The Artificial Heart Prototypes, Policies, and Patients (1991) / Chapter Skim
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1. The Artificial Heart Program: Current Status and History
1. The Artificial Heart Program: Current Status and History
Pages 14-25
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From page 14... ...
. The implant will begin a clinical trial of a VAD developed by the Novacor Division of Baxter Healthcare Corporation and is the result of a major effort by the artificial heart program of the National Heart, Lung, and Blood Institute (NHLBI)
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End-stage heart disease may result from a variety of cardiovascular causes; "heart failure" sometimes called congestive heart failure is, technically speaking, not itself a disease but a condition that is caused by many different disease processes. The most common causes of end-stage heart disease and heart failure are hypertension and coronary atherosclerosis (also called coronary artery disease or coronary heart disease, a constriction of the arteries that convey blood to the heart muscle itself)
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From page 16... ...
may ultimately reduce the number of patients with end-stage heart disease resulting from coronary artery disease. Patients who already have coronary artery disease may have the natural history of their disease altered, at least temporarily, by coronary artery bypass surgery,
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For the large number of heart failure patients who are unable to receive a transplant, either because of limited donor availability or because they do not meet transplant criteria, the only current alternative is drug treatment. Annual mortality rates of patients receiving conventional medical treatment range from 15 to 50 percent, depending on the severity and rate of progression of the underlying disease.
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From page 18... ...
Each pumping stroke of the VAD is coordinated with the left ventricle's contraction, so as to optimize the functioning of both the device and the natural heart. Inside the VAD's rigid casing, an electrically powered mechanism squeezes a plastic blood sac between two plates; the direction of blood flow is controlled by a pair of valves, the same types used when a natural heart valve must be replaced (e.g., valves from pigs' hearts or ones made of metal and plastic)
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From page 19... ...
In the models currently under development, top portions of the natural heart's atria are left in place when the heart's larger components are removed, to facilitate suturing the TAH into position. In models in which the TAM's pumping speed is synchro\ Artificial Heart ~V( Right Pump 7< 1~ ,~g-O, , Electronic Controller and Implanted Batteries Implanted Secondary Transformer External Primary Transformer 1\ Artificial Heart I\ Left Pump Energy Converter FIGURE 1.3 A fully implantable total artificial heart.
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From page 20... ...
Some researchers believe that most patients' needs could be satisfied by a VAD assisting the left ventricle, particularly if it is implanted before serious right heart failure and damage to other organ systems has occurred. Others believe that, regardless of when the implant procedure occurs, a TAH will be needed by a substantial number of endstage heart disease patients.
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From page 21... ...
Most of the institutes that make up NIH do not fund later developmental stages of medical technologies, focusing instead on fundamental or basic research. The NHLBI artificial heart program is, however, a notable exception to this generalization.
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From page 22... ...
TABLE 1.2 Previous Evaluations of the NHLBI Mechanical Circulatory Support Program 1969 1973 1 977 1980 Cardiac Replacement: Medical, Ethical, Psychological, and Economic Implications; Ad Hoc Task Force on Cardiac Replacement The Totally Implantable Artificial Heart: Legal, Social, Ethical, Medical, Economic, Psychological Implications; Artificial Heart Assessment Panel Mechanically Assisted Circulation: The Status of the NHLBI Program and Recom.
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\ \. ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 1 1 66 68 70 72 74 76 78 80 82 84 86 88 90 91 Fiscal Year - · Current$ I Constant 1991$ FIGURE 1.5 Total annual expenditures of the NHLBI artificial heart program.
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From page 24... ...
The report's scope is, moreover, broader than the nine questions, including consideration of several issues of R&D policy and decision making. TABLE 1.3 Nine Questions Identified by the Institute of Medicine Planning Study for the Main Evaluation and Chapters Where Mainly Considered in This Report 1.
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From page 25... ...
1990. Heart failure: Mechanisms of cardiac and vascular dysfunction and the rationale for pharmacologic intervention.
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