Stress Testing

What Is a Stress Test, and Why Am I Having One?

A stress test is a diagnostic screening tool to see how well the heart performs with the added demands of physical exertion, This can be done with the use of a treadmill or, for those unable to walk because of severe arthritis, amputation or severe lung problems, a medication is injected into a vein that speeds up the heart and mimics exercise. As your body works harder by exercise or medication infusion, it needs more oxygen. In turn, your heart must pump more blood to nourish the heart muscle and help it meet the demands of exertion. If it is unable to meet these demands due to blockage or severe narrowing in one or more of the coronary arteries, you may develop changes in your EKG tracings and/or you may complain of chest discomfort or inappropriate shortness of breath. 

At SJH Cardiology Associates we perform several types of stress tests: 

• Basic ETT ( Exercise Treadmill Test) - analyzes the electrical activity of the heart (EKG tracings) during and immediately following exercise 
  
• Stress Echocardiogram - analyzes electrical and mechanical response of the heart to physical exercise by use of EKG tracings and cardiac ultrasound imaging 
  
• Dobutamine Stress Echocardiogram - analyzes electrical and mechanical response of the heart by use of EKG tracings and cardiac ultrasound imaging during and immediately following intravenous infusion of Dobutamine 
  
• Nuclear Stress Test (see separate procedure) 

Your doctor may want you to have a stress test for a number of reasons. You yourself may have significant risk factors for developing coronary artery disease such as high blood pressure, high cholesterol, diabetes, obesity and a family history of heart disease. Or, during an office visit you may have confided to your doctor that you had a little discomfort in your chest, throat or arm while walking, climbing stairs or in stressful situations. You may have unexplained fatigue and shortness of breath or been experiencing irregular heartbeats or "palpitations". The stress test would be used as a screening tool to rule out any significant coronary artery disease in these instances. In the event that you've had "work" done on your heart such as angioplasty with or without stent placement or open heart surgery such as bypass grafting (CABG), your doctor may want a periodic evaluation to assess the effectiveness of the procedure. 

Is there any preparation or a stress test, how long does it take and when can I expect the results? 

Preparations for the exam include: 

• You may be asked to stop certain medications called "beta blockers" for 24-48 hours prior to the exam on the advice of your cardiologist or the doctor that referred you to us. These medications tend to slow the heart rate and may be counter productive in trying to increase your heart rate while walking on the treadmill or receiving the Dobutamine infusion.
• You may eat a "light meal" at least 2 hours before the exam. Patients taking insulin should check with the ordering physician to see if a dose adjustment maybe needed. Oral agents maybe taken with a light breakfast or after the test with your first meal. 
• If you will be walking on the treadmill wear comfortable clothing and shoes suitable for exercise. 

You should allow 1 1/2 to 2 hours for the exam, including the preparation, echo imaging and stress test. 

The cardiologist supervising the exam will be able to give you a brief preliminary report before you leave. However, the official result may take a few days to complete. It will be sent to your doctor who will review the results in depth with you. In the event that the exam is "positive", meaning that we are suspicious you may have a significant blockage in one or more of your coronary arteries further testing, called a cardiac catheterization, may be needed. This may be scheduled at the time of the abnormal stress test. 

What can I expect when I'm taken into the testing area? 

You will be asked a brief medical history by the nurse or echo technician. You will be asked to sign a consent form giving us permission to perform the test. After a detailed explanation of the exam is given to you, you will be asked to remove all clothing from the waist up. Females will be provided with a gown. The chest is then prepared for the placement of 10 sticky discs called electrodes. A belt with the EKG recording module will be strapped to your waist. Baseline blood pressure and EKG tracings are taken both in the lying and standing positions. If you are having a basic ETT, the supervising cardiologist will be introduced and the exercise portion of the test will begin. 

If you are having a stress echo or a Dobutamine stress echo, the technician will ask you to lie on your left side with your left arm under your pillow so a complete baseline echocardiogram to your chest and a can be performed. A gel will be applied to your chest and a transducer will send and receive sound waves to and from the heart so images can be visualized on a video monitor. These images will assess the size, the pumping ability and the valvular function of your heart at rest. Particular attention is paid to the movement of the walls of the heart. The supervising cardiologist will be introduced, he will review your images and the exercise or medication infusion will begin.

For both the ETT and the stress echo, a treadmill will be used for exercise. It will begin at a slow "warm up" speed and a slight elevation. Every three minutes, the treadmill will increase its speed and elevation forcing the heart to work harder to provide the muscle with the blood and oxygen it needs.

Your EKG will be monitored continuously and your blood pressure taken every few minutes into each stage.

You will be asked to continue to go as far as you are able or at least until your "target" heart rate is achieved which is based on your age. The farther you are able to go, the better diagnostic tool this test becomes. With the standard ETT, when the treadmill is stopped, your EKG and blood pressure will be monitored for an appropriate "recovery" time. If you are having the "stress echo", immediately after stopping the treadmill you will be asked to move directly to the exam table, lay on your left side with your left arm under your head so that post exercise images of your heart can be obtained with ultrasound. 

With the Dobutamine stress echo, an intravenous line will be placed preferably in your hand or arm. A tourniquet is applied, the area cleansed with alcohol and a small puncture is made into the vein with the IV catheter. After the presiding cardiologist has viewed your baseline echo images, the Dobutamine infusion begins at a "low" dose. Every 3 minutes the Dobutamine dose will be increased, making the heart work faster and harder until your "target" heart rate is achieved, based on your age.

You may be asked to squeeze a ball or do leg lifts to help increase your heart rate as well. At each 3 minute stage your blood pressure will be taken by the nurse and ultrasound images digitally stored by the technician. The cardiologist continually monitors your EKG tracings. The medication may make you feel anxious, your heart will pound and you may develop a little tremor or shake which will subside soon after the medication is discontinued. You will be periodically questioned as to how you are feeling, whether you are having any chest discomfort or inappropriate shortness of breath. 

After the completion of your stress test, the electrodes are removed from your chest, the IV discontinued (if used) and you will be able to dress, Any questions you might have will be attempted to be answered to your satisfaction before you leave.