Promoting Suitable Hemodynamic Conditions for Thrombus Formation in Abdominal Aortic Aneurysms With Multilayer Stents

2016 ◽  
Author(s):  
Juan S. Stockle ◽  
David A. Romero ◽  
Cristina H. Amon
Keyword(s):  
Flow Resistance ◽  
Thrombus Formation ◽  
Abdominal Aortic Aneurysms ◽  
Sensitivity Study ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Multilayer Stent ◽  
The Impact

Multilayer stents or flow modulators are novel devices used for endovascular repair of abdominal aortic aneurysms (AAAs) in patients with unsuitable or complex endovascular geometries. The use of this device is still controversial due to insufficient patient follow-up data and the lack of CFD studies addressing the problem. In this work, we present a methodology to design the flow resistance characteristics needed from multilayer stents to induce suitable hemodynamic conditions inside the aneurysm sac. A hypothetical AAA geometry with and without the device is employed to study the impact on hemodynamic factors of interest such as: the shear stress and pressure distribution on the aneurysm wall, their maximum and average values, and the flow fields inside the aneurysm sac. To model the stent, the porosity and the flow resistance values are used to scale the mass and the Naviers’Stokes equations, including the contribution of the flow resistance on the momentum source term. Through a sensitivity study, the magnitude of the porosity is systematically varied to find the resistance profile that promotes suitable hemodynamic conditions inside the AAA, consistent with the goal of promoting intraluminal thrombus formation. Our results have important implications for designing the layer structures of the multilayer stent to reduce the risks of aneurysm rupture.

scholarly journals The Impact of Endovascular Repair of Abdominal Aortic Aneurysms on Vascular Surgery Training in Open Aneurysm Repair

2021 ◽  
Vol 74 (3) ◽  
pp. e158-e159
Author(s):  
Nadin Elsayed ◽  
Maryam A. Khan ◽  
Isaac Naazie ◽  
Jaideep Das Gupta ◽  
Randall De Martino ◽  
...  
Keyword(s):  
Vascular Surgery ◽  
Endovascular Repair ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Surgery Training ◽  
Abdominal Aortic ◽  
Aneurysm Repair ◽  
The Impact

Material Properties of Abdominal Aortic Aneurysm Wall From Uniaxial Tests

2000 ◽  
Author(s):  
Mano J. Thubrikar ◽  
Michel Labrosse ◽  
Jihad Al-Soudi ◽  
Brett Fowler ◽  
Francis Robicsek
Keyword(s):  
Experimental Data ◽  
Material Properties ◽  
Aortic Wall ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Modeling Tools ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Abdominal Aortic Aneurysm Wall ◽  
Mechanical Models

Abstract Abdominal aortic aneurysms (AAA) rupture when the aortic wall cannot withstand the stresses and strains induced by the pulsatile blood pressure. In recent years, different mechanical models of aneurysms have been presented (Vorp et al., 1998, Di Martino et al., 1998, Thubrikar et al., 1999). Although powerful modeling tools such as finite elements are available, there is still a need for experimental data concerning the mechanical properties of the aneurysm wall.

Presence of NGAL/MMP-9 complexes in human abdominal aortic aneurysms

2007 ◽  
Vol 98 (08) ◽  
pp. 427-433 ◽  
Author(s):  
Chaoyong Zhu ◽  
Angela Silveira ◽  
Anne-Louise Hemdahl ◽  
Anders Hamsten ◽  
Ulf Hedin ◽  
...  
Keyword(s):  
Elective Surgery ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Intraluminal Thrombus ◽  
Neutrophil Gelatinase Associated Lipocalin ◽  
Reducing Conditions ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Aneurysm Growth ◽  
Neutrophil Gelatinase

SummaryIt has been suggested that the intraluminal thrombus of abdominal aortic aneurysms (AAAs) predisposes for AAA enlargement and rupture.The growth of theAAA is dependent on proteolytic degradation of elastin. Here, we analysed whether the neutrophil gelatinase-associated lipocalin (NGAL) is expressed within the thrombus and the aneurysm wall. NGAL can bind to metalloproteinase- 9 (MMP-9) and inhibit its degradation,thereby preserving enzymatic activity. Biopsies were obtained from thrombus- free and thrombus-covered aneurysm wall and the intraluminal thrombus from patients undergoing elective surgery for AAA. Immunohistochemistry and real-time PCR were used to study NGAL and MMP-9 expression. Immunoprecipitation, gel zymography,Western blot and ELISA were used to detect and quantify NGAL/MMP-9 complexes. NGAL was detected in the thrombus, the interface between the thrombus and the underlying wall and in the wall itself.Double staining showed that neutrophils are the major source of NGAL expression. Immunoprecipitation of MMP-9 with antibody against NGAL showed that complexes of NGAL and active MMP-9 were present in thrombus, the interface fluid and the aneurysm wall.Western blot analyses using non-reducing conditions and gel zymography demonstrated that high-molecular-weight complexes of NGAL/MMP-9 were present within the different regions.The concentration of the NGAL/MMP-9 complex was highest in the luminal part of the thrombus. In conclusion, NGAL in complex with activated MMP-9 is present in AAA wall and thrombus. Neutrophil-derived NGAL could enhance the proteolytic activity associated with AAA, but the importance of this mechanism for aneurysm growth remains to be shown.

Flow-Induced Wall Pressure Under Average Resting Hemodynamic Conditions for Patient-Specific Abdominal Aortic Aneurysms

2002 ◽  
Author(s):  
Ender A. Finol ◽  
Shoreh Hajiloo ◽  
Keyvan Keyhani ◽  
David A. Vorp ◽  
Cristina H. Amon
Keyword(s):  
Imaging Techniques ◽  
Abdominal Aortic Aneurysms ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Mortality And Morbidity ◽  
Abdominal Aortic ◽  
Lethal Event ◽  
Overall Mortality

Abdominal Aortic Aneurysms (AAAs) are characterized by a continuous dilation of the infrarenal segment of the abdominal aorta. Despite significant improvements in surgical procedures and imaging techniques, the mortality and morbidity rates associated with untreated ruptured AAAs are still outrageously high. AAA disease is a health risk of significant importance since this kind of aneurysm is mostly asymptomatic until its rupture, which is frequently a lethal event with an overall mortality rate in the 80% to 90% range. From a purely biomechanical viewpoint, aneurysm rupture is a phenomenon that occurs when the mechanical stress acting on the dilating inner wall exceeds its failure strength. Since the internal mechanical forces are maintained by the dynamic action of blood flowing in the aorta, the quantification of the hemodynamics of AAAs is essential for the characterization of their biomechanical environment.

A Relation Between Particle Hemodynamics and Intraluminal Thrombus Formation in Abdominal Aortic Aneurysms

2009 ◽  
Author(s):  
Christopher A. Basciano ◽  
Julie H. Y. Ng ◽  
Ender A. Finol ◽  
Clement Kleinstreuer
Keyword(s):  
Particle Deposition ◽  
Thrombus Formation ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Blood Proteins ◽  
Intraluminal Thrombus ◽  
Abdominal Aortic ◽  
Cellular Debris ◽  
The Us ◽  
Normal Diameter

Abdominal aortic aneurysms (AAAs) are local dilations of the aorta below the renal arteries where the lumen diameter is ≥ 1.5 times the normal diameter of the healthy blood vessel. Ruptured aneurysms are the 13th leading cause of death in the US [1]. In approximately 75% of all AAAs, a particle-deposition layer forms adjacent to the arterial wall within the lumen called the intra-luminal thrombus (ILT). The thrombus composition has been shown to be a fibrin structure composed of blood cells, platelets, blood proteins, and other cellular debris [2]. Additionally, Yamazumi et al. [3] have presented data that suggest AAA morphology is associated with an elevated state of blood coagulation and fibrinolysis within the aneurysm.

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