California Workers' Compensation
The following describes the various testing procedures used by physicians for evaluating cardiovascular impairments. It is important to be familiar with the tests because a cardiovascular impairment rating is, to a large degree, dependent upon symptoms associated with the applicant performing activities of daily living. As these symptoms may contain a subjective component, the Guides recommend the physician “obtain objective data about the extent of the limitation and integrate the findings with the subjective data to estimate the degree of permanent impairment” (AMA Guides, page 26). Different cardiovascular testing yields different data.
Cardiovascular Impairment Tests
Multiple-Gated Acquisition Scan (MUGA): The MUGA scan produces a moving image of the beating heart, and from this image several important features can be determined about the health of the cardiac ventricles (the heart's major pumping chambers). A MUGA scan is performed by attaching a radioactive substance, Technetium 99, to red blood cells, then injecting the red blood cells into the patient's bloodstream. The patient is then placed under a special camera (a gamma camera), which is able to detect the low-level radiation being given off by the Technetium-labeled red cells. Since the red blood cells (including those that are radio-labeled) fill the cardiac chambers, the image produced by the gamma camera is essentially an outline of those chambers. With computer manipulation, the final product is a movie of the heart beating.
Several important features of cardiac function can be measured from the MUGA scan. If a patient has had a heart attack, or any other disease that affects the heart muscle, the MUGA scan can localize the portion of the heart muscle that has sustained damage, and can assess the degree of damage. The MUGA scan gives an accurate and reproducible means of measuring and monitoring the ejection fraction of the cardiac ventricles.
The left ventricular ejection fraction (LVEF) is an excellent, and the most commonly used, measure of overall cardiac function. The ejection fraction is simply the proportion of blood that is expelled from the ventricle with each heartbeat. So, for instance, if the left ventricle ejects 60% of its blood volume with each beat, the LVEF is 0.6. (A normal L VEF is 0.5 or greater)
Physiologic/Pharmacologic Stress Testing: Many patients are unable to exercise maximally for stress testing due to a variety of conditions including arthritis, severe lung disease, severe cardiac disease, orthopedic conditions, and diseases of the nervous system. In such patients, physiologic stress testing is often employed. During a physiologic stress test, certain medications are administered which stimulate the heart to mimic the physiologic effects of exercise.
Positron Emission Tomography (PET): A special type of camera and a tracer (radioactive chemical) are used to look at organs in the body The tracer liquid is put into a vein (intravenous, or IV) in the patient’s arm. The tracer moves through the body where much of it collects in the specific organ or tissue. The tracer gives off tiny positively charged particles (positrons). The camera records the positrons and turns the recording into pictures on a computer to check blood flow
Pulmonary Ventilation/Perfusion Scan: These tests use inhaled and injected radioactive material (radioisotopes) to measure breathing (ventilation) and circulation (perfusion) in all areas of the lungs. The ventilation scan is performed by scanning the lungs while the patient inhales radioactive gas. With a mask over the 110se and mouth, the patient breathes the gas while sitting or laying on the table beneath the scanner arm. A perfusion scan indicates a problem with blood flow, including occlusion of the pulmonary arteries. A localized decrease in perfusion scan uptake, particularly when the ventilation scan is normal, may indicate pulmonary embolus. Larger areas of decreased perfusion scan uptake rnay indicate a condition such as inflammation of the lung tissue.
Patients with abnormal perfusion scans are highly likely to have significant coronary artery disease. A normal thallium/cardiolite test is an excellent indication that the patient has no significant coronary artery disease.
Thallium Stress Test/Radionuclide Stress Test: A nuclear perfusion cardiac stress test to evaluate how well the heart muscle is being supplied with blood and how well the ventricles are working. This test is done during exercise or with a medication that stresses the heart. The results are used to determine best alternatives for treatment. Nuclear scans can show the size of the heart chambers, how effectively the heart pumps (ventricular function), how well the coronary arteries supply the heart with blood (myocardial perfusion), whether there is scarring of the heart muscle from previous heart attacks, and the status of the lung circulation.
During a stress test, either thalliumor cardiolite is injected into the patient's vein when the maximum level of exercise is reached. The radioactive substance distributes itself throughout the cardiac muscle in proportion to the blood flow received by that muscle.
Cardiac muscle receiving normal blood flow accumulates a larger amount of thallium/cardiolite than cardiac muscle that is supplied by diseased coronary arteries. A special camera that can ·see" the thallium/cardiolite then makes an image of the heart. From these pictures, portions of the heart that are not receiving normal blood flow can be identified.
Amazon Price: Buy Now
(price as of Jul 26, 2013)
Tilt Table Study: Designed to detect postural/orthostatic hypotension (abnormally low blood pressure upon standing), fainting or lightheadedness. Tilt-table testing may be done when heart disease is not suspected of being responsible for an attack of fainting (syncope) or near-syncope It tests a person's propensity to develop vasovagal syncope (sudden drop in heart rate and blood pressure, resulting in fainting) because a blockage in the coronary arteries can be identified. The patient is strapped to a table, which is then mechanically tilted to an upright position. While monitoring the pulse, blood pressure, electrocardiogram, and sometimes blood oxygen saturation, the patient is left in a "motionless standing position" for 20 to 30 minutes. When the patient's syncope is reproduced during the test, a "positive" tilt table study is said to have occurred. .
Ultrafast Computed Tomography (Cl)/Electron Beam Computerized Tomography Heart Scan (EBCl): A noninvasive test for the detection of coronary artery disease Unlike stress tests that measure the heart's physiology, EBCT, also known as Ultrafast CT, is designed to measure calcium deposits in the coronary arteries. In patients with coronary artery disease, the plaques which make up the blockages contain significant amounts of calcium, which can be detected with Ultrafast CT This test will identify calcium in blockages as mild as 10-20%, which would not be detected by standard physiological testing.
Amazon Price: $8.00 $4.86 Buy Now
(price as of Jul 26, 2013)