Why do patients who receive a heart transplant not live a complete lengthy life?

Because the new heart is not theirs and the body will always always always seek to reject any foreign bodies. That's just how it is no matter what kind of transplant you get.  That's why they have to take anti-rejection pills their entire life.  It's not that the heart isn't doing it's job, the body is fighting against it the entire time.

it really depends  sometimes its because the heart regeks the body or the blood but sometimes it works out ok  ma aunt had cancer and surived but had to had a heart transplant and was told she would only live another 2 years but she ended up living another 18 unfortuatly she got cancer again and died.  but some people get heart transplants and live like normal

Hi, great question. I wondered this too for a while. Basically in transplants, your body is always rejecting the organ. So your body is constantly mounting an immune response towards that organ.

Their are actually 4 types of transplant rejection.

Hyperacute- As soon as you put the organ in, it pretty much dies.

Acute- which occurs weeks after the organ is put in.

Chronic rejection is the one that people hope for and  is the one you're referring to. This takes months to years to occur. Basically their is an immune response occurring that causes scarring to that organ and eventually makes it useless. So in the case of a heart transplant, it becomes scarred to the point where it's unable to pump to meet the needs of the body. To lengthen the functioning of these organs what a person has to do is lower the immune response to the body. That's why a lot of transplant patients are on cortico steriods that inhibit or lower the human immune response. But it kind of becomes a balancing act because by lowering the immune response, these patients are now susceptible to illnesses that most people wouldn't even be bothered by.

Graft vs. Host Disease- The 4th type of rejection that occurs when the organ actually causes an immune response to the patient.

Hope this answers your question