Cardiac prostheses: toward permanent implantation1

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The pneumatically actuated total artificial heart (TAH) can maintain normal physiology in man and in experimental animals for several months with extracorporeal pneumatic actuation through the skin. The ultimate goal is the development of a totally implantable cardiac prosthesis that functions for a minimum of two years. The Cleveland Clinic Foundation’s cardiac prosthesis is a pusher-plate type of blood pump that uses protein-coated blood contact surfaces and trileaflet dura mater valves. The pusher-plate design for mechanical actuation provides a net stroke volume of 80 ml. It can pump as much as 9.6 L/min at 120 beats/min with 15 mm Hg inlet pressure. Total artificial hearts and the left ventricular assist devices (LVAD) were implanted in calves without anticoagulation for as long as seven months. Our group is developing a mechanically actuated universal blood pump for use as a TAH and LVAD, compatible with either thermal or electrical actuation systems. We have also developed a parathoracic version of the LVAD. The application of newly developed implantable actuation systems to cardiac prostheses offers many alternatives to the traditional pneumatic method. These methods should allow the patient to live a nearly normal life. We summarize the recent work in this area and identify the relevant design features and mechanical actuation systems for cardiac prostheses.



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