Ventricular Assist Devices

Ventricular assist devices come in three varieties, Left Ventricular Assist Device (LVAD), Right Ventricular Assist Device (RVAD), and Bi Ventricular Assist Device (BiVAD). Although all of them affect different parts of the heart., they all share the same goal, and that is to extend the life of a person either for a short period of time "destination therapy" or until a better solution can be found "bridge therapy." VAD's in general vary largely in design but most are implanted in a similar fashion. This method of insertion being the insertion of tubing into the affected ventricle(s) that leads to a pump which pumps the blood from the ventricle(s) to the outgoing vessel ie. the pulmonary artery, aorta, or both. Where VAD’s largely differ is in the pump design.

There are two main types of pumps when it comes to VAD’s, these two being pulsatile pumps and continuous flow pumps. Pulsatile pumps rely on some form of pneumatic device to push the blood along the blood vessels. This requires that there be an opening to an air source ( a tube leading from the displacement pump to the outer body). The other major type of pump, continuous flow pumps, utilizes continuous flow as the mechanism of blood transport. This is achieved by a rotary “centrifugal” pump, many continuous flow pumps are still very controversial both in their method or action and their implantation. There is a lot of controversy on how one should suspend the rotary mechanism, to do little damage to the blood and surrounding structure, another issue is the fact that there is little known about how the body deals with continued flow.

VAD’s are implanted into the body for bridge therapy and destination therapy, but how well do they achieve this? In one study it was shown that people who were on a VAD prior to heart transplant had a 40% better chance of survival without any complications as opposed to those on alternative treatments. ¹VAD’s are meant for short term use, but what if they were used for long term, about how long can you expect them to last? One could usually expect a longer life, as compared to those on medical treatment. According to one study you have a 15% better chance of surviving for 2+ years on a VAD than on medication.¹ Complications arise, as do with any type of major procedure, among possible problems, the largest causes of death are mechanical failure and infection. Being a machine, VAD’s can’t last forever, and they don’t, usually suffering some form of mechanical failure within the first 2 years. Disease is another factor, whether caused by surgery itself or assisted by the hospitable growing area that the VAD and components provide, it is a problem that causes many deaths related to VAD’s.

1: "Ventricular assist device." Wikipedia, The Free Encyclopedia. 19 Jun 2008, 02:04 UTC. Wikimedia Foundation, Inc. 18 Jul 2008 <http://en.wikipedia.org/w/index.php?title=Ventricular_assist_device&oldid=220274111>.