Heart Valve
Heart Valve Failure
Artificial Heart Valve
Heart valve
Definition:Heart valve is an organ of the body that allow fluid to move around the body.
Function:
To make sure blood flows in one direction.
Four main valves of the heart are:
1. Aortic valve
2. Pulmonary valve
3. Tricuspid valve
4. Mitral valve
Heart Valve Failure
Definition:A valve that does not fulfil their function correctly.
Two basic types of heart valve failures:
1. Regurgitation
2. Stenosis
Regurgitation:
Happens when a valve does not close tightly.
Stenosis:
Happens when the flaps of a valve thicken, stiffen, or fuse together and blocks the heart valve from fully opening.
These heart valve failures can be develops at birth and acquired at a later age. Severely damaged valves needs an artificial heart valve replacement. Valves that are not repaired or replaced can lead to mortality.
Artificial Heart Valve
Definition:An artificial heart valve is substitute heart valve that is implanted in patient with heart valve failure.
Function:
Artificial heart valve function as native heart valve normally to support living.
Two types of artificial heart valves are:
1. Mechanical Heart Valve
2. Biological Heart Valve
Mechanical Heart Valve
Definition:Mechanical heart valve are artificial heart valve that are made of material such as plastic, carbon or metal.
Three main design of mechanical heart valves are:
1. Caged ball Valve
2. Tilting Disc Valve (Monoleaflet Valve)
3. Bileaflet Valve
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Starr-Edwards Caged Ball Valve Caged ball valves that consist of a silastic ball with a circular sewing ring and a cage formed by 4 metal arches. |
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Medtronic Hall Tilting Disc Valve Monoleaflet valves are composed of a single disk secured by inlet or central outlet metal struts. The opening angle of the disk relative to valve annulus ranges from 60° to 80°, resulting in 2 distinct sizes for blood to flow. |
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St. Jude Medical Bileaflet Valve Bileaflet valves are made of 2 semi-lunar disks attached to a rigid valve ring by small hinges. The opening angle of the leaflets relative to the annulus plane ranges from 75° to 90°, and the open valve consists of 3 orifices: a small, slit-like central orifice between the 2 open leaflets and 2 larger semicircular orifices laterally. When the leaflets open, blood flow parallel to it and reduce damaging the blood cell. |
Biological Heart Valve
Definition:
Biological heart valve are valves made of animal tissue or taken from human tissue of donated heart.
Two types of biological heart valve are:
1. Xenograft: Valves from animal tissue.
2. Allograft: Valves from human tissue.
Two mainly used animal tissue for Xenograft:
1. Porcine valve (Pig’s tissue)
2. Bovine valve (Cow’s tissue)
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Porcine Stented Heart Valve Porcine Stented heart valve are mounted on a flexible stent which act as its frame. The bottom part of the valve is covered with knitted polytetrafluoroethylene (PTFE) cloth. This material facilitates the growth and healing of tissue around the implant. |
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Porcine Stent-less Heart Valve The valve does not use any stent or synthetic sewing ring similar to a homograft valve, but they are more difficult to implant. |
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Bovine Cardiac Tissue Made of bovine pericardial tissue which is a tissue from a cow heart, it is mounted on a flexible frame and a sewing ring of moulded silicone rubber, which allows the doctor to sew the valve to the patient. The frame and sewing ring are covering made from polytetrafluoroethylene (PTFE) cloth. This valve has enhanced durability because it is made from pericardium using a bioengineered valve design. |
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Homograft Valve Pregnant women and children can benefit lot from this type of valve since it does not require continuous anticoagulation therapy for blood thing process. Homograft also has the advantage of near-native hemodynamic performance. Hemodynamic are the term used to describe the blood flow through the heart valve. This is the best available tissue substitute which is harvested from cadavers or cyropreserved in liquid nitrogen, thus it is very limited. |
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