4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves

Abstract

The self-archived postprint version of this journal article is available at Linköping University Institutional Repository (DiVA): http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-153497 N.B.: When citing this work, cite the original publication.Ha, H., Escobar Kvitting, J., Dyverfeldt, P., Ebbers, T., (2019), 4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves, Magnetic Resonance Imaging, 55, 118-127. https://doi. AbstractPurpose -To assess valvular flow characteristics and pressure drop in a variety of normal and stenotic prosthetic heart valves (PHVs) using 4D Flow MRI. Materials and methods-In-vitro flow phantoms with four different PHVs were studied: Medtronic-Hall tilting disc, St. Jude Medical standard bileaflet (STJM), Medtronic CoreValve Evolut R and Edwards SAPIEN 3. The valvular flow characteristics were investigated in normal and stenotic PHVs by using 4D Flow MRI.Results -The results showed that each valve provided a different amount of signal loss in the 4D Flow MRI. The defect size of the signal loss from each valve was 37.5 mm, 39.0 mm, 37.5 mm and 51.0 mm for the Tilting disk, STJM, SAPIEN 3 and CoreValve, respectively.The 4D Flow MRI-based estimation of the elevation of the pressure drop through the stenotic PHV using both Bernoulli-based and turbulence-based methods correlated well with the true values for the Tilting disc, STJM and SAPIEN 3 valve. However, the obstructive hemodynamics in the stenotic CoreValve was not clearly identified due to the large signal void from the long struts, resulting in a severe underestimation of the pressure drop using 4D Flow MRI.Conclusion -The Tilting disc, STJM and SAPIEN 3 valves provided reasonable estimates of peak velocity, turbulence production and the corresponding pressure drop. In contrast, the large strut of the CoreValve and corresponding signal void prevented accurate measurements of the velocity and turbulence production; therefore, 4D Flow MRI prediction of the pressure drop through the CoreValve was not feasible.

Bicuspid aortic valve morphology and aortic valvular outflow jets: an experimental analysis using an MRI-compatible pulsatile flow circulation system

“…The use of saline solution might result in a relatively higher Reynolds number. However, the aortic flow belongs to the highly turbulent flow regime, where the effects of the viscosity is negligible 30 . We believe that the relative differences between the present results and in-vivo findings are expected to be small.…”

On the limitations of echo planar 4D flow MRI

“…Increasing interest in 4D flow MRI has emerged in recent years . Numerous studies have investigated blood flow patterns, turbulent blood flow with focus on turbulent kinetic energy and pressure loss in stenotic vessels using 4D flow MRI and have indicated the added value of these additional parameters.…”

Bicuspid aortic valve disease is associated with abnormal wall shear stress, viscous energy loss, and pressure drop within the ascending thoracic aorta

“…The measurement of these parameters in the context of BAV disease is novel, and therefore comparison to previous literature is very limited. This said, aortic EL and pressure loss are known to increase in the presence of valve stenosis, aortic dilation, and abnormal helical flow, [ 7 , 22 , 25 , 26 ] all of which typically accompany BAV aortopathy. Hence, the elevated EL and PD observed in our BAV disease population is consistent with prior knowledge.…”