health care proxy An advance medical directive in the form of a legal document that designates another person (a proxy) to make health care decisions in case a person is rendered incapable of making his or her wishes known. The health care proxy has, in essence, the same rights to request or refuse treatment that…
health outcomes research Research that measures the value of a particular course of therapy.
hearing aids Small electronic devices worn inside or behind the ear that improve the hearing and speech comprehension of people with hearing loss due to damage to the small sensory cells in the inner ear. Hearing aids contain a microphone, amplifier, and speaker.
heart The muscle that pumps blood received from veins into arteries throughout the body. The heart is positioned in the chest behind the sternum (breastbone); in front of the trachea, esophagus, and aorta; and above the diaphragm. A normal heart is about the size of a closed fist and weighs about 298 grams or 10.5…
heart, artificial A human-made heart that is used to replace a diseased or malfunctioning heart when a donor organ is not available.
heart, left The left atrium and left ventricle.
heart, right The right atrium and right ventricle.
heart attack A sudden blockage of a coronary artery. Not infrequently, this leads to the death of part of the heart muscle due to its loss of blood supply. Typically, the loss of blood supply is caused by a complete blockage of a coronary artery by a blood clot. The interruption of blood flow is…
heart block A blockage in the conduction of the normal electrical impulses in the heart. Heart block is not uncommon and is detected with an electrocardiogram. Heart block occurs from degeneration or scarring of the electrical pathways in the heart muscle, either naturally or as a result of disease. Heart block typically requires no treatment,…
heart conduction system See cardiac conduction system.
heart failure See congestive heart failure.
heart murmur An unusual, “whooshing” heart sound that may be innocent or may reflect disease or malformation. A heart murmur is created by blood flow through a heart valve, by blood flow through a narrowed chamber, or by an unusual connection between the chambers, as seen with congenital heart disease. Sometimes a heart murmur does…