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A Bridge to Recovery or Transplantation
Artificial hearts developed since the beginning of the 90ties consist of separate pumping chambers for the left and right ventricels, with small, brushless DC motors powering either a hydraulic fluid or directly activating the blood containing sacs. As energy is transmitted via inductive coupling and there are no longer tubes or wires crossing the skin, infection risks are minimised.
Widely used and commonly implanted are Left Ventricular Assist Devices (LVADs). Taking over most of the heart’s pumping function, these heart-assist devices can provide a temporary bridge to recovery – or in the most severe cases serve as a bridge to transplantation until a suitable donor heart is identified. According to recent studies (e.g. REMATCH), permanent use of the devices offers a suitable alternative to transplantation, as cardiac replacement therapy for patients ineligible for transplantation, for example the Jarvik 2000.
These devices are also less expensive than a transplantation – the costs of a go-home LVAD are estimated at around $50,000-$70,000, while costs of a transplant are usually around $200,000.
Several of these partially or nearly completely implantable devices are available. One of these is the Novacor system, which is using biological valves. Patients provided with this device are maintained on long term anticoagulation, while users of the Thoratec pump are commonly treated with low dose heparin or Coumandin. This systems relies on tilting disk type mechanical valves, while the HeartMate assist pump uses tissue valves.
Promising news are coming from the developers of artificial hearts: Last september, a recipient of the AbioCor Implantable Replacement Heart reached one year with the articificial heart. The 70 year old male patient was the second recipient of the device and the first replacement heart patient ever to be discharged home. Apart from Abiomed and the Texas Heart Institute, current working on artificial hearts are Nimbus Inc. and the Cleveland Clinic Foundation, the 3M Company and the The Pennsylvania State University.
MEDICA.de; Sources: American College of Cardiology Consensus Conference Report: Mechanical Cardiac Support; World Heart: Novacor LVAS; Texas Heart Institute: Jarvik 2000; Abiomed: AbioCor; Thoratec: HeartMate