The Artificial Heart Prototypes, Policies, and Patients (1991) / Chapter Skim
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2. Total Artificial Hearts: Technological Potential and Research and Development Costs
2. Total Artificial Hearts: Technological Potential and Research and Development Costs
Pages 26-43
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From page 26... ...
The evaluation examines the current technological potential and limitations of the devices and compares these estimates with data on existing treatments for end-stage heart disease. Then, because actually fulfilling the potential of a technology is directly related to the further research and development provided, current and future funding from the National Heart, Lung, and Blood Institute (NHLBI)
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From page 27... ...
TEMPORARY CIRCULATORY SUPPORT The use of MCSSs for temporary support has evolved, in the absence of totally implantable systems, to meet patient needs and to evaluate the feasibility of mechanically substituting for the pumping action of the heart. These systems have all been connected or "tethered" to cumbersome external power sources by skin-penetrating tubes or wires, limiting acceptance as permanent devices and increasing the risk of infection.
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From page 28... ...
LVAD, left ventricular assist device; MCSSs, mechanical circulatory support systems; TAH, total artificial heart; VAD, ventricular assist device. SOURCES: Graham and Chalmers, 1989; Macoviak et al., 1990; Rosenberg, 1990.
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From page 29... ...
This VAD uses textured blood-contacting surfaces, enabling the growth of a living lining of endothelial cells within the device that could reduce the likelihood of thromboembolic events.3 FDA has also approved a TCI electrically powered, tethered VAD for investigational temporary use in five patients (Altman, 1991~. ENGINEERING ASSESSMENT OF MECHANICAL CIRCULATORY SUPPORT DEVICES4 Testing of mechanical circulatory devices occurs in three phases: bench testing, also known as in vitro device readiness testing; in vivo trials in animals; and clinical trials in humans.
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From page 30... ...
Recent bench testing of the pumping system of the long-term Novacor VAD involved 12 devices operating unattended for 2 years in a simulated in vivo situation. This rigorous reliability testing was, however, a trial of a small number of devices in a simulated environment, and therefore the positive results of the trial are not directly transferable to evaluation of the device's clinical potential.
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From page 31... ...
Another solution would be thermal power sources; NHLBI has for several years supported two thermal power developers, who reported promising results at the annual contractors' conference in December 1990.5 A specific advantage of thermal power sources is that the patient would be independent of the external battery pack, with recharging limited to perhaps one hour for every eight hours of continuous operation (Butler et al., 1990; White et al., 19901. Further exploration of alternative power sources might lead to significant improvements in patient quality of life and could obviate the longevity problem of current implantable batteries.
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From page 32... ...
CLINICAL COMPLICATIONS WITH MECHANICAL CIRCULATORY SUPPORT DEVICES There has been extensive temporary use of MCSSs, particularly ventricular assist devices, with over 1,300 documented applications. Of these, 400 patients have been temporarily supported before transplantation and 68 percent of these lived to receive a donor heart (Miller et al., 1990~.
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From page 33... ...
16 Thromboembolic complications 12 13 Emboli 7 9 Thrombi 5 4 LVAD, left ventricular assist device; MCSSs, mechanical circulatory support systems; TAH, total artificial heart; VAD, ventricular assist device. SOURCE: Combined Registry for the Clinical Use of Mechanical Ventricular Assist Pumps and the Total Artificial Heart, verbal communication to G
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From page 34... ...
They are not, however, able to prevent end-stage heart disease itself. Most notable among these current and emerging alternative technologies are: short-term intra-arterial assist devices, surgical techniques for augmenting the function of the heart muscle with a skeletal muscle, and heart transplantation.
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From page 35... ...
More potent positive inotropic and vasodilating drugs are available for intravenous use in the intensive care unit for treatment of acute decompensation, but these are not currently practical for long-term management. In summary, in spite of many advances in the conventional medical therapy of congestive heart failure, the primary goals of therapy remain those of symptomatic relief and palliation of a chronic and inexorably progressive disorder.
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From page 36... ...
Even among those patients who are clearly eligible for transplantation, many will prefer receiving a long-term device to waiting for an available donor heart. The second consideration is that heart transplantation and circulatory 7New York Heart Association functional classification for Class IV: Patients with cardiac disease resulting in inability to carry on any physical activity without discomfort.
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From page 37... ...
In predicting future use when TAHs and heart transplantation are both available, it will be important to determine whether early TAH performance can be maintained over a 5- and then a 10-year span of clinical use. SUMMARY OF THE CURRENT AND FUTURE STATE OF TOTAL ARTIFICIAL HEART TECHNOLOGY Major limitations on long-term, widespread use of mechanical circulatory support are the devices' current power sources, biomaterials, valves, and design.
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From page 38... ...
Finally, comparison with other technologies for treating end-stage heart disease indicates that well-performing long-term TAHs could provide care to end-stage heart disease patients that is currently unavailable through heart transplantation, other technologies, or established drug treatment. RESEARCH AND DEVELOPMENT COSTS OF TOTAL ARTIFICIAL HEARTS Stages of the Innovative Process A brief examination of the various stages of the innovation process in medical technology will help to put the research and development process for MCSSs in perspective.
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From page 39... ...
The federal funds spent specifically on MCSS research and development are disbursed through NHLBI grants and contracts. From the inception of the artificial heart program in 1964 through fiscal year (FY)
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From page 40... ...
For medical devices, the uncertainty and difficulty of comparing cost estimates increase, but it is clear that many factors, including the nature of the device, its stage in the development process, the costs of mass production, and quality assurance and testing requirements, are potential considerations in calculating total costs. Chapters 3 and 9 address other aspects of industry R&D.
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From page 41... ...
1990. Presentation at the public meeting of the Institute of Medicine Committee to Evaluate the Artificial Heart Program of the National Heart, Lung, and Blood Institute.
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From page 42... ...
1990. Combined registry for the clinical use of mechanical ventricular assist pumps and the total artificial heart in conjunction with heart transplantation: Fourth official report 1989.
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From page 43... ...
1989. Thromboembolic complications with the Pierce-Donachy ventricular assist device.
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