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

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

10.1055/s-0038-1643878 ◽

1987 ◽

Author(s):

V Pengo ◽

M Boschello ◽

P Peruzzi ◽

D Pagotto ◽

L Schivazappa ◽

...

Keyword(s):

Heart Valve ◽

Healthy Subjects ◽

Artificial Heart ◽

Heart Valves ◽

Oral Anticoagulants ◽

Heart Valve Prosthesis ◽

Artificial Heart Valve ◽

Valve Prosthesis ◽

Artificial Heart Valves ◽

Thrombin Formation

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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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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Oral anticoagulation, stroke and thromboembolism in patients with atrial fibrillation and valve bioprosthesis

Thrombosis and Haemostasis ◽

10.1160/th16-01-0007 ◽

2016 ◽

Vol 115 (05) ◽

pp. 1056-1063 ◽

Cited By ~ 12

Author(s):

Raphael Philippart ◽

Anne Brunet-Bernard ◽

Nicolas Clementy ◽

Thierry Bourguignon ◽

Alain Mirza ◽

...

Keyword(s):

Atrial Fibrillation ◽

Vitamin K ◽

Artificial Heart ◽

Heart Valves ◽

Vitamin K Antagonists ◽

Female Gender ◽

Thromboembolic Risk ◽

Increased Risk ◽

Artificial Heart Valves

SummaryVitamin K antagonists are currently recommended in patients with ‘valvular’ atrial fibrillation (AF), e. g. those having mitral stenosis or artificial heart valves. We compared thromboembolic risk in patients with ‘non valvular’ AF and in those with AF and biological valve replacement (valve bioprosthesis). Among 8962 AF patients seen between 2000 and 2010, a diagnosis of ‘non-valvular AF’ was found in 8053 (94 %). Among patients with ‘valvular’ AF, 549 (6 %) had a biological prosthesis. The patients with bioprosthesis were older and had a higher CHA2DS2-VASc score than those with non valvular AF. After a follow-up of 876 é 1048 days (median 400 days, interquartile range 12–1483), the occurrence of thromboembolic events was similar in AF patients with bioprosthesis compared to those with ‘non valvular’ AF (hazard ratio [HR] 1.10 95 % confidence interval [CI] 0.83–1.45, p=0.52, adjusted HR 0.93, 95 %CI 0.68–1.25, p=0.61). Factors independently associated with increased risk of stroke/TE events were older age (HR 1.25, 95 %CI 1.16–1.34 per 10-year increase, p> 0.0001) and higher CHA2DS2-VASc score (HR 1.35, 95 %CI 1.24–1.46, p> 0.0001) whilst female gender (HR 0.75, 95 %CI 0.62–0.90, p=0.002), use of vitamin K antagonist (HR 0.83, 95 %CI 0.71–0.98, p=0.03) were independently associated with a lower risk of stroke/TE. Neither the presence of bioprosthesis nor the location of bioprosthesis was independent predictor for TE events. In conclusion, AF patients with bioprosthesis had a non-significantly higher risk of stroke/TE events compared to patients with non-valvular AF. Second, the CHA2DS2-VASc score was independently associated with an increased risk of TE events, and was a valuable determinant of TE risk both in AF patients with non-valvular AF as well as those with bioprosthesis, whether treated or not treated with OAC.Note: The review process for this paper was fully handled by Christian Weber, Editor in Chief.

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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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Design and Fabrication of a Mock Circulatory System for Reliability Tests on Aortic Heart Valves

ASME 2007 Summer Bioengineering Conference ◽

10.1115/sbc2007-176638 ◽

2007 ◽

Author(s):

Dhruv Singh ◽

Abhishek Singhal

Keyword(s):

Aortic Valve ◽

Artificial Heart ◽

Heart Valves ◽

Dynamic Stress ◽

Circulatory System ◽

Artificial Valve ◽

Mock Circulatory System ◽

Artificial Heart Valves ◽

Prosthetic Implant ◽

Dynamic Stress Analysis

The dynamic stress analysis and response of artificial heart valves — specifically the aortic valve is impending following the increasing number of artificial valve failures. This calls for the development of a mock circulatory system in order to establish clearly the parameters associated with the circulatory system in the heart and their effects on the robustness of a prosthetic implant.

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