Types of Stress Tests

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

A Sestimibi Stress Test is a diagnostic xray study that uses a radioactive tracer, called sestimibi, or cardiolite, to create pictures of the heart muscle. When combined with stress either by exercising or by use of a medicine, the sestimibi scan helps determine if the heart muscle is getting enough blood.

As Coronary Artery Disease (CAD) progresses, the heart muscle may not get enough blood when under stress (for example, when exercising). This often results in chest pain called angina. On the other hand, there may be no signs or symptoms of the disease. If CAD is reducing blood flow to part of your heart, the stress test with sestimibi may help show this.

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

• Sestimibi will be given through your IV while you are at rest, and a special camera will take pictures of your heart.
• Sestimibi will be given to you by IV one other time during the stress portion of the test, and then more 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.

What is Sestimibi (Cardiolite)?

Sestimibi (Cardiolite) is a radioactive substance(tracer). It is given through an IV. As it travels in the bloodstream and through the heart arteries, it is picked up by the heart muscle cells. The areas of the heart that have a good blood supply pick up the tracer right away and more completely. Areas that do not have a good blood supply pick up the tracer very slowly or not at all.

Sestimibi gives off a small amount of radiation that is seen with a nuclear scanning camera. A computer takes the information and makes a picture of the radioactivity picked up by the heart muscle.

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."

Sestimibi is given while you are at rest and while your heart is under stress (during exercise). Rest and stress images are taken. This will allow the doctor 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 about the same as that from an X-ray.
Generally, your body is able to break down and clear the sestimibi from your body in 24 hours. You won't feel any different after you are given sestimibi. Most patients experience no side effects. Occasionally patients have a metallic taste in their mouth.

How do I prepare for the test?

• For 48 hours before the test, do not drink or eat caffeine in any form (coffee, teas, chocolate, sodas or medications such as Anacin, Cafergot, or Excedrin), and do not take the medication pentoxifylline (Trental®).
• Eat a light, low-fat meal at least 2 hours before the test. Choose foods such as fruit, juice, and cereal with skim milk, toast, English muffins or bagels with jam or jelly, but no butter. 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 hard physical exercise on the day of the test because you will need to exercise your hardest if you are doing the exercise stress test.
• You will have some waiting times during 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. You should wear slacks or shorts if you are exercising. Wear comfortable shoes that are good 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.
• Be sure to tell your doctor if you take beta-blocker medication such as metoprolol (Lopressor®), atenolol (Tenormin®), propranolol (Inderal®) or nadolol (Corgard®). 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 stop any medication without first talking with your physician.

What happens during the test?

The Cardiology Tech/Nurse will explain the test, answer any questions you may have, and then ask you to sign a consent form for the test. An IV will be started in your arm. The Nuclear Medicine Tech will give the first dose of sestimibi through the IV. You will wait in the waiting room for at least 45 minutes to let the sestimibi travel to your heart.

Once your waiting time 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 pictures are being taken. The camera will move about you but never actually touch you during the scan.

After the scan, you will be lead to a stress testing room. The Cardio Tech/Nurse will have you lay on a bed while he/she hooks you up to a heart monitor. A bag of normal saline will be attached to your IV. The chest will be prepped. Ten electrode patches are placed on your chest and abdomen area. Wires will be attached to the electrodes in order to monitor your heart rate and EKG. A blood pressure cuff will be placed on your arm. A resting EKG and blood pressure are recorded. Once the Cardiologist arrives in the room, your test will begin.

Dipyridimole (Persantine) Sestimibi (Cardiolite) Stress Test

Patients who are unable to exercise on the treadmill may be given the drug dipyridimole. This medicine produces an effect on the heart similar to exercise. It works by dilating or widening the heart arteries in order to increase blood flow to the heart. During the test, you will be lying on the bed. The drug dipyridimole will be given through your IV. The dipyridimole dose you will be given is based on your body weight. You may feel warm and flushed from the medicine. You may also feel some chest pressure, headache, dizziness, nausea or shortness of breath. Some patients may feel a burning or stinging sensation at their IV site because Dipyridimole is more acidic than your blood. These symptoms are perfectly normal, but make sure to let the Cardiologist know how you feel. The dipyridimole is given over 4 minutes. Two minutes will pass. Then you will be given another dose of the tracer. When the test is finished you may be given the drug Aminophylline to reverse any symptoms from the dipyridimole.

Dipyridimole is not used in patients who have a hypersensitivity or are allergic to this drug. Dipyridimole can also cause bronchospasm so your doctor may order a different test for you if you have a lung condition that would be made worse by using dipyridimole.

Adenosine Cardiolite Stress Test

An adenosine sestimibi stress test is similar to a dipyridimole sestimibi stress test, using a different dilating medication, Adenosine.

What is Adenosine?

Adenosine is another medicine used in nuclear stress testing. Adenosine works similar to that of dipyridimole. It also increases the blood vessel size of the coronary arteries (arteries that feed the heart) in order to increase blood flow to the heart. Any side effects you may have are generally mild and last only a short time. Side effects include: chest pressure, dizziness, shortness of breath, flushing, headache, lightheadedness, nausea, or numbness. Adenosine is not used in patients who have a hypersensitivity to this drug and in patients who have lung diseases (e.g., asthma).

If you do develop side effects to Adenosine that do not disappear quickly, the Cardiologist will use the drug Aminophylline to reverse your side effects.

Dobutamine Sestimibi Stress Test

For patients who are unable to exercise on the treadmill, the drug Dobutamine may be given to produce an effect on the heart similar to exercise. During the test, you will be lying on the bed. The drug Dobutamine will be given through your IV. The Dobutamine dose you will be given is based on your body weight. Dobutamine is given slowly through your IV with a special pump, and the dose is increased every 3 minute. The Dobutamine is turned off after it has been running for about 12 minutes. The Dobutamine may be turned off early if:

• You exceed a "target" heart rate based on your age
• The Cardiologist or Cardio Tech/Nurse detects abnormal changes on your EKG
• You have side effects such as shortness of breath, chest pain, chest tightness, dizziness, etc. that do not let you to exercise any longer.
• Your blood pressure goes up too high

The dobutamine is given longer than the 12 minutes if your heart rate has not reached the predicted "target" heart rate. You may be asked to do some arm or leg raises or hand squeezing exercises while laying on the bed. These all help to increase your heart rate. Sometimes the Cardiologist will have the Nurse give you a drug called Atropine through your IV if your heart rate has not increased enough. You will be given one more dose of the tracer Sestimibi once your heart rate is at or has exceeded your "target" heart rate. Sometimes the Cardiologist will have the Nurse give you a drug called Lopressor through your IV if your heart rate is taking a long time to decrease.

6/16/2008