Glossary of Terms

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acute myocardial infarction:
an acute process of prolonged myocardial ischemia of sufficient severity and duration to result in permanent damage to heart muscle; commonly known as a “heart attack”. This damage occurs when part of the heart muscle is deprived of blood flow, usually as the result of a blockage that stops flow down one of the major arteries that supply the heart (coronary artery). A scar usually forms in the heart.

Adenosine (Adenoscan):
One of several drugs used stress imaging of the heart when someone cannot exercise (pharmacologic/chemical stress testing). Adenosine is a naturally occurring chemical in the body. Adenosine is given intravenously (through an IV) and works very rapidly. Its effects disappear within seconds after the infusion is stopped. Patients sometimes feel flushed or even develop chest pain during its use but these symptoms are usually quite mild and short-lived.

adverse cardiac event:
Unstable angina, myocardial infarction or death due to cardiac causes are collectively called adverse cardiac events.

anaphylactic shock:
a severe form of hypersensitivity reaction to the injection or ingestion of a substance (generally food or medication) to which the person has previously been exposed. Unless treated promptly, this can result in death or severe disability.

the bodily structure of a plant or an animal or of any of its parts. The anatomy can be studied by direct examination of an organism, structure or an organ or by its examination under a microscope or indirect examination with the help of X-rays, ultrasonic waves or other imaging modalities. See physiology.

the abnormal dilation or out-pouching of a blood vessel or ventricle, which may result in the formation of blood clots. If an aneurysm ruptures, it usually results in death unless treated immediately.

angina pectoris (angina):
symptoms experienced when the heart is not receiving enough blood. Typically, it is characterized by a deep, poorly localized chest or arm discomfort that is reproducibly associated with physical exertion or emotional stress and relieved promptly by nitroglycerin given under the tongue. Commonly referred to as “chest pain” but this can be variable, and some people may experience abdominal, back, jaw, or arm discomfort (see or may have no symptoms at all.

angiographically significant coronary artery disease:
The severity of coronary artery disease is described as the percent of narrowing of its lumen. Coronary artery disease is judged “significant” at coronary angiography if there is at least a 70 percent diameter narrowing or stenosis of one or more major epicardial coronary segments, or at least a 50 percent diameter stenosis of the left main coronary artery.

A diagnostic test where the lumen (the open, inner space) of a blood vessel is studied by injecting a radiological contrast agent (dye).

A procedure, where the narrowing in the lumen of a blood vessel is treated by inflating a balloon attached to the tip of a catheter.

the large single artery arising from the left ventricle, carrying blood to all organs in the body.

aortic valve:
the valve separating the left ventricle from the aorta that prevents backflow of blood into the ventricle

irregularity or loss of rhythm of the heart beat. This often results in the feeling of palpitations In the chest

a small vessel that branches off an artery, and gives rise to a capillary network.

the process of thickening and loss of elasticity in the walls of an artery.

a blood vessel that carries blood away from the heart; arteries usually carry oxygenated (red) blood. When arteries of the heart become blocked, a heart attack or other adverse cardiac event occurs.

An abnormal-looking test result because of extraneous factors rather than due to a disease in the patient. In nuclear cardiology, an artifact is most commonly understood to be an error in a nuclear image resulting from factors such as patient motion during imaging or attenuation from breast tissue in women. Caution is required during image acquisition and interpretation to avoid errors due to artifacts.

ASNC (American Society of Nuclear Cardiology):
The American Society of Nuclear Cardiology is a professional medical society whose mission is to assure the optimal delivery of nuclear cardiology services. This mission is supported by educational programs, development of practice and training guidelines, and the promotion of research. The society’s membership includes nuclear cardiology physicians, nuclear cardiology technologists, nurses and scientists.

a form of arteriosclerosis in which plaques containing cholesterol, lipid material and inflammatory cells are formed in the lining of the arteries. These fatty plaques can sometimes rupture and thereby block the blood flow through the arteries. If the blockage is substantial enough, this may result in a heart attack or stroke.

of or referring to the chambers of the heart, called atrium (singular) or atria (plural).

a chamber affording entrance to another structure or organ;
right atrium is the upper right cardiac chamber that receives blood from the vena cava and delivers blood to the right ventricle.
left atrium is the upper left cardiac chamber that receives blood from the pulmonary veins and delivers blood to the left ventricle
(plural form is atria)

A type of artifact observed in myocardial perfusion images because of overlying, adjoining or overlapping dense tissues such as breasts or the diaphragm.


bundle branch block.

beta blocker (beta-adrenergic blocking agent):
a drug belonging to a class of drugs that produce a decrease in heart rate and in the oxygen needs of the myocardium, or heart. These drugs are commonly used for treating high blood pressure, angina or arrhythmias.

blood pool imaging:
A commonly used diagnostic test in which one performs radiolabeling of the blood components (blood pool labeling), and then makes a ‘movie’ of the beating heart to evaluate the squeezing power of the heart chambers. The technique measures the change in blood volume in the heart chambers during the heart’s beating.

blood volume:
the amount of blood circulating throughout the body in the vascular system. Nuclear scans can show the changes in blood volume in the heart chambers and determine the squeezing power of the heart.

basal metabolic rate. This is determined from the oxygen composition of the body at rest.

bypass graft; see coronary artery bypass graft

beats per minute; used to define heart rate.

the tubes or airways for the lungs that lead from the trachea to the alveoli, the tiny sac-like structures in the lungs where gas exchange occurs.

bundle branch block:
An ECG change characterized by a delay in the spread of electrical activity in the left ventricular walls during contraction. Acute occurrence sometimes results from myocardial ischemia.


coronary artery bypass graft.

coronary artery disease.

the smallest blood vessels in the body that connect arterioles and venules.

of or pertaining to the heart.

cardiac function:
Heart (muscle) function. Refers to how well (or poorly) the heart is able to contract and pump blood throughout the body. Several different tests, such as nuclear cardiac imaging and echocardiography, are performed to study different aspects of heart function.

cardiac mortality:
death due to cardiac cause.

cardiac catheterization:
passage of a thin, hollow tube called a catheter to the heart through a blood vessel for the purpose of measuring pressures inside the heart, obtaining cardiac blood samples, and/or imaging cardiac structures, such as coronary arteries, by injection of radio-opaque dye.

cardiac output:
the volume of blood pumped by the left ventricle over one minute

a disease or disorder affecting the heart muscle.

referring to the large arteries in the neck that carry blood to the brain and scalp.

catheterization, or to perform a procedure in which a catheter is introduced into a blood vessel or other hollow structure

A hollow, flexible tube for insertion into a body cavity, duct, or vessel to allow the passage of fluids or distend a passageway. Catheters of different types are used for a variety of procedures, including drainage of urine from the bladder through the urethra, or insertion through a blood vessel into the heart for diagnostic purposes.

to perform a procedure in which a catheter is introduced into a blood vessel or other hollow structure.

CHD (congenital heart disease):
a type of defect or malformation of one or more structures of the heart or blood vessels that occurs before birth.

congestive heart failure

a white crystalline substance found in animal fats and oils, bile, milk, egg yolk, blood, brain tissue, , myelin sheaths of nerves, liver, kidneys and adrenal glands. Increased blood levels of cholesterol are a risk factor for the development of coronary artery disease (CAD).

congestive heart failure (see CHF):
a malfunction of the heart muscle in which the heart doesn’t pump as much blood as the body needs. The failure of the heart to maintain adequate circulation of blood can leadsto retention of fluid in the body, which is described as “congestive” heart failure.

encircling in the manner of a crown; in cardiology this refers to the arteries of the heart and, by extension, to related diseases, defects or malfunctions of the heart.

coronary artery bypass graft (CABG):
vein or artery grafted surgically to permit blood to travel from the aorta to a branch of the coronary artery at a point past an obstruction, or blockage.

coronary artery disease (CAD):
usually refers to atherosclerosis, or the atherosclerotic narrowing of the major coronary arteries, though can involve a number of other disease processes that affect the coronary arteries.

coronary stenosis:
narrowing or constriction of a coronary artery.


referring to the diagnosis, or identification, of a disease or disorder. Nuclear cardiology is a tool used to diagnose the presence and extent of coronary and other heart diseases and disorders.

referring to the period of time during the heart beating cycle in which the ventricle(s) relax and fill with blood. See systole.

the spontaneous mixing of the molecules of two or more substances from an area of high concentration to low, resulting from random thermal motion. In scientific literature, we describe tracer diffusion across cell membranes.

An agent for pharmacological (or chemical) stress testing. This agent dilates blood vessels in the heart, which may be used to demonstrate regional differences in blood flow caused by blocked coronary arteries. For example, blood flow down a normal artery may increase to several times the normal flow after dipyridamole, while it may not increase at all if the artery has a significant blockage (stenosis). In this way, pictures that depict the amount of blood flow may show regional differences and suggest significant coronary artery blockages.

An agent for pharmacological (or chemical) stress testing. Also used for improving the functioning of a failing heart. In stress testing, Dobutamine produces changes similar to exercise – increase in heart rate and cardiac output. In this manner, it stresses the heart and may demonstrate limitations in blood flow during stress.

altered or impaired functioning of an organ, such as the heart.

the sensation of shortness of breath.



Or echocardiogram, a test which uses high-frequency sound waves to image the heart and surrounding tissues

the process of using high-frequency sound waves to image the heart and surrounding tissues, to diagnose and assess the severity of heart defects or disease.

ejection fraction.

ejection fraction:
measure of cardiac function; the percent of the ventricular blood volume that is ejected in one cardiac contraction. This tells the severity of dysfunction of the heart. Typically, normal ejection fraction is 50% or more. Abbreviated as EF.


a graphical record of the electrical activity in the heart during the cardiac cycle, abbreviated as both ECG and EKG.

exercise tolerance testing:
a type of stress test, in which the patient exercises on a treadmill, bicycle, or other equipment while heart activity is monitored by an ECG. This test is often combined with injection of radiotracers at peak exercise to obtain pictures of the heart (myocardial perfusion imaging). See pharmacologic stress testing .


FDG (fluorodeoxyglucose):
Fluorine-18 labeled deoxyglucose, a radiotracer used for studying glucose metabolism in various organs. Heart glucose metabolism is altered in some heart conditions, and images with a PET camera can show this. These techniques can be important in the assessment of viability of the heart muscle.

First Pass Imaging:
A nuclear imaging technique of the heart, in which heart function is studied while a radiotracer is injected into a vein in the forearm or in the neck of a patient. This technique is especially useful for studying the right side of the heart.


Gamma Camera:
A specialized type of imaging equipment that can obtain images of the heart and other organs after injection of a radiotracer. By detecting the gamma rays emitted by radioisotopes, these cameras can provide information which can be converted into pictures of the heart and other organs by highly sophisticated computers.

Gated (electrocardiogram gated):
A technique in which the pictures of the heart obtained by a gamma camera are linked to the electrocardiogram in a way which allows the creation of a moving picture of the heart, which can then be used for studying the heart’s squeezing power.

Gated SPECT:
A technique for obtaining three-dimensional pictures of the heart after injection of a radiotracer, where the heart can be seen contracting and relaxing. See SPECT.


the red pigmented protein complex found in red blood cells that functions to carry oxygen from the lungs to the tissues of the body.

decreased blood flow to an organ or tissue.

decreased blood pressure below normal levels.

decreased blood volume below normal.

reduction of oxygen level in the blood below normal.

reduction of oxygen level in tissues below normal.


in vitro:
in the laboratory or in the test tube outside a living organism.

in vivo:
within a living organism.

nsufficient blood flow to an organ (such as the heart), as can be seen when blood vessels have arteriosclerotic blockages.

ischemic heart disease:
a form of heart disease resulting primarily from myocardial ischemia (decreased blood supply to the heart) due to atherosclerosis of arteries.




left anterior descending coronary artery.

left bundle branch block.

left ventricular ejection fraction (LVEF):
a measure of the pumping function of the left ventricle, the main pumping chamber of the heart (see ejection fraction). LVEF is an important measure of the severity of heart muscle dysfunction, and can be readily determined by nuclear cardiology techniques.

left ventricular function:
function of the main pumping chamber of the heart (left ventricle), which receives blood from the left atrium and pumps it out into the systemic circulation through the aortic valve.

the open, inner space of an artery, which is studied in nuclear cardiology by injecting a radioisotope, and then taking a scan or picture with a gamma camera.


the process of the chemical reactions at the tissue level

MIBI (methoxyisobutyl isonitrile, sestamibi or Cardiolite):
a compound that is labeled with Technetium-99m and is absorbed from the circulation by heart muscle, allowing for the study of myocardial perfusion or blood flow to the heart using a gamma camera.

MUGA (Multiple Gated Acquisition Test):
a radionuclide test of myocardial performance, also known as equilibrium angiocardiography (ERNA) or radionuclide ventriculography (RNV) or blood pool imaging.

myocardial ischemia:
condition in which the blood supply to the heart is decreased below its needs

myocardial infarction (Ml):
damage to the heart muscle caused by blockage of one or more of the coronary arteries. See acute myocardial infarction.

myocardial perfusion imaging:
An imaging technique for studying the blood flow to heart muscle at rest or with exercise or pharmacological stress. This is commonly performed using radiotracers and a gamma camera to image the heart.

the muscular wall of the heart.


relating to the nucleus of the atom. Commonly used to describe radioisotopes and their use.

nuclear cardiologist:
a physician who is specially trained to perform and interpret nuclear tests for studying the cardiovascular system.

nuclear cardiology:
a specialty of cardiology that uses radioisotopes for diagnostic and therapeutic purposes.



percutaneous transluminal coronary angioplasty (PTCA):
compression of an arterial plaque by inflating a balloon catheter to dilate (expand) the vessel and clear the obstruction.

flowing over or through, as in blood flow through the organs and tissues of the body. See perfusion scan.

perfusion scan:
a test to determine the status of blood flow to an organ. Myocardial (heart) perfusion scans are done to determine the presence of coronary artery disease or heart muscle scarring.

the tough, non-elastic membrane surrounding the heart that attaches to the great vessels and other anatomical structures.

inflammation of the pericardium.

PET (Positron emission tomography):
A type of nuclear imaging in which radioisotopes that emit positrons are used. This requires a specialized type of imaging equipment called a PET camera. A wide variety of positron imaging radiotracers are used to study the structure and function of various organs.

pharmacologic stress test:
a test of heart function using medications such as adenosine, dipyridamole or dobutamine, often done in patients who are unable to exercise to an adequate level, or who have other conditions (such as LBBB that can make exercise testing less accurate). See exercise stress test.

the functions of a living organism or any of its parts or organ system. Disease results from the abnormalities in the anatomy, physiology or both of an organ system.
Whereas abnormalities of the two often coexist, abnormalities in anatomy may not always result in abnormal physiology and physiological abnormalities may sometimes exist without any anatomical abnormalities. This relationship is exemplified by the relationship between coronary angiography and nuclear myocardial perfusion imaging. Coronary angiography shows the presence of narrowing of the coronary arteries. Whereas nuclear myocardial perfusion imaging shows the degree and extent of impairment of myocardial blood flow under conditions of stress and at rest. The myocardial perfusion may not be affected by the presence of anatomic coronary artery disease under certain circumstances, whereas under certain other circumstances even relatively minor or insignificant appearing coronary angiographic abnormalities may result in severe perfusion abnormalities. A complete assessment of disease process generally requires evaluation of both anatomic and physiological abnormalities.

the liquid portion of the blood. (Plasma can be colored; jaundice for example)

post-Ml (myocardial infarction) angina:
angina occurring from 1 to 60 days after an acute myocardial infarction (heart attack).

pertaining to the prognosis, or prediction of the likelihood of a future event. In cardiology, generally refers to a heart attack, cardiac arrest, bypass surgery, or angioplasty. Nuclear imaging tests are important prognostic tests in patients with heart disease.

percutaneous transluminal coronary angioplasty.


the process of determining a deviation from normal in terms of percentages (or other specific measures), as compared to a qualitative determination, where a deviation may be defined as mild, moderate or severe.


elements that are spontaneously decaying because of unstable atomic structure. During the process of radioactive decay, they emit particles that can be used for diagnostic imaging or for therapeutic purposes.

The process of “tagging” the blood or chemicals with a radiopharmaceutical.

radionuclide test:
A diagnostic test in which a radioactive substance is injected into the bloodstream and the radioactivity emitted is detected by a gamma camera.

a pharmaceutical that incorporates a radioisotope. Also called medical isotope. Different radiopharmaceutical drugs are used for diagnostic imaging of the heart and other organs, and for therapy of cancers and other diseases. Below is a list of radiopharmaceuticals commonly used in nuclear cardiology.

Thirty-seventh element in the periodic table. The radioactive form of this element is known as Rubidium-82 or 82Rubidium. Rubidium-82 is used for studying myocardial perfusion or blood flow to the heart with a PET camera.

A radioisotope or a radiopharmaceutical used in medicine.

the recurrence of a stenosis after initial successful treatment with angioplasty or another catheter-based technique.

restoration of normal blood flow to the myocardium, or heart, by surgical (CABG) or percutaneous means, (through the skin, such as PTCA or with removal or reduction of an obstruction.


In nuclear cardiology, this refers to the pictures or images of the heart obtained by a gamma camera.

Sestamibi (methoxyisobutyl isonitrile, MIBI or Cardiolite)

SPECT (Single photon emission computed tomography):
A nuclear imaging technique for obtaining three-dimensional pictures of the heart after injection of a radiotracer, which is taken up by the heart. This technique is used commonly for the diagnosis of heart disease.

a narrowing or blockage of an artery or valve.

An increased demand on any organ. In cardiology, this refers to a condition of increased cardiac (heart muscle) work, which is accompanied by a need for increased blood flow to the heart. This can be accomplished with exercise or during injection of certain pharmacological stress agents.

stress testing:
This is a procedure used for detecting the presence of heart disease, or for assessing the severity of heart disease in those with known heart disease. Cardiovascular stress is brought about by exercise (usually by treadmill or bicycle) or by the administration of certain medications such as adenosine, dipyridamole or dobutamine. Sometimes emotional or mental stress testing is also used for studying heart function.

referring to the period of time during the heart cycle in which the ventricles pump blood through the aorta and pulmonary artery. See diastole.


Teboroxime: (Cardiotech)
a compound that is labeled with Technetium-99m and is absorbed from the circulation by heart muscle, allowing for the study of myocardial perfusion or blood flow to the heart using a gamma camera.

Forty-third element in the periodic table. The radioactive form of this element is referred as Technetium-99m, 99mTechnetium, or Tc-99m. This radioisotope can be incorporated into a number of different compounds, such as sestamibi or tetrofosmin, for studying different organs, including the heart. This is the most commonly used radioisotope in nuclear medicine.

a person who applies scientific knowledge in a specialized field or process. A nuclear cardiology technologist is a specialized healthcare professional who works directly with patients during an imaging procedure and works closely with the nuclear medicine physician and/or cardiologist


Teboroxime: (Cardiotech)

Tetrofosmin (ethoxy-ethyl phosphinoethane, Myoview):
a compound that is labeled with Technetium-99m and is absorbed from the circulation by heart muscle, allowing for the study of myocardial perfusion or blood flow to the heart using a gamma camera.

Eighty-first element in the periodic table. The radioactive form of this element is referred as Thallium-201, 201Thallium or Tl-201. Thallium-201 chloride is used in studying myocardial perfusion or blood flow to the heart.

through the skin.

the injection of whole blood or blood products into the blood stream.


unstable angina:
angina or chest pain, that occurs at rest, occurs with exertion for the very first time, or has accelerated (become more frequent, longer in duration, or brought on more easily than before).


pertaining to blood vessels or indicative of a copious blood supply

the decrease in diameter of a blood vessel, such as an arteriole, resulting in restricted blood flow to an organ or portion of the body

the increase in diameter of a blodd vessel, such as an arteriole, resulting in an increase inblood flow to an organ or portion of the body

a blood vessel that carries blood toward the heart; veins usually carry deoxygenated blood