Abstract 20132: Quantification of Multiple Mitral Regurgitant Jets: An in vitro Assessment of Doppler Methods Pertaining to MitraClip

Introduction: Mitraclip deployment creates a double orifice valve with multiple regurgitant jets making quantification of mitral regurgitation (MR) difficult. Hypothesis: Our objective was to evaluate the accuracy of double jet MR quantification by summation of individual jet 3D echo-derived vena contracta area (VCA) or 2D proximal isovelocity surface area (PISA) estimation of regurgitant volume (RV). Methods: In a pulsatile flow loop model, six valve constructs were evaluated with RV of 25 ml, 45 ml, and 65ml/beat. Regurgitant orifices tested were: a single circular hole (n=6), two symmetric circular holes (n=6), and an asymmetric configuration with a circular hole and an elliptical hole (n=6). RV was compared with true flow measurements from in vitro flow transducers. RV was calculated as: 1) PISA-Effective regurgitant orifice area x Doppler time velocity interval (TVI) or 2) VCA x Doppler TVI. Results: RV derived by PISA method correlated well with reference standard flow measures for both single orifice and double orifice valve constructs (R=0.96 vs R=0.90, p<0.0001, respectively). PISA-RV also demonstrated a good correlation to true RV when tested through symmetric or asymmetric double orifice disks (R=0.96 vs R=0.87,p<0.0001). 3D-VCA derived RV showed a superior correlation using the symmetric vs asymmetric disks (R=0.946 vs R=0.63,p<0.001). Conclusions: In a pulsatile model of double orifice MR, total RV is accurately measured by summation of PISA-derived RV or VCA -derived RV from each orifice. These methods deserve further evaluation in the clinical setting.

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Thrombogenicity assessment of Pipeline Flex, Pipeline Shield, and FRED flow diverters in an in vitro human blood physiological flow loop model

Journal of Biomedical Materials Research Part A ◽

10.1002/jbm.a.36514 ◽

2018 ◽

Vol 106 (12) ◽

pp. 3195-3202 ◽

Cited By ~ 12

Author(s):

Gaurav Girdhar ◽

Arielle Andersen ◽

Elizabeth Pangerl ◽

Reza Jahanbekam ◽

Samantha Ubl ◽

...

Keyword(s):

Human Blood ◽

Loop Model ◽

Flow Loop ◽

Physiological Flow ◽

Flow Diverters

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Preclinical safety and efficacy evaluation of the Pipeline Vantage Embolization Device with Shield Technology

Journal of NeuroInterventional Surgery ◽

10.1136/neurintsurg-2020-016043 ◽

2020 ◽

Vol 12 (10) ◽

pp. 981-986 ◽

Cited By ~ 2

Author(s):

Robert M Starke ◽

John Thompson ◽

Ariana Pagani ◽

Animesh Choubey ◽

John M Wainwright ◽

...

Keyword(s):

Platelet Activation ◽

Thrombin Generation ◽

Flow Diverter ◽

Loop Model ◽

Flow Loop ◽

Efficacy Evaluation ◽

Vessel Patency ◽

Aneurysm Occlusion

BackgroundThe Pipeline Vantage Embolization Device with Shield Technology is a next generation flow diverter developed to improve aneurysm occlusion and implant endothelialization in addition to lowering thrombogenicity. We report here the in vivo biocompatibility and in vitro hemocompatibility performance of the Pipeline Vantage Embolization Device with Shield Technology (Vantage) compared with the Pipeline Flex Embolization Device (Flex).MethodsBiocompatibility (via histology), aneurysm occlusion and vessel patency (via angiography), and endothelial coverage (via scanning electron microscopy (SEM)) for the Vantage and Flex devices were assessed in the rabbit elastase aneurysm model at 90 days (n=29) and 180 days (n=27). In vitro thrombogenicity for Flex and Vantage (n=16) was assessed using a human blood flow loop model at low heparin concentration (0.6 U/mL) with thrombin generation, platelet activation and thrombus visualization as outputs.ResultsRaymond Roy Occlusion Classification grade 1 was higher for Vantage (61%) compared with Flex (46%), but was not statistically significant (p>0.05). All branch vessels were patent. Histological measures for both devices were similar (p>0.05). Endothelial coverage of the implant was significantly better for Vantage compared with Flex (p<0.05). In vitro measurements of thrombin generation (thrombin-antithrombin complex (µg/mL): Vantage 0.49±0.45; Flex 10.57±9.84) and platelet activation (β-thromboglobulin (IU/µl): Vantage 0.41±0.19; Flex 4.14±2.38) were both statistically lower (p<0.05) for Vantage compared with Flex. High resolution microscopy showed less accumulation of thrombus on Vantage as compared with Flex.ConclusionVantage improved aneurysm occlusion and implant endothelialization and had significantly lower thrombogenicity as compared with Flex, while preserving the biocompatibility safety profile of Flex.

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Partition Coefficient of 133Xe between Blood and Eye Tissues

Nuklearmedizin ◽

10.1055/s-0038-1624911 ◽

1975 ◽

Vol 14 (04) ◽

pp. 301-309

Author(s):

A. Marczak ◽

A. Moszczyńska-Kowalska ◽

H. Kowalski

Keyword(s):

Partition Coefficient ◽

Aqueous Humour ◽

Vitreous Body ◽

Flow Measurements ◽

Solubility Coefficient ◽

Eye Muscles ◽

Eye Tissues ◽

Relative Solubility ◽

Blood Flow Measurements

SummaryThe relative solubility coefficient of 133Xe and the tissue-blood partition coefficient for the aqueous humour vitreous body, conjunctiva and external eye muscles of the rabbit were determined in vitro at 37° C and at various haematocrit values. The partition coefficient for haematocrit 40 was: for the aqueous humour 0,49 ml/ml, for the vitreous body 0,50 ml/ml, for the conjunctiva 0,81 ml/g and for the external eye muscles 0,77 ml/g. It was found that the solubility of 133Xe in rabbit erythrocytes is about 50 per cent higher than that in human red cells. The consequences of this fact for the precision of blood flow measurements by the method of tissue clearance are discussed.

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In vitro evaluation of cerebrospinal fluid velocity measurement in type I Chiari malformation: repeatability, reproducibility, and agreement using 2D phase contrast and 4D flow MRI

Fluids and Barriers of the CNS ◽

10.1186/s12987-021-00246-3 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Gwendolyn Williams ◽

Suraj Thyagaraj ◽

Audrey Fu ◽

John Oshinski ◽

Daniel Giese ◽

...

Keyword(s):

Chiari Malformation ◽

Phase Contrast ◽

Patient Specific ◽

Type I ◽

4D Flow ◽

Csf Dynamics ◽

Flow Measurements ◽

Repeatability And Reproducibility ◽

Flow Techniques

Abstract Background Phase contrast magnetic resonance imaging, PC MRI, is a valuable tool allowing for non-invasive quantification of CSF dynamics, but has lacked adoption in clinical practice for Chiari malformation diagnostics. To improve these diagnostic practices, a better understanding of PC MRI based measurement agreement, repeatability, and reproducibility of CSF dynamics is needed. Methods An anatomically realistic in vitro subject specific model of a Chiari malformation patient was scanned three times at five different scanning centers using 2D PC MRI and 4D Flow techniques to quantify intra-scanner repeatability, inter-scanner reproducibility, and agreement between imaging modalities. Peak systolic CSF velocities were measured at nine axial planes using 2D PC MRI, which were then compared to 4D Flow peak systolic velocity measurements extracted at those exact axial positions along the model. Results Comparison of measurement results showed good overall agreement of CSF velocity detection between 2D PC MRI and 4D Flow (p = 0.86), fair intra-scanner repeatability (confidence intervals ± 1.5 cm/s), and poor inter-scanner reproducibility. On average, 4D Flow measurements had a larger variability than 2D PC MRI measurements (standard deviations 1.83 and 1.04 cm/s, respectively). Conclusion Agreement, repeatability, and reproducibility of 2D PC MRI and 4D Flow detection of peak CSF velocities was quantified using a patient-specific in vitro model of Chiari malformation. In combination, the greatest factor leading to measurement inconsistency was determined to be a lack of reproducibility between different MRI centers. Overall, these findings may help lead to better understanding for application of 2D PC MRI and 4D Flow techniques as diagnostic tools for CSF dynamics quantification in Chiari malformation and related diseases.

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Utilization of Double-Orifice Valve Plasty in Correction of Atrioventricular Septal Defect

The Annals of Thoracic Surgery ◽

10.1016/j.athoracsur.2005.10.034 ◽

2006 ◽

Vol 81 (4) ◽

pp. 1450-1454 ◽

Cited By ~ 9

Author(s):

Yong-Qiang Lai ◽

Yi Luo ◽

Chun Zhang ◽

Zhao-Guang Zhang

Keyword(s):

Septal Defect ◽

Atrioventricular Septal Defect ◽

Double Orifice ◽

Orifice Valve

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Hemodynamics in the abdominal aorta: a comparison of in vitro and in vivo measurements

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.4.1520 ◽

1994 ◽

Vol 76 (4) ◽

pp. 1520-1527 ◽

Cited By ~ 65

Author(s):

J. E. Moore ◽

S. E. Maier ◽

D. N. Ku ◽

P. Boesiger

Keyword(s):

Abdominal Aorta ◽

Velocity Profiles ◽

Flow Reversal ◽

Infrarenal Aorta ◽

Complex Flow ◽

Flow Measurements ◽

In Vivo Measurements ◽

Made In

In vivo measurements of blood velocity profiles are difficult to obtain and interpret, since the parameters that govern the normally highly complex flow situation may not be fully quantified or understood at the time of measurement. In vitro flow models have been used often to better understand vascular hemodynamics. The assumptions made in the design of these models limit the applicability of the results. In this study, in vitro flow measurements made in a carefully designed model of the abdominal aorta were compared with in vivo measurements obtained with magnetic resonance imaging. In the suprarenal aorta, the velocity profiles were mostly forward and axisymmetric in both the in vitro and in vivo cases. In the infrarenal aorta, there was extensive flow reversal noted near the posterior wall in both cases. In the aortic bifurcation, two peaks of flow reversal were noted near the lateral posterior walls, and M-shaped velocity profiles were observed in late diastole. The in vitro and in vivo measurements exhibited good qualitative agreement. The in vitro model was accurate in modeling the in vivo hemodynamics of the abdominal aorta. The complex phenomena observed in vivo were explained on the basis of knowledge gained from the in vitro study.

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Vascular Stenosis Asymmetry Influences Considerably Pressure Gradient and Flow Volume

Physiological Research ◽

10.33549/physiolres.932944 ◽

2016 ◽

pp. 63-69 ◽

Cited By ~ 2

Author(s):

L. NOVAKOVA ◽

J. KOLINSKY ◽

J. ADAMEC ◽

J. KUDLICKA ◽

J. MALIK

Keyword(s):

Pressure Drop ◽

Flow Volume ◽

Hemodynamic Changes ◽

Flow Measurements ◽

Stenosis Severity ◽

Vascular Stenosis ◽

Particle Imaging ◽

Different Levels ◽

Volume Decrease

Vascular stenosis is often described only by its percentage in both clinical and scientific praxis. Previous studies gave inconclusive results regarding the effect of stenosis eccentricity on its hemodynamic effect. The aim of this experimental study was to investigate and quantify the effect of stenosis severity and eccentricity on the pressure drop. A combination of pressure and flow measurements by Particle Imaging Velocimetry (PIV) method was used. Models of the same stenosis significance but with different levels of eccentricity were studied in vitro by PIV. This study has shown that stenosis asymmetry is associated with more profound pressure drop and flow volume decrease. On the contrary, pressure drop and flow volume decrease were not further significantly influenced by the level of asymmetry. Hemodynamic changes associated with stenosis eccentricity must be taken into account in both clinical and scientific studies.

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Toxin B Variants from Clostridium difficile Strains VPI 10463 and NAP1/027 Share Similar Substrate Profile and Cellular Intoxication Kinetics but Use Different Host Cell Entry Factors

Toxins ◽

10.3390/toxins11060348 ◽

2019 ◽

Vol 11 (6) ◽

pp. 348 ◽

Cited By ~ 6

Author(s):

Diana López-Ureña ◽

Josué Orozco-Aguilar ◽

Yendry Chaves-Madrigal ◽

Andrea Ramírez-Mata ◽

Amanda Villalobos-Jimenez ◽

...

Keyword(s):

Clostridium Difficile ◽

Small Gtpases ◽

Cell Entry ◽

Intestinal Loop ◽

Loop Model ◽

Toxin B ◽

Binding Domains ◽

Crucial Difference ◽

Sequence Variations

Clostridium difficile induces antibiotic-associated diarrhea due to the release of toxin A (TcdA) and toxin B (TcdB), the latter being its main virulence factor. The epidemic strain NAP1/027 has an increased virulence attributed to different factors. We compared cellular intoxication by TcdBNAP1 with that by the reference strain VPI 10463 (TcdBVPI). In a mouse ligated intestinal loop model, TcdBNAP1 induced higher neutrophil recruitment, cytokine release, and epithelial damage than TcdBVPI. Both toxins modified the same panel of small GTPases and exhibited similar in vitro autoprocessing kinetics. On the basis of sequence variations in the frizzled-binding domain (FBD), we reasoned that TcdBVPI and TcdBNAP1 might have different receptor specificities. To test this possibility, we used a TcdB from a NAP1 variant strain (TcdBNAP1v) unable to glucosylate RhoA but with the same receptor-binding domains as TcdBNAP1. Cells were preincubated with TcdBNAP1v to block cellular receptors, prior to intoxication with either TcdBVPI or TcdBNAP1. Preincubation with TcdBNAP1v blocked RhoA glucosylation by TcdBNAP1 but not by TcdBVPI, indicating that the toxins use different host factors for cell entry. This crucial difference might explain the increased biological activity of TcdBNAP1 in the intestine, representing a contributing factor for the increased virulence of the NAP1/027 strain.

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