VAD's

When looking for a VAD, there are two categories to examine: Durability and bio-friendliness. The first category is pretty much self explanitory, asking 'how long does the machine normaly last' and 'can I expect mechanical failure,' but the second is a little broader. It asks 'what kind of medication do I need to take,' 'how much medication do I need to take', and 'does it increase my chance of infection.' Depending on what country you're in, you may also have to examine legal issues, as a number of devices are only approved in certain countries.
Based purely on longevity of a singal user, the best choice for a VAD is the Jarvik 2000, a very compact system which was able to support a patient for 7.5 years. However, it is still waiting approval in the U.S and has not of yet been used on a large number of patients. The Novacor LVAD, however, has been used on over 1,700 patiens, has approval in the US, EU and Japan, and, "among these recipients, 45 have been supported for more than two years, 24 for more than three years, 11 for more than four years and 1 for more than six years. Only 1.4% of the pumps have needed replacement. No patient deaths have been attributed to Novacor® LVAS failure." Sadly, both require anticoagulation medicine, but so do nearly all other VADs on the market. The exception to this is the Heartmate, which uses a biologically friendly material called fibrin to prevent the immune system from attacking the device. However, this too has disadvantages, as it increased the chances of infection and is not a durable as either the Jarvik or Novacor.

http://www.thoratec.com/medical-professionals/vad-product-information/heartmate-xve-lvad.aspx
http://en.wikipedia.org/wiki/Ventricular_assist_device
http://www.worldheart.com/products/novacor_lvas.cfm
http://www.jarvikheart.com/basic.asp?id=26