Treadmill Stress Test

A stress test is not a test to see how stressed out you are, but rather a cardiac stress test is a way for doctors to see how your heart responds to an increased workload. One of the best ways to determine how the heart functions under stress is through a treadmill stress test.

 

Every tissue in the body needs oxygen to carry out its normal function. If that tissue or organ is more active or doing more work, it needs more oxygen than it would at rest. The blood is the main way we get oxygen to all tissues of the body—oxygen dissolved in the blood gets dispersed through the blood vessels to every corner of the body. When we exercise, muscles need more oxygen to be active. Thus the heart rate increases to pump more blood and we breathe faster to allow the lungs to supply oxygen to this rapidly moving blood.

 

 

The heart needs oxygen, too. The blood pumping through the chambers of the heart is not enough to deliver the oxygen that the heart needs. The heart requires a special set of blood vessels, called the coronary arteries, that surround the heart and penetrate into the heart muscle. As the heart beats faster during exercise, the heart needs more blood to course through these coronary arteries and deliver oxygen to the heart.

 

When people have coronary artery disease, like atherosclerosis of the coronary arteries, the walls of those arteries are damaged and partially blocked (full blockage is a myocardial infarction or heart attack). These partially blocked coronary arteries may not cause too much trouble when the patient is at rest, but when the body is exerted, the heart gears up to meet the demand, and the blood pumping through those diseased coronary arteries is not enough. Lack of blood flow to the heart causes a rather unique squeezing pain in the chest known as angina or anginal chest pain.

 

This biological process is the basis for the cardiac treadmill stress test. The patient undergoing a treadmill stress test is hooked up to an EKG (electrocardiogram; ECG) machine and made to walk or run on the treadmill for a certain period of time. As the body begins exercising, the oxygen demands on the body are increased and the heart needs more oxygen (blood flow). People with coronary artery disease undergoing an exercise stress test often will experience a cardiac chest pain because blood flow to the heart cannot keep up with demand. Also, when the heart is not getting the blood/oxygen that it needs, there are characteristic changes that can be seen on the EKG.

 

If certain EKG changes occur and/or the patient experiences cardiac chest pain, the test is stopped immediately. In this case the person is said to have had a positive cardiac treadmill stress test. A positive treadmill stress test allows doctors to consider other diagnostic and treatment options like coronary angioplasty and/or stenting.

 

There are other forms of cardiac stress tests that use medications to stimulate the heart and simulate exercise. These chemical stress tests do a reasonable job in diagnosing some coronary artery disease though they are not as sensitive as an exercise treadmill stress test. Of course patients that are handicapped or cannot otherwise exercise should have a chemical stress test when needed. However, if a patient is capable of performing even moderate exercise on a treadmill, then a treadmill stress test is the better choice, diagnostically.