It is an indirect coronary artery vasodilator. Patients with acute coronary syndrome or unstable angina or who experienced a myocardial infarction less than 1 week ago.ĭipyridamole was the first vasodilator used for myocardial perfusion stress testing.
Therefore, it is recommended to discontinue consumption of caffeine-containing medications, foods, or beverages for at least 12 hours and ideally 24 hours before adenosine stress testing. Methylxanthines such as theophylline or caffeine, block adenosine binding due to antagonistic action at A2A receptors and can reduce the coronary vasodilation effects of adenosine. The half-life of adenosine is less than 10 seconds. The infusion results in a 3.5- to 4-fold increase in coronary blood flow over baseline. Adenosine generally produces a modest increase in heart rate and a modest decrease in blood pressure. There is an additional methodology in which adenosine is given for 4 minutes as a continuous infusion, and its effects and outcomes are comparable to the continuous infusion lasting for 6 minutes. The radioactive material is normally given at 3 minutes, and then adenosine is kept infusing for 3 more minutes. The dose of adenosine used during a pharmacologic stress testing is 140 mcg/kg/min, and it is given continuously for 6 minutes duration. Pharmacologic stress testing is an alternative modality in patients who are unable to exercise and with the following conditions:Īctivation of the A2B and A3 receptors in bronchial beds can also result in bronchospasm. In general exercise, stress is preferred because it provides a gauge of functional capacity, exercise tolerance, and symptom provocation. Stress testing can also be used to obtain prognostic information to determine the patient's response to optical medical therapy, measure exercise capacity, evaluate ischemia who are already started on medical therapy for known CAD. Stress testing is most clinically useful in intermediate-risk patients for CAD that will help further reclassify these patients into low risk and high-risk depending on the stress test result. Those with high pretest probability have a high risk of false-negative results that can miss a critical diagnosis therefore, these patients should proceed directly to more confirmatory testing such as cardiac catheterization. Patients with a low probability of disease have a high risk of false-positive results and may end up further unnecessary invasive testing without changing patient outcomes. The utility of stress testing should be interpreted based on the likelihood of the disease. Cardiac stress testing is the most commonly used modality for diagnostic purposes in patients with known or suspected coronary artery disease (CAD).
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