Cardiologists commonly use stress tests to distinguish chest pain related to heart problems from chest pain caused by other ailments such as acid indigestion and inflammation of the chest wall. Depending on the degree of suspicion for heart disease, your ability to exercise and your other related medical problems, the cardiologist may recommend one of several alternative types of stress tests.
Treadmill Exercise Stress Testing
The treadmill test is the oldest of the different modalities. For this test, patients walk on a treadmill, while a trained technician monitors the blood pressure, pulse rate and a continuous electrocardiogram. The technician also questions the patient at set time intervals regarding symptoms such as chest pain, difficulty breathing, and lightheadedness.
The major advantage of treadmill exercise testing over chemical stress tests is the additional information the cardiologists gain by monitoring your response to exercise. Scientific data show patients who can exercise more strenuously are less likely to suffer life threatening heart attacks.
Treadmill stress testing is not one hundred percent accurate. Even experienced cardiologists will not detect every single patient with coronary artery disease from a treadmill stress test alone. Additional testing may be required and cardiologists will often combine the treadmill test with pictures of the heart obtained through nuclear imaging.
Chemical Stress Testing
Many patients cannot exercise on a treadmill due to back problems, leg pain, lung disease or other coexisting medical problems. If you fall into this category, we often use medications to speed up the heart rate and simulate exercise. We use an injected medicine called adenosine for performing our nuclear stress tests and an infusion called dobutamine for performing stress echocardiograms.
Nuclear Stress Testing
The term nuclear stress test refers to the modality used to obtain pictures of your heart. We obtain these pictures before and after exercise or before and after an injection of adenosine to speed up the heart rate. Our trained technologists will place an intravenous line prior to the test and will administer a small dose of a radioactive isotope agent. The radioactive isotope travels with your blood to different regions of the heart muscle and our gamma camera takes pictures of the heart to determine which areas of the heart muscle receive adequate amounts of blood. Those areas scarred from prior heart attacks will not receive blood and subsequently will not absorb the isotope.
Next we take a second set of pictures after administering a medication called adenosine or performing a treadmill exercise test. As the heart pumps harder with exercise or medication, more blood will flow to the muscle of the heart. Those areas of heart muscle connected to blocked arteries will not receive increased blood flow and subsequently will not absorb the radioactive isotope. Through this method our cardiologists can detect if block arteries exist and how severe the obstructions are.
In some cases, our cardiologists may recommend using sound waves in the form of ultrasound to visualize the heart. When performing stress echocardiography our technicians will image the heart at rest and than image the heart again after exercise or administration of an infusion called dobutamine. The heart muscle beats more forcefully with exercise or dobutamine administration and those areas of the heart receiving inadequate blood flow from blocked arteries will not pump as vigorously as normal areas of the heart.