What is a Stress Test?
Stress tests, also called cardiac stress tests, are conducted to assess the heart’s functioning when it is subjected to increased workload or physical activity. These tests help identify certain heart conditions that may become more apparent by pushing the heart to work harder. These tests involve monitoring your heart while you exercise on a treadmill or stationary bicycle. In situations where you are unable to exercise, medications can be administered to simulate the effects of exercise and make your heart work harder.
This allows healthcare professionals to evaluate your heart’s response and detect any underlying heart diseases more effectively. Stress tests help identify conditions such as coronary artery disease, abnormal heart rhythms, and insufficient blood supply to the heart. They also aid in determining appropriate exercise levels and guiding treatment plans for heart-related conditions.
In addition to monitoring the heart’s performance during exercise, certain stress tests (nuclear stress tests) also involve taking images of the heart both at rest and when it is under an increased workload. These images provide detailed information about the heart’s functioning and performance. By capturing pictures of the heart at different stages, healthcare professionals can obtain a more comprehensive understanding of how the heart is working and identify any potential abnormalities or issues. This additional imaging component enhances the diagnostic capabilities of stress tests and provides valuable insights into the heart’s functionality.
Stress tests are commonly conducted using either a treadmill or a bicycle ergometer. The treadmill is a more commonly used exercise mode and has demonstrated higher sensitivity in diagnosing heart conditions compared to the bicycle ergometer. However, it is more expensive and requires more space in the testing room. On the other hand, the bicycle ergometer is particularly suitable for individuals who are severely obese or experience difficulties with prolonged walking. The choice between the two exercise modalities depends on factors such as the patient’s condition, body weight, and ability to walk for extended periods.
Why is a Stress Test done?
A healthcare provider may suggest a stress test for conditions such as:
Diagnose coronary artery disease (CAD): Coronary artery disease (CAD) is a medical condition that impacts the coronary arteries responsible for delivering blood to the heart muscle. In CAD, there is a gradual accumulation of plaque within the arteries, leading to their narrowing or blockage. The primary symptom of CAD is chest discomfort, commonly known as angina. This condition can potentially result in severe complications such as heart attacks as well as other cardiac issues like arrhythmias (abnormal heart rhythms) or heart failure. It is important to recognise the signs and symptoms of CAD and seek appropriate medical attention for diagnosis and management.
Diagnose Arrhythmia (heart rhythm problems): An arrhythmia, also known as dysrhythmia, refers to an irregular heartbeat pattern. It occurs when the heart’s rhythm becomes abnormal, either too fast, too slow, or irregular. Typically, the heart beats in a synchronised and coordinated manner; however, disruptions in different regions of the heart or problems with the blood it pumps can disrupt the heart’s normal rhythm.
Diagnose congenital heart disease: Congenital heart disease (CHD) refers to problems or malformations in the structure of the heart that have existed since birth. These abnormalities can include conditions such as holes in the heart wall, abnormalities in the blood vessels (such as having too many or too few, blood flowing incorrectly or in the wrong direction), and issues with the heart valves. While some cases of CHD are uncomplicated and may not exhibit any noticeable symptoms, others can be severe and pose a life-threatening risk, necessitating medical intervention. It is important to recognise and diagnose CHD early on to ensure appropriate management and treatment.
Diagnose Heart Valve Disease: Heart valve disease encompasses a range of conditions that disrupt the normal functioning of one or more valves in the heart. When left untreated, heart valve disease can place increased strain on the heart, leading to diminished quality of life and potentially life-threatening complications.
Effectiveness of treatment: If you have a pre-existing heart condition, an exercise stress test can assist your healthcare provider in evaluating the effectiveness of your current treatment. Furthermore, the results of the test aid your provider in determining the most suitable course of treatment for your specific needs. By assessing your heart’s response to exercise, the stress test provides valuable information that guides healthcare professionals in managing your heart condition optimally.
Heart evaluation before surgical procedures: Assessing the condition of the heart before surgical procedures, such as valve replacement or heart transplant, is crucial to ensuring patient safety. A stress test serves as a valuable tool in determining whether such surgeries are appropriate and can be carried out without significant risks.
If you experience certain symptoms associated with heart disease, a stress test may be recommended for you. These symptoms include:
- Angina: This refers to chest pain or discomfort caused by insufficient blood flow to the heart
- Shortness of breath (dyspnoea): Difficulty breathing or a feeling of breathlessness
- Light-headedness or dizziness: Sensations of feeling faint or unsteady
If you exhibit any of these symptoms, a stress test can help evaluate your heart’s function and identify any underlying issues.
Types of Stress Tests
Various techniques are available to evaluate the performance of the heart during periods of increased activity. These cardiac stress tests involve monitoring essential factors such as heart rate, blood pressure, oxygen levels, and electrical activity. However, it is important to note that there are distinctions among these tests in terms of their specific procedures and approaches. While they share the common goal of assessing heart function, each method employs different strategies to gather information about the heart’s response to stress.
Exercise stress test
The most frequently performed and fundamental heart stress test involves walking on a treadmill or using a stationary bicycle. A skilled exercise physiologist adjusts the treadmill’s speed and incline based on your walking capacity and overall fitness level. In cases where physical exercise is not possible, medications are administered to simulate the effects of exertion on the heart, either by increasing its pumping rate or dilating the coronary arteries, which carry blood to the heart. Throughout the test, an electrocardiogram (EKG) records the electrical activity of your heart. By assessing various parameters, exercise stress tests are designed to identify indications of coronary artery disease, a condition characterised by reduced blood circulation to the heart muscle.
Nuclear stress test
An advanced heart stress test involves the use of a low-risk radioactive substance and a cardiac imaging scan to evaluate heart function. The procedure includes taking images of your heart both before (at rest) and after exercising. A cardiologist analyses the blood flow to the heart muscle during rest and stress conditions. A decrease in blood flow signals is typically indicative of a blockage in one or more of the heart’s arteries. This test provides valuable information about the presence of arterial blockages and helps healthcare providers assess the overall health and function of the heart.
Nuclear cardiac stress tests have the following capabilities:
- Evaluate the extent and severity of coronary artery disease blockages.
- Assess the effectiveness of prior interventions like stents or bypass surgery.
- Assist in avoiding the need for invasive cardiac procedures like cardiac catheterization.
- Determine the suitability of your heart for non-cardiac surgeries or physical activities.
Exercise stress echocardiogram
An exercise stress echocardiogram is a more detailed version of the basic stress test that provides additional information. It involves conducting an echocardiogram, which is an ultrasound of the heart, before and during peak exercise. This specialised cardiac imaging test utilises sound waves to assess blood flow within the heart, as well as the function of the heart’s pumping chambers and valves. If the results of the initial stress test are inconclusive, a stress echocardiogram may be recommended. This examination allows healthcare providers to observe the effects of exercise on blood flow through the heart’s chambers.
Cardiac rehabilitation stress test
If your healthcare provider suggests cardiac rehabilitation, stress testing may be incorporated into the program. Cardiac rehabilitation is a supervised exercise program designed to assist individuals with heart disease in increasing their physical activity levels under medical guidance.
Stress testing as part of cardiac rehabilitation involves two key components:
- Initial stress test: This test is conducted at the beginning of the rehabilitation program to assess your physical capabilities and determine an appropriate exercise plan for you.
- Final stress test: Once you have completed the rehabilitation program, a final stress test is performed to evaluate your progress and establish a long-term exercise regimen.
Cardiac MRI stress test
A cardiac MRI stress test uses advanced imaging technology involving radio waves, magnets, and computer processing to capture highly detailed images of the heart. This relatively recent diagnostic test is primarily employed for the evaluation of severe heart conditions.
During a cardiac MRI stress test, a healthcare provider may administer a contrast dye through an intravenous (IV) line in your arm to enhance the visualisation of fine details in the images. The procedure involves capturing images of your heart both before and after it has undergone exertion. To obtain these images, you will be positioned on a table that moves into a spacious MRI machine resembling a tunnel.
While the machine takes pictures, you will be exposed to loud noises. If exercise is involved in the test, you may either use a treadmill located near the MRI machine or perform exercises within the MRI machine using specialised devices to move your limbs.
Preparations required for a Stress Test
- Before undergoing the stress test, it is important to follow your doctor’s instructions regarding the use of medications. They may advise you to discontinue certain over-the-counter and prescription medications to avoid potential interference with the test results. However, it is crucial not to stop taking any medications unless specifically instructed by your doctor.
- In addition, you may be required to adhere to specific guidelines regarding food and beverage consumption before the test. This may involve avoiding eating, drinking caffeinated beverages, and smoking for a specified time.
- On the day of the stress test, it is recommended to wear comfortable attire and suitable footwear. If you use an inhaler, ensure that you have it with you during the test.
- Before commencing the test, your doctor will inquire about your medical history and exercise habits to determine the appropriate level and type of exercise. They will also conduct a physical examination, measure your vital signs, and auscultate your heart and lungs.
- It is important to communicate any underlying medical conditions or symptoms you may be experiencing, such as chest pain or difficulty breathing, to your doctor. Additionally, inform them of any physical limitations resulting from joint pain or arthritis that might affect your ability to perform the test.
What to Expect During the stress test?
Stress tests can be conducted with or without the use of imaging techniques to capture pictures of your heart. The exercise stress test is the most common test type and does not involve the use of imaging to obtain heart pictures.
Further steps include:
- During the stress test, a blood pressure cuff will be placed on your arm to monitor your blood pressure.
- Additionally, small sensors called electrodes will be attached to your body to conduct an electrocardiogram test (EKG or ECG). These electrodes, connected to a computer or EKG machine, record the electrical activity of your heart throughout the stress test.
- If you can exercise: During the stress test, you will engage in physical activity by either walking on a treadmill or riding a stationary bicycle. The intensity of the exercise will gradually increase as the treadmill incline and speed adjust or the bicycle resistance increases. The duration of exercise typically lasts around 10 to 15 minutes, aiming to reach a target heart rate specific to your fitness level and age. However, if you experience any symptoms such as shortness of breath, chest pain, fatigue, dizziness, or other discomfort, or if the EKG indicates a potential issue with your heart, you have the choice to stop the test earlier. Your safety and well-being are of utmost importance during the procedure.
- If you can’t exercise: During the stress test, an intravenous (IV) line will be placed in one of your arm veins. Through this IV line, medication will be administered to stimulate your heart and make it work harder for a duration of 10 to 20 minutes. Throughout this process, an electrocardiogram (EKG) will continuously monitor and record the electrical activity of your heart. It is important to note that medication can be utilised as an alternative to physical exercise in all types of stress tests.
What to Expect After the Stress Test?
Following the completion of the stress test, you will be provided with water and instructed to rest. If your blood pressure increases during the test, a nurse will continue to monitor it. A few days later, your doctor will schedule a follow-up appointment to discuss the test results with you. The results may reveal irregular heart rhythms or other symptoms that could indicate the presence of coronary artery disease, such as blockages in the arteries. If your doctor determines that you may have coronary artery disease or other heart conditions, they may initiate appropriate treatments or order additional tests, such as a nuclear stress test.
Risks associated with Stress Tests
An exercise stress test is generally considered a safe procedure with rare complications. However, there are potential risks associated with this test, which include:
- A potential risk during or immediately after exercise is a decrease in blood pressure, which can lead to feelings of dizziness or fainting. However, it is important to note that this issue typically resolves once the exercise session is concluded.
- Arrhythmias that occur during an exercise stress test typically subside shortly after the exercise is halted.
- While extremely uncommon, there is a remote possibility that an exercise stress test could trigger a heart attack.
