ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

INFLUENCE OF BIOMECHANICAL FACTORS IN THORACIC
AORTIC DISSECTION: A COMPUTATIONAL FLUID DYNAMICS
STUDY
A.Y.S. Tang 1 , S.K. Lai 2 , S.W.K. Cheng 3 , K.W. Chan 4 , A.C.H. Yu 5 and K.W. Chow 6
1. ABSTRACT
Thoracic aortic dissection is a severe pathological condition where blood infiltrates into
the layers of the vascular wall. As a result, the vascular wall layers are torn apart, and
this catastrophic separation creates an artificial channel, namely the false lumen, while
the original channel is termed the true lumen. Without appropriate medical treatment,
the expansion of the false lumen due to the weakened wall will increase the risk of
vessel rupture, which will result in a high mortality rate. In an attempt to evaluate the
hemodynamic effects on this cardiovascular disease quantitatively, a three-dimensional
(3D) thoracic aortic dissection model is constructed herein. By using computational
fluid dynamics techniques, the biomechanical factors associated with an idealized
dissection model can be investigated. In this paper, our main interest is to assess the
influence of the size of the dissecting aneurysm in the case of a partial thrombosis in the
false lumen. Partial thrombosis occurs since the blood flow may become stagnant only
in part of the false lumen. This is a difficult scenario clinically, as patients suffering
from such a condition might be exposed to several risk factors. From our simulation
results, the hydrodynamic force of blood flow exerted on the wall of the false lumen
generally becomes larger with increasing size of the dissecting aneurysm. Moreover,
ultrasound-based flow measurements of thoracic aorta phantom models are
being conducted to compare with those results obtained computationally. Such
quantitative information can assist clinicians to assess the risk of vessel rupture in
making therapeutic decision.
2. INTRODUCTION
Cardiovascular diseases, involving various disorders of the heart and blood vessels,
have long been a leading cause of death worldwide. According to the official statistics
from the World Health Organization [1], almost 17.3 million people (30% of all global
deaths) died from such diseases in 2008. It is well-known that the thoracic aortic
dissection (TAD) is one of the fatal cardiovascular diseases. In terms of pathology,
1 Postgraduate Student, Department of Mechanical Engineering, University of Hong Kong, Hong Kong
2 Research Associate, Department of Mechanical Engineering, University of Hong Kong, Hong Kong
3 Professor, Division of Vascular Surgery, Department of Surgery, Li Ka Shing Faculty of Medicine,
University of Hong Kong, Queen Mary Hospital, Hong Kong
4 Associate Professor, Department of Mechanical Engineering, University of Hong Kong, Hong Kong
5 Research Assistant Professor, Medical Engineering Program, University of Hong Kong, Hong Kong
6 Professor, Department of Mechanical Engineering, University of Hong Kong, Hong Kong