Echocardiography uses sound waves to produce images of the heart and heart function. Stress echocardiography (or stress echo) allows doctors to study the wall motion of the heart’s pumping chambers before and after exercise. Stress echo can help determine whether or not certain areas of the heart muscle are getting enough oxygen-rich blood.
A stress echo is performed essentially the same as exercise stress testing, except that when the patient’s heart rate reaches a certain number, he or she is asked to step off of the treadmill or stationary bike and lie down. Patients who are too sick to exercise can be given a drug that has a similar effect on the heart as does exercise. Examples of the drugs that may be given are dobutamine and adenosine. This type of test is also called a dobutamine stress echo.
How It Works
Echocardiography uses high-frequency sound waves (also called ultrasound) to produce moving pictures of the heart. The sound waves are sent through the body with a transducer. The sound waves bounce off of the heart and return to the transducer as echoes. The echoes are converted into images on a television monitor to produce a one-, two-, or three-dimensional picture of the heart.
• One-dimensional (M-mode) echocardiography is one beam of ultrasound directed toward the heart. Doctors most often use M-mode echocardiography to see just the left side (or main pumping chamber) of the heart.
• Two-dimensional echocardiography, one of the most important diagnostic tools for doctors, produces a broader moving picture of your heart.
• Three-dimensional echocardiography allows spatial orientation of the structures in the heart with respect to one another and a more surgically-oriented view of the heart. It allows physicians to see the actual shape of the heart chambers rather than assuming the shape is normal, and this shape can affect the calculations for cardiac volume.
• Doppler echocardiography measures blood flowing through the arteries and shows the pattern of blood flow through the heart.
What To Expect Before the Test
Patients will receive protocols from their doctors regarding eating, drinking, and smoking prior to the test and regarding taking medication before the test, including insulin. Patients should not apply lotions or creams to the chest area on the day of the test. As with most hospital procedures, patients should bring their list of medicines.
What To Expect During the Test
The patient arrives for the examination in comfortable exercise clothing and shoes. The patient is instructed by the technician to exercise on a treadmill or stationary bike. When directed to by the technician, the patient lies down on the examination table. The technician applies a thick gel to the patient’s chest. The gel may feel cold; it does not harm the skin. The technician then uses the transducer to send and receive the sound waves. The transducer is placed directly on the patient’s chest over the heart. The technician presses firmly to move the transducer across the chest. For most of the test the patient is still; however, he or she may be asked to breathe in or out or to hold his or her breath briefly during the test. Most stress echoes take about 45 minutes; a dobutamine stress echo takes longer.
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Diag/disecho.cfm