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Transcatheter aortic valves produce unphysiological flows which may contribute to thromboembolic events: An in-vitro study.

Ducci, A; Pirisi, F; Tzamtzis, S; Burriesci, G; (2016) Transcatheter aortic valves produce unphysiological flows which may contribute to thromboembolic events: An in-vitro study. Journal of Biomechanics , 49 (16) pp. 4080-4089. 10.1016/j.jbiomech.2016.10.050. Green open access

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Abstract

PURPOSE: Transcatheter aortic valve implantation (TAVI) has been associated with large incidence of ischemic events, whose sources are still unclear. In fact, sub-acute complications cannot be directly related to the severity of the calcification in the host tissues, nor with catheter manipulation during the implant. A potential cause could be local flow perturbations introduced by the implantation approach, resulting in thrombo-embolic consequences. In particular, contrary to the surgical approach, TAVI preserves the presence of the native leaflets, which are expanded in the paravalvular space inside the Valsalva sinuses. The purpose of this study is to verify if this configuration can determine hemodynamic variations which may promote blood cell aggregation and thrombus formation. METHODS: The study was performed in vitro, on idealized models of the patient anatomy before and after TAVI, reproducing a range of physiological operating conditions on a pulse duplicator. The fluid dynamics in the Valsalva sinuses was analyzed and characterized using phase resolved Particle Image Velocimetry. RESULTS: Comparison of the flow downstream the valve clearly indicated major alterations in the fluid mechanics after TAVI, characterized by unphysiological conditions associated with extended stagnation zones at the base of the sinuses. CONCLUSION: The prolonged stasis observed in the Valsalva sinuses for the configuration modelling the presence of transcatheter aortic valves provides a fluid dynamic environment favourable for red blood cell aggregation and thrombus formation, which may justify some of the recently reported thromboembolic and ischemic events. This suggests the adoption of anticoagulation therapies following TAVI, and some caution in the patients׳ selection.

Type: Article
Title: Transcatheter aortic valves produce unphysiological flows which may contribute to thromboembolic events: An in-vitro study.
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jbiomech.2016.10.050
Publisher version: http://dx.doi.org/10.1016/j.jbiomech.2016.10.050
Language: English
Additional information: © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Blood stagnation, Particle Image Velocimetry (PIV), Thrombo-embolism, Transcatheter aortic valve implantation (TAVI), Valsalva sinus
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1527532
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