In Vitro Doppler Ultrasound Investigation of Turbulence Intensity in Pulsatile Flow With Simulated Cardiac Variability

Flow disturbances in tapered arterial grafts of angles of taper between 0.5 and 1.0 deg were measured in vitro using a pulsed ultrasound Doppler velocimeter. The increase in transition Reynolds numbers with angle of taper and axial distance was determined for steady flow. The instantaneous centerline velocities were measured distal to a 50 percent area stenosis (as a model of a proximal anastomosis), in steady and pulsatile flow, from which the disturbance intensities were calculated. A significant reduction in post-stenotic disturbance intensity was recorded in the tapered grafts, relative to a conventional cylindrical graft. In pulsatile flow with a large backflow component, however, there was an increase in disturbance intensity due to diverging flow during flow reversal. This was observed only in the 1.0 deg tapered graft. These findings indicate that taper is an important consideration in the design of vascular prostheses.

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In vitro laser Doppler anemometry of pulsatile flow velocity and shear stress measurements downstream from a jellyfish valve in the mitral position of a ventricular assist device

Journal of Artificial Organs ◽

10.1007/bf01235527 ◽

1999 ◽

Vol 2 (1) ◽

pp. 62-73 ◽

Cited By ~ 6

Author(s):

Yos Morsi ◽

Masahisa Kogure ◽

Mitsuo Umezu

Keyword(s):

Shear Stress ◽

Flow Velocity ◽

Ventricular Assist Device ◽

Pulsatile Flow ◽

Laser Doppler Anemometry ◽

Assist Device ◽

Ventricular Assist ◽

Stress Measurements ◽

Mitral Position

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Prognostic appraisal of success and failure in an in vitro fertilization program by transvaginal Doppler ultrasound at the time of ovulation induction

Ultrasound in Obstetrics and Gynecology ◽

10.1046/j.1469-0705.1991.01040272.x ◽

1991 ◽

Vol 1 (4) ◽

pp. 272-274 ◽

Cited By ~ 24

Author(s):

H. Strohmer ◽

C. Herczeg ◽

B. Plöckinger ◽

P. Kemeter ◽

W. Feichtinger

Keyword(s):

In Vitro Fertilization ◽

Doppler Ultrasound ◽

Ovulation Induction ◽

Fertilization Program ◽

Vitro Fertilization

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The efficacy of sinus plication in aortic valvuloplasty for bicuspid aortic valve: experiments in a pulsatile flow simulation model

European Journal of Cardio-Thoracic Surgery ◽

10.1093/ejcts/ezab115 ◽

2021 ◽

Author(s):

Satoshi Arimura ◽

Jumpei Takada ◽

Gohki Nishimura ◽

Natsuki Nakama ◽

Eita Kawasaki ◽

...

Keyword(s):

Aortic Valve ◽

Bicuspid Aortic Valve ◽

Pulsatile Flow ◽

Flow Simulation ◽

Ultrasound Measurement ◽

Hydrodynamic Effect ◽

Promising Tool ◽

Aortic Valvuloplasty ◽

Flow Simulator

Abstract OBJECTIVES Sinus plication has emerged as a promising tool that can lead to better stability in bicuspid aortic valve (BAV) repair. However, the mechanisms underlying the efficacy of this technique are unclear. We evaluated the hydrodynamic effect of sinus plication using the experimental pulsatile flow simulator and our original BAV model in vitro. METHODS Based on the computed tomography data of a BAV patient who had undergone aortic valvuloplasty, a BAV model (group C, n = 6) was developed with bovine pericardium and vascular prosthesis (J-graft Shield Neo Valsalva 24 mm). We performed sinus plication (group SP, n = 6) in the BAV model and compared hydrodynamic data with the control model in the pulsatile flow simulator. Non-fused cusp angle, annulus diameter and effective height were measured by ultrasonography. RESULTS The average flow was significantly increased in group SP compared to group C (4.24 ± 0.14 l/min vs 4.14 ± 0.15 l/min, respectively, P = 0.034). The mean transvalvular pressure gradient and regurgitant fraction were significantly decreased in group SP compared to group C (11.6 ± 4.3 mmHg vs 16.6 ± 5.0 mmHg, respectively, P = 0.009 and 14.1 ± 2.0% vs 17.4 ± 2.1%, respectively, P = 0.001). Ultrasound measurement indicated that non-fused cusp angle was significantly increased in group SP compared to group C (163.8° ± 9.2° vs 153.0° ± 4.6°, respectively, P = 0.012). CONCLUSIONS Sinus plication in the BAV model significantly increased the commissural angle. It was effective in not only controlling regurgitation but also improving valve opening. These finding should be confirmed by evaluating cusp stress and/or long-term durability in the future studies.

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Instantaneous Cross-sectional Flow Velocity Profiles: A Comparative Study of Two Ultrasound Doppler Methods Applied to an In Vitro Pulsatile Flow Model

Journal of the American Society of Echocardiography ◽

10.1016/s0894-7317(14)80361-1 ◽

1990 ◽

Vol 3 (6) ◽

pp. 451-464 ◽

Cited By ~ 16

Author(s):

Stein O. Samstad ◽

Hans G. Torp ◽

Knut Matre ◽

Ole Rossvoll ◽

Leidulf Segadal ◽

...

Keyword(s):

Comparative Study ◽

Flow Velocity ◽

Pulsatile Flow ◽

Flow Model ◽

Velocity Profiles ◽

Cross Sectional ◽

Ultrasound Doppler

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Distribution of Artificial Thrombi Candidates Through Patient-Specific Aortic-Arch Phantoms under Pulsatile Flow Conditions

10.21203/rs.3.rs-455601/v1 ◽

2021 ◽

Author(s):

Marco Testaguzza ◽

Mehdi Benhassine ◽

Haroun Frid ◽

Laurence Gebhart ◽

Karim Zouaoui Boudjeltia ◽

...

Keyword(s):

Aortic Arch ◽

Pulsatile Flow ◽

Patient Specific ◽

Flow Profile ◽

In Vitro Test ◽

Flow Conditions ◽

Test Bed ◽

Arch Models ◽

Artificial Emboli

Abstract Ischemic Stroke is the most frequent type of stroke and is subject to many studies investigating prevention means. Avoiding the difficulties and ethical problems of experimental in-vivo research, in-vitro testing is a convenient way of studying in controlled conditions the morphological impact and mechanical aspects of emboli dynamics. This in-vitro study was performed with two realistic silicone aortic-arch phantoms submitted to physiological pulsatile flow conditions. In the in-vitro test bed, using automatic image tracking and analysis, it was made possible detecting and tracking artificial spherical emboli candidates circulating in the anatomic aortic-arch models under a realistic based-patient blood flow profile. The emboli trajectories as well as their repartition in the different supra-aortic branches are presented for the two aortic-arch geometries obtained from CT scans. Through a statistical analysis performed with several artificial emboli sizes, the experimental study shows that the repartition percentages of the emboli closely follow the flowrate repartition percentages for both aortic-arch models, suggesting that higher flowrates lead to higher concentrations of emboli in a given artery. Sets of human thrombi were also injected and the repartition percentages have been established, giving the same trend as for artificial emboli.

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