Prosthetic heart valve evaluation by magnetic resonance imaging

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Fluid Dynamics

Background:

• Prosthetic aortic valves are crucial for patients with aortic valve disease.
• Understanding hemodynamics downstream of these valves is vital for assessing performance and longevity.
• Magnetic resonance imaging (MRI) offers non-invasive visualization capabilities.

Purpose of the Study:

• To assess the utility of MRI for evaluating velocity fields distal to prosthetic aortic valves.
• To compare in vitro data from bileaflet aortic valve prostheses with in vivo patient data.

Main Methods:

• Utilized a 7.0 Tesla MRI scanner with a pulsatile flow loop to study fluid velocity downstream of a bileaflet aortic valve prosthesis in vitro.
• Employed a 1.5 Tesla MRI whole-body scanner to analyze blood velocity profiles in six patients with St. Jude Medical aortic valves.
• Visualized velocity fields using three-dimensional surface plots.

Main Results:

• In vitro studies revealed detailed fluid velocity distributions reflecting the valve design.
• In vivo human blood velocity profiles were smoother and often skewed towards the anterior-right ascending aortic wall.
• Significant differences were observed between in vitro and in vivo velocity profiles.

Conclusions:

• MRI is a feasible technique for displaying and interpreting fluid and blood velocity data downstream of prosthetic valves, both in vitro and in vivo.
• Simple in vitro models may not accurately replicate complex human hemodynamic conditions due to anatomical variations.
• Advancements in MRI technology hold significant potential for comparative hemodynamic evaluations of heart valves.