Background Abnormal aortic flow patterns in bicuspid aortic valve disease (BAV) may be partly responsible for the associated aortic dilation. Aortic valve replacement (AVR) may therefore slow the growth of concomitant aortic dilation via normalisation of flow patterns.

Methods and Results 90 participants underwent 4D flow cardiovascular magnetic resonance: 30 BAV patients with prior AVR (11 mechanical, 10 bioprosthetic, 9 Ross procedure), 30 BAV patients with a native aortic valve and 30 healthy volunteers. The majority of subjects with mechanical AVR or Ross showed normal flow pattern (73% and 67% respectively) with near normal rotational flow values (7.2 ± 3.9 and 10.6 ± 10.5 mm²/s respectively vs 3.8 ± 3.1 mm²/s for normal volunteers; both p > 0.05); and reduced in-plane wall shear stress (0.19 ± 0.13 N/m² for mechanical AVR vs. 0.40 ± 0.28 N/m² for native BAV, p < 0.05). By contrast, all subjects with bioprosthetic AVR had abnormal flow patterns (mainly marked right-handed helical flow), with similar rotational flow values to native BAV (20.7 ± 8.8mm²/s and 26.6 ± 16.6 mm²/s respectively, p > 0.05). Wall shear stress post-bioprosthetic AVR showed a similar pattern.

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Abstract YI-1 Figure 1

Ascending aortic flow patterns (A) healthy volunteer with a laminar flow pattern (B) native bicuspid aortic valve disease with a right-handed helical flow pattern (C) AVR mechanical with 2 laminar jets (D) AVR tissue with a right handed helical flow pattern (E) AVR-Ross with a laminary flow pattern.

Data before and after valve replacement (n = 16) supported these findings: mechanical AVR showed a significant reduction in rotational flow (30.4 ± 16.3 → 7.3 ± 4.1 mm²/s; p < 0.05) and in-plane wall shear stress (0.47 ± 0.20 → 0.20 ± 0.13 N/m²; p < 0.05), whereas these remained unchanged in the bioprosthetic AVR group.

Conclusion Abnormal flow patterns in bicuspid aortic valve disease are significantly reduced after mechanical AVR or Ross procedure, though remain similar after bioprosthetic AVR. The type of valve replacement may thus influence post-operative flow patterns, and could have important implications for future aortic growth.