What is Cardiolite?

Cardiolite is a nuclear radioactive isotope termed Technetium Tc99m Sestamibi. Cardiolite is injected through an IV and it travels in the bloodstream and through the coronary arteries until it is picked up by the heart muscle cells. The areas of the heart that have an adequate blood supply pick up the tracer right away and more completely. Areas that do not have adequate blood supply pick up the tracer very slowly or not at all.

Cardiolite gives off a small amount of radiation that is detected with a nuclear scanning camera. A computer processes the information and produces the images of the radioactivity distributed in the heart.

If an area receives less blood than the rest of the heart (because of a blocked or narrowed artery), it will pick up a lower level of radioactivity and will show up as a lighter area, called a "defect."

Cardiolite is injected while you are at rest and while your heart is under stress. Rest and stress images are taken to allow doctors to compare how much blood flows through the heart muscle during stress and at rest.

The amount of radiation you will be exposed to is comparable to that from an X-ray or CAT (CT) scan. The half-life of Cardiolite is 6.02 hours. This means that half of the dose you are given will decay in 6.02 hours.

Generally, Cardiolite is cleared from your body in 24 hours by natural processes. You won't feel any different after you are injected with Cardiolite. Most patients experience no side effects. Occasionally patients have a metallic taste in their mouth.

What is a Cardiolite Stress Test and what does it show?

A Cardiolite Stress Test is a diagnostic nuclear imaging study that uses a radioactive tracer, called Cardiolite, to produce images of the heart muscle. When combined with stress either through exercise or use of a pharmacological agent, the Cardiolite scan helps determine if the heart muscle is getting the blood supply it needs.

As Coronary Artery Disease (CAD) progresses, the heart muscle may not receive enough blood when under stress (for example, when exercising). This often results in chest pain called Angina Pectoris. On the other hand, there may be no outward physical signs of the disease. If CAD is limiting blood flow to part of your heart, the Stress Test with Cardiolite may be useful in detecting the presence and significance of CAD.

A Cardiolite Stress Test consists of two parts, rest and stress:

  • Cardiolite will be administered by injection through your IV while you are at rest, and a special camera will take pictures of your heart.
  • Cardiolite will be administered to you one other time by an IV injection during the stress portion of the test, and additional pictures will be taken of your heart.

This allows the doctor to compare the amount of blood flowing through the heart muscle during stress and at rest.

How do I prepare for the test?

  • Do not eat or drink for 4 hours prior to the test--this includes caffeine! The pictures of your heart are clearer when the stomach is not full. If you are diabetic or need to eat/drink with your medication, get special instructions from your doctor.
  • Avoid any strenuous physical activity on the day of the test because you will need to exert yourself maximally if you are doing an exercise test.
  • Bring busy material. You will have periods of waiting throughout the test so bring a book, newspaper, knitting, etc. to keep you busy.
  • No smoking 4 hours prior to the test. Smoking may interfere with the test results.
  • Wear a comfortable two-piece outfit and comfortable shoes. A hospital gown may be provided and men may be asked to take off their shirt. Slacks or shorts are preferred if you are exercising. You should wear comfortable footwear appropriate for brisk exercise if you are doing an exercise test.
  • Do not wear oils or lotions before your test. Small sticky patches (electrodes) will need to stick to your chest.
  • Do not take the following heart medications on the day of your test unless your physician tells you otherwise or if the medication is needed to treat chest discomfort:
  •  Isosorbide Dinitrate (for example: Isordil, Sorbitrate)
  • Isosorbide Mononitrate (for example: Ismo)
  • Nitroglycerin (for example: Deponit, Nitrostat)
  • Your physician may also ask you to stop taking other heart medications on the day of your test. If you have any questions about your medications, ask your physician.

NOTE: Do not discontinue any medication without first talking with your physician

What happens during the test?

When you enter the Stress Testing room, the Cardiology Tech/Nurse will have you sign a consent form and he/she will make sure you understand the test. An IV will be started in a vein in your arm. The Nuclear Medicine Tech will put your first injection of Cardiolite through the IV. You will wait in the waiting room for at least 45 minutes to let the Cardiolite circulate to your heart.

Once your waiting period is over, the Nuclear Medicine Tech will put you under the camera for about 15 minutes. You will lay on your back on a table with your hand behind your head. It is important for you to remain very still while the images are being taken. The camera will move about you but never come in contact with you during the scan.

Following the completion of the scan, you will be escorted to a Stress Testing room. The Cardio Tech/Nurse will have you lay on a stretcher while he/she hooks you up to equipment. A bag of normal saline will be attached to your IV. The chest will be abraded with alcohol and a cloth. If you have a hairy chest, patches will be shaven. Ten electrode patches are placed on your chest and torso. Wires will be attached to the electrodes in order to monitor your heart rate and EKG. A resting EKG and blood pressure are recorded. Once the Cardiologist arrives in the room, your test will begin.

Lexiscan Stress Test

For patients who are unable to exercise adequately on the treadmill, the drug Persantine may be given to Lexiscan stress test is a nuclear stress test that is only performed at the prescription of a physician. This is a non-evasive test aimed to detect heart problems and diseases. Your doctor will prescribe this test in case you are experiencing chest discomfort. The test may also be prescribed to monitor heart function in those who are undergoing treatment for heart diseases.

Preparation Required For a Lexiscan Stress Test

Before the Lexiscan stress test is performed, some preparation is required. Do not consume any caffeine at least 24 hours prior to the test. Do not eat or drink anything 4 to 6 hours before the test. If you have been taking any medications, do not take them prior to the test. You can bring your morning medications with you to consume them after the test.

Procedure

There are two parts to a Lexiscan stress test: the rest portion and the exercise portion. For the rest portion, a radioactive tracer is injected into your arm through the IV. After 30 to 60 minutes, the process of imaging will begin. A nuclear camera will be placed on your chest area and images are taken for the next 15 to 20 minutes. The Lexiscan stress test procedure is fairly simple in the resting phase. For the exercise portion, you will be asked to exercise on a treadmill. A nurse would attach EKG electrodes to your chest to monitor your heart rate. In case you are incapable of performing actual exercise, the drug Lexiscan is administered to simulate stress on the heart. Your heart rhythm will then be monitored for the next few minutes. Your blood pressure will also be monitored throughout the exercise portion. Midway through the exercise portion, a second round of radioactive tracer is injected into your body. Your heart rate and EKG will be monitored for another few minutes after administering the drug.

Side Effects

The Lexiscan side effects would range from mild allergies from the radioactive tracers to increased blood pressure due to the stress induced by exercise. Lexiscan stress test results are different for different labs and the interpretation is best performed by the doctor. The test may take several hours to complete, and since it is performed on an empty stomach, most doctors prefer doing the test in the morning.