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A Glossary of Heart Failure Terms

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Saphenous Vein: Vein located in the leg(s) and used for coronary artery bypass surgery. It is surgically removed from the leg and sewn from the aorta to the coronary artery beyond the site of blockage.

Septum: The muscular wall separating the right and left sides of the heart.

Sestamibi Exercise Stress Test (Sestamibi stress test, stress perfusion scan, stress Sestamibi): A diagnostic study, which uses a small amount of radioactive tracer, injected into the body, and a special camera, which detects the radiation, released by the substance to produce a computer image of the heart. Combined with exercise, the study can help determine if there is adequate blood flow to the heart at rest, as compared with activity.

Silent Ischemia: Inadequate supply of oxygen-rich blood to the heart that does not cause symptoms such as chest pain.

Sinoatrial Node (SA or sinus node): A specialized cluster of cells in the heart that initiates the heartbeat. Known as the heart's natural pacemaker.

Sodium (salt): A mineral found in most of the foods we eat. The largest source of dietary sodium comes from sodium chloride or table salt. Intake of sodium tends to increase the retention of water.

Sphygmomanometer: A device for measuring blood pressure.

Stenosis: Narrowing or restriction of a blood vessel or valve that reduces blood flow.

Stent: A small stainless steel mesh tube, inserted during an angioplasty, that acts as a scaffold to provide support inside the coronary artery.

Sternum (breastbone): Bone in chest separated during open heart surgery.

Stress Test: See Exercise Stress Test.

Stroke: A sudden loss of brain function due to decreased blood flow to an area of the brain. This can be caused by either a blood clot in the brain or bleeding into the brain.

Stunned Myocardium: If blood flow is returned to an area of heart muscle after a period of ischemia (lack of blood supply), the heart muscle may not pump normally for a period of days following the event. This is called "stunned" heart muscle or myocardium.

Subvalvular Aortic Stenosis: A narrowing of the flow of blood below the aortic valve in the left ventricle. It is usually caused by a membrane or thickening in the muscle in this area.

Syncope: Fainting.

Systole: The portion of the cardiac cycle in which the heart muscle contracts, forcing the blood into the main blood vessels.

Systolic Pressure: The pressure of the blood in the arteries when the heart pumps. It is the higher of two blood pressure measurements; for example, if the blood pressure is 120/80, then 120 is the systolic pressure.

Tachycardia: Rapid heartbeat. A heart rate above 100 beats per minute.

Thallium Exercise Stress Test (Stress thallium test, Perfusion scan): A type of nuclear scanning technique that uses the radioactive substance thallium. A thallium stress test combines nuclear scanning with exercise on a treadmill or stationary bicycle to assess heart function and determine if there is adequate blood flow to the myocardium. Sestamibi has mostly replaced thallium as the tracer for nuclear stress tests.

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