- Workshop presentation
- Open Access
Assessment of energy loss across aortic valves using accelerated CMR multi-point flow measurements
© Binter et al; licensee BioMed Central Ltd. 2012
- Published: 1 February 2012
- Turbulent Kinetic Energy
- Heart Valve
- Jude Medical
- Effective Orifice Area
- Artificial Heart Valve
A novel approach for evaluating the performance of artificial or diseased heart valves is presented and applied on in-vitro as well as in-vivo aortic valve data. The method, which is based on turbulence and flow measurements, provides a measure to assess and compare energy dissipation under varying flow conditions.
Diseased or artificial heart valves possibly lead to turbulent flow and regurgitation, both increasing the workload of the heart. Current measures for valve assessment, i.e. effective orifice area, only indirectly and partially correlate with the energy loss due to the valve . Phase-Contrast MRI makes it possible to directly quantify these energy losses, and by relating them to kinetic energy of the flow a parameter describing the hemodynamic performance of the valve can be obtained.
In-vitro measurements were performed using a home-built pulsatile flow phantom to study a mechanical St. Jude Medical standard bileaflet valve (St. Jude Medical Inc., St. Paul, MN, USA), as well as a biological Transcatheter Medtronic CoreValve (Medtronic Inc., Minneapolis, MN, USA). In vivo data were acquired in 6 healthy volunteers as well as in two patients with a stenotic valve (valve area 0.9 cm2, mean gradient 34 mmHg) and a Medtronic CoreValve, respectively.
All data were acquired on a 3T Achieva system (Philips Healthcare, Best, The Netherlands) with cardiac triggering and navigator gating. The voxel size was 2 mm isotropic, and temporal resolution was 34 ms. Employing 8-fold undersampling and k-t PCA reconstruction, the nominal scan time was about 8 min without navigator efficiency taken into account.
A method for assessing valve performance independent of flow rates has been proposed. It has been demonstrated that relative energy loss differs across heart valve designs and values have been found to be 6-fold higher compared to normal subjects. The work indicates that quantification of relative energy losses may provide a potential parameter to characterize the efficiency of the cardiovascular system in general and vascular prostheses in particular.
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.