A<unk>  <unk>  is an electromechanical<unk>  for<unk> ing cardiac circulation, which is used either to partially or to completely replace the function of a failing heart. The function of a<unk>  differs from that of an artificial cardiac pacemaker in that a<unk>  pumps blood, whereas a pacemaker delivers electrical impulses to the heart muscle. Some<unk> s are for short-term use, typically for patients recovering from myocardial infarction (heart attack) and for patients recovering from cardiac surgery; some are for long-term use (months to years to perpetuity), typically for patients suffering from advanced heart failure.<unk> s are designed to<unk>  either the right ventricle (RVAD) or the left ventricle (LVAD), or to<unk>  both ventricles (BiVAD). The type of<unk>  implanted depends on the type of underlying heart disease, and on the pulmonary arterial resistance, which determines the workload of the right ventricle. The left<unk>  (LVAD) is the most common<unk>  applied to a defective heart (it is sufficient in most cases; the right side of the heart is then often able to make use of the heavily increased blood flow), but when the pulmonary arterial resistance is high, then an (additional) right<unk>  (RVAD) might be necessary to resolve the problem of cardiac circulation. If both an LVAD and an RVAD is needed a BiVAD is normally used, rather than a separate LVAD and RVAD. Normally, the long-term<unk>  is used as a bridge to transplantation (BTT) – keeping the patient alive, and in reasonably good condition, and able to await heart transplant outside of the hospital. Other "bridges" include bridge to candidacy, bridge to decision, and bridge to recovery. In some instances<unk> s are also used as destination therapy (DT). In this instance, the patient will not undergo a heart transplantation and will rely on the<unk>  for the remainder of his or her life.<unk> s are distinct from artificial hearts, which are designed to assume cardiac function, and generally require the removal of the patient's heart.
Ventricular assist device
Mechanical filter 
Portacaval shunt
Artificial heart
Cardiopulmonary bypass
Intra-aortic balloon pump
Atriocaval shunt
Portosystemic shunt