Chest pain that feels like a pressure or squeezing in the chest. Angina may be associated with heart attack, but it can also be due to many other conditions or factors, such as overexertion.


A condition in which an artery wall thickens as the result of a buildup of plaque, which consists of fatty materials such as cholesterol.

Atria (Atrium, plural)

Hollow heart chambers located at the top of the heart on the right and left sides. Atria work with the lower heart chambers, or ventricles, to pump blood through the heart.

Blood clot

A blood mass that forms when components of blood, such as blood platelets and proteins, stick together.

Cardiac nuclear stress test

A cardiac stress test that uses a tracer to measure blood flow to the heart both at rest and during stress. It is performed similar to a routine exercise stress test or using a pharmacologic agent, and provides detailed images that can be used to diagnose and assess the significance of coronary artery disease (CAD).


A substance found in certain foods such as eggs, meat, and dairy products. There are two types of cholesterol: "bad" cholesterol, or low-density lipoprotein (LDL), which increases plaque deposits inside the arteries. "Good" cholesterol, or high-density lipoprotein (HDL), helps carry fat away from artery walls.

Coronary Arteries

Blood vessels that supply the heart with blood, oxygen, and vital nutrients.

Coronary Artery Disease (CAD)

Also referred to as coronary heart disease. This condition is a result of the build-up of plaque, a material made of fat, cholesterol, and other substances found in the blood. When plaque builds up over time, it can narrow the arteries, reducing normal blood flow to the heart. This narrowing can prevent the heart from pumping blood efficiently, which may cause many symptoms, such as chest pain. If not treated, CAD can lead to serious heart conditions, including heart attack.


A disease in which the body doesn't make enough insulin or use it properly, leading to a high level of glucose (sugar) in the blood.


This device measures the electrical activity of the heart, how fast the heart beats, and whether the heart rhythm is regular or irregular. It is used during a stress test to help detect whether CAD may be likely.

Exercise stress test

A diagnostic test that helps detect any potential problems that may be due to CAD. Your heart rate is measured while you walk or run on a treadmill or pedal a stationary exercise bike. When you exercise, your heart works harder and beats faster. This test can show potential signs of CAD, including abnormal changes in heart rhythm, electrical activity, heart rate, and blood pressure.

Heart attack

Occurs when a blood clot forms in an artery, cutting off blood and oxygen to the heart muscle, resulting in damage to that portion of the heart. Symptoms may include chest pain, nausea, sweating, shortness of breath, palpitations, vomiting, and dizziness.

Heart failure

Occurs when the heart can't pump adequate blood to the body due to CAD. Symptoms include shortness of breath, fatigue that increases with activity, and swelling in the feet, ankles, legs, and abdomen.

High blood pressure

Also known as hypertension, high blood pressure is when the pressure of the blood pumping through arteries is consistently too high.

Myocardial perfusion imaging (MPI)

Also referred to as a nuclear stress test, this is a technique in which radionuclide tracers are used to evaluate blood flow to the heart in order to diagnose and assess the significance of coronary artery disease (CAD).

Nuclear cardiologist

A doctor who specializes in taking and interpreting nuclear images of the heart. A nuclear test of the heart involves injecting radioactive elements into the body, then taking pictures of it.

Pharmacologic agent

A biologically active substance applied pharmacologically to the body for therapeutic effects on one or more tissues or organs.

Pharmacologic stress test

A diagnostic test used for people who are unable to exercise on a treadmill during a cardiac nuclear stress test. A medical technician will inject a drug that makes the heart respond as if the person is exercising.


A substance that is made up of cholesterol and other materials that deposit on the artery walls and can build up over time, thickening the walls. Plaque may also narrow the artery wall, constricting the delivery of oxygen, blood, and nutrients to the heart.

Radioactive isotope imaging tracer

Substances used for different medical procedures to help detect abnormalities in the body. For example, a tracer is used during myocardial perfusion imaging, which shows the blood flow to the heart and helps doctors see whether a patient has heart disease.


A doctor who specializes in taking pictures of the inside of the body using X-rays or other types of energy, and interpreting them.

Stress test

The most common type of test to diagnose coronary artery disease. There are several types, including exercise stress tests and pharmacologic stress tests. Either by exercising on a treadmill or using a chemical injection, a patient’s heart is stressed and monitored to detect any signs of CAD.


An interruption of the blood supply to any part of the brain, caused by a blood clot. Strokes can cause damage and/or death to a portion of the brain.


Substances used for different medical procedures to help detect abnormalities in the body. For example, a tracer is used during myocardial perfusion imaging, which shows the blood flow to the heart and helps doctors see whether a patient has heart disease.


Two large right and left hollow chambers at the bottom of the heart, which collect and expel blood received from an atrium. Atria work with the ventricles to pump blood through the heart.


Read Lexiscan® (regadenoson) injection Full Prescribing Information (PDF - 193 KB)

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Lexiscan (regadenoson) injection is a prescription drug given through an IV line that increases blood flow through the arteries of the heart during a cardiac nuclear stress test. Lexiscan is given to patients when they are unable to exercise adequately for a stress test.

Important Safety Information
  • Lexiscan should not be given to patients who have certain abnormal heart rhythms unless they have a pacemaker.
  • Lexiscan can cause serious or fatal cardiac arrest, abnormal heart rhythms or heart attack.
  • Allergic reactions can occur after Lexiscan injection.
  • Drugs such as Lexiscan may cause an increase or decrease in blood pressure, especially in patients with certain heart and blood vessel disorders.
  • Lexiscan can cause breathing difficulties. Before receiving Lexiscan, tell your doctor if you have respiratory diseases, such as COPD (chronic obstructive pulmonary disease) or asthma. Tell your doctor about all medications you use to manage these conditions.
  • Lexiscan can increase the risk of seizures. Before receiving Lexiscan, tell your doctor if you have a history of seizures.
  • Lexiscan can cause stroke, which may be a result of an increase or decrease in blood pressure.
  • The most common side effects that occurred in clinical trials of Lexiscan were shortness of breath, headache, flushing, chest discomfort or chest pain, dizziness, nausea, abdominal discomfort, a metallic taste in the mouth, and feeling hot. Most common side effects began soon after receiving Lexiscan and went away within 15 minutes except for headache, which resolved in most patients within 30 minutes.
  • Avoid consuming any caffeine-containing foods and beverages or medicines containing caffeine, aminophylline or theophylline in the 12 hours before your scheduled heart scan.
  • Ask your doctor if you should stop taking any medications you usually take before the day of the test.
  • For women who are nursing, pump and discard breast milk for 10 hours after receiving Lexiscan.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088.