TRISTAN+-+ARTIFICIAL+HEART

Back to YEAR 8 MP SCIENCE NEWSPAPER 2010

__ARTIFICIAL HEART__
**Charles Okeke, a 43-year-old father of three from Phoenix, Arizona, is the first person to leave hospital with a completely artificial heart. Since 3 May he has been home with his family, thanks to a backpack-sized device that is powerful enough to keep his artificial heart pumping while he awaits a donor heart. How does the artificial heart work?**

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**Who is qualified to use one?** People qualify to be fitted with one only if both left and right ventricles are failing. The artificial hearts are designed as a temporary arrangement until a real, donated heart becomes available. Until recently, patients have had to remain in hospital when fitted with one, sometimes for as long as two and half years. As many as 80 per cent of patients survive long enough to receive a donated heart. However a more permeant heart has been made but is still a little dodgy.

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 * Are patients fitted with this type of artificial heart in any danger?**

The biggest risk is of infection since pipes pass from outside the body to the heart. Another worry is that blood clots will form at points in the chambers where blood flow is sluggish. However, the artificial ventricles are specially shaped to prevent this happening. The artificial left ventricle is hooked up to receive oxygenated blood from the lungs and pump it out to the rest of the body. The artificial ventricles are able to pump blood because they receive pressurised air from a machine that has to be kept outside the body. The heart consists of a motor that operates a pump using membranes and valves made of a strong, flexible plastic invented by the company The motor is powered by internal lithium battery pack lasting about one and a half hours. When the batteries run low, they can be recharged from a portable external pack that passes energy through the patient's skin by a current induction method. Additional electronics use pressure measurements to determine when the heartbeat needs to speed up to cope with the demands of exercise or sudden alarm in the patient. The whole ensemble adds about two pounds to the weight of the patient. **Are patients fitted with this type of artificial heart in any danger? The biggest risk is of infection since pipes pass from outside the body to the heart. Another worry is that blood clots will form at points in the chambers where blood flow is sluggish. However, the artificial ventricles are specially shaped to prevent this happening ||
 * [[image:HEART.jpg]] || **How do the artificial hearts work?**
 * Surgeons remove both existing ventricles and replace each with a vessel, similar to an upturned funnel, which contains a flexible diaphragm. All four valves of the heart are also removed. The artificial right ventricle is then hooked up to the cardiovascular system so that it can accept "used" blood that arrives, de-oxygenated, from the rest of the body, and then pump this out to the lungs for re-oxygenation.
 * Who made this life saving device?**

The artificial heart was developed by Massachusetts-based Abiomed and, unlike heart assist devices, fits entirely inside the chest. A battery pack is positioned in the patients thorax.


 * Could someone ever have an artificial heart that would never need to be replaced by a donor heart?**

A promising idea is to take a heart from a cadaver and strip it of all flesh, leaving a scaffold of tough collagen tissue that the patients immune system would not reject as "foreign" or "Alien". Next, this scaffold could be coated with stem cells from the patients bone marrow, which would develop into the tissue and blood vessels of the heart, guided by various growth factors. An even more ambitious project is to follow a similar procedure, but using scaffolds from pig hearts.

Reference - [|http://www.newscientist.com]

