scholarly journals Numerical Investigation of the Fetal Left Heart Hemodynamics During Gestational Stages

2021 ◽  
Vol 12 ◽  
Author(s):  
Huseyin Enes Salman ◽  
Reema Yousef Kamal ◽  
Huseyin Cagatay Yalcin
Keyword(s):  
Blood Flow ◽  
Mitral Valve ◽  
Heart Defects ◽  
Shear Stresses ◽  
Ultrasound Images ◽  
Left Heart ◽  
Hemodynamic Forces ◽  
Hemodynamic Assessment ◽  
Peak Shear Stress ◽  
Gestational Week

Flow-driven hemodynamic forces on the cardiac tissues have critical importance, and have a significant role in the proper development of the heart. These mechanobiological mechanisms govern the cellular responses for the growth and remodeling of the heart, where the altered hemodynamic environment is believed to be a major factor that is leading to congenital heart defects (CHDs). In order to investigate the mechanobiological development of the normal and diseased hearts, identification of the blood flow patterns and wall shear stresses (WSS) on these tissues are required for an accurate hemodynamic assessment. In this study, we focus on the left heart hemodynamics of the human fetuses throughout the gestational stages. Computational fetal left heart models are created for the healthy fetuses using the ultrasound images at various gestational weeks. Realistic inflow boundary conditions are implemented in the models using the Doppler ultrasound measurements for resolving the specific blood flow waveforms in the mitral valve. Obtained results indicate that WSS and vorticity levels in the fetal left heart decrease with the development of the fetus. The maximum WSS around the mitral valve is determined around 36 Pa at the gestational week of 16. This maximum WSS decreases to 11 Pa at the gestational week of 27, indicating nearly three-times reduction in the peak shear stress. These findings reveal the highly dynamic nature of the left heart hemodynamics throughout the development of the human fetus and shed light into the relevance of hemodynamic environment and development of CHDs.

Numerical Analysis of Blood Flow in the Vertebral Artery

1982 ◽  
Vol 104 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Takayoshi Fukushima ◽  
Takehiko Azuma ◽  
Teruo Matsuzawa
Keyword(s):  
Blood Flow ◽  
Numerical Analysis ◽  
Vertebral Artery ◽  
Arterial Blood Flow ◽  
Vascular Lesions ◽  
Shear Stresses ◽  
Hemodynamic Forces ◽  
Atherosclerotic Lesions ◽  
Arterial Blood ◽  
Structure Of Flow

Abnormal hemodynamic forces associated with distortions of blood vessel lumen have been thought to play an important role in the pathogenesis of focal vascular lesions. In the vertebral artery, segments located between osseous rings are ectatic compared with those surrounded by the rings. Based on the assumption that arterial blood flow was quasi-steady, this work was undertaken to investigate the structure of flow through arterial models with one or two sinusoidal stenoses. Numerical analysis was performed by an integral-momentum method. The validity of the method was examined by comparison of experimental data so far reported with theoretical results. Velocity and wall shear stress distributions were explored in a model with two stenoses simulating a part of the vertebral artery. The ectatic segments of the vertebral artery have been known as predilection sites for atherosclerotic lesions. The present study suggested that the ectatic wall was under unstable shear stresses, the direction of which was dependent upon the magnitude of the Reynolds number.

scholarly journals Flow-mediated endothelial mechanotransduction

1995 ◽  
Vol 75 (3) ◽  
pp. 519-560 ◽  
Author(s):  
P. F. Davies
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Blood Vessel ◽  
Vascular Tone ◽  
Shear Stresses ◽  
Mechanical Forces ◽  
Hemodynamic Forces ◽  
Atherosclerotic Lesions ◽  
Arterial Structure ◽  
Gene Regulatory

Mechanical forces associated with blood flow play important roles in the acute control of vascular tone, the regulation of arterial structure and remodeling, and the localization of atherosclerotic lesions. Major regulation of the blood vessel responses occurs by the action of hemodynamic shear stresses on the endothelium. The transmission of hemodynamic forces throughout the endothelium and the mechanotransduction mechanisms that lead to biophysical, biochemical, and gene regulatory responses of endothelial cells to hemodynamic shear stresses are reviewed.

Hemodynamic Assessment of Hollow-Fiber Membrane Oxygenators Using Computational Fluid Dynamics in Heterogeneous Membrane Models

2021 ◽  
Author(s):  
Daniele Dipresa ◽  
Panagiotis Kalozoumis ◽  
Michael Pflaum ◽  
Ariana Peredo ◽  
Bettina Wiegmann ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Thrombus Formation ◽  
Shear Stresses ◽  
Fiber Membrane ◽  
Hemodynamic Assessment

Abstract Extracorporeal membrane oxygenation (ECMO) has been used clinically for more than 40 years as a bridge to transplantation, with hollow-fiber membrane (HFM) oxygenators gaining in popularity due to their high gas transfer and low flow resistance. In spite of the technological advances in ECMO devices, the inevitable contact of the perfused blood with the polymer hollow-fiber gas-exchange membrane, and the subsequent thrombus formation, limits their clinical usage to only 2-4 weeks. In addition, the inhomogeneous flow in the device can further enhance thrombus formation and limit gas-transport efficiency. Endothelialisation of the blood contacting surfaces of ECMO devices offers a potential solution to their inherent thrombogenicity. However, abnormal shear stresses and inhomogeneous blood flow might affect the function and activation status of the seeded endothelial cells (ECs). In this study, the blood flow through two HFM oxygenators, including the commercially-available iLA® MiniLung Petite Novalung (Xenios AG, Germany) and an experimental one for the rat animal model, was modelled using computational fluid dynamics (CFD), with a view to assessing the magnitude and distribution of the shear stress on the wall of the hollow fibers and flow fields in the oxygenators. This work demonstrated significant inhomogeneity in the flow dynamics of both oxygenators, with regions of high hollow-fiber wall shear stress and regions of stagnant flow, implying both regions of increased flow-induced blood damage and a variable flow-induced stimulation on seeded ECs in a biohybrid setting.

Experimental Investigation of the Local Blood Flow Pattern in Stented Coronary Bifurcations

2011 ◽  
Author(s):  
Stefano Morlacchi ◽  
Jaime Schmieg ◽  
Dan Cooper ◽  
Francesco Burzotta ◽  
Francesco Migliavacca ◽  
...  
Keyword(s):  
Blood Flow ◽  
Invasive Procedure ◽  
Cost Effective ◽  
Clinical Results ◽  
Shear Stresses ◽  
Local Blood Flow ◽  
Time Saving ◽  
Acute Thrombosis ◽  
Hemodynamic Forces ◽  
Stent Restenosis

Stenting procedures give the opportunity to treat cardiovascular diseases with a time saving, cost effective and minimally invasive procedure when compared to coronary artery by-pass, while ensuring improved clinical results than balloon angioplasty. However, despite their success, stenting procedures are still associated with some clinical problems like sub-acute thrombosis (ST) and in-stent restenosis (ISR). Several clinical studies associate these issues to the local blood flow alterations caused by stent implantation. In particular, hemodynamic forces like wall shear stresses induce endothelial cells to experience an enhanced proliferative attitude.

Ultrasound features of peripheral angiodistonic syndrome of the upper extremities in vibration disease

2020 ◽  
Vol 60 (11) ◽  
pp. 815-817
Author(s):  
Nadezhda I. Kuprina ◽  
Ekaterina V. Ulanovskaya ◽  
Olga A. Kochetova
Keyword(s):  
Blood Flow ◽  
Heart Defects ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Ulnar Artery ◽  
Upper Extremities ◽  
Disease Stage ◽  
Peripheral Blood Flow ◽  
Pronounced Increase ◽  
Vibration Disease

Introduction. Vibration disease (VD) is an example of the most common pathology due to the systematic exposure of the worker to intense vibration with sufficient work experience, the main manifestation of which is peripheral angiodystonic syndrome. The aim of study was to learn the features of peripheral blood flow in the arteries of the forearm in vibration disease using the ultrasound method. Materials and methods. The radial and ulnar arteries in patients with vibration disease were examined by ultrasound in B- and PW-mode. These materials present the results of an ultrasound assessment of the speed indicators of the main arteries of the forearm in vibration disease stages 1 and 2. The selection criteria for patients in the study ware the presence of pronounced clinical manifestations of angiodystonic syndrome in vibration disease, confirmed by instrumental research methods and data on the sanitary and hygienic characteristics of working conditions, the absence of cardiovascular chronic diseases (ischemic heart disease, heart defects, rhythm and conduction disturbances), rheumatic, oncological, infectious diseases, osteo-traumatic changes in the upper extremities. Results. The groups of patients with the established diagnosis of vibration disease of 1 and 2 degrees were studied. With vibration disease stage 1 a decrease in the pulse velocity of blood flow was observed in isolation on the ulnar artery and an increase in peripheral resistance (pulsation index and resistance index) in the radial and ulnar arteries symmetrically on both upper extremities. The second stage of vibration disease differed from the first by a more significant decrease in speed indicators both on the ulnar and radial arteries on both sides, symmetrically in combination with a more pronounced increase in peripheral resistance indicators on both main arteries of the forearm (pulsation index and resistance index). The revealed changes were determined with the same frequency in men and women. Conclusions. A significant decrease in speed indicators on the ulnar artery and an increase in peripheral resistance indicators are detected already at the initial stages of vibration disease. Thus, the method of ultrasound examination of the main arteries of the middle caliber of the upper extremities is currently the only available and objective method for examining the vascular system in vibration disease.

scholarly journals Fluid–structure interaction in a fully coupled three-dimensional mitral–atrium–pulmonary model

2021 ◽  
Author(s):  
Liuyang Feng ◽  
Hao Gao ◽  
Nan Qi ◽  
Mark Danton ◽  
Nicholas A. Hill ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Pulmonary Veins ◽  
Three Dimensional ◽  
Left Heart ◽  
Structure Interaction ◽  
Acute Mitral Regurgitation ◽  
Reversal Flow

AbstractThis paper aims to investigate detailed mechanical interactions between the pulmonary haemodynamics and left heart function in pathophysiological situations (e.g. atrial fibrillation and acute mitral regurgitation). This is achieved by developing a complex computational framework for a coupled pulmonary circulation, left atrium and mitral valve model. The left atrium and mitral valve are modelled with physiologically realistic three-dimensional geometries, fibre-reinforced hyperelastic materials and fluid–structure interaction, and the pulmonary vessels are modelled as one-dimensional network ended with structured trees, with specified vessel geometries and wall material properties. This new coupled model reveals some interesting results which could be of diagnostic values. For example, the wave propagation through the pulmonary vasculature can lead to different arrival times for the second systolic flow wave (S2 wave) among the pulmonary veins, forming vortex rings inside the left atrium. In the case of acute mitral regurgitation, the left atrium experiences an increased energy dissipation and pressure elevation. The pulmonary veins can experience increased wave intensities, reversal flow during systole and increased early-diastolic flow wave (D wave), which in turn causes an additional flow wave across the mitral valve (L wave), as well as a reversal flow at the left atrial appendage orifice. In the case of atrial fibrillation, we show that the loss of active contraction is associated with a slower flow inside the left atrial appendage and disappearances of the late-diastole atrial reversal wave (AR wave) and the first systolic wave (S1 wave) in pulmonary veins. The haemodynamic changes along the pulmonary vessel trees on different scales from microscopic vessels to the main pulmonary artery can all be captured in this model. The work promises a potential in quantifying disease progression and medical treatments of various pulmonary diseases such as the pulmonary hypertension due to a left heart dysfunction.

scholarly journals Fetal Unguarded Mitral Valve Orifice, Aortic Atresia, and Severe Left Heart Enlargement

2021 ◽  
Vol 3 (2) ◽  
pp. 206-211
Author(s):  
Lisa W. Howley ◽  
Janette Strasburger ◽  
Joseph J. Maleszewski ◽  
Saul Snowise ◽  
Amy Lund ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Left Heart ◽  
Valve Orifice ◽  
Aortic Atresia

scholarly journals Safety of Transseptal Puncture for Access to the Left Atrium in Infants and Children

2021 ◽  
Author(s):  
Matthias J. Müller ◽  
David Backhoff ◽  
Heike E. Schneider ◽  
Jana K. Dieks ◽  
Julia Rieger ◽  
...  
Keyword(s):  
Pericardial Effusion ◽  
Heart Defects ◽  
Standard Procedure ◽  
Interatrial Septum ◽  
Infants And Children ◽  
Transseptal Puncture ◽  
Left Heart ◽  
Urgent Surgery ◽  
In Infants And Children ◽  
Small Pericardial Effusion

AbstractTransseptal puncture (TSP) is a standard procedure to obtain access to the left heart. However, data on TSP in infants and children particularly with congenital heart defects (CHD) is sparse. Safety and efficacy of TSP in infants and children < 18 years with normal cardiac anatomy and with CHD were assessed. 327 TSP were performed in a total of 300 individuals < 18 years from 10/2002 to 09/2018 in our tertiary pediatric referral center. Median age at TSP was 11.9 years (IQR 7.8–15; range: first day of life to 17.9 years). 13 subjects were < 1 year. Median body weight was 43.8 kg (IQR 26.9–60; range: 1.8–121 kg). CHD was present in 28/327 (8.6%) procedures. TSP could be successfully performed in 323/327 (98.8%) procedures and was abandoned in 4 procedures due to imminent or incurred complications. Major complications occurred in 4 patients. 3 of these 4 subjects were ≤ 1 year of age and required TSP for enlargement of a restrictive atrial septal defect in complex CHD. Two of these babies deceased within 48 h after TSP attempt. The third baby needed urgent surgery in the cath lab. Pericardial effusion requiring drainage was noted in the forth patient (> 1 year) who was discharged well later. Minor complications emerged in 5 patients. The youngest of these individuals (0.3 years, 5.8 kg) developed small pericardial effusion after anterograde ballon valvuloplasty for critical aortic stenosis. The remaining 4/5 patients developed small pericardial effusion after ablation of a left-sided accessory atrioventricular pathway (6.1–12.2 years, 15.6–34.0 kg). TSP for access to the left heart was safe and effective in children and adolescents > 1 year of age. However, TSP was a high-risk procedure in small infants with a restrictive interatrial septum with need for enlargement of interatrial communication.

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