Multiphysics numerical simulations to predict the formation of abdominal aortic aneurysm and to produce rupture risk assessment

Cardiovascular diseases are responsible for the death of about 4 million individuals per year in Europe. The associated health care costs are estimated at 10 billion euros (8 billion pounds) for the UK alone.
One of the most common vascular diseases is abdominal aortic aneurysm. It can be described as a localised, irreversible permanent dilatation of the aorta, the main artery in the human body. Generally no obvious symptoms are exhibited by patients, and if left untreated this abnormal dilation tends to grow until rupture. This event is life threatening, in the vast majority of cases, and it is responsible for 8000 deaths every year in the UK. Aneurysm, once diagnosed, is routinely treated by surgical repair but this operation is not easy and presents some risks. Hence, it is of extreme importance that an early diagnosis of the disease is developed with prompt action when requested. This present research proposal aims to improve our understanding regarding the mechanical causes leading to aneurysm formation and the possibility of enhancing our ability to predict aneurysm rupture. A series of experimental investigations of healthy and damaged aorta are planned to acquire data to characterize the mechanical behaviour of aneurysms. This is a necessary step to produce an advanced numerical model that can improve our understanding of the disease. A preliminary comparison of experimental observations with numerical predictions will help the verification of computational methodologies that will be applied to patient specific geometries available as medical images. This work will allow clinicians to make better informed decisions for endovascular repair based on a more detailed knowledge of aneurysm development beyond the currently accepted criterion of maximum diameter, thus benefiting affected patients and society as a whole and leading to significant cost savings by reducing morbidity and premature death.
Furthermore, this research will help the UK to maintain its worldwide recognized high standard in healthcare.

Abdominal aortic aneurysm (AAA) represents a common vascular disease primarily affecting people over 60. Every year about 8000 deaths are registered in the UK due to AAA rupture. This figure has the potential to grow, in the next 30 years, due to the ageing of the population all over Europe. The number of people aged 65 and above is expected to increase by 70% and the number of people aged over 80 by 170%. Hence, management of diseases among the elderly will be one of the future challenges for the National Health Service (NHS) in the UK.
Medical professionals, routinely involved in AAA risk assessment such as vascular surgeons, cardiologists and radiologists will benefit greatly from the proposed research. The medical impact will be to stimulate new avenues of in vivo diagnosis. Current clinical diagnosis and decisions regarding surgical intervention is mainly based on the measurement of the maximum aortic diameter. This appears a too crude and outdated technique that does not take full advantage of modern technology. Medical images from computer tomography (CT) or ultra sound (US) can provide much more detailed data rather than just the maximum diameter; they permit a high definition 3D reconstruction (CT) and blood velocity waveform (US), that are potentially useful inputs that the proposed research will exploit.
The project aims to translate research into clinical diagnostics, supporting the clinician to design a better therapeutic management. The aim is to produce a more detailed and informed AAA rupture risk assessment and to make decisions for endovascular repair with increased effectiveness, embracing novel knowledge on aneurysm development. This also has the potential to influence future clinical policy. A revised policy can lead to significant benefit to the affected patients and to society as a whole. This could produce significant cost savings to the NHS by reducing morbidity and also reducing premature deaths. This will result in an improved quality of life, allowing people to remain active and productive for longer.
In addition, the proposed study will contribute to the advancement of interdisciplinary collaboration between workers in the health sector and researchers and engineers. A knowledge transfer will be facilitated informing clinicians of the full potential that computational tools can instil to their daily activities.
In addition clinicians can provide feedback and suggest ideas to researchers and engineers regarding their needs in daily practice.
Outcomes of this research will also positively feedback into the endovascular aneurysm repair stent industry.
An optimum stent for any given patient may not be solely determined by the diameter of the blood vessel, but other geometrical and mechanical factors established by this study may also need to be taken into consideration. This development will directly impact the design and durability of the next generation of stent grafts.
In a broader context, this study provides a further step towards the development of a predictive tool which takes into account CT inlet as well as a comprehensive patient-specific set of physiological factors to determine the overall risk of aneurysm rupture. This will support clinicians to assess the risk of treatment or intervention. Developing such techniques and technology is of key interest to cardiovascular specialists in the medical sector, the NHS and healthcare industries.