Pathophysiology of abdominal aortic aneurysms

Background: Abdominal aortic aneurysms (AAA) are a daily clinical challenge for vascular surgeons. In recent years, many pathological changes in the aneurysm wall have been investigated and a common model for aneurysm expansion has been developed. Objective: This theoretical model is presented based on a literature review. Results: Characteristic changes of the AAA wall include broadening of the media and alteration of the extracellular matrix, altered hemodynamics and force distribution, luminal thrombus formation, phenotype switch of vascular smooth muscle cells, angiogenesis as well as acute and chronic inflammatory infiltrates. These cause a proteolytic imbalance and altered pressure impact resulting in areas with increased biological activity and peak wall stress. The clinical risk factors smoking, dyslipidemia, male gender, age and genetic predisposition have defined biological effects causing additional weakening of the vessel wall. The differences between ruptured and intact aneurysm walls cannot be clearly defined. The initial cause of an aneurysm is also still unknown. Conclusion: A better understanding of the multifactorial AAA pathogenesis is mandatory to enable translational approaches towards a non-surgical treatment and an individual patient risk stratification. Basic research on human aneurysmal samples is also necessary even in the endovascular era and enables identification of the very specific pathological mechanisms involved. © 2018, Springer Medizin Verlag GmbH, ein Teil von Springer Nature.