Ultrasonic evaluation of abdominal aortic thrombus.

Harter, L P; Gross, B H; Callen, P W; Barth, Richard A.

doi:10.7863/jum.1982.1.8.315

Cited by 103 publications

(67 citation statements)

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“…Intramural thrombus is found in approximately 75% of all AAAs. 29 A thrombus can substantially reduce aneurysmal wall stress, and increase medial neovascularization and inflammation as well as local generation of proteases, 30 all of which could influence AAA expansion. Finally, the site of maximum wall stress, which is the site most susceptible to expansion, can be markedly heterogeneous between AAAs because of the considerable differences in hemodynamic conditions.…”

Section: Discussionmentioning

confidence: 99%

Inverse Correlation Between Calcium Accumulation and the Expansion Rate of Abdominal Aortic Aneurysms

Nakayama

Morita

Hayashi

et al. 2016

Circ J

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Section: Discussionmentioning

confidence: 99%

Inverse Correlation Between Calcium Accumulation and the Expansion Rate of Abdominal Aortic Aneurysms

Nakayama

Morita

Hayashi

et al. 2016

Circ J

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“…Most of the geometrical parameters considered in the present study correspond to limited size aneurysms (except for the case where H = 1) which are clinically shown to be devoid of an endoluminal thrombus (Harter et al 1982).…”

Section: Methodsmentioning

confidence: 99%

Dynamics of pulsatile flow through model abdominal aortic aneurysms

2014

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To contribute to the understanding of flow phenomena in abdominal aortic aneurysms, numerical computations of pulsatile flows through aneurysm models and a stability analysis of these flows were carried out. The volume flow rate waveforms into the aneurysms were based on measurements of these waveforms, under rest and exercise conditions, of patients suffering abdominal aortic aneurysms. The Reynolds number and Womersley number, the dimensionless quantities that characterize the flow, were varied within the physiologically relevant range, and the two geometric quantities that characterize the model aneurysm were varied to assess the influence of the length and maximal diameter of an aneurysm on the details of the flow. The computed flow phenomena and the induced wall shear stress distributions agree well with what was found in PIV measurements by Salsac et al. (J. Fluid Mech., vol. 560, 2006, pp. 19-51). The results suggest that long aneurysms are less pathological than short ones, and that patients with an abdominal aortic aneurysm are better to avoid physical exercise. The pulsatile flows were found to be unstable to three-dimensional disturbances if the aneurysm was sufficiently localized or had a sufficiently large maximal diameter, even for flow conditions during rest. The abdominal aortic aneurysm can be viewed as acting like a 'wavemaker' that induces disturbed flow conditions in healthy segments of the arterial system far downstream of the aneurysm; this may be related to the fact that one-fifth of the larger abdominal aortic aneurysms are found to extend into the common iliac arteries. Finally, we report a remarkable sensitivity of the wall shear stress distribution and the growth rate of three-dimensional disturbances to small details of the aneurysm geometry near the proximal end. These findings suggest that a sensitivity analysis is appropriate when a patient-specific computational study is carried out to obtain a quantitative description of the wall shear stress distribution.

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“…ILT is fibrin structure compound of platelets, blood cells, blood proteins, and cellular debris (20). ILT is more frequent in larger AAA since most patients develop thrombus as the aneurysm progresses.…”

mentioning

confidence: 99%

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

Arzani

Suh

Dalman

et al. 2014

American Journal of Physiology-Heart and Circulatory Physiology

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(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 (Ͼ0.4) and low TAWSS (Ͻ1 dyn/cm 2 ) did not appear to coincide with locations of thrombus deposition. computational fluid dynamics; hemodynamics; oscillatory shear index; thrombosis; wall shear stress ABDOMINAL AORTIC ANEURYSM (AAA) is a permanent dilation (50% greater than the normal arterial wall diameter) of the abdominal aorta. The disease is progressive and fatal if untreated. Between 11,000 and 17,000 patients die annually in the United States (18a) from AAA rupture following progressive, often asymptomatic, enlargement, and only invasive treatments have proven effective at preventing rupture and premature death (13). Male gender, age, smoking, genetic factors, hypertension, and high cholesterol are among known risk factors (10), and diabetes is a negative risk factor (47). Degradation of the aortic wall, inflammation with immune responses, and biochemical wall stress are mechanisms that promote AAA initiation, influenced by molecular genetics (1). After the irreversible process of aneurysm formation, the dilated vessel creates an environment with complex blood flow and wall shear stress distribution (4,5,9,14,22,37,38), which is thought to perpetuate aneurysm progression.The presence of intraluminal thrombus (ILT) complicates AAA growth. ILT is fibrin structure compound of platelets, blood cells, blood proteins, and cellular debris (20). ILT is more frequent in larger AAA since most patients develop thrombus as the aneurysm progresses. It has been proposed that platelets activate in regions of high shear and are subsequently advected towards the aneurysm wall where they accumulate in regions of low shear and form thrombus (8), with a possible role played by the vortical structures formed inside the aneurysm (9). It has also been shown that the flow field inside AAA may promote ILT formation by increasing residence time and trapping blood particles (7,37,38).The effect of ILT on AAA progression and rupture remains controversial (48). ILT may deprive the aneurysm wall of oxygen, which may exacerba...

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Ultrasonic evaluation of abdominal aortic thrombus.

Cited by 103 publications

References 1 publication

Inverse Correlation Between Calcium Accumulation and the Expansion Rate of Abdominal Aortic Aneurysms

Inverse Correlation Between Calcium Accumulation and the Expansion Rate of Abdominal Aortic Aneurysms

Dynamics of pulsatile flow through model abdominal aortic aneurysms

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

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