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An abdominal aortic aneurysm (AAA) is a typical aortic disease with serious complications. In clinical practice, the decision to intervene in treatment depends on the rupture risk of AAA. Therefore, monitoring the progression of the disease and accurately assessing the rupture risk is of great importance for its treatment. Studies have shown that the biomechanical indicators based on multi-scale models are more effective in accurately assessing the rupture risk of AAA. However, using computational fluid dynamics (CFD) to simulate the biomechanical environment is a cumbersome and time-consuming process, which is inadequate to meet the needs of clinical monitoring and quick decisions. While the hemodynamic environment of AAA is heavily dependent on geometry, more and more biomechanics-related morphological parameters have been raised and validated. In this review, we summarized typical morphological parameters associated with AAA rupture and their relationships with the mechanical environment, including maximum diameter, deformation rate, saccular index, asymmetry, AAA volume, tortuosity, and intraluminal thrombus (ILT), providing a reference for clinical preoperative risk assessment.Clinical Impact Studies have shown that the biomechanical indicators based on multi-scale models are more effective in accurately assessing the rupture risk of AAA. To meet the need for clinical monitoring and rapid decision making, the typical morphological parameters associated with AAA rupture and their relationships with the mechanical environment have been summarized, which provide a reference for clinical preoperative risk assessment of AAA.

Sutureless anastomosis devices have been developed to facilitate arterial bypass surgery on the beating heart. However, these devices can significantly alter the hemodynamics at the end-to-side anastomosis and in the host artery, leading to the formation of thrombus or/and intimal hyperplasia (IH). In this study, a numerical analysis was performed on the hemodynamic performance of the Graft Connector (GC), a sutureless anastomosis device, under pulsatile flow conditions. The results showed that blood flow was severely disturbed in the GC model with the formation of vortices and flow stagnation at the bed and the toe, and distal to each of the stent struts, which led to low wall shear stresses and high oscillating shear indices in these regions. This may cause severe IH in the host artery and compromise the performance of the device. Based on the numerical study, suggestions were proposed for the design of the GC to improve its performance.

In accordance with “the response to injury” theory, the entry of monocytes into the intima guided by inflammation signals, taking up cholesterol and transforming into foam cells, and egress from plaques determines the progression of atherosclerosis. Multiple cytokines and receptors have been reported to be involved in monocyte recruitment such as CCL2/CCR2, CCL5/CCR5, and CX3CL1/CX3CR1, and the egress of macrophages from the plaque like CCR7/CCL19/CCL21. Interestingly, some neural guidance molecules such as Netrin-1 and Semaphorin 3E have been demonstrated to show an inhibitory effect on monocyte migration. During the processes of monocytes recruitment and migration, factors affecting the biomechanical properties (e.g., the membrane fluidity, the deformability, and stiffness) of the monocytes, like cholesterol, amyloid-β peptide (Aβ), and lipopolysaccharides (LPS), as well as the biomechanical environment that the monocytes are exposed, like the extracellular matrix stiffness, mechanical stretch, blood flow, and hypertension, were discussed in the latter section. Till now, several small interfering RNAs (siRNAs), monoclonal antibodies, and antagonists for CCR2 have been designed and shown promising efficiency on atherosclerosis therapy. Seeking more possible biochemical factors that are chemotactic or can affect the biomechanical properties of monocytes, and uncovering the underlying mechanism, will be helpful in future studies.

Two mechanisms of shear stress and mass transport have been recognized to play an important role in the development of localized atherosclerosis. However, their relationship and roles in atherogenesis are still obscure. It is necessary to investigate quantitatively the correlation among low-density lipoproteins (LDL) transport, haemodynamic parameters and plaque thickness. We simulated blood flow and LDL transport in rabbit aorta using computational fluid dynamics and evaluated plaque thickness in the aorta of a high-fat-diet rabbit. The numerical results show that regions with high luminal LDL concentration tend to have severely negative haemodynamic environments (HEs). However, for regions with moderately and slightly high luminal LDL concentration, the relationship between LDL concentration and the above haemodynamic indicators is not clear cut. Point-by-point correlation with experimental results indicates that severe atherosclerotic plaque corresponds to high LDL concentration and seriously negative HEs, less severe atherosclerotic plaque is related to either moderately high LDL concentration or moderately negative HEs, and there is almost no atherosclerotic plaque in regions with both low LDL concentration and positive HEs. In conclusion, LDL distribution is closely linked to blood flow transport, and the synergetic effects of luminal surface LDL concentration and wall shear stress-based haemodynamic indicators may determine plaque thickness.