (0.35 ± 0.09 versus 0.24 ± 0.10; p = 0.009). The subgroup analysis revealed similar changes from preoperative to postoperative (e.g., at STJ): AR group (0.24 ± 0.09 versus 0.09 ± 0.05; p = 0.027) and AS group (0.19 ± 0.06 N/m² versus 0.03 ± 0.03 N/m²; p = 0.004). The WSS was significantly reduced at the midAAo (0.84 ± 0.36 N/m² versus 0.58 ± 0.19 N/m²; p = 0.04). However, no significant difference was observed at the STJ (p = 0.42). The subgroup analysis revealed that WSS was predominantly observed in the AS group at midAAO (p = 0.046) and proxAA (p = 0.002), but not in the AR group.

Conclusion: The Ross procedure reduces wall shear stress in the mid ascending aorta and the aortic arch postoperatively. The reduction in WSS is mainly seen in patients with aortic valve stenosis. Flow eccentricity after the Ross procedure is improved in all parts of the aorta, regardless of the underlying valve disease. The Ross procedure results in more physiological hemodynamics demonstrated by 4D flow MRI.

Publication History

Article published online:
11 February 2025