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Artificial heart valve
An artificial heart valve is a one-way valve implanted into a person's heart to replace a heart valve that is not functioning properly (valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical heart valves, bioprosthetic tissue valves and engineered tissue valves.
The human heart contains four valves: tricuspid valve, pulmonary valve, mitral valve and aortic valve. Their main purpose is to keep blood flowing in the proper direction through the heart, and from the heart into the major blood vessels connected to it (the pulmonary artery and the aorta). Heart valves can malfunction for a variety of reasons, which can impede the flow of blood through the valve (stenosis) and/or let blood flow backwards through the valve (regurgitation). Both processes put strain on the heart and may lead to serious problems, including heart failure. While some dysfunctional valves can be treated with drugs or repaired, others need to be replaced with an artificial valve.
A heart contains four valves (tricuspid, pulmonary, mitral and aortic valves) which open and close as blood passes through the heart. Blood enters the heart in the right atrium and passes through the tricuspid valve to the right ventricle. From there, blood is pumped through the pulmonary valve to enter the lungs. After being oxygenated, blood passes to the left atrium, where is it pumped through the mitral valve to the left ventricle. The left ventricle pumps blood to the aorta through the aortic valve.
There are many potential causes of heart valve damage, such as birth defects, age related changes, and effects from other disorders, such as rheumatic fever and infections causing endocarditis. High blood pressure and heart failure which can enlarge the heart and arteries, and scar tissue can form after a heart attack or injury.
The three main types of artificial heart valves are mechanical, biological (bioprosthetic/tissue), and tissue-engineered valves. In the US, UK and the European Union, the most common type of artificial heart valve is the bioprosthetic valve. Mechanical valves are more commonly used in Asia and Latin America.[citation needed] Companies that manufacture heart valves include Edwards Lifesciences, Medtronic, Abbott (St. Jude Medical), CryoLife, and LifeNet Health.
Mechanical valves come in three main types – caged ball, tilting-disc and bileaflet – with various modifications on these designs. Caged ball valves are no longer implanted. Bileaflet valves are the most common type of mechanical valve implanted in patients today.
The first artificial heart valve was a clear plastic tube with a free-moving ball, trapped between restrictions at the inlet and outlet. The early ball check valve design opened when the heart contracted and the blood pressure in the chamber exceeded the heart's outside pressure, allowing blood to flow. When the heart finished contracting, the pressure inside the chamber dropped, allowing the ball to move back against the base of the valve to form a seal. Charles A. Hufnagel implanted his tube and ball design into ten patients (six of whom survived the operation) in 1952, marking the first heart valve transplant with limited success. For the next 8 years, Hufnagel transplants continued. However, the design was never proven or adopted as a reliable medical treatment.
Miles 'Lowell' Edwards is recognized as the first to invent a truly successful heart valve. His design relied on a patented, caged-ball check valve. Edwards' design was surgically implanted by Albert Starr for the first time in 1960 and was successfully used to save heart patients around the world for the next 47 years. The design consisted of a silicone ball enclosed in a methyl metacrylate cage welded to a ring. Edward's invention is known today as the Starr-Edwards valve, which continues to provide life-saving service for many heart patients treated before 2007. The Star-Edwards valve set a record for providing a patient 48 years of service before requiring replacement. Mechanical heart valves, such as the Star-Edwards Valve, are strongly associated with blood clot formation and require a high dose of anticoagulant, usually with a target INR of 3.0–4.5. In 2007 the Starr-Edwards Valve was retired and replaced by Edwards Lifesciences with the Edwards Myxo ETlogix annuloplasty ring.
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Artificial heart valve
An artificial heart valve is a one-way valve implanted into a person's heart to replace a heart valve that is not functioning properly (valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical heart valves, bioprosthetic tissue valves and engineered tissue valves.
The human heart contains four valves: tricuspid valve, pulmonary valve, mitral valve and aortic valve. Their main purpose is to keep blood flowing in the proper direction through the heart, and from the heart into the major blood vessels connected to it (the pulmonary artery and the aorta). Heart valves can malfunction for a variety of reasons, which can impede the flow of blood through the valve (stenosis) and/or let blood flow backwards through the valve (regurgitation). Both processes put strain on the heart and may lead to serious problems, including heart failure. While some dysfunctional valves can be treated with drugs or repaired, others need to be replaced with an artificial valve.
A heart contains four valves (tricuspid, pulmonary, mitral and aortic valves) which open and close as blood passes through the heart. Blood enters the heart in the right atrium and passes through the tricuspid valve to the right ventricle. From there, blood is pumped through the pulmonary valve to enter the lungs. After being oxygenated, blood passes to the left atrium, where is it pumped through the mitral valve to the left ventricle. The left ventricle pumps blood to the aorta through the aortic valve.
There are many potential causes of heart valve damage, such as birth defects, age related changes, and effects from other disorders, such as rheumatic fever and infections causing endocarditis. High blood pressure and heart failure which can enlarge the heart and arteries, and scar tissue can form after a heart attack or injury.
The three main types of artificial heart valves are mechanical, biological (bioprosthetic/tissue), and tissue-engineered valves. In the US, UK and the European Union, the most common type of artificial heart valve is the bioprosthetic valve. Mechanical valves are more commonly used in Asia and Latin America.[citation needed] Companies that manufacture heart valves include Edwards Lifesciences, Medtronic, Abbott (St. Jude Medical), CryoLife, and LifeNet Health.
Mechanical valves come in three main types – caged ball, tilting-disc and bileaflet – with various modifications on these designs. Caged ball valves are no longer implanted. Bileaflet valves are the most common type of mechanical valve implanted in patients today.
The first artificial heart valve was a clear plastic tube with a free-moving ball, trapped between restrictions at the inlet and outlet. The early ball check valve design opened when the heart contracted and the blood pressure in the chamber exceeded the heart's outside pressure, allowing blood to flow. When the heart finished contracting, the pressure inside the chamber dropped, allowing the ball to move back against the base of the valve to form a seal. Charles A. Hufnagel implanted his tube and ball design into ten patients (six of whom survived the operation) in 1952, marking the first heart valve transplant with limited success. For the next 8 years, Hufnagel transplants continued. However, the design was never proven or adopted as a reliable medical treatment.
Miles 'Lowell' Edwards is recognized as the first to invent a truly successful heart valve. His design relied on a patented, caged-ball check valve. Edwards' design was surgically implanted by Albert Starr for the first time in 1960 and was successfully used to save heart patients around the world for the next 47 years. The design consisted of a silicone ball enclosed in a methyl metacrylate cage welded to a ring. Edward's invention is known today as the Starr-Edwards valve, which continues to provide life-saving service for many heart patients treated before 2007. The Star-Edwards valve set a record for providing a patient 48 years of service before requiring replacement. Mechanical heart valves, such as the Star-Edwards Valve, are strongly associated with blood clot formation and require a high dose of anticoagulant, usually with a target INR of 3.0–4.5. In 2007 the Starr-Edwards Valve was retired and replaced by Edwards Lifesciences with the Edwards Myxo ETlogix annuloplasty ring.