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Health Maintenance Organization (HMO) - An organization that provides health care in a geographic area, providing an agreed-upon set of benefits and serving a defined group of people.heart block - A heart condition resulting when the AV node blocks electrical impulses from reaching the heart's ventricles. The electrical signal from the SA node must pass through the AV node and continue on through the conduction pathways in the ventricles. If the AV node is impaired, the impulse may become slowed, irregular, or stopped. This condition is called heart block because the electrical impulse is blocked from proceeding normally from the atria to the ventricles. Heart block is described as first, second, or third degree. How slow the ventricular rate becomes depends on the degree of heart block. A pacemaker can correct the effects of this condition. heart chambers - The four sections of the heart through which blood is pumped. The two upper chambers are called the left atrium and right atrium. The two lower chambers are the left and right ventricles. Oxygen-rich blood from the lungs enters the left atrium, while oxygen-depleted blood from the rest of the body flows into the right atrium. Both atria simultaneously pump blood into the ventricles. The ventricles then pump the blood to the lungs and the rest of the body. heart rate - The number of times that the heart beats in a minute. A normal heart rate increases and decreases, depending on how strenuous one's activity level is. One's heart rate when sleeping is typically lower than when walking or running. Emotional changes can also cause one's heart rate to increase. heart valves - Valves within the human heart that open and close automatically to control the flow of blood into, through, and out of the heart. These valves open to ensure that blood flows into the heart chambers as needed, and they close to ensure that blood does not flow back into the heart after it has been pumped out to the lungs and body. heartbeat - The sound made each time the heart muscles contract to pump blood into the lungs and throughout the body. A heartbeat consists of the contraction of the atria, quickly followed by the contraction of the ventricles. The rate of the heartbeat varies according to different levels of activity: the higher the level of activity or emotional excitement, the faster the heart will beat. heat exchanger - A device used to cool or warm solutions and/or blood during extracorporeal circulation procedures. hemodilution - An increase in the fluid content of blood hemolysis - Refers to the destruction of the red cell membrane. May be caused by several factors including the immune response, bacterial or viral infection and red cell membrane stress. hemostasis - Process carried out by the body to maintain blood in the vascular system. heparin management - Heparin is a drug that prevents blood from clotting. Heparin management refers to monitoring the blood's ability to clot and adjusting the heparin dose accordingly. Blood must be completely free of clots before using cardiopulmonary bypass (heart-lung machine). hypertrophic - Enlargement of an organ or part of an organ due to an increase in its constituent cells |
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