Mechanisms of Abdominal Aortic Aneurysm Formation in Persons With Traumatic Amputation of a Lower Extremity

2011 ◽  
Author(s):  
Alexander V. Smolensky ◽  
Stephanie Clement-Guinaudeau ◽  
Michael K. Larche ◽  
John N. Oshinski ◽  
W. Robert Taylor
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Lower Extremity ◽  
Aortic Aneurysms ◽  
Arterial Blood Flow ◽  
Infrarenal Aorta ◽  
Traumatic Amputation ◽  
Arterial Blood ◽  
Abdominal Aortic ◽  
Retrograde Blood Flow

Abdominal aortic aneurysms (AAA) are a major cause of morbidity and mortality in the US. The incidence of AAA in older Americans approaches 30%. The most common place of AAA is infrarenal abdominal aorta where oscillatory shear stress (OSS) is present. OSS is known to initiate an inflammatory response in the endothelium. It is known that there is up to a 5-fold increase in the occurrence of AAA in individuals with traumatic amputation of a lower extremity. This increased AAA occurrence is unrelated to co-morbid conditions. We recruited 3 healthy volunteers who underwent infrarenal abdominal aortic Magnetic Resonance angiography and phase contrast imaging. These measurements were done at base line and with acute arterial blood flow occlusion to lower extremity with a blood pressure cuff to mimic amputation. The collected data was used to calculate systolic forward and diastolic retrograde blood flow and wall shear stress during cardiac cycle. Our results suggest that mimicking amputation produces a nearly doubling of retrograde blood flow with ∼50% increase of negative WSS. These changes are more pronounced on the contralateral to the “amputation” side. We conclude that lower extremity traumatic amputations may lead to augmentation of OSS in infrarenal aorta causing AAA development.

Spontaneously echogenic arterial blood flow in abdominal aortic aneurysms

1982 ◽  
Vol 138 (2) ◽  
pp. 350-352 ◽  
Author(s):  
DL King ◽  
FC Van Natta ◽  
K Thorsen ◽  
RL Lechich
Keyword(s):  
Blood Flow ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Abdominal Aortic

A model of anemic tissue perfusion after blood transfusion shows critical role of endothelial response to shear stress stimuli

2021 ◽  
Author(s):  
Weiyu Li ◽  
Amy G. Tsai ◽  
Marcos Intaglietta ◽  
Daniel M. Tartakovsky
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Blood Transfusion ◽  
Critical Role ◽  
Cardiovascular Responses ◽  
Arterial Blood Flow ◽  
Microvascular Blood Flow ◽  
No Production ◽  
Arterial Blood ◽  
Transfusion Requirements

­­ ­Although some of the cardiovascular responses to changes in hematocrit (Hct) are not fully quantified experimentally, available information is sufficient to build a mathematical model of the consequences of treating anemia by introducing RBCs into the circulation via blood transfusion. We present such a model, which describes how the treatment of normovolemic anemia with blood transfusion impacts oxygen (O2) delivery (DO2, the product of blood O2 content and arterial blood flow) by the microcirculation. Our analysis accounts for the differential response of the endothelium to the wall shear stress (WSS) stimulus, changes in nitric oxide (NO) production due to modification of blood viscosity caused by alterations of both hematocrit (Hct) and cell free layer thickness, as well as for their combined effects on microvascular blood flow and DO2. Our model shows that transfusions of 1- and 2-unit of blood have a minimal effect on DO2 if the microcirculation is unresponsive to the WSS stimulus for NO production that causes vasodilatation increasing blood flow and DO2. Conversely, in a fully WSS responsive organism, blood transfusion significantly enhances blood flow and DO2, because increased viscosity stimulates endothelial NO production causing vasodilatation. This finding suggests that evaluation of a patients' pre-transfusion endothelial WSS responsiveness should be beneficial in determining the optimal transfusion requirements for treating anemic patients.

scholarly journals Temporal Vascular Changes in Leg with Ulcer Due to Autonomic Neuropathy

2019 ◽  
Vol 28 (03) ◽  
pp. 167-172
Author(s):  
Behçet K. Ener ◽  
Handan Uçankale ◽  
Reyhan Sürmeli
Keyword(s):  
Blood Flow ◽  
Lower Extremity ◽  
Autonomic Neuropathy ◽  
Arterial Blood Flow ◽  
Recurrent Ulcer ◽  
Functional Changes ◽  
Arterial Blood ◽  
Clinical Stages ◽  
The Mean ◽  
Stage 1

Background Vascular dysfunction dominates the clinical picture of peripheral autonomic neuropathy in lower extremity. Patients and Methods We have studied functional changes of leg vasculature in 30 patients with chronic ulceration due to peripheral autonomic neuropathy between clinical stages 1 and 3. They suffered from lower extremity wounds. After sympathetic skin response test, pedal arterial blood flow analysis including peak systolic velocity (PSV) and pulsatility index (PI) was made by duplex ultrasonography (DUS) in involved legs. Vascular anatomy of leg was also examined by magnetic resonance angiography. Results The mean PSV value was found 58.32 cm/s in stage 1, 35.31 cm/s in stage 2, and 15.71 cm/s in stage 3. The mean PI value was observed 1.17 in stage 1, 1.43 in stage 2, and 1.87 in stage 3. In chronic stage 3, three patients had inadequate arterial blood supply and recurrent ulcer. Conclusions We suggest that reduced sympathetic activity due to small fiber neuropathy causes temporal variations in leg blood flow. There was a nonlinear relationship between vascular functional changes and stages of disease with increased, intermediate, and decreased blood flow, respectively. DUS assessment of pedal arteries contributed to differentiation of clinical stages and permitted vascular evaluation in the course of peripheral autonomic neuropathy.

Assessment of lower extremity arterial blood flow in females with knee osteoarthritis

2013 ◽  
Vol 34 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Ahmet Boyaci ◽  
Ahmet Tutoglu ◽  
Nurefsan Boyaci ◽  
Irfan Koca ◽  
Rifat Aridici ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lower Extremity ◽  
Knee Osteoarthritis ◽  
Arterial Blood Flow ◽  
Arterial Blood

scholarly journals Retrograde blood flow in the internal jugular veins of humans with hypertension may have implications for cerebral arterial blood flow

2020 ◽  
Vol 30 (7) ◽  
pp. 3890-3899
Author(s):  
Jonathan C. L. Rodrigues ◽  
Galina Strelko ◽  
Esther A. H. Warnert ◽  
Amy E. Burchell ◽  
Sandra Neumann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Blood Flow ◽  
Jugular Veins ◽  
Arterial Blood ◽  
Retrograde Blood Flow ◽  
Internal Jugular Veins

scholarly journals Hemodynamic Shear Stress and Endothelial Dysfunction in Hemodialysis Access

2014 ◽  
Vol 7 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Michelle K Fitts ◽  
Daniel B Pike ◽  
Kasey Anderson ◽  
Yan-Ting Shiu
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Neointimal Hyperplasia ◽  
Vascular Wall ◽  
Chronic Hemodialysis ◽  
Arterial Blood Flow ◽  
Venous Anastomosis ◽  
Arterial Blood ◽  
Arteriovenous Access ◽  
The Impact

Surgically-created blood conduits used for chronic hemodialysis, including native arteriovenous fistulas (AVFs) and synthetic AV grafts (AVGs), are the lifeline for kidney failure patients. Unfortunately, each has its own limitations; AVFs often fail to mature to become useful for dialysis and AVGs often fail due to stenosis as a result of neointimal hyperplasia, which preferentially forms at the graft-venous anastomosis. No clinical therapies are currently available to significantly promote AVF maturation or prevent neointimal hyperplasia in AVGs. Central to devising strategies to solve these problems is a complete mechanistic understanding of the pathophysiological processes. The pathology of arteriovenous access problems is likely multi-factorial. This review focuses on the roles of fluid-wall shear stress (WSS) and endothelial cells (ECs). In arteriovenous access, shunting of arterial blood flow directly into the vein drastically alters the hemodynamics in the vein. These hemodynamic changes are likely major contributors to non-maturation of an AVF vein and/or formation of neointimal hyperplasia at the venous anastomosis of an AVG. ECs separate blood from other vascular wall cells and also influence the phenotype of these other cells. In arteriovenous access, the responses of ECs to aberrant WSS may subsequently lead to AVF non-maturation and/or AVG stenosis. This review provides an overview of the methods for characterizing blood flow and calculating WSS in arteriovenous access and discusses EC responses to arteriovenous hemodynamics. This review also discusses the role of WSS in the pathology of arteriovenous access, as well as confounding factors that modulate the impact of WSS.

The Effect of Asymmetry in Abdominal Aortic Aneurysms Under Physiologically Realistic Pulsatile Flow Conditions

2003 ◽  
Vol 125 (2) ◽  
pp. 207-217 ◽  
Author(s):  
E. A. Finol ◽  
K. Keyhani ◽  
C. H. Amon
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Pulsatile Flow ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Aortic Aneurysms ◽  
Pulsatile Blood Flow ◽  
Abdominal Aortic ◽  
Wall Shear

In the abdominal segment of the human aorta under a patient’s average resting conditions, pulsatile blood flow exhibits complex laminar patterns with secondary flows induced by adjacent branches and irregular vessel geometries. The flow dynamics becomes more complex when there is a pathological condition that causes changes in the normal structural composition of the vessel wall, for example, in the presence of an aneurysm. This work examines the hemodynamics of pulsatile blood flow in hypothetical three-dimensional models of abdominal aortic aneurysms (AAAs). Numerical predictions of blood flow patterns and hemodynamic stresses in AAAs are performed in single-aneurysm, asymmetric, rigid wall models using the finite element method. We characterize pulsatile flow dynamics in AAAs for average resting conditions by means of identifying regions of disturbed flow and quantifying the disturbance by evaluating flow-induced stresses at the aneurysm wall, specifically wall pressure and wall shear stress. Physiologically realistic abdominal aortic blood flow is simulated under pulsatile conditions for the range of time-average Reynolds numbers 50⩽Rem⩽300, corresponding to a range of peak Reynolds numbers 262.5⩽Repeak⩽1575. The vortex dynamics induced by pulsatile flow in AAAs is depicted by a sequence of four different flow phases in one period of the cardiac pulse. Peak wall shear stress and peak wall pressure are reported as a function of the time-average Reynolds number and aneurysm asymmetry. The effect of asymmetry in hypothetically shaped AAAs is to increase the maximum wall shear stress at peak flow and to induce the appearance of secondary flows in late diastole.

A new method for visualizing pulmonary artery microvasculature using synchrotron radiation pulmonary microangiography: the measurement of pulmonary arterial blood flow velocity in the high pulmonary blood flow rat model

2018 ◽  
Vol 59 (12) ◽  
pp. 1482-1486 ◽  
Author(s):  
Chiho Tokunaga ◽  
Shonosuke Matsushita ◽  
Hiroaki Sakamoto ◽  
Kazuyuki Hyodo ◽  
Misao Kubota ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Synchrotron Radiation ◽  
Pulmonary Artery ◽  
Rat Model ◽  
Vascular Remodeling ◽  
Pulmonary Blood Flow ◽  
Arterial Blood Flow ◽  
Non Invasive ◽  
Arterial Blood

Background Increased pulmonary blood flow (PBF) and shear stress may provoke irreversible vascular remodeling, yet invasive visualization of the microvasculature complicates monitoring. A non-invasive imaging methodology would therefore safely provide mechanistic insights into the progression of high PBF-induced vascular remodeling. Purpose To establish a novel microvasculature visualization method using synchrotron radiation pulmonary microangiography (SRPA) that can also calculate PBF velocity in vivo. Material and Methods A high PBF rat model was established by making a fistula between the abdominal aorta and inferior vena cava. After eight weeks, SRPA was performed and the dynamic density changes in the right lower pulmonary artery (PA) were calculated by software. SRPA was performed with a HARP (High-Gain Avalanche Rushing amorphous Photoconductor) receiver. PBF velocity was calculated by contrast medium transit time within the PA. All data were presented as mean ± standard error (SE). Student's t-test was used for comparison between the two groups. Results High dynamic spatial and contrast resolution from SRPA in the PA allowed for clear pulmonary microangiography and accurate detection of higher PBF in the rat model (82.3 ± 8.5 mm/s high-PBF group vs. 46.1 ± 4.3 mm/s control group, P < 0.01). Conclusions These novel results demonstrate that SRPA was useful in both visualizing the dynamic flow distribution within the microvasculature and calculating PBF velocity. This newly developed, non-invasive technology may become a powerful tool in clarifying the mechanism of vascular remodeling associated with high PBF-induced shear stress.

scholarly journals Cardiovascular and hemorheological effects of three modified human hemoglobin solutions in hemodiluted rabbits

1999 ◽  
Vol 86 (2) ◽  
pp. 541-548 ◽  
Author(s):  
Alexis Caron ◽  
Patrick Menu ◽  
Beatrice Faivre-Fiorina ◽  
Pierre Labrude ◽  
Abdu I. Alayash ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiovascular Effects ◽  
Human Albumin ◽  
Arterial Blood Flow ◽  
Human Hemoglobin ◽  
Shear Rates ◽  
Arterial Blood ◽  
High Shear Rates ◽  
Abdominal Aortic ◽  
The Impact

The cardiovascular effects of human albumin (Alb) and three human hemoglobin (Hb) solutions, dextran-benzene-tetracarboxylate Hb, αα-crosslinked Hb, and o-raffinose-polymerized Hb were compared in anesthetized rabbits undergoing acute isovolemic hemodilution with Hct reduction from 41.4 ± 2.7 to 28.8 ± 1.6%. The impact of the vasoconstricting properties of Hb was examined by measuring heart rate (HR), mean arterial pressure (MAP), abdominal aortic, and femoral arterial blood flow, vascular resistance (VR), and aortic distension during the first 3 h after hemodilution. The impact of the hemorheological parameters was assessed by measurements of hemodiluted blood viscosity. In contrast to Alb, the Hb solutions elicited an immediate increase in MAP (20–38%). The effects of Alb and Hb solutions on HR, as well as on aortic and femoral arterial blood flow, were similar. VR decreased with Alb (20–28%) and increased with all three Hb solutions (30–90%), but the MAP and VR rising trends were different with each Hb solution. Aortic distension decreased in Hb groups compared with the Alb group for the first 60 min. The viscosity of hemodiluted blood was similar for all groups at high shear rates but was dependent on the viscosity of the solutions at low shear rates. We conclude that the vasoconstriction elicited by the Hb solutions overrides the vasodilation associated with viscosity changes due to hemodilution and would be the major factor responsible to the cardiovascular changes.

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