Cardiac Stress Tests

The non-invasive stress tests have similarities and differences that make them more specific to the patients' situation. In other words the type of stress test your doctor recommends should be a direct reflection of your symptoms and situation.

The basic concept behind a stress test is simple: if there is a blockage in a coronary artery (the arteries that feed the heart) exercise will make the problem worse and doctors will be able to identify the issue.

The reason people with semi-blocked coronary arteries get symptoms with exercise is because exercise makes the heart work harder, which means it demands more oxygen, which means it needs more blood flow. If there is a partial blockage, the heart may not get the oxygen it needs and will result in either symptoms, like chest pain, or observable data, like EKG changes. Since the blockage may not be severe, the symptoms and signs may not be there during normal everyday life; they only appear with exercise.

There are different kinds of heart stress tests to choose from, the most common being the standard treadmill test. Be sure to wear comfortable clothes and shoes for all stress tests.

For the standard treadmill test a nurse will take the patient through an evaluation process. Multiple blood pressures will be taken with the patient lying down, sitting, standing and hyperventilating. The nurse will listen to your heart and breathing with a stethoscope.

EKG patches will be attached to the patients' chest, arms, and legs and many recordings of the heartbeat will be printed. A gritty, sandpaper like material will be used on the skin to assure a good EKG patch attachment. If the patient's male, there may be some hair removal involved.

Once all the resting data is complete, the nurse will put the patient on the treadmill. Most people have used a treadmill at some point, but not in the way you will during this test. The treadmill will be set to a certain protocol, which will dictate the speed and incline of the treadmill belt.

The most common protocol followed is called, the Bruce protocol. The belt will start at a slow pace of 1.7mph with an incline of 10%. It remains at this level for 3 minutes then increases to 2.3mph at 12% incline for another 3 minutes, then goes to 3.2mph at 14%, then 4.2mph at 16%, then 5.0mph at 18%, then 5.5mph at 20%, then finally 6mph at 22%. During each 3-minute phase the nurse will take a blood pressure and be monitoring your EKG readout.

This progression doesn't look hard on paper, but once you get past the third or fourth stage you'll really start feeling the incline. It's rare to see patients make it to the 7th stage, but if they do they are basically sprinting straight uphill. There is no 8th stage so the treadmill will continue cranking along in the seventh stage until the patient cries "uncle." No matter what the treadmill always wins.

When the patient's through exercising the nurse will monitor the recovery period. Once full recovery to baseline is accomplished the test is finished and the patient will leave and wait for the results to be read and evaluated. If there's a problem with the coronary arteries the EKG tracings will show the issue.

The standard treadmill procedure is most helpful for men with cardiac risk factors. It has a good chance of picking up any coronary artery problems that may come out with exercise. This test isn't as helpful for women, however, because women have a higher incidence of "false positives", with the standard treadmill test. Women are better served with the stress echocardiogram.

The stress echocardiogram is basically the same as the standard treadmill test, but there is one important difference. Not only will the patient be monitored by the EKG patches, but also with ultrasound.

After being hooked up to the EKGs a cardiac sonographer will take 4 different resting ultrasound pictures of the heart. After the patient has exercised, the sonographer will take the same 4 pictures but at an increased heart rate. The pre-exercise and post-exercise images will be put side by side and a Cardiologist will look at the EKG tracings and the ultrasound images. If there is a change in the EKG tracings there should also be a change in the ultrasound images.

If the EKG changes don't coincide with the ultrasound images, chances are the EKG changes are "false positives". A false positive means the EKG tracings showed an abnormality that wasn't actually there.

False positives are fairly common in women. Because of this it is a good idea to have a stress echocardiogram rather than a standard treadmill test if you are female. In fact, if a female patient has an EKG change on her standard treadmill test, the doctor may order a stress echo just to make sure it's not a false positive. It makes sense to skip the standard treadmill test and go straight to the stress echo.

Each stress test is helpful in its own way. It's important to ask questions though, to make sure you are getting the best test for you.