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Encyclopedia > Artificial heart valve
It has been suggested that this article or section be merged with Heart valve prosthesis. (Discuss)


An artificial heart valve is a device which is implanted in the heart of patients who suffer from valvular diseases in their heart. When one or two of the four heart valves of the heart have a malfunction, the choice is normally to replace the natural valve by an artificial valve. This requires Open-Heart Surgery. Wikipedia does not have an article with this exact name. ... It has been suggested that this article or section be merged with Artificial heart valve. ... Grays Fig. ... Cardiac surgery is surgery on the heart, typically to treat complications of ischemic heart disease (e. ...


There are two types of artificial heart valves: the mechanical and the biological valves.

A mechanical artificial heart valve with a pivoting disc
A mechanical artificial heart valve with a pivoting disc

There are several varieties of mechanical valves. Some mechanical valves are made of a metal ring covered by a tissue, into which the suture threads are stitched, in order to keep the valve in place once implanted. The metal ring holds, by means of two metal supports, a disc which opens and closes as the heart pumps blood through the valve. The disc is usually made of an extremely hard carbon material (pyrolitic carbon), in order to allow the valve to function during years without wearing out. In some models of mechanical valves, the disc is divided into two parts, which open and close as a door. Another variety, utilizes a metal cage to house a metal ball. When blood pressure in the in the chamber of the heart exceeds that of the pressure on the outside of the chamber the ball is pushed against the cage and allows blood to flow. When the chamber has emptied the majority of the blood and the pressure outside the chamber exceeds that inside the chamber the ball moves back against the base of the valve forming a seal. The Ball valve was invented by Miles "Lowell" Edwards and Albert Starr in 1960 (commonly referred to as the Starr-Edwards Silastic Ball Valve). The first human inplant occured on Sept 21, 1960. Image File history File links Heartvalve. ... Image File history File links Heartvalve. ... A wound before and after being closed by sutures Sutures are the stitches doctors, and especially surgeons, use to hold skin, internal organs, blood vessels and all other tissues of the human body together, after they have been severed by injury or surgery. ...


Mechanical heart valves are today very reliable and allow the patients to live a normal life. One of the main advantages of these valves is that they are well tolerated by the body. Only a small amount of blood thinner is needed to be taken by the patient each day, in order to prevent clotting of the blood when flowing through the valve. Any medication however can lead to other complications.


Biological valves are valves of animals, like pigs, which undergo several chemical procedures in order to make them suitable for implantation in the human heart. The porcine (or pig) heart is most similar to the human heart, and therefore represents the best anatomical fit for replacement. Implantation of a porcine valve is a type of Xenograft which means a transplant from one species (in this case a pig) to another. There are some risks associated with a Xenograft such as the human bodies tendency to reject foreign material. Medication can be used to retard this effect, but is not always successful.


Another type of biological valve utilizes biological tissue to make leaflets that are sewn into a metal frame. This tissue is typically harvested from the Pericardial Sac of either Bovine (cows) or Equine (horses). The pericardial sac is particularly well suited for a valve leaflet due to it's extremely durable physical properties. This type of biological valve is extremely effective means of valve replacement. The tissue is sterilized so that the biological markers are removed eliminating a response from the host's immune system. The leaflets are flexible and durable and do not require the patient to take blood thinners for the rest of their life.


The most used heart valves in the US and EU are those utilizing tissue leaflets. Mechanical valves are more commonly used in Asia and Latin America. The following companies manufacture artifical heart valves: Medtronic, Edwards Lifesciences, and St. Jude.


  Results from FactBites:
 
Heart valve Summary (2474 words)
Mitral valve insufficiency is a term used when the valve between the upper left chamber of the heart (atrium) and the lower left chamber (ventricle) doesn't close well enough to prevent back flow of blood when the ventricle contracts.
Mitral valve stenosis refers to a condition in the heart in which one of the valve openings has become narrow and restricts the flow of blood from the upper left chamber (left atrium) to the lower left chamber (left ventricle).
In anatomy, the heart valves are valves in the heart that maintain the unidirectional flow of blood by opening and closing depending on the difference in pressure on each side.
Prosthetic Heart Valves (2388 words)
In the heart the valves open and close in response to pressure gradients, i.e., valves open when pressure in the preceding chamber is higher and close when the gradient reverses.
The valve in question should (1) function efficiently and present the minimum load to the heart, (2) be durable and maintain its efficiency for the patient's entire lifespan, and (3) not cause damage to molecular or cellular blood components or stimulate thrombus formation (blood clotting).
The large size of the ball valve was thought to be associated with certain deaths--deaths that were the result of irritation of the ventricular cavity at the hands of the ball valve's large cage.
  More results at FactBites »


 

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