Publication

An experimental and computational investigation into procedural complications relating to transcatheter aortic heart valves

McGee, Orla
Citation
Abstract
Although transcatheter aortic valves are widely used for treatment of high to medium risk patients with severe aortic stenosis, there are still many associated procedural complications. In particular, new on-set conductance interference is a common complication of transcatheter aortic valve implantation, but the exact cause is unknown. It has been proposed that this is due to injury in the vicinity of the heart’s conductance system, which is located at the base of the interleaflet triangle between the non-coronary and the right coronary aortic sinus. However, a further understanding of the levels of stress in the vicinity of the conductance system after valve deployment and the impact of positioning on these stresses is required. Additionally, the impact of calcification on the tissue-stent interaction has not yet been quantified. In particular it is not yet known what role the calcification plays in securing the stent and preventing migration in vivo. Finally, as transcatheter valves are being touted as a treatment for younger patient cohorts, there is further knowledge required regarding the sizing of transcatheter valves in bicuspid patients. Therefore, the objectives of this thesis are to (1) develop a finite element framework simulating deployment of a Lotus™ valve in a patient-specific aortic root to investigate the impact of stent implantation depth and orientation on stress related to conductance interference, (2) quantify the impact of calcification on the tissue-stent interaction and (3) investigate valve sizing in a stenosed bicuspid aortic valve. The results of this thesis provide evidence that sub-annular positioning leads to higher stress in the vicinity of the heart’s conductance system and demonstrate that preoperative planning of the Lotus™ valve stent orientation within the aortic sinus has the potential to minimise conductance interference. It was shown that calcification increases the coefficient of friction in the interaction between the aortic root and stent further securing transcatheter aortic valves in place. Finally, the results of this thesis inform device positioning and patient sizing for the Lotus™ valve and provide knowledge for the development of next-generation transcatheter aortic valve devices.
Publisher
NUI Galway
Publisher DOI
Rights
Attribution-NonCommercial-NoDerivs 3.0 Ireland