Preface

 Contemporary treatment of patients with abdominal aortic aneurysm has become complex and requires general knowledge from both basic science and clinical research.

 Experimental studies that elucidate the process of aneurysm development, growth, and rup‐ ture are improving potential conservative therapy, which is still inefficient. With the reduc‐ tion of risk factors, rupture risk has diminished, but we are still lacking medical therapies to amplify this tendency toward slower growth and rupture rate. Also, experimental and com‐ puted studies are illuminating the process of aneurysm rupture, especially focusing on risk predictors among biomechanical and biochemical factors. Wall stress, and other similar fea‐ tures, derived from aneurysm geometry are crucial and their assessment is quite achievable nowadays; however, published results are not standardized and they are difficult to interpret.

 In clinical practice, preoperative assessment of patients with abdominal aortic aneurysms has numerous challenges. The decision to treat is mostly based on risk-benefit ratio, with periprocedural risk on one side and rupture risk on the other. Besides diameter and other biomechanical parameters, rupture risk is determined with life expectancy and biological capacity of the human body to reach a moment of aneurysm progression and consequent rupture. In this regard, patients with concomitant aneurysms and malignant diseases are a very delicate subgroup frequently facing oncological surgical, aggressive medical, and radio therapy procedures when baring untreated aneurysm is additional challenge for treating on‐ cologist . The periprocedural risk of patients with abdominal aortic aneurysm is determined by anatomy, while aneurysms causing neck pain are one of the most frequent challenges for both open and endovascular methods. Finally, once it is decided to treat a patient, careful planning is crucial.

 Postoperative complications, early or late, and their management are very important parts of the everyday work of the vascular physician, fluctuating from postimplantation syn‐ drome, to underestimated problems, toward detection and treatment of endoleaks and eventual conversion.

 This book, intended for all vascular physicians who are facing patients with abdominalaort‐ ic aneurysms, covers all the above-mentioned problems. It was assembled by interested, in‐ vited authors and contains important topics from basic research to clinical practice.

> **Igor Koncar, Vascular Surgeon**  Clinic for Vascular and Endovascular Surgery Serbian Clinical Centre Belgrade Medical School University of Belgrade, Serbia

**Section 1**

**Research of Abdominal Aortic Aneurysm**

**Research of Abdominal Aortic Aneurysm** 

**Chapter 1**

**Provisional chapter**

**Biomechanic and Hemodynamic Perspectives in**

**Biomechanic and Hemodynamic Perspectives in** 

Nikolaos Kontopodis, Konstantinos Tzirakis,

Nikolaos Kontopodis, Konstantinos Tzirakis,

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Emmanouil Tavlas, Stella Lioudaki and

Emmanouil Tavlas, Stella Lioudaki and

http://dx.doi.org/10.5772/intechopen.76121

Christos Ioannou

Christos Ioannou

**Abstract**

**1. Introduction**

**Abdominal Aortic Aneurysm Rupture Risk Assessment**

Abdominal aortic aneurysms (AAAs) pose a significant source of mortality for the elderly, especially if they go on undetected and ultimately rupture. Therefore, elective repair of these lesions is recommended in order to avoid risk of rupture which is associated with high mortality. Currently, the risk of rupture and thus the indication to intervene is evaluated based on the size of the AAA as determined by its maximum diameter. Since AAAs actually present original geometric configurations and unique hemodynamic and biomechanic conditions, it is expected that other variables may affect rupture risk as well. This is the reason why the maximum diameter criterion has often been proven inaccurate. The biomechanical approach considers rupture as a material failure where the stresses exerted on the wall outweigh its strength. Therefore, rupture depends on the pointwise comparison of the stress and strength for every point of the aneurysmal surface. Moreover, AAAs hemodynamics play an essential role in AAAs natural history, progression and rupture. This chapter summarizes advances in AAAs rupture risk esti-

mation beyond the "one size fits all" maximum diameter criterion.

**Keywords:** abdominal aortic aneurysm, rupture risk, wall stress, shear stress, wall strength, biomechanics, hemodynamics, intraluminal thrombus, rupture potential index

Abdominal aortic aneurysms (AAAs) are balloon like dilatations of the abdominal aorta with a diameter exceeding 50% of the diameter of the normal vessel [1, 2]. These are lesions affecting

**Abdominal Aortic Aneurysm Rupture Risk Assessment**

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.76121
