PATIENTS WITH ARTIFICIAL BUT NOT BIOLOGICAL HEART VALVE PROSTHESIS PRESENT A HYPERCOAGULABILITY RELATED TO THE INTENSITY OF ANTICOAGULATION

Long term anticoagulant therapy is mandatory for patients with artificial heart valve prosthesis and is suggested for some patients with biological heart valve prosthesis. Oral anticoagulants reduce but not abolish thromboembolic complication in these patients. They act lowering the level of vitamin K-dependent coagulation factors and that in turn should result in a depression of "in vivo" thrombin formation. Fibrinopeptide A (FpA) is a good marker of thrombin formation and therefore we ascertained in several occasions the thrombin formation in 43 patients with artificial and 18 with biological heart valve prosthesis, all the patients being on oral anticoagulant treatment at least from 1 year. FpA was significantly higher in patients with artificial (determinations n = 138) with respect to biological (n=73) heart valve prosthesis (p 0.01). The FpA level in biological valves was close to that obtained in 22 not anticoagulated healthy subjects. When we divided FpA values in artificial heart valves according to the intensity of anticoagulation, we obtained a decreasing FpA mean levels with the increase of the degree of anticoagulation. In particular FpA values with an INR 4.5 were close to values obtained in healthy subjects. These data support the concept that patients with artificial heart valves are at higher risk of thromboembolism and therefore the intensity of anticoagulation should be different with respect to biological valves and probably a little higher than that recommended at the Leuven Consensus Conference.

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Anticoagulation after Artificial Valve Replacement with or without Atrial Fibrillation: How Much Is Really Needed?

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615571 ◽

1999 ◽

Vol 82 (S 01) ◽

pp. 130-135 ◽

Cited By ~ 1

Author(s):

Freek W. A. Verheugt

Keyword(s):

Atrial Fibrillation ◽

Heart Valve ◽

Oral Anticoagulation ◽

Artificial Heart ◽

Heart Valves ◽

Oral Anticoagulant Therapy ◽

International Normalized Ratio ◽

Artificial Heart Valve ◽

Artificial Valve ◽

Artificial Heart Valves

SummaryInsertion of a mechanical artificial heart valve is an absolute indication for the use of lifelong oral anticoagulation, irrespective the presence or absence of atrial fibrillation. Depending on the type and position of the artificial valve the optimal International Normalized Ratio (INR) for these patients is between 2.5 and 4.5, although more prospective studies on the optimal range of oral anticoagulation are necessary. Addition of low dose antiplatelet therapy may further decrease the rate of thromboembolism, but also here more studies are needed. Patients with a bioprosthesis need only oral anticoagulation for the first three months following surgery in the absence of an indication for anticoagulation for other conditions.Atrial fibrillation is often seen in patients with artificial heart valves. Stroke prevention can be instituted by the mandatory oral anticoagulant therapy. The presence of atrial fibrillation and the use of oral anticoagulation prior to heart valve surgery support the indication for the insertion of a mechanical artificial heart valve. However, relative contraindications to oral anticoagulation and the presence of sinus rhythm may favor the use of a bioprosthesis.

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Use of Computational Fluid Dynamics to Analyze Blood Flow, Hemolysis and Sublethal Damage to Red Blood Cells in a Bileaflet Artificial Heart Valve

Fluids ◽

10.3390/fluids4010019 ◽

2019 ◽

Vol 4 (1) ◽

pp. 19 ◽

Cited By ~ 3

Author(s):

Madison James ◽

Dimitrios Papavassiliou ◽

Edgar O’Rear

Keyword(s):

Blood Flow ◽

Red Blood Cells ◽

Heart Valve ◽

Blood Cells ◽

Artificial Heart ◽

Heart Valves ◽

High Stress ◽

Leading Edge ◽

Artificial Heart Valve ◽

Artificial Heart Valves

Artificial heart valves may expose blood to flow conditions that lead to unnaturally high stress and damage to blood cells as well as issues with thrombosis. The purpose of this research was to predict the trauma caused to red blood cells (RBCs), including hemolysis, from the stresses applied to them and their exposure time as determined by analysis of simulation results for blood flow through both a functioning and malfunctioning bileaflet artificial heart valve. The calculations provided the spatial distribution of the Kolmogorov length scales that were used to estimate the spatial and size distributions of the smallest turbulent flow eddies in the flow field. The number and surface area of these eddies in the blood were utilized to predict the amount of hemolysis experienced by RBCs. Results indicated that hemolysis levels are low while suggesting stresses at the leading edge of the leaflet may contribute to subhemolytic damage characterized by shortened circulatory lifetimes and reduced RBC deformability.

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Assessment of hemodynamics properties of a new-type artificial heart valve prosthesis using catheterization and echocardiography

American Journal of Hematology ◽

10.1002/ajh.20686 ◽

2006 ◽

Vol 81 (8) ◽

pp. 563-567 ◽

Cited By ~ 1

Author(s):

Y.J. Zeng ◽

S.W. Xu ◽

Q. Wang ◽

Y. Chang ◽

A.Q. Dong ◽

...

Keyword(s):

Heart Valve ◽

Artificial Heart ◽

Heart Valve Prosthesis ◽

Artificial Heart Valve ◽

Valve Prosthesis ◽

New Type

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PIV Measurements of Flow Downstream of Polyurethane Heart Valve Prosthesis for Artificial Heart: Pulsatile Flow Experiment

Transactions of the Korean Society of Mechanical Engineers B ◽

10.3795/ksme-b.2002.26.5.629 ◽

2002 ◽

Vol 26 (5) ◽

pp. 629-639

Author(s):

Jeong-Yeol Yu ◽

Jung-Gyeong Kim ◽

Jae-Yong Seong ◽

Jun-Geun Jang ◽

Byeong-Gu Min

Keyword(s):

Heart Valve ◽

Pulsatile Flow ◽

Artificial Heart ◽

Heart Valve Prosthesis ◽

Valve Prosthesis ◽

Piv Measurements ◽

Flow Experiment

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Improving Blood Compatibility of Cardiovascular Devices by Surface Modification

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.342-343.801 ◽

2007 ◽

Vol 342-343 ◽

pp. 801-804 ◽

Cited By ~ 2

Author(s):

Nan Huang ◽

Ping Yang ◽

Yong Xiang Leng ◽

Jun Ying Chen ◽

Jin Wang ◽

...

Keyword(s):

Surface Modification ◽

Artificial Heart ◽

Heart Valves ◽

Blood Compatibility ◽

Artificial Heart Valve ◽

Cardiovascular Devices ◽

Inorganic Films ◽

Artificial Heart Valves ◽

Plasma Grafting ◽

Circulation Tube

This paper presents recent activities on the surface modification of blood contacting biomaterials and devices in the author’s laboratory. Surface coating of inorganic films on materials for artificial heart valves, ventricular pumps and coronary stents, such as titanium, stainless steel and low temperature isotropic pryolitc carbon, etc, shows a significant improvement in the anticoagulation behavior. Further, the formation of functional groups such as hydroxyl or amino groups and the binding of biomolecules as well as seeding of endothelial cell shows the promise of biomimetic surface formation. Plasma grafting on materials for artificial heart valve sewing cuff, extracorporeal circulation tube, etc, such as PET, PU, PVC polymers, revealed a significant improvement of anti-platelet adhesion as well as anti-bacterial properties.

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LONG TERM PROPHYLAXIS OF THROMBOEMBOLISM IN OUTPATIENTS WITH LOW MOLECULAR WEIGHT HEPARIN

10.1055/s-0038-1644190 ◽

1987 ◽

Author(s):

J Harenberg ◽

P Leber ◽

R Raedsch ◽

R Zimmermann

Keyword(s):

Molecular Weight ◽

Low Molecular Weight Heparin ◽

Artificial Heart ◽

Heart Valves ◽

Oral Anticoagulants ◽

Low Molecular Weight ◽

Average Dose ◽

Fatal Bleeding ◽

Artificial Heart Valves

The prophylaxis of thromboembolism with oral anticoagulants and low dose heparin is established. However, bleeding episodes and other side effects may occur. Alternative compunds for further anticoagulation do not exist so far. We report, therefore, of the experiences of 66 outpatients who were treated with low molecular weight heparin up to nineteen months.All patients had major bleeding on conventional anticoagulants. Further anticoagulation was strongly indicated because of recurrent thromboembolism, artificial heart valves, dilative cardiomyopathy or heart valve diseases with artrial fibrillation. The dose ranged from 2.500 to 15.000 aXa units once daily subcutaneously. The LMW heparin Tedelparin (Kabi 2165) was used. The dose was chosen according to the risk ofbleeding or thromboembolism, and body weight of eachpatient. In patients with high bleeding risks (esophagiai varices) the average dose was 100 units/kg bodyweight and in patients with high risk of thromboembolism (artificial heart valves) the average dose was140 units/kg bodyweight. The dose was adjusted according to the aXa activity and aPTT inhibition: 2-4 hours after the s.c. administration 0,3 - 0,6 heparin units/ml or 0,6 - 1,0 units/ml in the above mentioned groups should be reached respectively, and the aPTT should be not more than 10 sec above the upper normal limit.Four of 66 patients experienced rethrombosis, 2 of them were non- compliant. Six of 66 patients had minor haemorrhages, 0 major or fatal bleeding occured. Bleeding was more frequent when the aXa activity increased to more than 1 unit/ml. With a dose reduction of 20 % no recurrence of bleeding was seen and antithrombotic effect was still maintained.The data demonstrate that LMW heparin can be safely and effectively used for long term anticoagulation in patients with major haemorrhage due to cönventional anticoagulants.

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Numerical Simulation of the Dynamics of Heart Valves: A Literature Review

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.444-445.1211 ◽

2013 ◽

Vol 444-445 ◽

pp. 1211-1217

Author(s):

Qi Zhong ◽

Wen Hua Zeng ◽

Xiao Yang Huang ◽

Bo Liang Wang

Keyword(s):

Numerical Simulation ◽

Heart Valve ◽

Artificial Heart ◽

Heart Valves ◽

Surgical Repair ◽

Imaging Techniques ◽

Artificial Heart Valve ◽

Future Research ◽

Critical Issues ◽

Development Tendency

Imaging techniques allow the visualization of the heart valves, but do not yields any information regarding the load applied to the heart valve information that provides key clues to the cause of valve deterioration. Numerical simulation, which is able to replicate and understand the dynamics of the valve, would benefit studies on heart valves surgical repair and prostheses design. Modeling and simulation of heart valves dynamics is a challenging biomechanical problem. Many researchers have taken various approaches to model the heart valve. But systematical categorization and development tendency of their research have never been discussed before. This paper reviews their models and divides them into wet models or dry models, in the light of whether considering blood flow and valve interaction. These simulations also can be categorized as native heart valve or artificial heart valve simulation by a different model prototype. The critical issues for future research are presented.

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