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Regadenoson, sold under the brand name Lexiscan among others, is an A 2A adenosine receptor agonist that is a coronary vasodilator that is commonly used in pharmacologic stress testing. It produces hyperemia quickly and maintains it for a duration that is useful for radionuclide myocardial perfusion imaging . [ 1 ]
A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) or intravenous pharmacological stimulation of heart rate.
Myocardial perfusion imaging or scanning (also referred to as MPI or MPS) is a nuclear medicine procedure that illustrates the function of the heart muscle (). [1]It evaluates many heart conditions, such as coronary artery disease (CAD), [2] hypertrophic cardiomyopathy and heart wall motion abnormalities.
As the gamma camera images are acquired, the patient's heart beat is used to 'gate' the acquisition. The final result is a series of images of the heart (usually sixteen), one at each stage of the cardiac cycle. [citation needed] Depending on the objectives of the test, the doctor may decide to perform either a resting or a stress MUGA.
Most heart tumors begin with myxomas, fibromas, rhabdomyomas, and hamartomas, although malignant sarcomas (such as angiosarcoma or cardiac sarcoma) have been known to occur. In a study of 12,487 autopsies performed in Hong Kong seven cardiac tumors were found, most of which were benign. [ 1 ]
Single photon emission computed tomography imaging of the heart is performed using a gamma camera to detect the gamma rays emitted by the technetium-99m as it decays. Two sets of images are acquired. For one set, 99m Tc MIBI is injected while the patient is at rest and then the myocardium is imaged. In the second set, the patient is stressed ...
Rubidium-82 (82 Rb) is a radioactive isotope of rubidium. 82 Rb is widely used in myocardial perfusion imaging.This isotope undergoes rapid uptake by myocardiocytes, which makes it a valuable tool for identifying myocardial ischemia in Positron Emission Tomography (PET) imaging.
Coronary steal is also the mechanism in most drug-based cardiac stress tests; When a patient is incapable of doing physical activity they are given a vasodilator that produces a "cardiac steal syndrome" as a diagnostic procedure. The test result is positive if the patient's symptoms reappear or if ECG alterations are seen. [citation needed]