Coronary Angiography-YouTube Video
Radionuclide angiography
Purpose
MUGA is typically ordered for the following patients:
- With known or suspected coronary artery disease, to diagnose the disease and predict outcomes
- With lesions in their heart valves
- With congestive heart failure
- Who have undergone percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery, or medical therapy, to assess the efficacy of the treatment
- With low cardiac output after open-heart surgery
- Who are undergoing cardiotoxic drug agents such as in chemotherapy e.g., with doxorubicin or immunotherapy (herceptin)
- Who have had a cardiac transplant
Coronary angiography procedure-You Tube
Procedure
At a high level, the MUGA test involves the introduction of a radioactive marker into the bloodstream of the patient. The patient is subsequently scanned to determine the circulation dynamics of the marker, and hence the blood.The introduction of the radioactive marker can either take place in vivo or in vitro. In the in vivo method, stannous (tin) ions are injected into the patient's bloodstream. A subsequent intravenous injection of the radioactive substance, technetium-99m-pertechnetate, labels the red blood cells in vivo. With an administered activity of about 800 MBq, the effective radiation dose is about 8 mSv to 12 mSv. In thein vitro method, some of the patient's blood is drawn and the stannous ions (in the form of stannous chloride) are injected into the drawn blood. The technetium is subsequently added to the mixture as in the in vivo method. In both cases, the stannous chloride reduces the technetium ion and prevents it from leaking out of the red blood cells during the procedure.The patient is placed under a gamma camera, which detects the low-level 140keV gamma radiation being given off by technetium-99m. 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.Depending on the objectives of the test, the doctor may decide to perform either a resting or a stress MUGA. During the resting MUGA, the patient lies stationary, whereas during a stress MUGA, the patient is asked to exercise during the scan. The stress MUGA measures the heart performance during exercise and is usually performed to assess the impact of a suspected coronary artery disease. In some rare cases, a nitroglycerin MUGA may be performed, where nitroglycerin (a vasodilator) is administered prior to the scan.The resulting images show that the volumetrically derived blood pools in the chambers of the heart and timed images may be computationally interpreted to calculate the ejection fraction and injection fraction of the heart. This nuclear medicine scan yields an accurate, inexpensive and easily reproducible means of measuring and monitoring the ejection and injection fractions of the ventricles, which are one of many of the important clinical metrics in assessing global heart performance.External links
- Radionuclide+Angiography at the US National Library of Medicine Medical Subject Headings (MeSH)
- YouTube - Angiography
ACC/AHA Guidelines for Coronary Angiography: Executive Summary and Recommendations
A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Coronary Angiography) Developed in collaboration with the Society for Cardiac Angiography and Interventions