Haemodynamic patterns in different aortic valve and root prosthesis
Research type
Research Study
Full title
In-vivo Assessment of The Haemodynamic Properties of Different Aortic Valve and Root Prosthesis Using Advanced Cardiac Magnetic Resonance Imaging and Computational Modelling Technology
IRAS ID
156165
Contact name
Thanos Athanasiou
Contact email
Sponsor organisation
Imperial College London
Duration of Study in the UK
3 years, 10 months, 1 days
Research summary
Research Summary
In certain diseases the aortic valve (AV) or root (first part of aorta) need to be replaced, using surgical operations called aortic valve replacement (AVR) and aortic root replacement (ARR), respectively. Different artificial aortic valve and root, called Composite Valve-Graft (CVG) prosthesis have been designed and used over the time to improve outcomes. The success of AVR or ARR have been measured mainly clinically such as short and long term mortalities and morbidities. Advances in computation technology and cardiovascular imaging enable us to obtain detailed information about hemodynamic properties, which is important because of its effect on heart muscle,organ perfusion, particularly the coronaries, and long term outcome.Such data significantly improve our understanding of hemodynamic performance following prosthetic implantation.
We aim to assess the haemodynamic properties of different aortic valve and root prostheses using MRI and Computational Modelling (computer analysis and re-construction of the MRI pictures) pre- and post-operatively (AVR and ARR). Furthermore, miRNAs, which have emerged as novel and sensitive biomarkers for the diagnosis and progression of different diseases, include cancer and cardiovascular (CV) disease, will be analysed and profiled for the different subgroups, to create an interesting preliminary miRNA data that may significantly increase our pathophysiological knowledge in such patients’ population.
Results from our study can identify the variances in hemodynamics between different types and designs of prostheses, and demonstrate which one (s) is (are) most comparable to native tissue. Such study may clear some of the uncertainty around some of the surgical indications and prostheses selection in AVR and ARR and may help in personalising treatment. It may also stimulate new prostheses designing or developmental concepts by identifying major weaknesses/differences from the normal tissue. Finally, it will support our proposed concept to use in-vivo computational modelling as an essential validation and approval tool.
Summary of Results
In this state of the art study, we developed a method to assess aortic blood flow patterns (how blood flows out of the heart and around the body) using cardiovascular magnetic resonance imaging technology. This was combined with a technique called computational fluid dynamics to very accurately measure important parameters of blood flow. An example of this is the measurement of 'wall shear stress', which has been implicated in many diseases of the aortic wall.
Using the above, we assessed blood flow in a large cohort of patients undergoing open heart surgery, where the first part of their aorta was replaced.
There were five key findings. Firstly, there were significant geometrical changes in patients aorta's after aortic surgery, in terms of tortuosity and curvature. Secondly, there were significant geometrical changes in the alignment of patients coronary arteries, especially after a procedure called aortic root replacement. Thirdly, certain valve replacement procedures (mechanical valves) seemed to have less physiological flow characteristics compared to biological solutions (tissue valves). Fourthly, after mechanical valve implantation, blood flow to the head and neck potentially decreases. Lastly, aortic surgery seems to restore overall flow and shear stress patterns closer to normal, but this restoration is often not complete, with regional areas of high velocity jets and elevated shear stress.
Although not proven, some of the above findings may be associated with adverse clinical consequences such as aortic dissection, stroke, and increased recurrence. This justifies further larger studies linked with longitudinally linked clinical and ideally, genomic data.
Based on our research we founded the London Aortic Mechanobiology Working Group: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fu2790089.ct.sendgrid.net%2Fls%2Fclick%3Fupn%3DXv3JSvJ-2B3M71ppf7N9agbci-2B4prh4I8ssYUxwTsEjykF-2BCcekIkp-2BUd8Q8ctIBQ9iJZWf8TrQvUsryexVQYTk9hvnf02wYMYGTeS7tf3KnsnwmKBQRMoV96vn4SSRKYyz9FO0s3xHmacDa-2Bwm1VK8A-2Fzn6pLlBwfKfJ14fkH8z8FBRUiZkdiolip2Hf2Xfu8kknx_E1aO2-2BZlVOSJJV-2FajQqskegTd6IRomHYTi-2Fbt8SH3YIxdrDM-2F0DBEhAbx5HEtecHkgoJd5qiyfOv9lN2gGZc0VipyVPSXY86cazePPZHwEabnL26HrBglqweuIRYFIfpEa3tIHkt-2FHUCxCFwEmzWxT8qajM-2BDlyt3-2FBxVzAqfT3jmQaAz6U9wP8Pzd4ormmVw2jS0MbJbLa60-2BcVsb3lZg-3D-3D&data=05%7C01%7Capprovals%40hra.nhs.uk%7C7de516a9f5a7482a2c6708da731f3ecf%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C637948875275080013%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=wEx%2Fjk1bM%2BQD8O8XjyqrDBpfvu2LuWuaoJHwydsvkyk%3D&reserved=0
We obtained further funding to continue this work which has been published in prestigious peer reviewed journals. We have held patient and public involvement events to disseminate the results and involve our patients.
REC name
Wales REC 6
REC reference
14/WA/1225
Date of REC Opinion
4 Nov 2014
REC opinion
Favourable Opinion