Cardiac Stress Test

A cardiac stress test aids in assessing how the heart can cope during exercise, especially when the body need for oxygen puts extra demands on the heart. A cardiac stress test is called a graded test or exercise tolerance test, exercise stress test or exercise electrocardiography. It helps to primarily evaluate the heart and vascular systems during the exercise. In fact, the American Heart Association has recommended the Cardiac stress test (EKG treadmill in particular) as the first choice to be tried on patients with medium risk of coronary heart disease and who exhibit certain risk factors of smoking, family history of coronary stenosis, high blood pressure, and high cholesterol.

• It helps to determine whether coronary arteries are clogged or blocked.
  
• To find the cause of chest pain.
  
• To assess the heart's capability after a heart attack or heart surgery.
  
• To discover the presence of any heart disease.
  
• To set limits on a person's exercise.
  
• To detect arrhythmia, that is extra heart beats, during the exercise.
  
• To assess the capacity of medicine used to control chest pain or extra beats during exercise.

The cardiac stress test can be done in a clinic or a hospital. The patient may be asked to exercise using a bicycle, treadmill or arm ergometer. The patient is attached to an ECG machine. The blood pressure cuff is placed on any one arm. The patient's heart is usually monitored using a 12 - lead EKG or ECG machine. A heart monitor may be used during and after exercise. After a baseline ECG is obtained, the patient begins to perform a low level of exercise, either by walking on a treadmill or pedaling on a stationary bicycle.

At each stage of the exercise, the pulse, the blood pressure and ECG are recorded along with any symptoms that the patient may be experiencing.

The level of exercise is gradually increased until the patient cannot keep up any longer because of fatigue or until symptoms like chest pain, shortness of breath or lightheadedness prevent further exercise. The goal of this stress test is to diagnose the presence or absence of coronary artery disease. In a sub maximal stress test, the patient exercises only until a pre-determined level of exercise is attained. These tests are used in patients with known coronary artery disease, to measure whether the patient can perform a specific level of exercise with relative safety.

The side effects of a cardiac stress test also include palpitation, chest pain, and shortness of breath, headache, nausea and fatigue. The hypertension caused by stress testing is always considered abnormal and it may lead to severe coronary disease. In stress tests, false positive results are not uncommon. There can be occasions when the patient's ECG changes could suggest ischemia, even in the absence of coronary artery disease. Similarly, in stress test, false negatives are also not uncommon. In some patients, no significant ECG changes will be seen even in the presence of coronary artery disease. Presently, a new concept called nuclear perfusion study is added to the stress test. This factor has helped to minimize the limitations and improve the diagnostic capability of stress tests.

Treadmill stress test

A treadmill stress test is used to evaluate any irregular heart beats on exercise and exertion. Those suffering from borderline hypertension may be asked to undergo treadmill stress test to evaluate blood pressure response to exercise. The treadmill stress test is a cardiac stress test that is used to diagnose coronary artery disease or any heart-related ailments. Treadmill Stress Test is sometimes called an exercise electrocardiogram. The person is fitted with electrodes in about 10 locations on the arm and chest to measure blood pressure and EKG. Then the treadmill is started, initially at slow pace and later much faster. Some heart medications may be need to be stopped for a day or two. The treadmill stress test is much like any strenuous exercise such as running up a flight of stairs. It is essential that the treadmill stress test is conducted under proper supervision. This test indicates how well the heart functions and if the blood supply in the arteries is reduced on exertion. Persons scheduled for treadmill stress test must not eat or drink for about 3 hours prior to the test.

SPECT

SPECT or Single Photon Emission Computed Tomography is a diagnostic tool that that uses gamma camera to collect gamma rays that are emitted from the patient. Radioactive isotope is administered to the patient either as injection or inhalation or ingested liquid. SPECT imaging helps acquire multiple images from multiple angles. The gamma camera is rotated around the patient. Dual-headed cameras can help in accelerating the test. Often triple-headed cameras are also used. SPECT is particularly useful in imaging of tumors, bones, thyroid and infections. Cardial imaging and brain imaging provide critical information about localized functions. MPI (Myocardial perfusion imaging) is an important cardiac stress test. SPECT images allow diagnosis of ischemic heart disease. This test is comparable to stress echocardiography. SPECT imaging of the brain aids in distinguishing Alzheimer's disease from other vascular dementia. Nearly 30 or more images are taken of the specific body area that is being viewed. SPECT scanning is time consuming.