Wall shear stress alterations at left atrium and left atrial appendage employing abnormal blood velocity profiles

2020 ◽  
Author(s):  
Grigoris I. Grigoriadis ◽  
Antonis I. Sakellarios ◽  
Ioanna Kosmidou ◽  
Katerina K. Naka ◽  
Christopher Ellis ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Velocity Profiles ◽  
Blood Velocity ◽  
Atrial Appendage ◽  
Wall Shear

scholarly journals Hemodynamic parameters and vessel tortuosity: an investigation with a mesenterial vascular network

2017 ◽  
Vol 1 (4) ◽  
pp. 62-68
Author(s):  
Roberto Annunziata ◽  
Bettina Reglin ◽  
Axel Pries ◽  
Emanuele Trucco
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Oxygen Saturation ◽  
Wall Thickness ◽  
Blood Velocity ◽  
Vascular Network ◽  
Hemodynamic Parameters ◽  
Vessel Tortuosity ◽  
Wall Shear ◽  
Quantitative Definition

Purpose: The effect of hemodynamic parameters on vessel tortuosity remains un-clear. Here we investigate the correlation of tortuosity with a set of hemodynamicparameters in a mesenterial vascular network.Methods: A mesenterial vascular network of 389 vessels (131 arteries, 132 veins, and 126 capillaries) was imaged. Eleven hemodynamic parameters were measured (pressure, wall shear stress, diameter, blood velocity and flow, viscosity, haematocrit, partial oxygen saturation, oxygen saturation, wall thickness, and local vessel density). Tortuosity was assessed quantitatively with a validated algorithm and correlation computed with subsets of hemodynamic parameters selected by a lasso regressor.Results: Results suggest that tortuosity is related to pressure, wall shear stress, diameter, blood velocity, viscosity, partial but not full oxygen saturation, and wall thickness for the arteries; diameter, blood flow, hematocrit, and density for the veins; and viscosity (but not hematocrit), partial and full oxygen saturation, and density for the capillaries. The combination of hemodynamic parameters correlating best with tortuosity is the set of all parameters except density (r = 0.64, p < 0.01), using as tortuosity definition the set of tortuosity features (geometric measures) correlating best with a single hemodynamic factor for the arteries.Conclusion: This pilot suggests two general conclusions. First, the quantitative definition of tortuosity (i.e., the set of geometric features adopted) should be tuned to the specific data and problem considered. Second, tortuosity is caused by a combination of hemodynamic factors, not a single one.

scholarly journals Effect of the Alterations in Contractility and Morphology Produced by Atrial Fibrillation on the Thrombosis Potential of the Left Atrial Appendage

2021 ◽  
Vol 9 ◽  
Author(s):  
Danila Vella ◽  
Alessandra Monteleone ◽  
Giulio Musotto ◽  
Giorgia Maria Bosi ◽  
Gaetano Burriesci
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Atrial Appendage ◽  
Primary Role ◽  
Shear Strain Rate ◽  
Increased Risk

Atrial fibrillation (AF) is a common arrhythmia mainly affecting the elderly population, which can lead to serious complications such as stroke, ischaemic attack and vascular dementia. These problems are caused by thrombi which mostly originate in the left atrial appendage (LAA), a small muscular sac protruding from left atrium. The abnormal heart rhythm associated with AF results in alterations in the heart muscle contractions and in some reshaping of the cardiac chambers. This study aims to verify if and how these physiological changes can establish hemodynamic conditions in the LAA promoting thrombus formation, by means of computational fluid dynamic (CFD) analyses. In particular, sinus and fibrillation contractility was replicated by applying wall velocity/motion to models based on healthy and dilated idealized shapes of the left atrium with a common LAA morphology. The models were analyzed and compared in terms of shear strain rate (SSR) and vorticity, which are hemodynamic parameters directly associated with thrombogenicity. The study clearly indicates that the alterations in contractility and morphology associated with AF pathologies play a primary role in establishing hemodynamic conditions which promote higher incidence of ischaemic events, consistently with the clinical evidence. In particular, in the analyzed models, the impairment in contractility determined a decrease in SSR of about 50%, whilst the chamber pathological dilatation contributed to a 30% reduction, indicating increased risk of clot formation. The equivalent rigid wall model was characterized by SSR values about one order of magnitude smaller than in the contractile models, and substantially different vortical behavior, suggesting that analyses based on rigid chambers, although common in the literature, are inadequate to provide realistic results on the LAA hemodynamics.

Pericardial Patch Exclusion Technique for Left Atrial Appendage Closure

2018 ◽  
Vol 13 (2) ◽  
pp. 144-146
Author(s):  
Olivia K. Ginty ◽  
Ferns H. Khaliel ◽  
Corey Adams ◽  
Michael W. A. Chu
Keyword(s):  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Atrial Appendage ◽  
Pericardial Patch ◽  
Left Atrial Appendage Closure ◽  
Risk Of Bleeding ◽  
Left Atrial Appendage Occlusion ◽  
Autologous Pericardial Patch ◽  
Patch Closure

We describe a technique of left atrial appendage occlusion that consists of autologous pericardial patch closure of the left atrial appendage orifice from within the left atrium. This pericardial patch exclusion technique has little added risk of bleeding, can be performed through sternotomy or right minithoracotomy, and can be used in re-operative situations.

scholarly journals 1112 Discovering the origin of a mysterious heart cavity

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
V Vidal Urrutia ◽  
P Garcia Gonzalez ◽  
J L Perez Bosca ◽  
D Escribano Alarcon ◽  
J M Simon Machi ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Contrast Echocardiography ◽  
Left Ventricular ◽  
Atrial Appendage ◽  
Invasive Approach ◽  
Cardiovascular Morbidity And Mortality ◽  
Doppler Color

Abstract Left atrial appendage aneurysm is an infrequent cardiac malformation, with less than 150 cases reported in the literature. It is a congenital anomaly in the majority of cases, related to a dysplasia of pectinate muscles and atrial muscle bands, which tends to grow with age. At the present time, and despite of being not considered in current guidelines, surgical resection is the standard of treatment in the current literature, even in asymptomatic cases, based on cardiovascular morbidity and mortality by predisposing to atrial tachyarrhythmia, thromboembolism, and other rare conditions as coronary or left ventricular compression and rupture of the aneurysm. We report the case of a 53-year-old male patient presenting an episode of supraventricular paroxysmal tachycardia with the casual finding of a mysterious cavity in the transthoracic echocardiography. We found out the presence of a 50 mm cavity adjacent to the left atrium and left ventricle, with a bidirectional blood flow between the left atrium and the cavity when applying Doppler color and with contrast echocardiography. Given this finding, several differential diagnosis had to be considered, including vascular and structural disorders. In order to clarify the diagnosis, a cardiac magnetic resonance was performed. It revealed the presence of a huge aneurysm of the left atrial appendage (50 x 53 mm) causing a mild compression of the left ventricle, with no thrombus and no other significant findings. Due to its size, the compression of the left ventricle and the history of atrial arrhythmia we decided to manage it with an invasive approach by performing a middle thoracotomy, in order to prevent potentially serious complications. Abstract 1112 Figure. CMR 3D reconstruction; echocardiography

Image-Based Flow Simulations of Pre- and Post-left Atrial Appendage Closure in the Left Atrium

2019 ◽  
Vol 10 (2) ◽  
pp. 225-241 ◽  
Author(s):  
Dongjie Jia ◽  
Byunghwan Jeon ◽  
Hyung-Bok Park ◽  
Hyuk-Jae Chang ◽  
Lucy T. Zhang
Keyword(s):  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Atrial Appendage ◽  
Left Atrial Appendage Closure ◽  
Flow Simulations

scholarly journals Biorheological Model on Flow of Herschel-Bulkley Fluid through a Tapered Arterial Stenosis with Dilatation

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
S. Priyadharshini ◽  
R. Ponalagusamy
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pressure Gradient ◽  
Power Law ◽  
Flow Resistance ◽  
Velocity Profiles ◽  
Arterial Stenosis ◽  
Axial Distance ◽  
Tapered Artery ◽  
Wall Shear

An analysis of blood flow through a tapered artery with stenosis and dilatation has been carried out where the blood is treated as incompressible Herschel-Bulkley fluid. A comparison between numerical values and analytical values of pressure gradient at the midpoint of stenotic region shows that the analytical expression for pressure gradient works well for the values of yield stress till 2.4. The wall shear stress and flow resistance increase significantly with axial distance and the increase is more in the case of converging tapered artery. A comparison study of velocity profiles, wall shear stress, and flow resistance for Newtonian, power law, Bingham-plastic, and Herschel-Bulkley fluids shows that the variation is greater for Herschel-Bulkley fluid than the other fluids. The obtained velocity profiles have been compared with the experimental data and it is observed that blood behaves like a Herschel-Bulkley fluid rather than power law, Bingham, and Newtonian fluids. It is observed that, in the case of a tapered stenosed tube, the streamline pattern follows a convex pattern when we move fromr/R=0tor/R=1and it follows a concave pattern when we move fromr/R=0tor/R=-1. Further, it is of opposite behaviour in the case of a tapered dilatation tube which forms new information that is, for the first time, added to the literature.

scholarly journals Atrial Fibrillation Increases Production of Superoxide by the Left Atrium and Left Atrial Appendage

Circulation ◽  
2005 ◽  
Vol 112 (9) ◽  
pp. 1266-1273 ◽  
Author(s):  
Samuel C. Dudley ◽  
Nyssa E. Hoch ◽  
Louise A. McCann ◽  
Clegg Honeycutt ◽  
Laura Diamandopoulos ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Atrial Appendage

Compliance of left atrium with and without left atrium appendage

1990 ◽  
Vol 259 (4) ◽  
pp. H1006-H1008 ◽  
Author(s):  
C. A. Davis ◽  
J. C. Rembert ◽  
J. C. Greenfield
Keyword(s):  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Atrial Appendage ◽  
Volume Data ◽  
Hemodynamic Function

Compliance of the left atrial chamber was estimated with and without the appendage intact in six isolated canine left atria. Pressure-volume determinations were measured over a range of 5-30 mmHg for the whole left atrium and were repeated with the appendage excluded. The slope of the pressure vs. normalized volume data for the left atrium without the appendage (10.45 +/- 0.87) was significantly greater (P less than 0.01) than with the appendage intact (4.10 +/- 0.72). These data suggest that the left atrial appendage is more compliant than the remaining left atrium. Assuming that this relationship remains in vivo, the left atrial appendage may play an augmented role in maintaining hemodynamic function when filling pressures are elevated.

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