With the use of radionuclides and scintillation cameras, radionuclide angiograms can be used to assess left ventricular performance.
- Thallium 201 is a radionuclide (an unstable atom that produces a small amount of energy in the form of g-rays) that behaves like potassium in the body and is distributed throughout the myocardium in proportion to blood flow.
- Technetium-99m- labeled sestamibi is a myocardial perfusion marker used to assess cell membrane and mitochondrial integrity and to reveal myocardial perfusion.
- Sestamibi is not taken up by acute or chronic infarct tissue, and the amount of uptake of the radionuclide by other tissue correlates with the size of the infarction, the amount of CK released in the blood, and the postinfarction left ventricular ejection fraction (LVEF).
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- Hot spot or positive imaging with technetium 99m stannous pyrophosphate is used when diagnosis of MI is unclear.
- Negative result of cold spot imaging with thallium 201 rules out MI. A positive result, on the other hand, is inconclusive because it cannot differentiate between old and new infarction or areas of ischemia versus infarction.
- Radionuclide ventriculogram with technetium 99m is used to evaluate valve structure and ventricular function. In this test, a contrast medium is injected through a catheter, opacifying the ventricular cavity to enable measuring of right and LVEF. The test also distinguishes regional from global ventricular wall motion and allows subjective analysis of cardiac anatomy to detect intracardiac shunts as well as valvular or congenital abnormalities.
- Complications of ventriculography include arrhythmias, intramyocardial or pericardial injection of contrast medium and, possibly, development of emboli due to injection of air or a thrombosis through the catheter.
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Nursing and Patient Care Considerations
- Advise patient that a radionuclide will be injected through a central venous, Swan-Ganz, or I.V. catheter, or into an antecubital vein.
- Reassure patient that the radionuclide will not cause radiation injury or affect heart function.
- Explain to patient that he may experience hot flashes and nausea or vomiting. A test dose will be administered before the dose required for contrast to assess patient's tolerance of radionuclide.
- The results of the study will be discussed with patient by the physician or primary care provider.
