02:01pm Wednesday 23 August 2017

Life-saving bypass surgery made more reliable

A computer-generated image of the artificial artery with internal helical grooves and external helical twist

LIFE-saving arterial bypass surgery could become more reliable and longer lasting through new blood flow research.

Scientists are working to create long-lasting ‘grafts’, where fat-clogged arteries are replaced with new ones, by generating better blood flow conditions at the graft-artery junction.

The grafts are commonly used in heart bypass surgery to treat coronary artery disease (CAD) or for peripheral vascular diseases (PVD), but the junctions can fail over time.

Wear of conventional bypass grafts is currently a major concern for medical practitioners. Coronary artery bypass grafts are the most common cardiac operation in England with 20,000 each year but they have a limited lifespan of 8-15 years.

‘Huge impact’

MMU engineers are drawing inspiration from industry to cause blood to spiral through synthetic arteries, much like the rifling in the barrel of a gun. By creating a smoother flow it will reduce wear and tear as it passes by the artery-graft junction and increase its lifespan.

Blood spiral flow is a natural phenomenon already established in the arterial system, caused by the rotational compressive pumping of the heart and supported by the tapered and curved geometry of the arterial system.

Dr Amir Keshmiri, senior lecturer in Fluid Dynamics in the School of Engineering and director of the Advanced Design and Simulation Group, is leading the 18-month project and and will work closely with Prof Mark Slevin, from the School of Healthcare Science.

Dr Keshmiri said: “The impact could be huge. If it works, it will improve the fluid dynamics of the blood and delay the failure of the graft. It could save millions of pounds and a lot of time for health services.

Applications

“In a lot of cases, the graft junction fails and blocks the blood flow. We want to be able to avoid these hotspots by optimising the graft design by inducing a spiral flow.

“If you can get the blood to swirl before joining the junction it will help the fluid dynamics through accelerating the blood to improve the life of the graft. The body is familiar with the spiral flow and encourages it in different parts of the body – so we can apply the same idea to the grafts.”

The technique could be expanded to include aterio-venous access grafts in haemodialysis treatment for kidney failure patients.

Dr Keshmiri modelled the research on his early work in the nuclear industry where he analysed the enhanced heat transfer in nuclear cooling rods, achieved by the spiral flow of coolant.

Partnership

Initially, scientists will use computational fluid dynamics (CFD) analysis and later expand to clinical trials.

Partners for the project are: The Cardiovascular Research Centre in Barcelona, University College London, The National University of Singapore and The Manchester Biomanufacturing Centre. The £200,000 study has been funded by the EPSRC, MMU and collaborators.

Manchester Metropolitan University is a leading university for the professions and a powerful driver of the North West economy.

The University educates and trains large numbers of the region’s legal and business professionals, scientists, engineers, teachers, health workers and creative professionals. It enjoys an excellent reputation for teaching and applied research and is a recognised innovator in partnership working with its local communities. The University is currently investing almost £300 million in its estate and facilities.


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