Ventricular Assist Devices

Several different types exist: short-term vs long-term, right-ventricular vs left-ventricular vs bi-ventricular VADs.
Becoming used more and more for several different purposes:
1. “Bridge to transplant” – most often used for people with refractory cardiogenic shock, to keep them alive until a heart transplant becomes available. 
2. “Bridge to recovery” – occasionally, patients will recover function and be able to be weaned off the VAD, as in our patient with myocarditis.
3. “Destination therapy” – VADs are being used more and more for patients with end-stage CHF who are not transplant candidates.  More data is accumulating showing improved survival vs medical rx alone and better quality of life as well.

2 main types of pumps:
1. Pulsatile pumps – use positive displacement pumps to mimic the natural pulsing action of the heart.  Basically, sucks blood from the LV and pumps it into the aorta.  This concept was used more in the “1st Generation VADs” (first approved in 1994) as the devices are quite bulky.
2. Centrifugal pumps - use either Centrifugal pumps or Axial Flow pumps, have a central rotor that spins causing acceleration of blood flow around it.  Does not cause pulsatile flow.  This is more common with the “2nd Generation VADs” as they are simpler, smaller and more reliable generally.  This includes the Impella, which can be placed percutaneously via the femoral artery in the cath lab. 

Complications of VADs:
1. Clotting and thrombosis risk – typically need continuous anticoagulation, which in turn leads to bleeding risk.
2. Infection – huge cause of morbidity and mortality, and infections include endocarditis.  Gram positives, gram negatives, and fungal organisms (esp candida) are all to blame.
3. Ventricular arrhythmias – common, due to irritation of the ventricles.
4. Thrombocytopenia – common
5. Hemolysis – common but usually mild.

(Chanu Rhee MD, 11/30/10)