Overview of the treadmill stress test
Exercise testing is a form of cardiovascular stress testing that uses exercise with electrocardiography (ECG) and blood pressure monitoring. This form of stress testing is usually performed with exercise protocols using either a treadmill or bicycle. Patients who are unable to exercise may benefit from the administration of a pharmacologic agent that stimulates the activity of the heart during exercise. This article will specifically focus on treadmill exercise stress testing.
With a treadmill stress test, we can determine a patient’s functional capacity, assess the likelihood and extent of coronary artery disease (CAD), as well as assess the risks, prognosis, and effects of therapy.
Exercise is associated with sympathetic stimulation and changes in coronary vasomotor tone that affect coronary blood flow. Several studies have reported that the coronary arteries dilate during exercise. Some reported mechanisms that may contribute to this dilation include the release of vasoactive substances from the endothelium due to increased myocardial oxygen consumption, passive relaxation due to increased coronary artery pressure, and limitation of the constrictive effects of catecholamine mediated by the endothelium.
During exercise, increased myocardial oxygen demand and coronary vasodilation allow for increased oxygen supply, which is crucial for myocardial perfusion, thus avoiding ischemia.
Indications of treadmill stress test
Indications for treadmill testing include:
- Symptoms that suggest myocardial ischemia.
- Acute chest pain in patients excluded from acute coronary syndrome (ACS).
- Recent ACS treated without coronary angiography.
- Known CAD with worsening of symptoms
- Previous coronary revascularization.
- Valvular heart disease (to assess exercise capacity and the need for surgical intervention).
- Certain cardiac arrhythmias to assess chronotropic competence.
- Newly diagnosed heart failure or cardiomyopathy.
Purpose of treadmill exercise stress test
A treadmill exercise stress test is used to regulate the effects of exercise on the heart. Exercise lets doctors detect abnormal heart rhythms (arrhythmias) and diagnose the presence or absence of coronary artery disease.
This test involves walking in place on a treadmill while nursing the electrical activity of your heart. Through the test, the speed and incline of the treadmill increase. The results show how well your heart responds to stress from different levels of exercise.
Before your test
For 48 hours before the test, stop taking Viagra, Cialis, and Levitra.
On the day of your test
- For two hours before the test: Do not eat or drink.
- Take your usual medications unless your doctor tells you otherwise. Bring all your medications in the original bottles.
- Wear comfortable clothes and shoes that are suitable for walking on a treadmill.
After your test
There are no restrictions after the treadmill stress test.
Preparation before the treadmill stress test
- Eating or drinking anything other than water should be prohibited for nearly four hours before starting TMT.
- You must refrain from drinking any beverage containing caffeine for a period of twelve hours before the test.
- You should stop taking all your heart medications, if applicable, on the day of the test, unless your doctor tells you something specific.
- In case you are diabetic, you should seek confirmation from your physician on the amount of injected insulin to be administered on the day the test is scheduled. Also, if you are taking pills, you should be careful to resume taking the medication only after completing the TMT test.
- You should consider wearing comfortable clothing and shoes for the TMT.
What is the procedure to perform a treadmill stress test?
The initial step for the TMT test is the assignment of electrodes on the chest by a technician or nurse. The electrodes are then connected to the ECG machine’s monitoring and recording devices through leads to measure the electrical function of your heart.
Before the start of the test, the ECG will record your idle heart rate on paper. This is known as a resting ECG. The treadmill is then turned on at a relatively slow speed for an initial warm-up. Then, in three-minute intervals, known as stages, both the speed and incline of the belt are increased.
During the treadmill stress test, the ECG machine captures your blood pressure reading in the second minute of each stage. Generally, stress tests like TMT continue for 90 minutes from start to finish. However, the actual exercise portion of the test is covered in 20 minutes. At that point, you develop restlessness while exercising, treadmill stress test stops before reaching the target heart rate.