PIV and LIF Measurements in Aortic Dissection Models

2017 ◽  
Author(s):  
Elie Salameh ◽  
Wadih Khoury ◽  
Charbel Saade ◽  
Ghanem F. Oweis
Keyword(s):  
Aortic Dissection ◽  
Flow Behavior ◽  
False Lumen ◽  
Blood Stream ◽  
Flow Patterns ◽  
Vascular Abnormalities ◽  
Transport Dynamics ◽  
Mixing Behavior ◽  
Contrast Ct

In this work an in-vitro flow experiment is conducted to elucidate the flow behavior in simplified aortic dissection (AD) disease geometries. In AD, the innermost layer of the aortic wall is locally and partially torn allowing blood to flow between the wall layers forming a parallel blood stream in what is known as the false lumen. The aim of this work is to elucidate the disease flow physics, and to provide guidance in diagnostic radiology, particularly contrast injected computed tomography (CT), where understanding flow patterns and mixing behavior is important for accurate diagnosis. In contrast-CT, dye is injected in the peripheral blood stream to illuminate the blood vessels and identify vascular abnormalities. The flow patterns and the dye transport dynamics impact the nature of the CT images and their interpretation. Particle image velocimetry (PIV) is used to quantify the AD flow fields, and laser-induced fluorescence (LIF) is implemented to visualize and assess the mixing behavior of dye in the false and true lumens. Interesting flow patterns are revealed and discussed in the context of their possible contribution to tear expansion and flapping, and to the elevated mean pressure in the false lumen that is reported in the literature.

Abstract 102: Number of Reentry Tears Influences Flap Motion and Flow Reversal in an in vitro Model of Type B Aortic Dissection

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Joav Birjiniuk ◽  
Mark Young ◽  
Lucas H Timmins ◽  
Bradley G Leshnower ◽  
John N Oshinski ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Flow Reversal ◽  
Patient Specific ◽  
Type B ◽  
True Lumen ◽  
Flow Rates ◽  
Custom Made ◽  
Type B Dissection

Objectives: Aortic remodeling after dissection is poorly understood. Thus, optimal patient-specific recommendations for treatment are lacking. An in vitro aortic model of Type B dissection was used to interrogate local aortic hemodynamic parameters implicated in thrombosis and aneurysm formation. We hypothesize that dissections with multiple reentry tears will exhibit decreased flap motion, and, as a result, reduce flow reversal. Methods: Anatomic models of aortic dissection with fidelity to patient CT images were fabricated out of silicone. Models with primary entry and single fenestration (Figure 1A), two fenestrations (Figure 1B), and three fenestrations (Figure 1C) were installed in a flow loop. Physiologic flow was established at a cardiac index of 4 L/min. Flow velocities were acquired using phase contrast magnetic resonance (PCMR) imaging. Flow rates and flap motion were quantified using custom made software. Results: Relative true lumen area (RTLA) varied along the dissection (entry: 55% +/- 3, middle: 34% +/-7, exit: 91%+/-3, p<0.00001 pair-wise for 2-tear model). At mid-dissection, RTLA was lower in dissections with fewer tears (p<0.01). Total flow was nearly identical in all cases, while true and false lumen flow rates differed significantly across tear configurations and along the dissection (p<0.01). Secondary tears allowed for flow communication within the dissected portion of the aortic model. Flow reversal was seen in the false lumen at the mid-dissection plane in the absence of secondary tears (Figure 1D). However, as secondary tears were added, the flow reversal in the false lumen decreased, with concomitant flow reversal in the true lumen (Figure 1E,F). Conclusions: Anatomic characteristics of dissection, such as number of tears, affect blood flow and motion of the dissection flap, as shown quantitatively. This compliant aorta model illustrates alterations in flow reversal in both true and false lumina that may lead to aneurysmal degeneration.

scholarly journals The Influence of Aortic Wall Elasticity on the False Lumen in Aortic Dissection: An In Vitro Study

2020 ◽  
Vol 54 (7) ◽  
pp. 592-597
Author(s):  
Hugo T. C. Veger ◽  
Erik H. Pasveer ◽  
Jos J. M. Westenberg ◽  
Jan J. Wever ◽  
Randolph G. Statius van Eps
Keyword(s):  
Aortic Dissection ◽  
Aortic Wall ◽  
Ex Vivo ◽  
False Lumen ◽  
Circulatory System ◽  
In Vitro Study ◽  
Vitro Study ◽  
Major Influence ◽  
Distal Location

Background: Hemodynamics, dissection morphology, and aortic wall elasticity have a major influence on the pressure in the false lumen. In contrast to aortic wall elasticity, the influence of hemodynamics and dissection morphology have been investigated often in multiple in vitro and ex vivo studies. The purpose of this study was to evaluate the influence of aortic wall elasticity on the diameter and pressure of the false lumen in aortic dissection. Methods: An artificial dissection was created in 3 ex vivo porcine aortas. The aorta models were consecutively positioned in a validated in vitro circulatory system with physiological pulsatile flow. Each model was imaged with ultrasound on 4 positions along the aorta and the dissection. At these 4 locations, pressure measurement was also performed in the true and false lumen with an arterial catheter. After baseline experiments, the aortic wall elasticity was adjusted with silicon and the experiments were repeated. Results: The aortic wall elasticity was decreased in all 3 models after siliconizing. In all 3 siliconized models, the diameters of the true and false lumen increased at proximal, mid, and distal location, while the mean arterial pressure did not significantly change. Conclusions: In this in vitro study, we showed that aortic wall elasticity is an important parameter altering the false lumen. An aortic wall with reduced elasticity results in an increased false lumen diameter in the mid and distal part of the false lumen. These results can only be transferred to corresponding clinical situations to a limited extent.

A Mock Circulation Loop for In Vitro Hemodynamic Evaluation of Aorta: Application in Aortic Dissection

2021 ◽  
pp. 152660282110348
Author(s):  
Duanduan Chen ◽  
Shichao Liang ◽  
Zhenfeng Li ◽  
Yuqian Mei ◽  
Huiwu Dong ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Peripheral Resistance ◽  
Flow Distribution ◽  
Circulation Loop ◽  
Patient Specific ◽  
Mock Circulation ◽  
Blood Transport ◽  
Mock Circulation Loop

Purpose Aortic dissection (AD) is a catastrophic disease with complex hemodynamic conditions, however, understandings regarding its perfusion characteristics were not sufficient. In this study, a mock circulation loop (MCL) that integrated the Windkessel element and patient-specific silicone aortic phantoms was proposed to reproduce the aortic flow environment in vitro. Materials and Methods Patient-specific normal and dissected aortic phantoms with 12 branching vessels were established and embedded into this MCL. Velocities for aortic branches based on 20 healthy volunteers were regarded as the standardized data for flow division. By altering boundary conditions, the proposed MCL could mimic normal resting and left-sided heart failure (LHF) conditions. Flow rates and pressure status of the aortic branches could be quantified by separate sensors. Results In normal resting condition, the simulated heart rate and systemic flow rate were 60 bpm and 4.85 L/minute, respectively. For the LHF condition, the systolic and diastolic blood pressures were 75.94±0.77 mmHg and 57.65±0.35 mmHg, respectively. By tuning the vascular compliance and peripheral resistance, the flow distribution ratio (FDR) of each aortic branch was validated by the standardized data in the normal aortic phantom (mean difference 2.4%±1.70%). By comparing between the normal and dissected aortic models under resting condition, our results indicated that the AD model presented higher systolic (117.82±0.60 vs 108.75±2.26 mmHg) and diastolic (72.38±0.58 vs 70.46±2.33 mmHg) pressures, the time-average velocity in the true lumen (TL; 36.95 cm/s) was higher than that in the false lumen (FL; 22.95 cm/s), and the blood transport direction between the TL and FL varied in different re-entries. Conclusions The proposed MCL could be applied as a research tool for in vitro hemodynamic analysis of the aorta diseases under various physical conditions.

Ultrastructural studies on the interaction of haemophilus influenzae with human endothelial cells in vitro

1990 ◽  
Vol 48 (3) ◽  
pp. 636-637
Author(s):  
D.J.P. Ferguson ◽  
M. Virji ◽  
H. Kayhty ◽  
E.R. Moxon
Keyword(s):  
Endothelial Cells ◽  
Haemophilus Influenzae ◽  
Intercellular Junctions ◽  
Blood Stream ◽  
Ultrastructural Studies ◽  
Endothelial Barriers ◽  
Serotype B ◽  
Meningitis In Children ◽  
Respiratory Epithelial

Haemophilus influenzae is a human pathogen which causes meningitis in children. Systemic H. influenzae infection is largely confined to encapsulated serotype b organisms and is a major cause of meningitis in the U.K. and elsewhere. However, the pathogenesis of the disease is still poorly understood. Studies in the infant rat model, in which intranasal challenge results in bacteraemia, have shown that H. influenzae enters submucosal tissues and disseminates to the blood stream within minutes. The rapidity of these events suggests that H. influenzae penetrates both respiratory epithelial and endothelial barriers with great efficiency. It is not known whether the bacteria penetrate via the intercellular junctions, are translocated within the cells or carried across the cellular barrier in 'trojan horse' fashion within phagocytes. In the present studies, we have challenged cultured human umbilical cord_vein endothelial cells (HUVECs) with both capsulated (b+) and capsule-deficient (b-) isogenic variants of one strain of H. influenzae in order to investigate the interaction between the bacteria and HUVEC and the effect of the capsule.

False Lumen Catheterization in a Patient Who Has Type A Aortic Dissection That Mimics Acute Inferior Myocardial Infarction: A Case Report

2015 ◽  
Vol 18 (5) ◽  
pp. 208
Author(s):  
Erhan Kaya ◽  
Hakan Fotbolcu ◽  
Zeki Şimşek ◽  
Ömer Işık
Keyword(s):  
Myocardial Infarction ◽  
Case Report ◽  
Aortic Dissection ◽  
Cardiac Catheterization ◽  
False Lumen ◽  
Type A ◽  
Inferior Myocardial Infarction ◽  
Type A Aortic Dissection ◽  
Acute Inferior Myocardial Infarction ◽  
Catheterization Procedure

We report a 61-year-old patient who suffered from a type A aortic dissection that mimicked an acute inferior myocardial infarction. During a routine cardiac catheterization procedure, diagnostic catheters can be inserted accidentally into the false lumen. Invasive cardiologists should keep this complication in mind.

Cannulating a Dissecting Aorta Using Ultrasound-Epiaortic and Transesophageal Guidance

2011 ◽  
Vol 14 (6) ◽  
pp. 373 ◽  
Author(s):  
Saina Attaran ◽  
Maria Safar ◽  
Hesham Zayed Saleh ◽  
Mark Field ◽  
Manoj Kuduvalli ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Aortic Dissection ◽  
Acute Aortic Dissection ◽  
False Lumen ◽  
Type A ◽  
Ascending Aorta ◽  
Type A Aortic Dissection ◽  
Complete Rupture

<p>Management of acute Stanford type A aortic dissection remains a major surgical challenge. Directly cannulating the ascending aorta provides a rapid establishment of cardiopulmonary bypass but consists of risks such as complete rupture of the aorta, false lumen cannulation, subsequent malperfusion and propagation of the dissection.</p><p>We describe a technique of cannulating the ascending aorta in patients with acute aortic dissection that can be performed rapidly in hemodynamically unstable patients under ultrasound-epiaortic and transesophageal (TEE) guidance.</p>

Management of Residual False Lumen Flow After Thoracic Endovascular Repair in Chronic Type B Aortic Dissection

2020 ◽  
Vol 04 (05) ◽  
Author(s):  
Hervé Rousseau ◽  
Paul Revel-Mouroz ◽  
Charline Zadro ◽  
Camille Dambrin ◽  
Christophe Cron ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Endovascular Repair ◽  
False Lumen ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Chronic Type ◽  
Thoracic Endovascular Repair

scholarly journals The effect of beta-blockers on hemodynamic parameters in patient-specific blood flow simulations of type-B aortic dissection: a virtual study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Amin Abazari ◽  
Deniz Rafieianzab ◽  
M. Soltani ◽  
Mona Alimohammadi
Keyword(s):  
Aortic Dissection ◽  
Clinical Decision Making ◽  
Beta Blockers ◽  
False Lumen ◽  
Specific Treatment ◽  
Left Ventricular ◽  
Patient Specific ◽  
Type B ◽  
Windkessel Model ◽  
Computed Tomography Images

AbstractAortic dissection (AD) is one of the fatal and complex conditions. Since there is a lack of a specific treatment guideline for type-B AD, a better understanding of patient-specific hemodynamics and therapy outcomes can potentially control the progression of the disease and aid in the clinical decision-making process. In this work, a patient-specific geometry of type-B AD is reconstructed from computed tomography images, and a numerical simulation using personalised computational fluid dynamics (CFD) with three-element Windkessel model boundary condition at each outlet is implemented. According to the physiological response of beta-blockers to the reduction of left ventricular contractions, three case studies with different heart rates are created. Several hemodynamic features, including time-averaged wall shear stress (TAWSS), highly oscillatory, low magnitude shear (HOLMES), and flow pattern are investigated and compared between each case. Results show that decreasing TAWSS, which is caused by the reduction of the velocity gradient, prevents vessel wall at entry tear from rupture. Additionally, with the increase in HOLMES value at distal false lumen, calcification and plaque formation in the moderate and regular-heart rate cases are successfully controlled. This work demonstrates how CFD methods with non-invasive hemodynamic metrics can be developed to predict the hemodynamic changes before medication or other invasive operations. These consequences can be a powerful framework for clinicians and surgical communities to improve their diagnostic and pre-procedural planning.

scholarly journals 1293. Sulbactam-durlobactam is active against recent, multi-drug resistant Acinetobacter baumannii clinical isolates from the Middle East

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S662-S662
Author(s):  
Alita Miller ◽  
Sarah McLeod ◽  
Samir Moussa ◽  
Meredith Hackel
Keyword(s):  
Antibacterial Activity ◽  
Middle East ◽  
Acinetobacter Baumannii ◽  
United Arab Emirates ◽  
Blood Stream ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Surveillance Systems ◽  
Spectrum Activity

Abstract Background The incidence of infections caused by multidrug-resistant (MDR) Acinetobacter baumannii (Ab) is increasing at an alarming rate in certain regions of the world, including the Middle East. Sulbactam (SUL) has intrinsic antibacterial activity against Ab; however, the prevalence of β-lactamases in Ab has limited its therapeutic utility. Durlobactam (DUR, formerly ETX2514) is a diazabicyclooctenone β-lactamase inhibitor with broad-spectrum activity against Ambler class A, C and D β-lactamases that restores SUL activity in vitro against MDR Ab. SUL-DUR is an antibiotic designed to treat serious infections caused by Acinetobacter, including multidrug-resistant strains, that is currently in Phase 3 clinical development. In global surveillance studies of &gt;3600 isolates from 2012-2017, the MIC90 of SUL-DUR was 2 mg/L. Although surveillance systems to monitor MDR infections in the Middle East are currently being established, quantitative, prevalence-based data are not yet available. Therefore, the potency of SUL-DUR was determined against 190 recent, diverse Ab clinical isolates from this region. Methods 190 Ab isolates were collected between 2016 - 2018 from medical centers located in Israel (N = 47), Jordan (N = 36), Qatar (N = 13), Kuwait (N = 42), Lebanon (N = 8), Saudi Arabia (N = 24) and United Arab Emirates (N = 20). Seventy-five percent and 20.5% of these isolates were from respiratory and blood stream infections, respectively. Susceptibility to SUL-DUR and comparator agents was performed according to CLSI guidelines, and data analysis was performed using CLSI and EUCAST breakpoint criteria where available. Results This collection of isolates was 86% carbapenem-resistant and 90% sulbactam-resistant (based on a breakpoint of 4 mg/L). The addition of SUL-DUR (fixed at 4 mg/L) decreased the sulbactam MIC90 from 64 mg/L to 4 mg/L. Only 3 isolates (1.6%) had SUL-DUR MIC values of &gt; 4 mg/L. This potency was consistent across countries, sources of infection and subsets of resistance phenotypes. Conclusion SUL-DUR demonstrated potent antibacterial activity against recent clinical isolates of Ab from the Middle East, including MDR isolates. These data support the global development of SUL-DUR for the treatment of MDR Ab infections. Disclosures Alita Miller, PhD, Entasis Therapeutics (Employee) Sarah McLeod, PhD, Entasis Therapeutics (Employee) Samir Moussa, PhD, Entasis Therapeutics (Employee)

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