TREAD MILL TEST (TMT) (ALSO CALLED EXERCISE STRESS TEST)

A Tread Mill Test (TMT) or an exercise stress test (ETT) helps determine how well your heart responds during times when it’s working its hardest. It typically involves walking on a treadmill while hooked up to a CONTINOUS ECG and COMPUTER CONSOLE to monitor your heart’s activity while you are exercising.

With treadmill stress testing, we can determine a patient’s functional capacity, assess the probability and extent of coronary artery disease (CAD) (blocks in arteries that supply blood to your heart) and assess the risk of a heart attack and effects of treatment.

EXERCISE PHYSIOLOGY- WHAT HAPPENS WHEN YOU EXERCISE?

Exercise is associated with sympathetic stimulation and changes in the coronary vasomotor tone, which affects coronary blood flow. Several studies have reported that the coronaries dilate during exercise. Some reported mechanisms contributing to this dilatation include the release of vasoactive substances from the endothelium due to increased myocardial oxygen consumption, passive relaxation due to the increase in coronary arterial pressure, and endothelium-mediated limitation of constrictor effects of catecholamine.

During exercise, the increase in muscle oxygen demand of the heart and dilation of the arteries that supply blood to your heart (coronary vasodilation) allows for increased oxygen delivery. If you had a significant narrowing in your coronary artery (blocks more than 50%) this increased blood flow will not happen as narrowed vessels do not vasodilate as well as normal vessels.

WHAT IS THE PURPOSE OF TMT?

The TMT helps determine how well the heart receives oxygen and blood flow, and how it responds to exercise. It can help diagnose heart disease, coronary artery disease, and abnormal heart rhythms. It can also help determine a patient’s safe exercise level.

WHAT TO EXPECT WHEN UNDERGOING TMT?

• In men with hairy chest, we may ask you to remove hair in the front of chest with an electronic hair trimmer (provided by us) as this will be necessary to stick the ECG electrodes to the chest to get good skin contact.
• We will provide a loose-fitting gown to wear over the leads to protect your modesty (particularly in women).
• For all women undergoing this test, it will be done and monitored by a female technician throughout the test so that you don’t feel uncomfortable.

Before the test, it is preferable that you

• Avoid eating for a few hours
• Avoid caffeine for 24 hours
• Avoid smoking or using tobacco products
• Stop taking certain prescription medications (we will tell you which ones, if any)
• Wear comfortable clothes and sturdy walking shoes

Treadmill tests are usually safe, but you should be aware of the following:

• Medicines that make the heart work harder can cause symptoms like chest pain, dizziness, or nausea.
• If you use an inhaler, you should bring it with you to the test.
• If you are pregnant or breastfeeding, you should talk with your doctor before the test.

TREADMILL (RMS VEGA) AND COMPUTER CONSOLE IN VIRGO HEART CENTER.

EXAMPLE OF A SUBJECT CONNECTED TO TMT

WHEN WILL I GET THE RESULT OF THE TEST?

The results will be immediately printed and given to you. I will discuss the findings and recommend appropriate next steps in treatment.

The test will be reported as POSITIVE (abnormal), NEGATIVE (normal) or INCONCLUSIVE based on the ECG findings and the level of exercise that you were able to do.

WHAT DOES A POSITIVE TMT MEAN?

If the test is reported as positive, it means that you had changes during the exercise that indicated reduced blood flow to your heart muscles and this could be due to a significant narrowing in one of your coronary arteries (all of us born with 3 or 4 coronary arteries)

If TMT is POSITIVE, I usually recommend the next step in testing for block in your coronary arteries which is usually either an Invasive Coronary Angiogram or a CT-Coronary Angiogram.

If the clinical suspicion of a significant narrowing is high, I will directly advice an Invasive Coronary Angiogram as CTCA will only add extra cost, inconvenience and radiation as you will still need an invasive coronary angiogram to confirm the findings and plan treatment (such as Coronary Angioplasty and Stent Insertion)

If a coronary angiogram is deemed necessary, I will usually do it in my primary work place- East Point Hospital and this is a simple day care procedure with very minimal risk involved.