Negative Pressure Transients with Mechanical Heart-Valve Closure: Correlation between In Vitro and In Vivo Results

10.1114/1.79 ◽  
1998 ◽  
Vol 26 (4) ◽  
pp. 546-556 ◽  
Author(s):  
K. B. Chandran ◽  
E. U. Dexter ◽  
S. Aluri ◽  
W. E. Richenbacher
Keyword(s):  
Heart Valve ◽  
Negative Pressure ◽  
Mechanical Heart Valve ◽  
Valve Closure ◽  
Pressure Transients ◽  
Negative Pressure Transients ◽  
Closure Correlation

Enhanced Response to Chemotactic Activation of Polymorphonuclear Leukocytes from Patients with Heart Valve Replacement

1997 ◽  
Vol 77 (01) ◽  
pp. 071-074 ◽  
Author(s):  
Norma Maugeri ◽  
Ana C Kempfer ◽  
Virgilio Evangelista ◽  
Chiara Cerletti ◽  
Giovanni de Gaetano ◽  
...  
Keyword(s):  
Valve Replacement ◽  
Heart Valve ◽  
Thrombus Formation ◽  
Oral Anticoagulant Therapy ◽  
Thrombotic Event ◽  
Mechanical Heart Valve ◽  
Cathepsin G ◽  
Heart Valve Replacement

SummaryArtificial surfaces activate blood components. Since anticoagulant and antiplatelet therapy fail to abolish thromboembolic complications in patients with mechanical heart valve replacement (MHVR), other mechanisms might contribute to switch on a thrombotic event. We therefore investigated the reactivity to chemotactic activation of PMN from patients with MHVR. PMN responses were analyzed in 3 groups: 130 patients with MHVR and oral anticoagulant therapy, with or without aspirin, 57 patients on a comparable antithrombotic regimen, but without MHVR and 50 healthy subjects. In vitro studies showed that the release of cathepsin G and elastase from fMLP-stimulated PMN was significantly higher in the MHVR group, the leukocyte content of α1-antitrypsin (an inhibitor of both enzymes) being similar in all three groups. CD1 lb expression after stimulation with fMLP was also significantly higher on PMN from MHVR patients than from control patients or healthy volunteers, while PMN CD 11b basal expression was similar in all three groups. This increased PMN response in vitro in the absence of an obvious activation in vivo, may reflect a modified reactivity of circulating PMN passing through the artificial valves. Increased reactivity to local stimuli might allow PMN to participate in thrombus formation, despite conventional antithrombotic therapy.

scholarly journals A novel trileaflet mechanical heart valve: first in vitro results

2018 ◽  
Vol 28 (5) ◽  
pp. 689-694 ◽  
Author(s):  
Kathrin Schubert ◽  
Tim Schaller ◽  
Elisabeth Stojenthin ◽  
Christian Stephan ◽  
Hans-Hinrich Sievers ◽  
...  
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve

Static and Dynamic Stresses during Valve Closure of a Bileaflet Mechanical Heart Valve Prosthesis

1991 ◽  
Vol 14 (12) ◽  
pp. 781-788 ◽  
Author(s):  
T.H. Chiang ◽  
H. Lam ◽  
R. Quijano ◽  
R. Donham ◽  
P. Gilliam ◽  
...  
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Heart Valve Prosthesis ◽  
Valve Prosthesis ◽  
Valve Closure ◽  
Element Analysis ◽  
Dynamic Stresses ◽  
Magnitude Distribution ◽  
Bileaflet Mechanical Heart Valve ◽  
The Impact

The effect of contact geometry and component compliance on the magnitude, distribution, and state of various types of stresses on a bileaflet mechanical heart valve prosthesis during valve closure was analyzed using an Edwards-Duromedics™ mitral valve as example. Static and dynamic stresses developing on both the leaflet and pivot ball during valve closure were modeled using finite element analysis (FEA). Uniform contact between the leaflet and housing as well as between the pivot ball and pivot slot can significantly reduce both static and dynamic stresses around the contact area. The level of the dynamic flexural stresses can be an order of magnitude higher than that of the static stresses. When both the radial and axial compliance of the housing are taken into consideration, peak dynamic stress was more than 40% less than that generated through the impact between a moving leaflet and a non-compliant rigid housing.

In Vitro Hemolysis by Mechanical Heart Valve Prostheses with Tilting Disc

1992 ◽  
Vol 15 (11) ◽  
pp. 681-685 ◽  
Author(s):  
M.O. Wendt ◽  
M. Pohl ◽  
S. Pratsch ◽  
D. Lerche
Keyword(s):  
Heart Valve ◽  
Test Chamber ◽  
Mechanical Heart Valve ◽  
Hemoglobin Concentration ◽  
Clinical Results ◽  
Artificial Heart Valve ◽  
Valve Prosthesis ◽  
Heart Valve Prostheses ◽  
Valve Prostheses

Hemolytic and subhemolytic blood damage by mechanical heart valve prostheses have been observed in both clinical and in vitro investigations. A direct comparison between these studies is not possible. Nevertheless the transfer of some in vitro results to the behaviour of the valve in situ may be performed considering the similarity principle. This requires the use of dimensionless similarity numbers such as the plasma's hemoglobin concentration (PHb) or others, instead of dimensioned parameters. To evaluate the in vitro hemolysis of valve prosthesis a test chamber filled with human banked blood was used. An artificial ventricle ensuring an oscillatory flow through the valve was also used. The rise of PHb was evaluated in terms of a similarity number, called the lysis number. This number describes the probability of destroying a single red blood cell participating once in the hemolytic process under consideration. The lysis number, a Björk-Shiley valve (TAD 29), was found to be in the order of 2 × 10−4. From this, the survival time of erythrocytes in patients with an artificial heart valve was estimated. It was found to be in the order of 20 d of T50 Cr in agreement with clinical results

scholarly journals Design, development, testing at ISO standards and in vivo feasibility study of a novel polymeric heart valve prosthesis

2020 ◽  
Vol 8 (16) ◽  
pp. 4467-4480
Author(s):  
Joanna R. Stasiak ◽  
Marta Serrani ◽  
Eugenia Biral ◽  
James V. Taylor ◽  
Azfar G. Zaman ◽  
...  
Keyword(s):  
Heart Valve ◽  
Feasibility Study ◽  
Heart Valve Prosthesis ◽  
Valve Prosthesis ◽  
Design Development ◽  
Iso Standards ◽  
Bench Testing ◽  
Bioprosthetic Valves

A novel polymeric heart valve shows durability equivalent to 25 years in accelerated bench testing, in vitro hydrodynamics equivalent to existing bioprosthetic valves; and good performance in a small acute feasibility study in sheep.

In Vivo Evaluation of a Trileaflet Mechanical Heart Valve

ASAIO Journal ◽  
1994 ◽  
Vol 40 (3) ◽  
pp. M707-M713 ◽  
Author(s):  
Didier M. Lapeyre ◽  
O H Frazier ◽  
Jeff L. Conger ◽  
Michael P. Macris ◽  
P Perrier ◽  
...  
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
In Vivo Evaluation

An In Vivo Method for Measuring Turbulence in Mechanical Prosthesis Leakage Jets

2004 ◽  
Vol 126 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Brandon R. Travis ◽  
Thomas D. Christensen ◽  
Morten Smerup ◽  
Morten S. Olsen ◽  
J. Michael Hasenkam ◽  
...  
Keyword(s):  
Mechanical Heart Valve ◽  
Maximum Velocity ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Mechanical Prosthesis ◽  
Analytical Technique ◽  
In Vivo Measurement ◽  
Measurement And Analysis

This work introduces a method for the in vivo measurement and analysis of turbulence within the leakage of a mechanical heart valve. Several analysis techniques were applied to ultrasound measurements acquired within the atrium of a pig, and error associated with these techniques was analyzed. The technique chosen applies cyclic averaging to mean and maximum velocity measurements within small, normalized phase windows to calculate Reynolds normal stresses in the direction of the ultrasound beam. Maximum shear stresses are estimated from these normal stresses using an analytical technique. The stresses observed were smaller than those reported from previous in vitro simulations.

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