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Bicuspid aortic valve fusion resulted in hemodynamic abnormalities
Bicuspid aortic valve fusion was associated with regional wall shear stress distribution, systolic flow imbalance and bicuspid aortic valve aortopathy in a recent study.
Researchers performed four-dimensional flow MRI in 75 patients to determine aortic valve anatomy and function. Patients were divided into three groups according to leaflet fusion pattern: 15 with right-left bicuspid aortic valve (RL-BAV; mid-altered ascending aorta diameter of 39.9 ± 4.4 mm); 15 with right-noncoronary bicuspid aortic valve (RN-BAV; mid-altered ascending aorta diameter of 39.6 ± 7.2 mm); and 30 aorta size-matched controls with tricuspid aortic valves and aortic dilatation (diameter of 41 ± 4.4 mm). The cohort also included 15 healthy volunteers with anatomically normal tricuspid aortic valves and no history of CV anomalies (diameter of 24.9 ± 3 mm).
MRI results were analyzed for ascending aorta hemodynamics, including aortopathy type (0-3), systolic flow angle and displacement and regional wall shear stress.
The groups had significantly different systolic wall shear stress distribution in all segments of the ascending aorta except for one (S1, left anterior; P=.051). Both groups with bicuspid aortic valve had increased and asymmetrical stress at the sinotubular junction compared with aorta size-matched controls. Flow displacement also was significantly increased at the sinotubular junction in both groups vs. controls (P<.0125).
Peak systolic velocities were centrally distributed among most healthy volunteers vs. concentration toward the outer aortic walls among those with bicuspid aortic valves. Asymmetric outflow jet patterns in the RN-BAV patients were related to elevated regional wall shear stress at the right-anterior walls for RL-BAV, and at the right-posterior walls for RN-BAV.
Dilatation of the aortic root only (type 1 aortopathy; 53%) or the entire ascending aorta and arch (type 3; 34%) were prevalent in the RN-BAV group, but both aortopathy types were less common among RL-BAV patients, of whom 87% had enlargement of the ascending aorta involving the tubular portion (type 2). Variations in the type of aortopathy between RL-BAV and RN-BAV patients were linked to changes to flow displacement in the proximal and mid-ascending aorta among those with type 1 aortopathy (42%-81% decrease vs. type 2) and in the distal ascending aorta for those with type 3 (33%-39% increase vs. type 2).
The researchers wrote that flow displacement was the parameter with the most pronounced response to differences in bicuspid aortic valve aortopathy phenotype, and added that this factor may offer a new means of quantifying hemodynamic abnormalities in aortic heart disease.
“Future longitudinal studies are warranted to evaluate the impact of [bicuspid aortic valve] valve morphology and the associated hemodynamic alterations in determining the risk for aortopathy development and progression,” the researchers concluded.
Disclosure: The researchers report no relevant financial disclosures.