Cardiac Tests
Gated Nuclear Angiogram (Wall Motion Study)
 A
gated nuclear angiogram (nuclear wall motion study, radio-nuclide angiogram,
MUGA scan) is a technique using radioisotopes to measure the pump function
of the heart. Usually we use this technique to measure the function of
the left ventricle (LV), which is the major pumping chamber of the heart.
The LV receives blood from the lungs and pumps blood to the rest of the
body. A gated nuclear angiogram is more accurate than echocardiography
and even cardiac catheterization in measuring the pumping capacity of
the left ventricle.
This test requires an intravenous site. Otherwise the test is painless
and non-invasive. Your own red blood cells are tagged with a radioactive
material called Technetium (99m Tc). As these red blood cells circulate
through the heart, counts of their radioactivity are obtained with a gamma
camera. A computer constructs moving pictures of the heart by timing and
counting radioactivity throughout the contraction and relaxation phases
of the heart’s cardiac cycle.
A cardiologist or radiologist interprets the moving pictures and comments
on the size and contractility (strength) of the left ventricle. If localized
areas of the heart do not contract normally, these “regional wall
motion” abnormalities usually indicate damaged heart muscle from
coronary artery disease. If there is generalized weakness of the heart
muscle, other conditions such as hypertensive heart disease, valvular
heart disease, or cardiomyopathy (Greek for “sick heart”) may
be present.
The nuclear angiogram is the best way to measure the ejection fraction
or EF of the heart. This is the percentage of the heart’s internal
blood volume that is ejected with every beat. A normal ejection fraction
is > 55%. An EF of 40-55% is considered mild LV (left ventricular)
dysfunction. An EF of 30-40% is considered moderate LV (left ventricular)
dysfunction. An EF of < 30% is considered severe LV (left ventricular)
dysfunction. The EF is a very important measurement and is one of the
best prognostic indicators we have in assessing heart disease.
A Gated Nuclear Angiogram is a medically safe and approved test that helps
your physician to properly assess your heart’s pumping function.
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