Author + information
- Koohyar Vahidkhah1,
- Mohammad Barakat2,
- Mostafa Abbasi3,
- Shahnaz Javani4,
- Peyman Azadani5,
- Anwar Tandar6,
- Danny Dvir7 and
- Ali Azadani8
- 1University of Denver, Denver, Colorado, United States
- 2University of Denver
- 3University of Denver, Denver, Colorado, United States
- 4University of Denver
- 5University of Utah School of Medicine
- 6University of Utah School of Medicine, Salt Lake City, Utah, United States
- 7St. Paul's Hospital, Vancouver, British Columbia, Canada
- 8University of Denver, Denver, Colorado, United States
Formation of leaflet thrombosis following transcatheter aortic valve replacement (TAVR) has been increasingly recognized. However, the underlying mechanisms have remained unclear. This study aimed to shed light on such mechanisms from a fluid mechanics standpoint via quantification of blood residence time (BRT) on the transcatheter aortic valve (TAV) leaflets.
Unlike surgical bioprostheses, the aortic portion of the TAV frame is circumferentially surrounded by calcified leaflets in TAVR, or by degenerated bioprostheses in valve-in-valve setting (Figure 1). Two computational models representing a surgical bioprosthesis and a TAV were developed. 3D flow fields were obtained via a one-way fluid-solid interaction modeling approach validated by experimental testing. Subsequently, a particle tracking procedure was applied to calculate BRT on the valve leaflets. Finally, statistical analysis was performed to compare the BRT values in the two models.
Significantly larger values of BRT on the leaflets were obtained for the TAV than the surgical bioprosthesis (Figure 1). During forward flow, the mean value of BRT was 35% higher in the TAV compared to the surgical bioprosthesis (p<0.0001). During diastole, from end of closing to mid-diastole and mid-diastole to systole, BRT was longer for the TAVR model by 139% and 24%, respectively (p<0.0005).
TAVR, as opposed to surgical valve replacement, may alter the natural flow field around the leaflets. The geometric confinement of the TAV increases the BRT on the TAV leaflets. The increased BRT may act as a permissive factor for thrombogenesis.
STRUCTURAL: Valvular Disease: Aortic