Fluid Stresses in the Vicinity of Disk, Ball, and Tilting Disk Prosthetic Heart Valves From In-Vitro Measurements

1977 ◽  
Vol 99 (4) ◽  
pp. 173-177 ◽  
Author(s):  
R. S. Figliola ◽  
T. J. Mueller
Keyword(s):  
Heart Valves ◽  
High Stress ◽  
Test Chamber ◽  
Prosthetic Heart Valve ◽  
Separated Flow ◽  
Reynolds Numbers ◽  
Prosthetic Heart Valves ◽  
In Vitro Measurements ◽  
Turbulence Data

Experiments were conducted in a steady flow test apparatus with an axisymmetric aortic shaped test chamber using hot-wire anemometry to obtain local momentum transfer and turbulence data in the vicinity of the model disk, Kay-Shiley disk, Starr-Edwards ball and Bjork-Shiley tilting disk prosthetic heart valve configurations. These data for Reynolds numbers of 2000, 4000, and 6000 were used to locate regions of high stress where erythrocytes may be lysed or severely strained. Nondimensionalized velocity profiles downstream of the valves indicated a similarity of behavior for all Reynolds numbers at an axial location. Velocity gradients of magnitudes potentially damaging to erythrocytes were found. These gradients were largest for disk-type occluders. Large regions of separated flow were found to occur behind the valve sewing ring, distal to the valve occluder, and along the test chamber wall distal to the valve for all valves tested. Relatively high turbulence was found to exist distal to all valves tested. Turbulent stresses of magnitudes potentially hemolytic were measured.

On the Hemolytic and Thrombogenic Potential of Occluder Prosthetic Heart Valves From In-Vitro Measurements

1981 ◽  
Vol 103 (2) ◽  
pp. 83-90 ◽  
Author(s):  
R. S. Figliola ◽  
T. J. Mueller
Keyword(s):  
Heart Valves ◽  
Thrombus Formation ◽  
Test Chamber ◽  
Separated Flow ◽  
Prosthetic Heart Valves ◽  
Shear Stresses ◽  
Flow Loop ◽  
Mean Velocity ◽  
Test Loop

An experimental investigation was conducted to determine the magnitude of shear stresses and areas of stasis of several types of prosthetic occluder heart valves. These experiments were performed in a steady-flow test loop using an axisymmetric aortic-shaped test chamber and an aqueous-glycerine solution. The flow loop produced a low-turbulence intensity and uniform mean velocity profile upstream of the test chamber. Tests were perfomed on a Kay-Shiley disk, a Bjork-Shiley tilting disk and Starr-Edwards Models 1260 and 2320 ball prostheses at Reynolds numbers between 2000 and 6200. Momentum transfer and turbulence data were obtained both around and distal to the valve occluders using laser Doppler and hot-film anemometry. The region directly surrounding the valve occluders contained the largest stresses measured. Aortic wall shear measurements revealed magnitudes potentially damaging to the vessel lining. Regions of slowly moving separated flow found to exist in these occluder valve flow fields correlated with clinical findings of thrombus formation.

Simulations of the Hinge Flow Fields of a Bileaflet Mechanical Heart Valve Under Physiologic Pulsatile Aortic Conditions

2008 ◽  
Author(s):  
Hélène A. Simon ◽  
Liang Ge ◽  
Iman Borazjani ◽  
Fotis Sotiropoulos ◽  
Ajit P. Yoganathan
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Prosthetic Heart Valve ◽  
Prosthetic Heart Valves ◽  
Valve Design ◽  
Bileaflet Mechanical Heart Valve ◽  
Hinge Flow ◽  
Blood Elements

Native heart valves with limited functionality are commonly replaced by prosthetic heart valves. Since the first heart valve replacement in 1960, more than three million valves have been implanted worldwide. The most widely implanted prosthetic heart valve design is currently the bileaflet mechanical heart valve (BMHV), with more than 130,000 implants every year worldwide. However, studies have shown that this valve design can still cause major complications, including hemolysis, platelet activation, and thromboembolic events. Clinical reports and recent in vitro experiments suggest that these thrombogenic complications are associated with the hemodynamic stresses imposed on blood elements by the complex non-physiologic flow induced by the valve, in particular in the hinge region.

The Design, Fabrication and Evaluation of a Trileaflet Prosthetic Heart Valve

1980 ◽  
Vol 102 (1) ◽  
pp. 34-41 ◽  
Author(s):  
G. E. Chetta ◽  
J. R. Lloyd
Keyword(s):  
Heart Valve ◽  
Performance Index ◽  
Test Section ◽  
Heart Valves ◽  
Prosthetic Heart Valve ◽  
Prosthetic Heart Valves ◽  
In Vitro Evaluation ◽  
Design Considerations ◽  
Evaluation Techniques

Although prosthetic heart valves have been in existence for many years, the need for new improved designs and in-vitro evaluation techniques are apparent. This paper presents details on the design considerations, fabrication techniques and heart valve evaluation equipment. A valve performance index is discussed in light of various valve and mock circulatory test section designs. The need for national and indeed international valve evaluation techniques is made apparent.

The Effect of Dipyridamole and RA 233 on Human Platelet Function in Vitro

1973 ◽  
Vol 29 (03) ◽  
pp. 694-700 ◽  
Author(s):  
Paul L. Rifkin ◽  
Marjorie B. Zucker
Keyword(s):  
Mechanism Of Action ◽  
Human Blood ◽  
Glass Bead ◽  
Heart Valves ◽  
Human Platelet ◽  
Drug Effects ◽  
Simple Relation ◽  
Prosthetic Heart Valves ◽  
Induced Aggregation

SummaryDipyridamole (Persantin) is reported to prolong platelet survival and inhibit embolism in patients with prosthetic heart valves, but its mechanism of action is unknown. Fifty jxM dipyridamole failed to reduce the high percentage of platelets retained when heparinized human blood was passed through a glass bead column, but prolonged the inhibition of retention caused by disturbing blood in vitro. Possibly the prostheses act like disturbance. Although RA 233 was as effective as dipyridamole in inhibiting the return of retention, it was less effective in preventing the uptake of adenosine into erythrocytes, and more active in inhibiting ADP-induced aggregation and release. Thus there is no simple relation between these drug effects.

Noninvasive Electromagnetic Evaluation of Bjo¨rk-Shiley Heart Valves: Lifetime Prediction

2008 ◽  
Author(s):  
Raimond Grimberg ◽  
Adriana Savin ◽  
Shiu C. Chan ◽  
Rozina Steigmann ◽  
Lalita Udpa ◽  
...  
Keyword(s):  
Eddy Current ◽  
Heart Valves ◽  
Probability Of Detection ◽  
New Method ◽  
Lifetime Prediction ◽  
Prosthetic Heart Valves ◽  
In Vitro Experiments ◽  
Current Transducer ◽  
Eddy Current Transducer

Prosthetic heart valves of the Bjork-Shiley Convexo-Concave (BSCC) type have long been used extensively in implants; however, there have been reports of cases where one component of the valves failed, leading to the demise of the patient. This paper presents a new method for noninvasive electromagnetic evaluation for this type of valve, using an eddy current transducer with orthogonal coils. In vitro experiments have shown that discontinuities of outlet strut with depths equal or larger than 0.4mm can be detected with a probability of detection (POD) of 86.4%, and in the case of discontinuities with depth equal or larger than 0.6mm with POD of 97%.

Pressure drops across prosthetic aortic heart valves under steady and pulsatile flow—In vitro measurements

1979 ◽  
Vol 12 (2) ◽  
pp. 153-164 ◽  
Author(s):  
Ajit P. Yoganathan ◽  
William H. Corcoran ◽  
Earl C. Harrison
Keyword(s):  
Pulsatile Flow ◽  
Heart Valves ◽  
Pressure Drops ◽  
In Vitro Measurements

Can the Hemodynamics of Prosthetic Heart Valves be Evaluated Sufficiently by In Vitro Tests?

1986 ◽  
pp. 47-54
Author(s):  
Martin Gottwik ◽  
S. Hartung ◽  
O. Epe ◽  
S. Langsdorf ◽  
J. Thormann ◽  
...  
Keyword(s):  
Heart Valves ◽  
In Vitro Tests ◽  
Prosthetic Heart Valves

scholarly journals Hemodynamic Performance of Dysfunctional Prosthetic Heart Valve with the Concomitant Presence of Subaortic Stenosis: In Silico Study

2020 ◽  
Vol 7 (3) ◽  
pp. 90
Author(s):  
Othman Smadi ◽  
Anas Abdelkarim ◽  
Samer Awad ◽  
Thakir D. Almomani
Keyword(s):  
Early Detection ◽  
Heart Valve ◽  
Heart Valves ◽  
Cfd Simulation ◽  
Treatment Plan ◽  
Mechanical Heart Valve ◽  
Prosthetic Heart Valve ◽  
Subaortic Stenosis ◽  
Prosthetic Heart Valves ◽  
The Impact

The prosthetic heart valve is vulnerable to dysfunction after surgery, thus a frequent assessment is required. Doppler electrocardiography and its quantitative parameters are commonly used to assess the performance of the prosthetic heart valves and provide detailed information on the interaction between the heart chambers and related prosthetic valves, allowing early detection of complications. However, in the case of the presence of subaortic stenosis, the accuracy of Doppler has not been fully investigated in previous studies and guidelines. Therefore, it is important to evaluate the accuracy of the parameters in such cases to get early detection, and a proper treatment plan for the patient, at the right time. In the current study, a CFD simulation was performed for the blood flow through a Bileaflet Mechanical Heart Valve (BMHV) with concomitant obstruction in the Left Ventricle Outflow Tract (LVOT). The current study explores the impact of the presence of the subaortic on flow patterns. It also investigates the accuracy of (BMHV) evaluation using Doppler parameters, as proposed in the American Society of Echocardiography (ASE) guidelines.

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