Data-Guided Growth and Remodeling Model of Abdominal Aortic Aneurysm Accounting for the Bio-chemical Effects of Intraluminal Thrombus

Most of the abdominal aortic aneurysms (AAA) include an intraluminal thrombus (ILT) deposited on their internal wall. Active proteolytic enzymes in the ILT may cause bio-chemically weakening the aneurysmal wall, which leads to elevation of the aneurysm rupture risk. On the other hand, lack of oxygen on the aneurysmal wall beneath a thick ILT (hypoxia) causes proteolytic activity on the wall as a secondary effect. In this paper we develop an axisymmetric growth and remodeling model of the AAA considering the bio-chemical effects of the ILT mentioned above. We then estimate the model parameters using nine patients’ longitudinal CT data. The parametric study shows that AAA’s radius and volume increases significantly in existence of ILT because of both hypoxia and proteolytic activity. However, the relation between the AAA volume and its maximum diameter slightly changes due to hypoxia while this relation highly changes because of the proteolytic activity in the luminal layer of the ILT. We also show that our numerical results for the AAA expansion as a function of its maximum diameter can be very close to the clinical data with a proper estimation of the model parameters.