The presence of absence of thallium is a useful indicator for assessing the presence of limited blood flow or dead muscle cells in the heart. Therefore, if an area of of the heart does not receive adequate blood flow, only a small amount of thallium will be detected. Since thallium mixes with all the blood in the bloodstream, the more blood that flows to a region, the more thallium that will be viewed. Then, the patient is placed under special imagine cameras that view the thallium throughout the bloodstream. Begins like any exercise stress test on a bicycle or treadmill, but a small amount of radioactive thallium is injected into the patient's bloodstream when he reaches his maximum level of exercise. Useful in determining the extent of preexisting damage or blockage to the heart, the effectiveness or cardiovascular therapies, or the cause of CP. Thallium stress test -Nuclear imaging test used in conjunction with exercise stress testing to determine the amount of blood flow to the myocardium.
An exercise stress test may require 10 or more METs, depending on the type of test and the limitations of the individual being tested. Vigorous physical activity requires more than 6 METs. Daily activites require varying amounts of oxygen consumption and, therefore, the workload or intensity of various activities is measured in METs. Exercise tolerability during a stress test is measured in METs. This is the oxygen consumption while the body is at rest. One MET is equal to 3.5 millimetes of oxygen consumption per kilogram of body weight per minute. How measuring METs is important in understanding the stress test. If a double-product of 20,000 was not achieved, likely due to early termination of the test, the test may not be able to detect the presence of heart disease and may report a false-negative result. In most cases, if a double product of at least 20,000 is achieved, the test is considered adequate for determine the presence of heart disease. Calculation of the double product in exercise stress testing and how it is used -The double product is calculated by multiplying the maximum systolic BP by the maximum HR achieved during the test. Patient should also bring his glucose monitor to the stress test. If patient has DM, special instructions must be obtained regarding the amount of insulin to take and the amount of food that should be eaten prior to test. Patient should wear loose, comfortable clothing and supportive shoes suitable for exercise. Patient should inform physician or stress test technician if he has taken any drugs in the nitrate class or drugs for ED, such as Viagra. _Patient should continues taking all medication as prescribed, unless otherwise instructed. Caffeine should not be ingested in the pre-testing period either. Further, patients should not smoke for at least three hours prior. How patients prepare for an exercise stress test -Patients should not eat or drink anything except water for three hours prior to the test. This protocol determines the workload on the heart at a heart rate of 170 bpm. The Strong protocol consists of three-minute stages in which workload is based on the patient's weight. The stages increase linearly in workload. The McMaster protocol consists of two-minute stages in which workload is based on gender and height. Each stage progresses in workload with rates being determined by gender and body surface are.
The James protocol consists of three three-minute stages. Each stage is increased by approximately two to three METs.ĭifferentiate between common bicycle protocols used in exercise stress testing -Several protocols exist to determine the duration and intensity of exercise on a bicycle during the test. Standard Bruce protocol begins at approximately 5 METs in Stage 1. One MET is equal to 3.5 milliliters of oxygen per kilogram of body weight per minute. The workload of the exercise stress test is measured in metabolic equilalents (METs), the amount of oxygen sonsumed. There are seven stages in the Bruce protocol, but most indiviuals are unable to complete all of the stages. This protocol has larger increments between stages than other protocols. Allows three-minute periods (stages) before increasing the intensity of exercise. The standard Bruce protocol starts with the treadmill speed at 1.7 mph and a 10% grade. Many protocols are available to define the intensity and duration of exercise: Bruce, Modified Bruce, Naughton, Weber, and Asymptomatic Cardiac Ischemia Pilot study. Treadmill is most commonly used piece of equipment of exercise stress testing. Most commonly used protocol in the United States for exercise stress testing.
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