Glossary

Allograft

Transplantation of an organ between members of the same species. Also called homograft.

Appropriateness of care

An aspect of quality care that emphasizes “using what works.”

Artificial heart

A generic term referring to a device (or equipment, or system of these) designed to support or replace the pumping function of the heart or one of its ventricles. Depending on the context of the usage, the term can include one or more of these: total artificial heart, left ventricular assist device, and right ventricular assist device. The terms “artificial heart” and “mechanical circulatory support system” have frequently been used interchangeably in the literature but not in this report. This report uses the term “artificial heart ” either as a generic, descriptive modifier, namely the NHLBI artificial heart program, or as a specific device, namely the total artificial heart.

Base case

In a cost-effectiveness analysis, the assumptions that represent the best estimates of all probabilities and costs.

Bench testing

Testing of a device against specifications in a simulated environment that does not include the living body of a human or animal. Also known as in vitro device readiness testing.

Bioengineering research

The application of engineering knowledge and concepts to the understanding of the human body and its interactions with machines, and to the development of new and improved medical devices.



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The Artificial Heart: Prototypes, Policies, and Patients Glossary Allograft Transplantation of an organ between members of the same species. Also called homograft. Appropriateness of care An aspect of quality care that emphasizes “using what works.” Artificial heart A generic term referring to a device (or equipment, or system of these) designed to support or replace the pumping function of the heart or one of its ventricles. Depending on the context of the usage, the term can include one or more of these: total artificial heart, left ventricular assist device, and right ventricular assist device. The terms “artificial heart” and “mechanical circulatory support system” have frequently been used interchangeably in the literature but not in this report. This report uses the term “artificial heart ” either as a generic, descriptive modifier, namely the NHLBI artificial heart program, or as a specific device, namely the total artificial heart. Base case In a cost-effectiveness analysis, the assumptions that represent the best estimates of all probabilities and costs. Bench testing Testing of a device against specifications in a simulated environment that does not include the living body of a human or animal. Also known as in vitro device readiness testing. Bioengineering research The application of engineering knowledge and concepts to the understanding of the human body and its interactions with machines, and to the development of new and improved medical devices.

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The Artificial Heart: Prototypes, Policies, and Patients Biventricular support The use of either a total artificial heart or two ventricular assist devices to support or replace the function of both the right and the left ventricles. Clinical practice guidelines Systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances. Congestive heart failure (CHF) Heart failure in which the heart is unable to maintain adequate circulation of blood in the tissues of the body or to pump out the venous blood returned to it by the venous circulation. Coronary heart disease (CHD) A condition that reduces the blood flow through the coronary arteries to the heart muscle. Also called coronary artery disease or coronary disease. Cost-benefit analysis (CBA) An analytical technique that compares the costs of a project or technological application to the resultant benefits, with both costs and benefits expressed by the same measure. This measure is nearly always monetary. Cost-effectiveness analysis (CEA) An analytical technique that compares the costs of alternative projects to the resultant benefits, with costs and benefits or effectiveness expressed by different measures. Costs are usually expressed in dollars, but benefits or effectiveness are ordinarily expressed in terms such as “lives saved,” “disability avoided,” “quality-adjusted life years gained,” or any other relevant objectives. Diffusion The spread of a technological innovation over time. Fully implanted mechanical circulatory support device A mechanical circulatory support system in which all components are implanted so the patient can be free of all external apparatus and can continue normal activities for at least short periods of time. In some systems, the patient would wear a battery pack; others are powered by an implanted energy source that is charged periodically, e.g., several times a day. Hard device failure A term used to describe an occurrence or health state created from a mechanical failure of a circulatory support device that results in high risk of immediate death. Health-related quality of life The value assigned to duration of life as modified by the key facets of life such as impairments, functional states, and social opportunities that are influenced by health factors such as disease, injury, treatment, or health policy. Health state utility An index indicating the value attributed to a specific health state. The value reflects the overall “quality” of life associated with a health state from the perspective of the individual assigning preferences. Health state utilities are commonly used in cost-effectiveness analysis.

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The Artificial Heart: Prototypes, Policies, and Patients Heart failure A condition in which the heart is unable to pump blood at an adequate rate or in adequate volume. Heterotopic graft Transplantation of a donor organ without removing the patient's organ. Also called piggybacked transplant. Incidence The rate of occurrence of new cases of a particular disease in a population. In vitro bench testing See Bench testing. In vivo testing Testing in the living body of a plant or animal. Left ventricular assist device (LVAD) A device that supports or replaces the function of the left ventricle by pumping blood from the left heart to the aorta. The patient's heart remains in place when this device or system is used. Long-term device A mechanical circulatory support system that is employed with the anticipation that it will function for years. Manufacturability A technology design, characteristic, or process that allows fabrication in quantity, achieving a balance between low cost and high quality for the purpose of maximizing production efficiency. Also called value engineering. Mechanical circulatory support system (MCSS) A generic term referring to a device used to supplement or take over the pumping function of the heart or one of its ventricles. The terms “artificial heart” and “mechanical circulatory support system” are frequently used interchangeably in the literature but not in this report. This term includes total artificial hearts and both types of ventricular assist devices. Opportunity cost The cost included in the CBA or CEA of an expenditure (such as the research and development cost of the artificial heart program) because resources directed to the expenditure are no longer available (“ a lost opportunity”) for alternate uses. Orthotopic graft Transplantation with the donor organ placed at the site of the organ that was removed. Practice guidelines See Clinical practice guidelines. Prevalence The number of persons in a population that are affected with a particular disease at a given time. Quality-adjusted life years (QALYs) A concept that provides a single combined measure of gains in both the quantity and quality of life. QALYs are used with cost-effectiveness analyses of health technologies, frequently derive their weights from utilities assessment, and are expressed as a ratio in terms of cost per QALY gained. Quality of care The degree to which health services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge.

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The Artificial Heart: Prototypes, Policies, and Patients Right ventricular assist device (RVAD) A device that supports or replaces the function of the right ventricle by pumping blood from the right heart to the pulmonary artery. The patient's heart remains in place when this device or system is used. Short-term or temporary device A mechanical circulatory support system that is employed for a relatively short period of time in anticipation of either recovery of function by the patient's natural heart or a second intervention such as cardiac transplantation that would permit removal of the device. An often-used definition is an implantation intended to be less than 180 days. A short-term device used in connection with transplantation may be referred to as a “bridge” to the subsequent procedure. Soft device failure A term used to describe an occurrence or health state created from a mechanical failure of a circulatory support device that results in a non-life-threatening condition. Spin-off technologies The development or application of technologies (or subcomponents) for a use other than the initially intended use. Also called spillover or fallout technologies. Technological diffusion The process by which the use of a technological innovation in a given social system spreads over a period of time. Technological innovation The process of creating or inventing any technology which is new for a given sector of society, organization, or user. Tethered device A mechanical circulatory support system that is constantly connected to external control or energizing systems by wires or tubes leading from the implanted device through the skin to the external component. By requiring continuous connection, all such devices tether the patient to the external component. Thromboembolism The blocking of a blood vessel by a particle that has broken away from a blood clot at its site of formation. Total artificial heart (TAH) A device that replaces the heart and its function. The patient's heart is removed when such a device is used. Ventricular assist device (VAD) A device that supports or replaces the function of a ventricle. LVAD and RVAD indicate which ventricle is supported or replaced. Xenograft Transplantation of an organ between members of different species (i.e., animal to human). Also called heterograft.