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Journal of the Royal Society, Interface Oct 2012To test the hypothesis that disturbed flow can impede the transport of nitric oxide (NO) in the artery and hence induce atherogenesis, we used a lumen-wall model of an...
To test the hypothesis that disturbed flow can impede the transport of nitric oxide (NO) in the artery and hence induce atherogenesis, we used a lumen-wall model of an idealized arterial stenosis with NO produced at the blood vessel-wall interface to study the transport of NO in the stenosis. Blood flows in the lumen and through the arterial wall were simulated by Navier-Stokes equations and Darcy's Law, respectively. Meanwhile, the transport of NO in the lumen and the transport of NO within the arterial wall were modelled by advection-diffusion reaction equations. Coupling of fluid dynamics at the endothelium was achieved by the Kedem-Katchalsky equations. The results showed that both the hydraulic conductivity of the endothelium and the non-Newtonian viscous behaviour of blood had little effect on the distribution of NO. However, the blood flow rate, stenosis severity, red blood cells (RBCs), RBC-free layer and NO production rate at the blood vessel-wall interface could significantly affect the transport of NO. The theoretical study revealed that the transport of NO was significantly hindered in the disturbed flow region distal to the stenosis. The reduced NO concentration in the disturbed flow region might play an important role in the localized genesis and development of atherosclerosis.
Topics: Arteries; Biological Transport; Blood Flow Velocity; Computer Simulation; Constriction, Pathologic; Endothelium, Vascular; Erythrocytes; Finite Element Analysis; Humans; Models, Cardiovascular; Nitric Oxide
PubMed: 22593099
DOI: 10.1098/rsif.2012.0224 -
Brain and Behavior Sep 2020High-resolution magnetic resonance imaging (HR-MRI) has high spatial resolution and can simultaneously perform wall and lumen imaging. Dynamic contrast-enhanced magnetic...
PURPOSE
High-resolution magnetic resonance imaging (HR-MRI) has high spatial resolution and can simultaneously perform wall and lumen imaging. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can evaluate the integrity of the blood-brain barrier. In this paper, the result of 3.0T HR-MRI and 3.0T DCE-MRI has been evaluated to explore the application value of unilateral middle cerebral artery inflammatory stenosis and changes in vascular permeability parameters of stroke events.
METHODS
Thirty-six cases of neurological suspicion of central nervous system vasculitis of our hospital were selected from 20 January 2018 to 1 January 2019, who were diagnosed as unilateral middle cerebral artery M1 stenosis/occlusion by 3D TOF MRA. 3.0T HR-MRI and 3.0T DCE-MRI has been applied.
RESULTS
Among the 36 patients who met the inclusion criteria, 23 patients with central nervous system vasculitis were diagnosed. The 23 patients with HR-MRI showed diffuse thickening and enhanced stenosis. The K value of 10/23 patients with acute-subacute cerebral infarction and 3/23 patients in chronic phase were significantly higher than that of the mirror side, and the K value of these patients remeasured in the same region of interest is lower than before after 6 months treatment. The K value in the target area of 10 patients without cerebrovascular events was not statistically significant compared with the mirror side. The K value of patients with acute-subacute cerebral infarction was significantly higher than that without cerebrovascular events (0.098 ± 0.038 vs. 0.007 ± 0.001, p = .000), and there was no significant difference between K in the chronic infarction group and the other two groups (0.098 ± 0.038 vs. 0.044 ± 0.012, p = .058; 0.044 ± 0.012 vs. 0.007 ± 0.001, p = .057).
CONCLUSION
HR-MRI is an accurate direct imaging method and has a high value for the etiological diagnosis of central nervous system vasculitis. DCE-MRI could be an effective way to evaluate and monitor blood-brain barrier to prevent clinical ischemic stroke.
Topics: Blood-Brain Barrier; Constriction, Pathologic; Contrast Media; Humans; Magnetic Resonance Imaging; Middle Cerebral Artery
PubMed: 32767660
DOI: 10.1002/brb3.1732 -
Cardiovascular and Interventional... Nov 2023Pediatric liver transplant surgery is burdened by arterial complications whose endovascular treatment is not standardized. We report the outcomes of a cohort of...
PURPOSE
Pediatric liver transplant surgery is burdened by arterial complications whose endovascular treatment is not standardized. We report the outcomes of a cohort of pediatric recipients with hepatic artery complications treated by endoluminal procedures.
MATERIALS AND METHODS
From December 2019 to December 2022, consecutive transplanted pediatric patients who underwent endovascular treatment of hepatic artery complications were reviewed. The analysis included: type of complication (occlusion, stenosis, pseudoaneurysm); onset (acute = < 15 days, subacute = 15-90 days, late = > 90 days); endovascular technique (angioplasty, stenting); complications and outcomes. Technical success was defined as the opacification of the hepatic artery at the final angiogram with < 50% residual stenosis and no pseudoaneurysms. Clinical success was defined by graft's and patient's survival.
RESULTS
Seventeen patients (8 males; median age 33 months, IQR 9-103) underwent 21 hepatic arteriography procedures for predominantly acute or subacute occlusions (n = 7) or stenosis (n = 11) with concurrent pseudoaneurysms (n = 4). Primary and secondary technical success was achieved in 13/18 and 3/3 procedures, respectively, with overall technical success of 76%. Angioplasty alone was successful in 5/21 procedures; stent-retriever thrombectomy was performed in one occlusion with thrombosis; stenting was required in 9/17 (53%) patients. Clinical success was obtained in 14/17 (82%) patients with hepatic artery patency after a median of 367 days (IQR 114.5-500). Clinical failure occurred in 3 permanent occlusions, with 2 deaths and 1 re-transplantation. Procedure-related complications included minor events in 3/17 (18%) patients and 1/17 (6%) death.
CONCLUSION
In liver transplanted children with hepatic artery complications, endovascular treatment may provide clinical success, with stenting often required in acute and subacute conditions.
LEVEL OF EVIDENCE
Level 4.
Topics: Male; Humans; Child; Child, Preschool; Liver Transplantation; Constriction, Pathologic; Hepatic Artery; Aneurysm, False; Endovascular Procedures
PubMed: 37831217
DOI: 10.1007/s00270-023-03557-0 -
Journal of Vascular Surgery Jun 2017Median arcuate ligament syndrome (MALS) is a condition characterized by chronic abdominal symptoms associated with median arcuate ligament compression of the celiac...
BACKGROUND
Median arcuate ligament syndrome (MALS) is a condition characterized by chronic abdominal symptoms associated with median arcuate ligament compression of the celiac artery. The selection of patients is difficult in the management of MALS. This study aimed to identify factors that predict outcomes of surgical and nonoperative treatment in these patients.
METHODS
Patients referred with a possible diagnosis of MALS between 1998 and 2013 were identified retrospectively. Only patients with chronic symptoms and radiologically confirmed celiac artery compression were included. The clinical features, investigations, and management were documented. Outcome was assessed using the Visick score, Gastrointestinal Symptom Rating Scale, and 12-Item Short Form Health Survey by telephone interview and review of medical records.
RESULTS
There were 67 patients, 43 (64%) treated surgically and 24 (36%) managed without surgery, with a median follow-up of 25 months and 24 months, respectively. After surgical treatment, 16 (37%) were asymptomatic, 24 (56%) were partially improved, 3 (7%) had no changes in symptoms, and none had worsening of symptoms. Postexertional pain predicted improvement after surgery (P = .022). Vomiting (P = .046) and unprovoked pain (P = .006) were predictors of poor surgical outcome. After nonoperative management, 1 (4%) was asymptomatic, 7 (29%) were partially improved, 12 (50%) had no changes in symptoms, and 4 (17%) had worsening of symptoms. No outcome predictors of nonoperative treatment were identified.
CONCLUSIONS
MALS was more likely to respond to decompression if patients had postexertional pain. Patients who presented with vomiting and unprovoked pain were unlikely to respond to surgery. In contrast with previous studies, postprandial pain was not found to be predictive of outcome.
Topics: Abdominal Pain; Adult; Aged; Celiac Artery; Constriction, Pathologic; Decompression, Surgical; Female; Humans; Laparoscopy; Male; Median Arcuate Ligament Syndrome; Middle Aged; Patient Selection; Queensland; Retrospective Studies; Risk Factors; Surveys and Questionnaires; Time Factors; Treatment Outcome; Vascular Patency; Vascular Surgical Procedures; Vomiting; Young Adult
PubMed: 28189355
DOI: 10.1016/j.jvs.2016.11.040 -
European Journal of Vascular and... Mar 2023
Topics: Humans; Constriction, Pathologic; Carotid Stenosis; Stents; Carotid Artery, Internal; Recurrence; Treatment Outcome
PubMed: 36481397
DOI: 10.1016/j.ejvs.2022.11.026 -
Atherosclerosis Aug 2014It is hypothesized that outward remodeling in systemic arteries is a compensatory mechanism for lumen area preservation in the face of increasing arterial stenosis....
OBJECTIVE
It is hypothesized that outward remodeling in systemic arteries is a compensatory mechanism for lumen area preservation in the face of increasing arterial stenosis. Large brain arteries have also been studied, but it remains unproven if all assumptions about arterial remodeling can be replicated in the cerebral circulation.
METHODS
The sample included 196 autopsied subjects with a mean age of 55 years; 63 % were men, and 74 % non-Hispanic whites. From each of 1396 dissected cadaveric large arteries of the circle of Willis, the areas of the lumen, intima, media, and adventitia were measured. Internal elastic lamina (IEL) area was defined as the area encircled by this layer. Stenosis was calculated by dividing the plaque area by the IEL area and multiplying by 100.
RESULTS
Plotting stenosis against lumen area or stratified by arterial size showed no preservation of the lumen in the setting of growing stenosis. We could not find an association between greater IEL proportion and stenosis (B = 0.44, P = 0.86). Stratifying arteries by their size, we found that smaller arteries have greater lumen reduction at any degree of stenosis (B = -23.65, P ≤ 0.0001), and although larger arteries show a positive association between IEL proportion and stenosis, this was no longer significant after adjusting for covariates (B = 6.0, P = 0.13).
CONCLUSIONS
We cannot confirm the hypothesis that large brain arteries undergo outward remodeling as an adaptive response to increasing degrees of stenosis. We found that the lumen decreases proportionally to the degree of stenosis.
Topics: Adult; Aged; Aged, 80 and over; Autopsy; Cerebral Arteries; Cerebrovascular Circulation; Cerebrovascular Disorders; Constriction, Pathologic; Disease Progression; Female; Humans; Intracranial Arteriosclerosis; Male; Middle Aged
PubMed: 24929285
DOI: 10.1016/j.atherosclerosis.2014.05.925 -
PLoS Computational Biology Jul 2022Collateral circulation in the circle of Willis (CoW), closely associated with disease mechanisms and treatment outcomes, can be effectively investigated using...
Collateral circulation in the circle of Willis (CoW), closely associated with disease mechanisms and treatment outcomes, can be effectively investigated using one-dimensional-zero-dimensional hemodynamic simulations. As the entire cardiovascular system is considered in the simulation, it captures the systemic effects of local arterial changes, thus reproducing collateral circulation that reflects biological phenomena. The simulation facilitates rapid assessment of clinically relevant hemodynamic quantities under patient-specific conditions by incorporating clinical data. During patient-specific simulations, the impact of clinical data uncertainty on the simulated quantities should be quantified to obtain reliable results. However, as uncertainty quantification (UQ) is time-consuming and computationally expensive, its implementation in time-sensitive clinical applications is considered impractical. Therefore, we constructed a surrogate model based on machine learning using simulation data. The model accurately predicts the flow rate and pressure in the CoW in a few milliseconds. This reduced computation time enables the UQ execution with 100 000 predictions in a few minutes on a single CPU core and in less than a minute on a GPU. We performed UQ to predict the risk of cerebral hyperperfusion (CH), a life-threatening condition that can occur after carotid artery stenosis surgery if collateral circulation fails to function appropriately. We predicted the statistics of the postoperative flow rate increase in the CoW, which is a measure of CH, considering the uncertainties of arterial diameters, stenosis parameters, and flow rates measured using the patients' clinical data. A sensitivity analysis was performed to clarify the impact of each uncertain parameter on the flow rate increase. Results indicated that CH occurred when two conditions were satisfied simultaneously: severe stenosis and when arteries of small diameter serve as the collateral pathway to the cerebral artery on the stenosis side. These findings elucidate the biological aspects of cerebral circulation in terms of the relationship between collateral flow and CH.
Topics: Cerebrovascular Circulation; Circle of Willis; Constriction, Pathologic; Humans; Machine Learning; Uncertainty
PubMed: 35867968
DOI: 10.1371/journal.pcbi.1009996 -
Korean Journal of Radiology 2016We aimed to evaluate the efficacy and safety of a newly developed, partially retrievable flow-diverter (the FloWise) in an elastase-induced rabbit aneurysm model.
OBJECTIVE
We aimed to evaluate the efficacy and safety of a newly developed, partially retrievable flow-diverter (the FloWise) in an elastase-induced rabbit aneurysm model.
MATERIALS AND METHODS
We developed a partially retrievable flow diverter composed of 48 strands of Nitinol and platinum wire. The FloWise is compatible with any microcatheter of 0.027-inch inner diameter, and is retrievable up to 70% deployment. The efficacy and safety of the FloWise were evaluated in the elastase-induced rabbit aneurysm model. The rate of technical success (full coverage of aneurysm neck) and assessment of aneurysm occlusion and stent patency was conducted by angiograms and histologic examinations at the 1-month, 3-month, and 6-month follow-up. The patency of small arterial branches (intercostal or lumbar arteries) covered by the FloWise were also assessed in the 5 subjects.
RESULTS
We attempted FloWise insertion in a total of 32 aneurysm models. FloWise placement was successful in 31 subjects (96.9%). Two stents (6.2%) were occluded at the 3-month follow-up, but there was no evidence of in-stent stenosis in other subjects. All stented aneurysms showed progressive occlusion: grade I (complete aneurysm occlusion) in 44.4% and grade II (aneurysm occlusion > 90%) in 55.6% at 1 month; grade I in 90% and II in 10% at 3 months; and grade I in 90% and II in 10% at 6 months. All small arterial branches covered by the FloWise remained patent.
CONCLUSION
A newly developed, partially retrievable flow-diverter seems to be a safe and effective tool of aneurysm occlusion, as evaluated in the rabbit aneurysm model.
Topics: Alloys; Aneurysm; Angiography; Animals; Arteries; Catheters; Cerebrovascular Circulation; Constriction, Pathologic; Disease Models, Animal; Humans; Male; Pancreatic Elastase; Platinum; Rabbits; Stents
PubMed: 26798228
DOI: 10.3348/kjr.2016.17.1.151 -
JACC. Cardiovascular Interventions Jul 2017
Topics: Constriction, Pathologic; Endarterectomy; Femoral Artery; Humans; Peripheral Vascular Diseases; Stents
PubMed: 28683942
DOI: 10.1016/j.jcin.2017.05.001 -
PloS One 2022Arterial stenosis is a common cardiovascular disease that restricts blood flow. A stenotic blood vessel creates tangent stress pressure, which lessens the arterial side...
Arterial stenosis is a common cardiovascular disease that restricts blood flow. A stenotic blood vessel creates tangent stress pressure, which lessens the arterial side and causes an aneurysm. The primary purpose of this study is to investigate blood flowing via an inclination pipe with stricture and expansion after stricture (widening) underneath the influence of a constant incompressible Casson liquid flowing with the magnetism field. The relations for surface shearing stress, pressure drop, flow resistance, and velocity are calculated analytically by applying a mild stenosis approximation. The effect of different physical characteristics on liquid impedance to flowing, velocity, and surface shearing stress are studied. With a non-Newtonian aspect of the Casson liquid, the surface shearing stress declines, and an impedance upturn. Side resistivity and shear-stress increase with the elevations of stricture, whilst together decreasing with a dilatation height.
Topics: Arteries; Constriction, Pathologic; Dilatation; Humans; Models, Theoretical; Stress, Mechanical
PubMed: 35776713
DOI: 10.1371/journal.pone.0266727