A Note on the Leakage of the New Omniscience/tm Pivoting Disk Prosthetic Heart Valve

1980 ◽  
Vol 102 (4) ◽  
pp. 342-344 ◽  
Author(s):  
T. H. Reif ◽  
G. Cocolin ◽  
M. C. Huffstutler
Keyword(s):  
Steady State ◽  
Flow Field ◽  
Heart Valve ◽  
Prosthetic Heart Valve ◽  
Cardiac Valve ◽  
General Nature ◽  
Valve Prosthesis

Measurements of the steady-state leakage of the new Medical Incorporated Omniscience/tm cardiac valve prosthesis are presented. These results are compared to those obtained from the SJM bi-leaflet cardiac valve/tm. The new Omniscience/tm valve shows significantly less leakage than the bi-leaflet valve. Consideration is given to problems in similitude as well as to the general nature of the flow field.

The Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Oleksandr Barannyk ◽  
Peter Oshkai
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Aortic Root ◽  
Reynolds Shear Stress ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics ◽  
Aortic Pressure ◽  
Valve Prosthesis ◽  
Aortic Heart Valve ◽  
Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases were classified into two clinical categories and were correlated with the corresponding changes in aortic root geometry while keeping the aortic base diameter fixed. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output, and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

scholarly journals Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

2017 ◽  
Vol 19 (2) ◽  
pp. 69-77
Author(s):  
K. Yu. Klyshnikov ◽  
E. A. Ovcharenko ◽  
A. N. Stasev ◽  
T. V. Glushkova ◽  
Yu. A. Kudryavtseva ◽  
...  
Keyword(s):  
Heart Valve ◽  
Prosthetic Heart Valve ◽  
Hydrodynamic Characteristics ◽  
Implantation Technique ◽  
Effective Orifice Area ◽  
Test Machine ◽  
Critical Surface ◽  
Valve Prosthesis ◽  
Valve In Valve ◽  
Valve Implantation

The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency of the developed design, intended for the replacement of a failed prosthetic valve of the heart with the «valve-in-valve» implantation.

Effect of Oral Anticoagulant during Pregnancy with Prosthetic Heart Valve

2002 ◽  
Vol 10 (4) ◽  
pp. 306-309 ◽  
Author(s):  
Ashok K Srivastava ◽  
Ashok K Gupta ◽  
Arvind V Singh ◽  
Tanveer Husain
Keyword(s):  
Heart Valve ◽  
Oral Anticoagulant ◽  
Oral Anticoagulants ◽  
Prosthetic Heart Valve ◽  
Premature Delivery ◽  
Valve Prosthesis ◽  
Childbearing Age ◽  
Skeletal Deformity ◽  
Mechanical Prosthesis ◽  
Valve Thrombosis

This retrospective study aimed to evaluate the risks and outcome of oral anticoagulant use during pregnancy in women with prosthetic heart valves. Between December 1989 and November 1998, 192 females of childbearing age underwent heart valve replacement with a mechanical prosthesis. There were 37 pregnancies in 30 patients during follow-up. Pregnancy was terminated on medical grounds in 5 cases, there were 2 (6%) spontaneous abortions, and 1 (3%) premature birth of a normal baby who died 24 hours later due to asphyxia. The other 29 pregnancies (91%) went to full term and the mothers continued taking oral anticoagulants until a week before the expected date of delivery, then switched to heparin. There was no thromboembolism, valve thrombosis, or maternal mortality. Three babies (10%) had a skeletal deformity: nasal hypoplasia in all 3, with cleft pinna in 1. Continuation of oral anticoagulants during pregnancy provided adequate protection against thromboembolism and valve thrombosis, but the risks of fetal abnormalities and premature delivery should be explained to women of childbearing age with a mechanical valve prosthesis.

19 mm Sized Bileaflet Valve Prostheses’ flow Field Investigated by Bidimensional Laser Doppler Anemometry (part I: Velocity Profiles)

1997 ◽  
Vol 20 (11) ◽  
pp. 622-628 ◽  
Author(s):  
V. Barbaro ◽  
M. Grigioni ◽  
C. Daniele ◽  
G. D'avenio ◽  
G. Boccanera
Keyword(s):  
Cardiac Output ◽  
Flow Field ◽  
Velocity Profiles ◽  
Cardiac Valve ◽  
Draft Guidance ◽  
Valve Prosthesis ◽  
Cardiac Valves ◽  
High Cardiac Output ◽  
Valve Prostheses ◽  
Bileaflet Valve

The investigation of the flow field downstream of a cardiac valve prosthesis is a well established task. In particular turbulence generation is of interest if damage to blood costituents is to be assessed. Several prosthetic valve flow studies are available in literature but they generally concern large-sized prostheses. The FDA draft guidance requires the study of the maximum Reynolds number conditions for a cardiac valve model to assess the worst case in turbulence by chosing both the minimum valve diameter and a high cardiac output value as protocol set up. Within the framework of a national research project regarding the characterization of cardiovascular endoprostheses, the Laboratory of Biomedical Engineering is currently conducting an in-depth study of turbulence generated downstream of bileaflet cardiac valves. Four models of 19 mm sized bileaflet valve prostheses, namely St Jude Medical HP, Edwards Tekna, Sorin Bicarbon, and CarboMedics, were studied in aortic position. The prostheses were selected for the nominal annulus diameter reported by the manufacturers without any assessment of the valve sizing method. The hemodynamic function was investigated using a bidimensional LDA system. Results concern velocity profiles during the peak flow systolic phase, at high cardiac output regime, highlighting the different flow field features downstream of the four small-sized cardiac valves.

Tornado-Compatible Mechanical Aortic Valve Prosthesis: Experimental and Clinical Application of Tornado Technology

2015 ◽  
Author(s):  
Alexander Gorodkov ◽  
Gennady Kiknadze ◽  
Andrey Agafonov ◽  
Shota Zhorzholiany ◽  
Ivan Krestinich ◽  
...  
Keyword(s):  
Exact Solution ◽  
Blood Flow ◽  
Aortic Valve ◽  
Left Ventricle ◽  
Flow Pattern ◽  
Heart Valve ◽  
Anticoagulation Therapy ◽  
Prosthetic Heart Valve ◽  
Valve Prosthesis ◽  
Mechanical Aortic Valve

Currently used mechanical heart valve prostheses does not fully restore the function of the valve and require aggressive anticoagulation therapy. One of the reasons leading to the prostheses disfunction is neglecting of hydrodynamic compatibility with the blood flow pattern Studies of the hydrodynamic structure of the blood flow in the heart and aorta are being performed in the Bakulev Center for Cardiovascular surgery since 1992. It has been shown that blood flow, generated in the left ventricle corresponds to the structure of self-organizing tornado-like flows described by the exact solution of unsteady hydrodynamic equations for this class of flows, published in 1986. The previous attempts to adapt the geometry of prosthetic heart valve to the swirling blood flow were not successful since there were no any quantitative criteria of the flow structere. A new model of a mechanical aortic valve — Tornado-compatible valve (TCV) (patent RU 2434604 C1), has the lumen completely free from any kind of obstacles that could disrupt the flow pattern. The valve consists of a body and three cusps which profile is adopted both to the flow in Aorta, and to the flow in Sinuses when the valve is closed. The standard hydrodynamic testing of this valve has shown its significant advantage compared with other valve types. A special testing was developed using the original bench which generates the Tornado-like jet. For this a converging channel was worked out, which profile corresponds to the streamlines of Tornado-like flow, calculated from the exact solution. The resulted jet manifested all principal properties of Tornado: laminar “glass-transparent” jet without any visible perturbations in the flow core. Several valve types were testing using this bench. TCV did not affected the jet structure, and time of water flowing out. The valve was implanted in the pig without anticoagulant administration. According to echocardiography and coagulation control the valve function was satisfactory up to ten months of observation. In the autopsy the luminal surface of outflow part of the left ventricle, and the ascending aorta were free of thrombi and pannus formation. The clinical implantation in the patient with aortic stenosis was performed. The follow-up period is 4 years.

In Vitro Study of the Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

2013 ◽  
Author(s):  
Oleksandr Barannyk ◽  
Satya Karri ◽  
Peter Oshkai
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Aortic Root ◽  
Reynolds Shear Stress ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics ◽  
In Vitro Study ◽  
Valve Prosthesis ◽  
Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted to the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases, classified into two clinical categories, were correlated with the corresponding changes of aortic root geometry. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

2C21 Challenge to develop a Japanese-made prosthetic heart valve : Stentless mitral valve prosthesis

2014 ◽  
Vol 2014.26 (0) ◽  
pp. 347-348
Author(s):  
Mitsuo UMEZU ◽  
Kiyotaka IWASAKI ◽  
Hitoshi KASEGAWA ◽  
Hiroshi KASANUKI ◽  
Hideki SAWA ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Heart Valve ◽  
Prosthetic Heart Valve ◽  
Valve Prosthesis ◽  
Mitral Valve Prosthesis ◽  
Stentless Mitral Valve

A Scaled-Up Mechanical Prosthetic Heart Valve Model for High-Resolution Flow Field Measurements

2007 ◽  
Author(s):  
Eilis M. Donohue ◽  
Kevin B. Heraty ◽  
Nathan J. Quinlan
Keyword(s):  
Fluid Dynamics ◽  
High Resolution ◽  
Flow Field ◽  
Heart Valve ◽  
Heart Valves ◽  
Thrombus Formation ◽  
Prosthetic Heart Valve ◽  
Quantitative Information ◽  
Prosthetic Heart Valves ◽  
High Resolution Data

Every year, over 250,000 patients undergo heart valve implantation [1]. Approximately 55% of implanted prosthetic heart valves (PHV) are mechanical. Patients must undergo lifelong anticoagulant medication in order to alleviate the risk of thrombus formation. In order to understand the complex fluid dynamics underpinning problems such as thrombosis, detailed high-resolution quantitative information on the flow field in PHVs is essential [2]. High-resolution data is also needed for the validation of Computational Fluid Dynamics (CFD) studies.

scholarly journals A NEWLY DEVELOPED TRI-LEAFLET POLYMERIC HEART VALVE PROSTHESIS

2015 ◽  
Vol 15 (02) ◽  
pp. 1540009 ◽  
Author(s):  
FRANCESCO DE GAETANO ◽  
PAOLA BAGNOLI ◽  
ADRIANO ZAFFORA ◽  
ANNA PANDOLFI ◽  
MARTA SERRANI ◽  
...  
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Prosthetic Heart Valve ◽  
Element Model ◽  
Effective Orifice Area ◽  
Valve Prosthesis ◽  
Flow Conditions ◽  
Orifice Area ◽  
Mechanical Valves

The potential of polymeric heart valves (PHV) prostheses is to combine the hemodynamic performances of biological valves with the durability of mechanical valves. The aim of this work is to design and develop a new tri-leaflet prosthetic heart valve (HV) made from styrenic block copolymers. A computational finite element model was implemented to optimize the thickness of the leaflets, to improve PHV mechanical and hydrodynamic performances. Based on the model outcomes, 8 prototypes of the designed valve were produced and tested in vitro under continuous and pulsatile flow conditions, as prescribed by ISO 5840 Standard. A specially designed pulse duplicator allowed testing the PHVs at different flow rates and frequency conditions. All the PHVs met the requirements specified in ISO 5840 Standard in terms of both regurgitation and effective orifice area (EOA), demonstrating their potential as HV prostheses.

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