A realistic way to investigate the design, and mechanical properties of flow diverter stents

Purpose: Braided flow diverters (FD) are highly sophisticated, delicate, and intricate mechanical devices used to treat intracranial aneurysms and thus saving lives. Testing such devices in vitro, however, remains an unsolved challenge. Here, we evaluate methods that access flow, design, and mechanical properties in vitro. Methods: Flow properties, cell porosity, and cell area were evaluated by placing FDs in patient-derived, 3D printed models of human vasculature. 4D flow MRI was used to measure fluid dynamics. Laser microscopy was used to measure porosity and cell area with the top of aneurysm sac cut off for the model. New testing methods were developed to investigate the bending, circumferential, and longitudinal radial force continuously over varying diameters. Results: The placement and flow properties of the FD in the vasculature models were successfully measured by MRI, although artifacts occurred. The setup to measure porosity and cell area inside of the model proved successful. The newly discussed methods allowed us to measure the indicated forces, to our knowledge for the first time, continuously. Conclusion: Modern and specifically tailored techniques, some of which were presented here for the first time, allow detailed insights into the flow and mechanical properties of braided flow diverter stents.

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In Vitro Degradation Behaviours of PDO Monofilament and Its Intravascular Stents with Braided Structure

Autex Research Journal ◽

10.1515/aut-2015-0031 ◽

2016 ◽

Vol 16 (2) ◽

pp. 80-89 ◽

Cited By ~ 8

Author(s):

Cong-er Wang ◽

Pei-hua Zhang

Keyword(s):

Mechanical Properties ◽

Vascular Wall ◽

Radial Force ◽

Temporary Increase ◽

Crystalline Region ◽

Bending Rigidity ◽

Intravascular Stents ◽

Braided Structure ◽

Intravascular Stent

Abstract Biodegradable intravascular stent has attracted more and more focus in recent years as an effective solution for angiostenosis. Ideal stents were expected to exhibit sufficient radial force to support the vascular wall, while suitable flexibility for the angioplasty. After vascular remodeling, stents should be degraded into small molecular and be eliminated from human body, causing no potential risk. In this paper, poly-p-dioxanone (PDO) monofilament was braided into net structure with four different braiding density, two of which exhibited sufficient radial force larger than 30 kPa, and three of which showed the bending rigidity within 11.7–88.1 N•mm2. The degradation behaviors of monofilaments and stents have been observed for 16 weeks. The findings obtained indicate that degradation first occurred in morphology region, which induced temporary increase of crystallinity, monofilament bending rigidity and stent mechanical properties. During this period, monofilament tends to be hard and brittle and lost its tensile properties. Then the crystalline region was degraded and stent mechanical properties decreased. All the results reveal that the PDO intravascular stents with braided structure were able to afford at least 10 weeks of sufficient support to the vascular wall.

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Valvular regurgitation flow jet assessment using in vitro 4D flow MRI: Implication for mitral regurgitation

Magnetic Resonance in Medicine ◽

10.1002/mrm.29082 ◽

2021 ◽

Author(s):

Jeesoo Lee ◽

Aakash N. Gupta ◽

Liliana E. Ma ◽

Michel B. Scott ◽

O’Neil R. Mason ◽

...

Keyword(s):

Mitral Regurgitation ◽

Valvular Regurgitation ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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In vitro experiments on ICOSA6 4D flow MRI measurement for the quantification of velocity and turbulence parameters

Magnetic Resonance Imaging ◽

10.1016/j.mri.2020.06.020 ◽

2020 ◽

Vol 72 ◽

pp. 49-60

Author(s):

Hojin Ha ◽

Kyung Jin Park ◽

Petter Dyverfeldt ◽

Tino Ebbers ◽

Dong Hyun Yang

Keyword(s):

In Vitro Experiments ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri ◽

Turbulence Parameters

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Surgical planning for living donor liver transplant using 4D flow MRI, computational fluid dynamics and in vitro experiments

Computer Methods in Biomechanics and Biomedical Engineering Imaging & Visualization ◽

10.1080/21681163.2017.1278619 ◽

2017 ◽

Vol 6 (5) ◽

pp. 545-555 ◽

Cited By ~ 7

Author(s):

David R. Rutkowski ◽

Scott B. Reeder ◽

Luis A. Fernandez ◽

Alejandro Roldán-Alzate

Keyword(s):

Living Donor ◽

Surgical Planning ◽

In Vitro Experiments ◽

4D Flow Mri ◽

Donor Liver ◽

4D Flow ◽

Living Donor Liver Transplant ◽

Flow Mri ◽

Donor Liver Transplant

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A technique for intra-procedural blood velocity quantitation using time-resolved 2D digital subtraction angiography

CVIR Endovascular ◽

10.1186/s42155-020-00199-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Carson Hoffman ◽

Sarvesh Periyasamy ◽

Colin Longhurst ◽

Rafael Medero ◽

Alejandro Roldan-Alzate ◽

...

Keyword(s):

Blood Velocity ◽

Contrast Injection ◽

4D Flow ◽

Flow Probe ◽

Time Resolved ◽

Accuracy And Precision ◽

Flow Mri ◽

Projection Angle

Abstract Background 2D digital subtraction angiography (DSA) is utilized qualitatively to assess blood velocity changes that occur during arterial interventions. Quantitative angiographic metrics, such as blood velocity, could be used to standardize endpoints during angiographic interventions. Purpose To assess the accuracy and precision of a quantitative 2D DSA (qDSA) technique and to determine its feasibility for in vivo measurements of blood velocity. Materials and methods A quantitative DSA technique was developed to calculate intra-procedural blood velocity. In vitro validation was performed by comparing velocities from the qDSA method and an ultrasonic flow probe in a bifurcation phantom. Parameters of interest included baseline flow rate, contrast injection rate, projection angle, and magnification. In vivo qDSA analysis was completed in five different branches of the abdominal aorta in two 50 kg swine and compared to 4D Flow MRI. Linear regression, Bland-Altman, Pearson’s correlation coefficient and chi squared tests were used to assess the accuracy and precision of the technique. Results In vitro validation showed strong correlation between qDSA and flow probe velocities over a range of contrast injection and baseline flow rates (slope = 1.012, 95% CI [0.989,1.035], Pearson’s r = 0.996, p < .0001). The application of projection angle and magnification corrections decreased variance to less than 5% the average baseline velocity (p = 0.999 and p = 0.956, respectively). In vivo validation showed strong correlation with a small bias between qDSA and 4D Flow MRI velocities for all five abdominopelvic arterial vessels of interest (slope = 1.01, Pearson’s r = 0.880, p = <.01, Bias = 0.117 cm/s). Conclusion The proposed method allows for accurate and precise calculation of blood velocities, in near real-time, from time resolved 2D DSAs.

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Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent

Journal of Endovascular Therapy ◽

10.1177/1526602816671134 ◽

2016 ◽

Vol 24 (1) ◽

pp. 130-137 ◽

Cited By ~ 20

Author(s):

Christian Wissgott ◽

Wolfram Schmidt ◽

Christoph Brandt-Wunderlich ◽

Peter Behrens ◽

Reimer Andresen

Keyword(s):

Mechanical Properties ◽

Double Layer ◽

Clinical Results ◽

Radial Force ◽

Bending Stiffness ◽

Lesion Length ◽

Collapse Pressure ◽

Stent System ◽

In Vitro Investigation

Purpose: To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent’s mechanical properties. Methods: A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. Results: The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm2). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Conclusion: Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

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Hemodynamic study of TCPC using in vivo and in vitro 4D Flow MRI and numerical simulation

Journal of Biomechanics ◽

10.1016/j.jbiomech.2015.03.009 ◽

2015 ◽

Vol 48 (7) ◽

pp. 1325-1330 ◽

Cited By ~ 13

Author(s):

Alejandro Roldán-Alzate ◽

Sylvana García-Rodríguez ◽

Petros V. Anagnostopoulos ◽

Shardha Srinivasan ◽

Oliver Wieben ◽

...

Keyword(s):

Numerical Simulation ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri ◽

Hemodynamic Study

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In Vitro Assessment of Flow Variability in an Intracranial Aneurysm Model Using 4D Flow MRI and Tomographic PIV

Annals of Biomedical Engineering ◽

10.1007/s10439-020-02543-8 ◽

2020 ◽

Vol 48 (10) ◽

pp. 2484-2493 ◽

Cited By ~ 3

Author(s):

Rafael Medero ◽

Katrina Ruedinger ◽

David Rutkowski ◽

Kevin Johnson ◽

Alejandro Roldán-Alzate

Keyword(s):

Intracranial Aneurysm ◽

4D Flow Mri ◽

4D Flow ◽

Tomographic Piv ◽

Flow Variability ◽

Flow Mri ◽

In Vitro Assessment ◽

Aneurysm Model

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In vitro contact guidance of glioblastoma cells on metallic biomaterials

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-021-06503-z ◽

2021 ◽

Vol 32 (4) ◽

Author(s):

B. Uzer-Yilmaz

Keyword(s):

Mechanical Properties ◽

Cell Attachment ◽

Cancer Invasion ◽

Contact Guidance ◽

Metallic Biomaterials ◽

Cellular Aspect ◽

Cancer Dissemination ◽

First Time ◽

The Relationship

AbstractCancer cells’ ability to sense their microenvironment and interpret these signals for the regulation of directional adhesion plays crucial role in cancer invasion. Furthermore, given the established influence of mechanical properties of the substrate on cell behavior, the present study aims to elucidate the relationship between the contact guidance of glioblastoma cell (GBM) and evolution of microstructural and mechanical properties of the implants. SEM analyses of the specimens subjected to 5 and 25% of plastic strains revealed directional groove-like structures in micro and submicro-sizes, respectively. Microscale cytoplasmic protrusions of GBMs showed elongation favored along the grooves created via deformation markings on 5% deformed sample. Whereas filopodia, submicro-sized protrusions facilitating cancer invasion, elongated in the direction perpendicular to the deformation markings on the 25% deformed sample, which might lead to easy and rapid retraction. Furthermore, number of cell attachment was 1.7-fold greater on 25% deformed sample, where these cells showed the greatest cellular aspect ratio. The directional attachment and contact guidance of GBMs was reported for the first time on metallic implants and these findings propose the idea that GBM response could be regulated by controlling the spacing of the deformation markings, namely the degree of plastic deformation. These findings can be applied in the design of cell-instructive implants for therapeutic purposes to suppress cancer dissemination.

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