Rising Star – Dr Lorenza Grechy
In this article, we profile Dr Lorenza Grechy, Postdoctoral Research Student, Imperial College London, EPSRC Doctoral Prize Fellow, who focuses on biological fluid dynamics, specifically, modelling and simulating blood flow.
What is your background and area of study?
I have recently finished studying for a PhD which investigates flow unsteadiness in arterio-venous fistulae (AVF), (artificial vascular junctions formed in the wrists of patients who need dialysis), modelling the flow of blood using Computational Fluid Dynamics (CFD). Kidney dialysis patients undergo a procedure to create a new blood vessel or AVF, which commonly blocks and in some cases, fails requiring further operations. My research and focus is studying how blood flow can affect surgical procedures, enabling a better understanding of the development and management of heart and kidney disease.
I started studying for my PhD at Imperial College London in October 2015. Prior to this I completed a BSc and MSc in Medical Engineering at the University of Rome Tor Vergata between 2007 – 2011 and 2011 – 2013.
During my research career I have gained skills in computational fluid dynamics, high performance computing, programming and analysing large data sets. I have also had the opportunity to work in a multidisciplinary environment, benefiting from a close collaboration with clinicians and engineers from different departments.
Why did you decide to study in this particular area?
I was interested in the composition and dynamic simulation of blood flow. My interest began in the last year of my Master’s degree where we had to choose the subject we wanted to explore further. This gave me the opportunity to join Imperial College London and to broaden my experience in this particular subject, which I really enjoy. It has enabled me to explore and study many different, but related areas to modelling and simulating blood flow. The research will hopefully have a very beneficial impact to the health and medical sector.
Tell us about the medical device you developed
The objective was tounderstand whether 'abnormal' flow patterns within fistulae cause them to block and fail. One of the project's main achievements was the design and patenting of a novel medical device for shaping artificial cardiovascular connections through a machine-learning based optimisation framework. In fact, the inherently unphysiological blood flow patterns within AVF seems to play an important role in AVF failure. What I found was a shape that will suppress unsteady flow in these connections, so we have developed a medical device (shown in the picture above) that will hold this shape and is as least invasive as possible, so it can be implanted.
The geometry is completely novel, and the method employed to achieve it, is also novel. The device has also been patented via Imperial Innovations. The picture here presents a snapshot in time of the streamlines in the optimal geometry coloured by the velocity magnitude.
In terms of the medical sector, and the use of modelling and simulation, are there any interesting trends?
There are a lot of very interesting areas that are going on right now. One promising area of research I can think about, is focusing on better understanding and quantifying the uncertainties in patient specific simulations. This is because when you are dealing with live subject, the data you can collect is not only very limited, but also variable and potentially affected by error, therefore uncertainty quantification is a significant subject. Another very promising research subject which is also becoming popular in the medical field, is the use of artificial intelligence and surrogate models, such as Kriging, to build predictive tools and estimate simulations results.
What are your most notable projects/awards/areas of study?
Highlights of my work includes four research papers (below), presenting at five international conferences and the production of multimedia material for interviews which featured our team’s work for 'BBC 4', 'The Times' and 'Channel 4'. I also received an EPSRC Doctoral Prize Fellowship in 2017.
The Effect of Arterial Curvature on Blood Flow in Arterio-Venous Fistulae: Realistic Geometries and Pulsatile Flow, Cardiovascular Engineering and Technology, 8(3): 313–329, 2017. https://doi.org/10.1007/s13239-017-0321-2
The Effect of In-Plane Arterial Curvature on Blood Flow and Oxygen Transport in Arterio-Venous Fistulae, Physics of Fluids, 27(3):031903, 2015. https://doi.org/10.1063/1.4913754
The Royal Society of Medicine also ran a competition, where the picture here won The Images in Nephrology Prize.
This is a temporal snapshot of streamlines (coloured according to velocity magnitude on a continuum from blue-high to red-low) of a computational fluid dynamic model of blood flow within a semi-realistic AVF. Anatomical data comprising bone landmarks and arterial vasculature were re-created from patient specific data; an idealised fistula was then formed by the anastomosis of a vessel onto the outer curvature of the brachial artery.
What are your career aspirations?
I would like to stay focused on the medical area and in the development of medical devices, which could be in academia or industry. I don’t have a specific preference right now, but the medical sector is what I am interested in.
Who do you most aspire to and why?
That is a very tough question. My parents are my role models as they taught me how to be independent, to critique and remain open minded, which is very useful.