Date of Award

2022

Document Type

Dissertation

Degree Name

Ph.D.

Department

Mechanical Engineering

First Advisor

Ali N. Azadani

Second Advisor

Yan Qin

Third Advisor

Yun-bo Yi

Fourth Advisor

Chadd Clary

Keywords

Computational fluid dynamics, Finite element analysis, Hemodynamic analysis, Structural analysis, TAVR

Abstract

The transcatheter aortic valve replacement (TAVR) procedure has become a well-established procedure for high, intermediate-risk, and low-risk patients. However, there is limited clinical data on the TAV's long-term durability, unlike SAV devices. Computational simulations can be an alternative way to evaluate the TAV devices. This dissertation aims to conduct structural and hemodynamic analyses on the TAV devices under different conditions using computational simulation approaches.

Initially, the impact of the bicuspid aortic valve on the TAV devices was evaluated. The result indicated that the CoreValve-like supra-annular self-expandable device was likely to have increased stress and strain on the leaflet when it was elliptically deployed. The impact on the intra-annular balloon-expandable design was minor in the clinic. Subsequently, the effect of regional under-expansion on the supra-annular self-expandable device was studied. The simulations showed that the reduced leaflet angle could impair leaflet motion and increase stress. The small-angle leaflet was likely to fail over time. The hemodynamic analysis was conducted on both super-annular and intra-annular designs in pulse duplicator models. The result proves that the thrombosis is likely to initiate at the fixed edge of the intra-annular design and lower belly region of the supra-annular design. Most of the blood within the neo-sinus region in the supra-annular design could be washed out within one cardiac cycle. However, the blood near the fixed could accumulate and increase thrombosis risk.

Furthermore, the BASILICA procedure was investigated with an intra-annular design in a patient-specific geometry. This procedure could considerably reduce the blood stasis on the leaflets. The reduction can be as high as13.2 % on the left coronary leaflet. The presented works showed that the design improvement should be focused on the region at the lower belly region in the supra-annular design and the fixed edges in the fixed edge of the intra-annular design to improve the long-term durability of the TAV devices. The BASILICA could be an alternative way for physicians to reduce the thrombosis risk.

Publication Statement

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8.1.mp4 (19570 kB)
Video 8.1 Comparison of experimental and simulation results when the CoreValve device is highly elliptically expanded

8.2.mp4 (5459 kB)
Video 8.2 Comparison between the pulse duplicator testing and the experiment

8.3.mp4 (11546 kB)
Video 8.3 Comparison of the experimental record and the simulation result of fully expanded 26-mm CoreValve leaflet motion from the top view

8.4.mp4 (42442 kB)
Video 8.4 Video of the 26 mm-CoreValve motion in two cardiac cycles

8.5.mp4 (15333 kB)
Video 8.5 The velocity contour of Supra-annular TAV design in the second cardiac cycle with particles

8.6.mp4 (36922 kB)
Video 8.6 Particle movement in the intra-annular TAV design neo-sinus region

Provenance

Received from ProQuest

Rights holder

Dong Qiu

File size

163 pgs

File format

application/pdf

Language

en

Discipline

Mechanical engineering, Biomedical engineering, Biomechanics

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