scholarly journals Does the Intraluminal Thrombus Provoke the Rupture of the Abdominal Aortic Aneurysm Wall?

2021 ◽  
Vol 11 (21) ◽  
pp. 9941
Author(s):  
Mohammed Almijalli
Keyword(s):  
Computer Modelling ◽  
Aortic Aneurysms ◽  
Oxygen Flow ◽  
Patient Specific ◽  
Aortic Blood Flow ◽  
Intraluminal Thrombus ◽  
Volume Percentage ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Risk Of Rupture

The role of intraluminal thrombus (ILT) in the rupture of abdominal aortic aneurysms (AAA) is controversial, and it is unclear whether it increases or decreases the risk of rupture. This research aims to find a clear answer to this question. Previous computer modelling suggests that an ILT lowers oxygen dissemination to the AAA wall, contributing to wall thinning. The methodology used in this study determines the amount of oxygen reaching the aneurysm wall after passing through the ILT by using the porous nature of the ILT to recreate the condition as closely as feasible. Using computed tomographic images, patient-specific three-dimensional (3D) AAA geometries were recreated. Modelling blood and oxygen flow in AAA was obtained using a computational fluid dynamics (CFD) approach. Our findings indicated that the oxygen volume percentage had completely reached the aneurysm wall. Only at the inlet and outflow did the greatest wall shear stress (WSS) occur, with a significant drop in the central region of the aneurysm wall. CFD was used to calculate the velocity, pressure, and WSS of aortic blood flow. ILT had no effect on oxygen flow to the aneurysm wall, disproving the theory that it produces local hypoxia.

scholarly journals On the Relative Impact of Intraluminal Thrombus Heterogeneity on Abdominal Aortic Aneurysm Mechanics

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Joseph R. Leach ◽  
Evan Kao ◽  
Chengcheng Zhu ◽  
David Saloner ◽  
Michael D. Hope
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Intraluminal Thrombus ◽  
Element Analysis ◽  
Aneurysm Wall ◽  
Abdominal Aortic

Intraluminal thrombus (ILT) is present in the majority of abdominal aortic aneurysms (AAA) of a size warranting consideration for surgical or endovascular intervention. The rupture risk of AAAs is thought to be related to the balance of vessel wall strength and the mechanical stress caused by systemic blood pressure. Previous finite element analyses of AAAs have shown that ILT can reduce and homogenize aneurysm wall stress. These works have largely considered ILT to be homogeneous in mechanical character or have idealized a stiffness distribution through the thrombus thickness. In this work, we use magnetic resonance imaging (MRI) to delineate the heterogeneous composition of ILT in 7 AAAs and perform patient–specific finite element analysis under multiple conditions of ILT layer stiffness disparity. We find that explicit incorporation of ILT heterogeneity in the finite element analysis is unlikely to substantially alter major stress analysis predictions regarding aneurysm rupture risk in comparison to models assuming a homogenous thrombus, provided that the maximal ILT stiffness is the same between models. Our results also show that under a homogeneous ILT assumption, the choice of ILT stiffness from values common in the literature can result in significantly larger variations in stress predictions compared to the effects of thrombus heterogeneity.

Abstract 261: Neutrophil Elastase Derived Fibrin Degradation Products are Increased in the Plasma of Patients with Abdominal Aortic Aneurysms and Correlate to the Intraluminal Thrombus Volume

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Joy Roy ◽  
Angela Silveira ◽  
Moritz Liljeqvist Lindquist ◽  
Maggie Folkesson ◽  
Siw Frebelius ◽  
...  
Keyword(s):  
Degradation Products ◽  
Sandwich Elisa ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Intraluminal Thrombus ◽  
Fibrin Degradation Products ◽  
Aortic Repair ◽  
Abdominal Aortic ◽  
Risk Of Rupture

Introduction: Abdominal Aortic Aneurysms (AAA) often contain an intraluminal thrombus (ILT). AAA diameter and ILT volume are associated with growth of the aneurysm. Neutrophils, present in the ILT, contain elastase (NE). NE activity leads to production of fibrin degradation products (FDPs) with a specific epitope [[Unable to Display Character: &#8211;]] XDP. The present study evaluates NE-derived FDPs in aneurysm patients scheduled for elective aortic repair. The purpose of the study is to introduce an additional bio-marker for presence of AAA and possibly risk of rupture by measuring levels of NE derived FDPs in plasma of patients with AAA. Materials and Methods: 42 male patients, undergoing aortic repair for AAA were included. As controls, we collected blood samples from 42 men who attended an AAA screening program but had no AAAs on ultrasound. Computed Tomography (CT) images were available for 34 AAA patients and analyzed using A4 Clinics software (VASCOPS, Austria). Patient demographics, maximum diameter, aortic volume and ILT volume were recorded. Peak wall stress (PWS), peak wall rupture index (PWRI) and mean ILT stress were estimated by Finite Element Analysis using the A4 Clinics software. Plasma levels of elastase digests of cross-linked fibrin (E-XDP) were determined with a sandwich ELISA. Results: E-XDP levels were higher in AAA patients than in age-matched controls (8.5 vs 1.2 U/ml, p<0.0001). E-XDP levels correlated with ILT volume (r = 0.64, p<0.0001), aortic volume (r = 0.64, p<0.0001) and maximum diameter (r = 0.59, p=0.0003). AAA patients with other concomitant peripheral aneurysms had higher E-XDP levels than those with only an AAA (13.6 vs 6.8 U/ml, p=0.028). PWS, PWRI and bleeding signs in the thrombus did not significantly affect E-XDP levels. Interestingly, the mean ILT stress correlated significantly to E-XDP levels (r= 0.45, p=0.008). Conclusions: The study shows that it is feasible to measure E-XDP levels in plasma of patients with AAA and that E-XDP correlates with ILT volume and mean ILT stress. These results support the notion that the resident neutrophils in the ILT can actively lyse fibrin in the ILT, which may decrease ILT strength. E-XDP holds potential as a biomarker of the ILT in AAA patients and needs to be further investigated in AAA rupture risk assessment.

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.

Intraluminal thrombus and risk of rupture in patient specific abdominal aortic aneurysm – FSI modelling

2009 ◽  
Vol 12 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Danny Bluestein ◽  
Kris Dumont ◽  
Matthieu De Beule ◽  
John Ricotta ◽  
Paul Impellizzeri ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Patient Specific ◽  
Intraluminal Thrombus ◽  
Abdominal Aortic ◽  
Risk Of Rupture

Risk of Rupture in AAA and Vulnerable Plaques: Patient Based FSI Simulation

2007 ◽  
Author(s):  
Danny Bluestein ◽  
Yared Alemu ◽  
Peter Rissland ◽  
Mikahil Britan ◽  
Idit Avrahami ◽  
...  
Keyword(s):  
Vulnerable Plaque ◽  
Material Model ◽  
Patient Specific ◽  
Rupture Risk ◽  
Fibrous Cap ◽  
Wall Properties ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Risk Of Rupture ◽  
Failure Location

Two separate fluid structure interaction (FSI) simulations were performed: a patient-specific Abdominal Aortic Aneurysm (AAA) geometry, and an idealized coronary vulnerable plaque (VP) geometry. VP FSI simulations were later performed in patient based geometries reconstructed from intravascular (IVUS) measurements. (AAA): The patient specific AAA FSI simulation was carried out with both isotropic and anisotropic wall properties. An orthotropic material model was used to describe wall properties, closely approximate experimental results [1]. Results show peak wall stresses are dependent on the geometry of the AAA and the region of highest stress corresponds to expected failure location. The ability to quantify stresses developing within the aneurysm wall based on FSI simulations will facilitate clinicians to reach informed decisions in determining rupture risk of AAA and the need for surgical intervention. (Vulnerable Plaque): To study the risk of rupture of a vulnerable plaque in an idealized coronary artery geometry, an FSI simulation was performed. This model of vulnerable plaque includes vessel wall with calcification spot embedded in the fibrous cap, and a lipid core. Identifying rupture risk, regions susceptible to failure and the contribution of the various components were studied. This work led to predicting the rupture risk in patient specific geometries. The results show the upstream side of vulnerable plaque fibrous cap has the highest stresses. The presence of the calcified spot is shown to enhance stresses within the fibrous cap, significantly contributing to its risk of rupture.

Effect of Intraluminal Thrombus on Wall Stress and Growth Rate of Abdominal Aneurysms

2010 ◽  
Author(s):  
Lambert Speelman ◽  
E. Marielle H. Bosboom ◽  
Geert Willem H. Schurink ◽  
Jaap Buth ◽  
Marcel Breeuwer ◽  
...  
Keyword(s):  
Risk Estimation ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Intraluminal Thrombus ◽  
Abdominal Aortic ◽  
Risk Of Rupture ◽  
Peak Wall Stress ◽  
Higher Sensitivity ◽  
Main Factor

In the decision for surgical repair of abdominal aortic aneurysms (AAAs), the risk of rupture is weighed carefully against the risk of the surgical procedure. Currently, AAA diameter is the main factor that determines the decision for surgery. However, in rupture risk estimation AAA wall stress has higher sensitivity and specificity than maximum diameter [1]. Moreover, peak wall stress was higher for ruptured than for non-ruptured or asymptomatic AAAs [2, 3].

scholarly journals A longitudinal comparison of hemodynamics and intraluminal thrombus deposition in abdominal aortic aneurysms

2014 ◽  
Vol 307 (12) ◽  
pp. H1786-H1795 ◽  
Author(s):  
Amirhossein Arzani ◽  
Ga-Young Suh ◽  
Ronald L. Dalman ◽  
Shawn C. Shadden
Keyword(s):  
Spin Echo ◽  
Aortic Aneurysms ◽  
Fast Spin Echo ◽  
Patient Specific ◽  
Black Blood ◽  
Hemodynamic Parameters ◽  
Dynamics Modeling ◽  
Spatially Resolved ◽  
Abdominal Aortic ◽  
Risk Of Rupture

Abdominal aortic aneurysm (AAA) is often accompanied by in traluminal thrombus (ILT), which complicates AAA progression and risk of rupture. Patient-specific computational fluid dynamics modeling of 10 small human AAA was performed to investigate relations between hemodynamics and ILT progression. The patients were imaged using magnetic resonance twice in a 2- to 3-yr interval. Wall content data were obtained by a planar T1-weighted fast spin echo black-blood scan, which enabled quantification of thrombus thickness at midaneurysm location during baseline and followup. Computational simulations with patient-specific geometry and boundary conditions were performed to quantify the hemodynamic parameters of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and mean exposure time at baseline. Spatially resolved quantifications of the change in ILT thickness were compared with the different hemodynamic parameters. Regions of low OSI had the strongest correlation with ILT growth and demonstrated a statistically significant correlation coefficient. Prominent regions of high OSI (>0.4) and low TAWSS (<1 dyn/cm2) did not appear to coincide with locations of thrombus deposition.

Trans-Thrombus Blood Pressure Effects in Abdominal Aortic Aneurysms

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Clark A. Meyer ◽  
Carine Guivier-Curien ◽  
James E. Moore
Keyword(s):  
Wall Stress ◽  
Aortic Aneurysms ◽  
Pressure Effects ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Histopathological Studies ◽  
Von Mises ◽  
Von Mises Stresses

How much and how the thrombus supports the wall of an abdominal aortic aneurysm (AAA) is unclear. While some previous studies have indicated that thrombus lacks the mechanical integrity to support much load compared with the aneurysm wall, others have shown that removing thrombus in computational AAA models drastically changes aneurysm wall stress. Histopathological studies have shown that thrombus properties vary through the thickness and it can be porous. The goal of this study is to explore the variations in thrombus properties, including the ability to isolate pressure from the aneurysm wall, incomplete attachment, and their effects on aneurysm wall stress, an important parameter in determining risk for rupture. An analytical model comprised of cylinders and two patient specific models were constructed with pressurization boundary conditions applied at the lumen or the thrombus/aneurysm wall interface (to simulate complete transmission of pressure through porous thrombus). Aneurysm wall stress was also calculated in the absence of thrombus. The potential importance of partial thrombus attachment was also analyzed. Pressurizing at either surface (lumen versus interface) made little difference to mean von Mises aneurysm wall stress values with thrombus completely attached (3.1% analytic, 1.2% patient specific) while thrombus presence reduced mean von Mises stress considerably (79% analytic, 40–46% patient specific) in comparison to models without it. Peak von Mises stresses were similarly influenced with pressurization surface differing slightly (3.1% analytic, 1.4% patient specific) and reductions in stress by thrombus presence (80% analytic, 28–37% patient specific). The case of partial thrombus attachment was investigated using a cylindrical model in which there was no attachment between the thrombus and aneurysm wall in a small area (10 deg). Applying pressure at the lumen resulted in a similar stress field to fully attached thrombus, whereas applying pressure at the interface resulted in a 42% increase in peak aneurysm wall stress. Taken together, these results show that the thrombus can have a wall stress reducing role even if it does not shield the aneurysm wall from direct pressurization—as long as the thrombus is fully attached to the aneurysm wall. Furthermore, the potential for porous thrombus to transmit pressure to the interface can result in a considerable increase in aneurysm wall stress in cases of partial attachment. In the search for models capable of accurately assessing the risk for rupture, the nature of the thrombus and its attachment to the aneurysm wall must be carefully assessed.

Geometry of Abdominal Aortic Aneurysms and the Intraluminal Thrombus From 3D Image Reconstruction Using Active Contours

2009 ◽  
Author(s):  
John H. Ashton ◽  
Avinash Ayyalasomayajula ◽  
Jonathan P. Vande Geest
Keyword(s):  
Active Contours ◽  
The United States ◽  
Aortic Aneurysms ◽  
Local Drug Delivery ◽  
Patient Specific ◽  
Rupture Risk ◽  
Intraluminal Thrombus ◽  
3D Image Reconstruction ◽  
Abdominal Aortic ◽  
Significant Disease

Abdominal aortic aneurysm (AAA) is a significant disease in the United States, and an intraluminal thrombus (ILT) develops in the majority of AAAs. Rupture prediction of AAA has been performed on patient specific models based on reconstruction of computed tomography (CT) images. The ILT alters stress distribution in the AAA wall [1], and ILT growth and thickness are correlated to rupture risk [2, 3]. Drug treatment of AAA is under investigation by several groups [4]. It is also known that the wall covered by the ILT is weaker than other areas [1]. If local drug delivery through the lumen is to be achieved, the barriers for transport through the ILT must be investigated. Patient specific geometries of the ILT would be necessary for such analysis.

Sign in / Sign up

Export Citation Format

Share Document