scholarly journals Computational analysis of aortic haemodynamics in the presence of ascending aortic aneurysm

2021 ◽  
pp. 1-14
Author(s):  
Aleksandra Petuchova ◽  
Algirdas Maknickas
Keyword(s):  
Blood Flow ◽  
Aortic Aneurysm ◽  
Computational Analysis ◽  
Aortic Wall ◽  
Cardiac Cycle ◽  
Vascular Wall ◽  
Blood Velocity ◽  
Oscillatory Shear Index ◽  
Ascending Aortic Aneurysm ◽  
Haemodynamic Parameters

BACKGROUND: The usefulness of numerical modelling of a patient’s cardiovascular system is growing in clinical treatment. Understanding blood flow mechanics can be crucial in identifying connections between haemodynamic factors and aortic wall pathologies. OBJECTIVE: This work investigates the haemodynamic parameters of an ascending aorta and ascending aortic aneurysm in humans. METHODS: Two aortic models were constructed from medical images using the SimVascular software. FEM blood flow modelling of cardiac cycle was performed using CFD and CMM-FSI at different vascular wall parameters. RESULTS: The results showed that highest blood velocity was 1.18 m/s in aorta with the aneurysm and 1.9 m/s in healthy aorta model. The largest displacements ware in the aorta with the aneurysm (0.73 mm). In the aorta with the aneurysm, time averaged WSS values throughout the artery range from 0 Pa to 1 Pa. In the healthy aorta, distribution of WSS values changes from 0.3 Pa to 0.6 Pa. CONCLUSIONS: In the case of an ascending aortic aneurysm, the maximum blood velocity was found to be 1.6 times lower than in the healthy aorta. The aneurysm-based model demonstrates a 45% greater wall displacement, while the oscillatory shear index decreased by 30% compared to healthy aortic results.

scholarly journals Aortic wall thickness in patients with ascending aortic aneurysm versus acute aortic dissection

2015 ◽  
Vol 49 (3) ◽  
pp. 756-762 ◽  
Author(s):  
Joeri Van Puyvelde ◽  
Eric Verbeken ◽  
Peter Verbrugghe ◽  
Paul Herijgers ◽  
Bart Meuris
Keyword(s):  
Aortic Aneurysm ◽  
Aortic Dissection ◽  
Wall Thickness ◽  
Aortic Wall ◽  
Acute Aortic Dissection ◽  
Ascending Aortic Aneurysm ◽  
Aortic Wall Thickness

scholarly journals The Importance of Velocity Acceleration to Flow-Mediated Dilation

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Lee Stoner ◽  
Joanna M. Young ◽  
Simon Fryer ◽  
Manning J. Sabatier
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Vascular Tone ◽  
Cardiac Cycle ◽  
Blood Velocity ◽  
Rate Of Change ◽  
Flow Mediated Dilation ◽  
Flow Pulsatility ◽  
Poiseuille's Law ◽  
Poiseuille’S Law

The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone.

scholarly journals Fibromuscular dysplasia of aortic aneurysm vasa vasorum (a rare case report)

2020 ◽  
Vol 27 (4) ◽  
pp. 169-178
Author(s):  
S. S. Todorov ◽  
V. Yu. Deribas ◽  
A. S. Kaz’min ◽  
S. S. Todorov
Keyword(s):  
Aortic Aneurysm ◽  
Histological Examination ◽  
Fibromuscular Dysplasia ◽  
Aortic Wall ◽  
Vasa Vasorum ◽  
Wall Thickening ◽  
Elastic Fibres ◽  
Ascending Aortic Aneurysm ◽  
Aneurysm Wall ◽  
Smooth Myocytes

Aim. To describe a rare occurrence of fibromuscular vasa vasorum dysplasia of the aortic aneurysm wall.Materials and methods. Surgical material from the ascending aortic aneurysm wall was examined. Longitudinal strips of the aortic wall were excised for histological examination with subsequent 24-h fixation in 10% buffered formalin. A histological isopropanol assay was performed with an automated Logos microwave tissue processor (Milestone, Italy) with subsequent sample embedding into paraffin. Sections were obtained with a rotary microtome (Leica, Germany). Staining was performed with haematoxylin-eosin, van Gieson’s picrofuchsin, orcein for elastic fibres, Hotchkiss’ PAS reaction with alcian blue for glycosaminoglycans. Histological and histochemical properties of the aortic wall were studied and imaged with a Leica DM 1000 microscope (Germany) equipped with a camera ICC50 E at magnifications 40x, 100x, 200x, 400x.Results. The conducted histological examination of the aortic aneurysm wall revealed most pronounced changes in media and adventitia layers. Elastic fibres in media were swollen, homogeneous, crimped, with pronounced dystrophic and necrobiotic changes in smooth myocytes. Regions of compromised cells and elastic fibres in media contained pockets of alcian-positive glycosaminoglycans. Specific changes were revealed in adventitia vasa vasorum in the form of a pronounced wall thickening and lumen narrowing due to dysplastic fibromuscular tissues.Conclusion. A rare form of fibromuscular dysplasia of the vasa vasorum of the ascending aortic aneurysm wall observed in a 43 years-old woman demonstrated the morbid morphology of smooth myocytes, as well as fibrous collagenous and elastic structures. The described features were likely associated with the aortic wall trophic structure and aneurysm morphogenesis.

IMPACT OF VISCOSITY ON BLOOD FLOW IN ASCENDING AORTIC ANEURYSM

2021 ◽  
Author(s):  
Gabriela de Castro Almeida ◽  
BRUNO Nieckele Azevedo ◽  
Julia de Almeida Silva ◽  
ivan fernney ibanez aguilar ◽  
BRUNO AZEVEDO ◽  
...  
Keyword(s):  
Blood Flow ◽  
Aortic Aneurysm ◽  
Ascending Aortic Aneurysm

On the severity of aortic stenosis in ascending aortic aneurysm: A computational tool to examine ventricular-arterial interaction and aortic wall stress

2020 ◽  
Vol 110 ◽  
pp. 103621
Author(s):  
Federica COSENTINO ◽  
Marzio DI GIUSEPPE ◽  
Valentina AGNESE ◽  
Giovanni GENTILE ◽  
Giuseppe M RAFFA ◽  
...  
Keyword(s):  
Aortic Aneurysm ◽  
Aortic Stenosis ◽  
Aortic Wall ◽  
Wall Stress ◽  
Computational Tool ◽  
Ascending Aortic Aneurysm

scholarly journals Evaluation of Distensibility and Stiffness of Ascending Aortic Aneurysm using Magnetic Resonance Imaging

2016 ◽  
Vol 55 (204) ◽  
pp. 67-71
Author(s):  
Kaushal Kishore Tiwari ◽  
Stefano Bevilacqua ◽  
Giovanni Aquaro ◽  
Pierluigi Festa ◽  
Lamia Ait-Ali ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Aortic Aneurysm ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Aortic Wall ◽  
Pulse Wave ◽  
Ascending Aorta ◽  
Resonance Imaging ◽  
Ascending Aortic Aneurysm

Introduction: Magnetic resonance imaging emerging as a new tool for the diagnosis and evaluation of ascending aortic aneurysm. The aim of our study is to evaluate in vivo distensibility and pulse wave velocity of the aortic wall using functional magnetic resonance imaging technique.Methods: We enrolled 25 patients undergoing surgery for ascending aortic aneurysm and or aortic valve replacement for a period of 8 months. Preoperatively, all the patients underwent functional MRI study of the aorta. Aortic wall distensibility and pulse wave velocity of ascending aorta was evaluated. Results: Mean age of the patient was 66 years (66.68 ± 5.62 years) with 60% (15) male patients. More than fifty percentages of patients were smoker (52%), hypertensive (64%) and diabetic (56%). We have observed significant decrease of distensibilty in the patients with aortic diameter above 50 mm (p-0.0002). Furthermore, we have found a significant inverse correlation between aortic distensibility and pulse wave velocity (R= -0.650, R2= 0.42, p-0.0004). Similarly, we have found a significant inverse correlation between ascending aortic diameter and distensibility of the aorta (R= -0.785, R2= 0.61, p-0.00001). Statistically significant positive correlation was observed between aortic diameter and pulse wave velocity (R= 0.865, R2= 0.74, p-0.00001).Conclusions: MRI measurement of aortic diameters, distensibility, and flow wave velocity is an easy, reliable and reproducible technique. Distensibility and pulse wave velocity define the elasticity of the aorta. We have observed that elasticity of aortic wall is decreased in ascending aorta aneurysm patients. Keywords: ascending aorta aneurysm; distensibility; pulse wave velocity; MRI. | PubMed

scholarly journals FloWave.US: validated, open-source, and flexible software for ultrasound blood flow analysis

2016 ◽  
Vol 121 (4) ◽  
pp. 849-857 ◽  
Author(s):  
Crystal L. Coolbaugh ◽  
Emily C. Bush ◽  
Charles F. Caskey ◽  
Bruce M. Damon ◽  
Theodore F. Towse
Keyword(s):  
Blood Flow ◽  
Muscle Contraction ◽  
Open Source ◽  
Cardiac Cycle ◽  
Flow Analysis ◽  
Vessel Diameter ◽  
Blood Velocity ◽  
Lower Extremity Muscle ◽  
Blood Flow Analysis

Automated software improves the accuracy and reliability of blood velocity, vessel diameter, blood flow, and shear rate ultrasound measurements, but existing software offers limited flexibility to customize and validate analyses. We developed FloWave.US —open-source software to automate ultrasound blood flow analysis—and demonstrated the validity of its blood velocity (aggregate relative error, 4.32%) and vessel diameter (0.31%) measures with a skeletal muscle ultrasound flow phantom. Compared with a commercial, manual analysis software program, FloWave.US produced equivalent in vivo cardiac cycle time-averaged mean (TAMean) velocities at rest and following a 10-s muscle contraction (mean bias <1 pixel for both conditions). Automated analysis of ultrasound blood flow data was 9.8 times faster than the manual method. Finally, a case study of a lower extremity muscle contraction experiment highlighted the ability of FloWave.US to measure small fluctuations in TAMean velocity, vessel diameter, and mean blood flow at specific time points in the cardiac cycle. In summary, the collective features of our newly designed software—accuracy, reliability, reduced processing time, cost-effectiveness, and flexibility—offer advantages over existing proprietary options. Further, public distribution of FloWave.US allows researchers to easily access and customize code to adapt ultrasound blood flow analysis to a variety of vascular physiology applications.

scholarly journals Features of Morphogenesis of Aortic Aneurysms on the Background of Hypertension and Associated Risk Factors

2021 ◽  
pp. 62-66
Author(s):  
V. Zakharova ◽  
O. Rudenko ◽  
V. Kravchenko
Keyword(s):  
Risk Factors ◽  
Aortic Aneurysm ◽  
Aortic Wall ◽  
Elevated Pressure ◽  
Aortic Aneurysms ◽  
Vasa Vasorum ◽  
Morphological Examination ◽  
Ascending Aortic Aneurysm ◽  
The Media ◽  
Associated Risk Factors

The aim. To investigate the role of hypertension and associated risk factors in the formation of aortic aneurysms. Material and methods. Retrospective analysis of 196 case histories of patients who were successively operated on for ascending aortic aneurysm at the National Amosov Institute of cardiovascular surgery. The history was analyzed, the duration and degree of hypertension were recorded, as well as other factors that may have influenced the development of ascending aortic aneurysm in some way. A pathomorphological examination of fragments of the aortic wall that were excised during the operation was performed. Out of all 294 examined patients operated for ascending aortic aneurysm, hypertension was reported in 196 (66.7%) patients. The incidence of ascending aortic aneurysm positively correlated with the duration of hypertension. The ma-jority of patients (118 [60.2%]) had signs of hypertension for more than five years. Additional ethiopathogenetic fac-tors were identified in patients with ascending aortic aneurysm and hypertension, with atherosclerosis ranking first (66 [33.6%]). The next factors that demonstrated the same incidence were the inflammatory process in the aorta and AV, and smoking: 45 cases each (22.9%). Then, in descending order, were: xenobiotics exposure (43 [21.9%]), rheumatic stenosis of AV (40 [20.4%]), chest injury (33 [16.8%]), dysplasia of AV (28 [14.3%]), alcohol abuse (13 [6.6%]), Marfan syndrome (9 [4.6%]), other (8 [4.1%]). The results of comparison of the history and pathomorphological findings allowed to develop a scheme of ascending aortic aneurysm pathogenesis in hypertension. The scheme of ascending aortic aneurysm pathogenesis in hypertension is discussed in the work. The results of morphological examination show that hypertension is associated with the dam-age to the aortic endothelium, which leads to fibromuscular proliferation of the intima with subsequent hypoxic damage to the inner layer of the media. Hypoxic damage to the media, which is associated with vasa vasorum remodeling due to hypertension, is also observed in the subventricular layer. Weakening of the aortic wall at elevated pressure causes dila-tation of the aorta, i.e. the formation of an aortic aneurysm. This process may be exacerbated by additional factors, with atherosclerosis being the most common (33.6%)

Endothelium in Aortic Aneurysm Disease: New Insights

2020 ◽  
Vol 27 (7) ◽  
pp. 1081-1088 ◽  
Author(s):  
Eleftherios Spartalis ◽  
Michael Spartalis ◽  
Antonios Athanasiou ◽  
Stavroula A. Paschou ◽  
Nikolaos Patelis ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Smooth Muscle ◽  
Aortic Aneurysm ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Aortic Wall ◽  
Muscle Cells ◽  
Aortic Aneurysms

Inflammation is recognized as a fundamental element in the development and growth of aortic aneurysms. Aortic aneurysm is correlated with aortic wall deformities and injury, as a result of inflammation, matrix metalloproteinases activation, oxidative stress, and apoptosis of vascular smooth muscle cells. The endothelial wall has a critical part in the inflammation of the aorta and endothelial heterogeneity has proven to be significant for modeling aneurysm formation. Endothelial shear stress and blood flow affect the aortic wall through hindrance of cytokines and adhesion molecules excreted by endothelial cells, causing reduction of the inflammation process in the media and adventitia. This pathophysiological process results in the disruption of elastic fibers, degradation of collagen fibers, and destruction of vascular smooth muscle cells. Consequently, the aortic wall is impaired due to reduced thickness, decreased mechanical function, and cannot tolerate the impact of blood flow leading to aortic expansion. Surgery is still considered the mainstay therapy for large aortic aneurysms. The prevention of aortic dilation, though, is based on the hinderance of endothelial dysregulation with drugs, the reduction of reactive oxygen and nitrogen species, and also the reduction of pro-inflammatory molecules and metalloproteinases. Further investigations are required to enlighten the emerging role of endothelial cells in aortic disease.

Lack of PI 3-kinase isoform p110alpha in smooth muscle cells impairs aortic wall homoeostasis and thus promotes aortic aneurysm formation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Vantler ◽  
E Berghausen ◽  
M Zierden ◽  
M Mollenhauer ◽  
D Mehrkens ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Aortic Aneurysm ◽  
Smooth Muscle Cells ◽  
Aortic Wall ◽  
Muscle Cells ◽  
Vascular Wall ◽  
Aortic Diameter ◽  
Funding Source ◽  
Wild Type ◽  
Tunica Media

Abstract Background In smooth muscle cells (SMCs), the PI 3-kinase isoform p110α mediates receptor tyrosine kinase dependent proliferation, chemotaxis and cell survival. Since mice, harbouring a smooth muscle specific p110α deficiency (SM-p110α−/−), display reduced vascular wall thickness, we hypothesized that SM-p110α−/− mice might be prone to aortic aneurysm (AA) formation. The pathogenesis of AA is characterized by increased dedifferentiation of SMCs, extracellular matrix (ECM) degeneration and inflammation in the aortic wall. Herein, we investigated how p110α-dependent signal transduction in SMCs affects these processes. Methods and results We examined AA formation in SM-p110α−/− mice and wild-type littermates using the “porcine pancreatic elastase” (PPE) AA model. PPE was infused into the infrarenal aorta to induce AA formation. Ultrasound examination of the aorta revealed an enlarged aortic diameter in all PPE-treated mice. The aortic diameter in SM-p110α−/− mice (0.46±0.12 mm) was significantly increased compared to wild-type animals (0.18±0.03 mm, p&lt;0.01). These data indicate a protective function of p110α in AA formation. Immunocytochemical examination of the tunica media of PPE-perfused SM-p110α−/− mice revealed significantly increased infiltration of CD45+ leukocytes. In particular, the number of MOMA-2+ monocytes / macrophages in the vessel wall was significantly increased indicating elevated inflammation of the aortic wall during AA progression in comparison to wild-type control mice. Ultrastructural analysis of aortic wall morphology in SM-p110α−/− mice using transmission electron microscopy (TEM) showed a deranged tunica media and increased apoptotic cell death. In addition, the media thickness in the abdominal aorta was significantly reduced in SM-p110α−/− mice (29.0±3.1 μm vs. 42.5±4.1 μm). Western blots demonstrated a reduced elastin and fibrillin expression in SMCs from SM-p110α−/− mice. p110α−/− SMCs showed significantly reduced expression of differentiation markers SM-α-actin and SM-MHC. In addition, aortic p110α-deficient SMCs were significantly impaired in their ability to proliferate and migrate. These findings indicate that p110α−/− SMCs are neither differentiated nor dedifferentiated and have therefore largely lost their plasticity. Consequently, p110α deficiency significantly diminished responsiveness of aortic rings to vasodilator acetylcholine and NO-donor nitroglycerin, further indicating impaired contractility of SMCs. Mechanistically, we demonstrated that PDGF and insulin induced phosphorylation and inactivation of key regulators of SMC differentiation and dedifferentiation, Foxo4 and GSK3b, respectively, were abrogated in p110α−/− SMCs. Conclusion These data show that deficiency of p110α in SMCs promotes the formation and progression of AA. Causative are impaired SMC plasticity and ECM homeostasis as well as inflammatory processes in the vascular wall. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG)

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