Stress Testing/Stress Echocardiogram
A stress echocardiogram is a non-invasive test that combines two tests--a treadmill stress test (TST) and an echocardiogram (ECHO). This test is used to see how the heart muscle contracts during rest and during exercise. A stress echo is made up of three parts: a resting echo study, a stress test, and a repeat echo while the heart is beating fast. (See also Drug Induced Stress Test or Nuclear Stress Test--below)
Do not eat, drink, or smoke four hours prior to your appointment (except for water). Your last meal should not include any caffeine or alcohol. Please wear the appropriate clothing and not wear dresses, skirts, one piece outfits, stirrup pants, panty hose, girdles, or tights. Do not use any creams, lotions, oils, or powders on your body for 48 hours prior to your appointment.
The test takes from 30-60 minutes. Prior to exercising, an echocardiogram is done by applying colorless gel to the chest and placing the echo transducer on top of it. You will also wear a blood pressure cuff to allow blood pressure monitoring. Recordings will then be taken from different parts of the chest to obtain several views of the heart. An echocardiogram is done again at peak heart rate by having the patient walk on a treadmill starting out very slowly but gradually increasing the speed and incline. Your blood pressure will be taken at each change. The patient will exercise from a few minutes up to 15 minutes depending upon his level of ability. The test will be stopped if the patient becomes too tired or has any symptoms such as chest pain. The cardiologist will be looking for changes in the EKG pattern and any symptoms that the patient may experience. At the peak of exercise, the treadmill will be stopped, and the patient will be instructed to lie down immediately on a bed so that a second echocardiogram can be taken to visualize the heart's motion with exercise. The resting echocardiogram done before the exercise and the stress echocardiogram done during exercise will be compared and analyzed.
Drug Induced Stress Test (Dobutamine)
This test is intended to evaluate how well the heart muscle and valves are working and how they function under stress as well as the size of the heart’s pumping chambers (ventricles). This test is used for patients who are unable to exercise on a treadmill. The heart is stressed by using an intravenous chemical called dobutamine. This medication increases your heart rate and enables the doctor to learn how your heart functions when it is "stressed" to work harder. The rise in heart rate increases the oxygen demand of the heart and helps to determine if the heart muscle is getting enough blood and oxygen.
Preparing for the Test
Do not eat or drink for 6 hours prior to the test, except for water. This will help prevent nausea which may occur with the infusion of dobutamine. Do not smoke at least 4 hours prior to the test. Do not apply lotions, oils or powders to the chest area. If you are currently taking any heart medications, check with your doctor. You may be instructed to take some medications with sips of water. Consult your doctor if you are diabetic. You may be asked to hold your insulin until after the test. Wear comfortable clothing.
The test takes about an hour. You will be asked to lie on an exam table. An IV will be inserted into a vein in your arm to allow injection of the dobutamine. You will be asked to remove clothing above the waist and put on a gown to help keep you warm and comfortable. Several small sticky patches (electrodes) will be placed on your chest to obtain a recording of your heart’s electrical activity (electrocardiogram). An echocardiogram is performed before, during and after the infusion of dobutamine. The technician will continue to record images of your heart as the rate gradually increases. The cardiologist will observe for any symptoms, irregular heart rhythms, and an inappropriate heart rate or blood pressure responses. Your blood pressure and EKG will be continuously monitored during the test. Your peak heart rate is usually reached in 12 to 15 minutes. At this time, the dobutamine infusion will be stopped. Your heart rate will begin to return to normal in 1 to 3 minutes. Once your heart rate has slowed, one more set of images will be recorded.
Nuclear Stress Test (Thallium)
A Nuclear Stress Test is similar to a standard exercise treadmill stress test, but provides the doctor with additional information by using an isotope (Cardiolite or Thallium) to evaluate coronary blood flow. This test will give the doctor the same information as a exercise treadmill stress test, plus indicate which area(s) of the heart is not getting enough blood and oxygen, how quickly the heart recovers after exercise, any irregular heart rhythms, and if the patient has had a heart attack in the past.
Patients who are unable to exercise will be given an injection of Persantine, a drug that will produce maximal heart rate with a minimal amount of exertion.
Do not eat or drink anything except water four hours prior to the test. Do not smoke at least four hours prior to the test. Do not apply any lotions, oils or powders to the chest area. Wear comfortable clothing (shorts or pants with shirt or blouse) and walking or athletic shoes.
Besides the normal stress testing, an intravenous (IV) line will be placed in your arm to inject a small dose of the isotope at the peak of exercise as you walk on the treadmill. The isotope is not harmful to the patient or the heart. This test is performed in two phases with each phase lasting 30-60 minutes.
Upon completion of the stress test, you will be escorted to the imaging room and asked to lie flat on a stretcher for the first set of cardiac scans. It is essential that you remain as still as possible during the 45 minute scanning test.
There is an approximate three hour wait before the second set of images are taken. The technician will let you know the exact time phase two will begin. You may leave the office but may not have solid food until after the second part of the test is completed. You may have water, black coffee, or tea but sugar, cream, or artificial sweeteners are not permitted. Diabetics will be allowed a light meal during this waiting period. When you return, a technician will escort you to the imaging room and a resting scan of your heart will be done. It will take about 45 minutes to acquire this set of images.
Once all the imaging data has been obtained, it will be processed and the results read by the physician who performed the test.
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