This procedure gives your physician the ability to view the flow of blood to the heart muscle. This helps them determine if your heart is receiving enough blood, if you have coronary artery disease (CAD) and if additional testing is required.
How does MPI Work?
There are two parts to this test that can be done in either order.
Part 1: The heart is stressed - the arteries are dilated or enlarged by means of exercise or by a prescription medication that helps create an effect on the heart similar to exercise. The healthier the coronary arteries are, the more dilated they will become. Once the coronary arteries are enlarged through dilation, a trace amount of radioactive imaging agent is then injected. A special camera is then used to take images of your heart. These images will show if there is any part of your heart that is not getting enough blood.
Part 2: Two sets of images of your heart will be taken by a special camera – one when your heart is stressed and the other when it is at rest. These images will take about 10 minutes while you are relaxing comfortably on your back with your arms extended above your head. Both sets of images will be compared and checked for differences. If you have healthy coronary arteries, there will be little to no difference between images, however if you have narrowed arteries there will be differences.
*The radiation amount you will receive during this test is the same or less than what you would receive during a normal x-ray and your body quickly gets rid of the radioactive imaging agent through natural means.
How Should I Prepare for this Test?
- Talk to your physician to find out if you should stop taking any medications prior to this test (if you’re diabetic and take insulin or oral hypoglycemic medications you’ll have special instructions to follow)
- Let your physician know if you have a history of wheezing, asthma or chronic lung disease
- Do not eat or drink for 3 – 6 hours prior to this test
- Do not consume caffeinated products for at least 24 hours prior to this test
- Do not apply creams, powder or lotions to your chest area the day of this test
- Be sure to wear comfortable clothes and shoes for brisk exercise on a treadmill
What if I Need Medication to Dilate My Arteries?
If you are not able to exercise briskly on a treadmill, you will be given a dilating medication for approximately 4 – 6 minutes. A blood pressure cuff will be on one arm while a small intravenous needle will be inserted into the other arm. Small round pads with wires attached leading to an electrocardiograph (ECG) will be carefully attached to your chest. Your physician will be continually monitoring your heart throughout this process. You may feel effects that mirror those of exercise including flushing, chest pain or pressure and shortness of breath. Most of these feelings will stop once the infusion has ended.