heart ventricle One of the two lower chambers of the heart. The right ventricle receives blood from the right atrium and pumps it into the lungs via the pulmonary artery, and the left ventricle receives blood from the left atrium and pumps it into the circulation system via the aorta.
heart valve One of the four heart valves. All four heart valves are one-way valves, permitting forward and avoiding backward flow of blood. Blood entering the heart first passes through the tricuspid valve, and then the pulmonary valve. After returning from the lungs, the blood passes through the mitral (bicuspid) valve and leaves the heart…
heart transplant An operation in which a diseased or malfunctioning heart is replaced with a healthy donor heart taken from a deceased person. See also transplant.
heart septum The dividing wall between the right and left sides of the heart. That portion of the septum that separates the right and left atria of the heart is termed the atrial, or interatrial, septum, whereas the portion of the septum that lies between the right and left ventricles of the heart is called…
heart rate The number of heartbeats per unit of time, usually per minute. The heart rate is based on the number of contractions of the ventricles (the lower chambers of the heart). The heart rate may be too fast (tachycardia) or too slow (bradycardia). The pulse is a bulge of an artery from waves of…
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…
heart failure See congestive heart failure.
heart conduction system See cardiac conduction system.
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 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, right The right atrium and right ventricle.
heart, left The left atrium and left ventricle.