How is Heart Disease Diagnosed? Learn About Measuring Ejection Fraction

The heart is a muscle that continuously supplies the body with oxygen and nutrients. The right side of the heart receives oxygen-depleted blood and pumps it to the lungs, while the left side of the heart receives oxygen-rich blood from the lungs and pumps it to the rest of the body. The percentage of blood that leaves the left ventricle during a contraction is called the ejection fraction. A normal heart's ejection fraction is between 55% and 70%. There are several ways to measure ejection fraction:

Echocardiogram

An echocardiogram utilizes sound waves to create pictures of the heart. From an echocardiogram, a cardiologist can determine the size and shape of the heart, the thickness of the heart muscle, how well the chambers and valves in the heart are working and the force with which the heart contracts. A cardiologist can calculate the ejection fraction and identify any problems with the heart, valves, or blood vessels.

Magnetic Resonance Imaging (MRI)

MRI uses a magnetic field - radiofrequency waves and a computer to make detailed 2- and 3- dimensional pictures of the heart and blood vessels. From an MRI, a cardiologist can view the structures of the heart, including valves, chambers of the heart, and how well the blood flows through the heart and blood vessels. This information is used to determine heart function and how much blood is pumped from the left ventricle to the aorta.

Cardiac Computed Tomography (CT)

A CT scan uses x-rays to take pictures of your beating heart from many angles. From a CT scan, a cardiologist can view the structures of the heart and its pumping ability. Using contrast dye, a cardiologist can see the flow of blood in the arteries.

Nuclear Imaging Tests

Radionuclide ventriculography or radionuclide angiography are nuclear imaging tests that show how well the heart is pumping blood. During the scan, a small amount of radioactive tracer is injected into the bloodstream. The tracer allows a special camera to take pictures of the heart during each beat. This measures the ejection fraction and shows the cardiologist how well the heart pumps with each beat. This scan may be done at both rest and during exercise to see how the heart functions under certain conditions. The radionuclide is safe and is usually eliminated from your body in 24 hours.

Cardiac Catheterization

The cardiac catheterization procedure examines how well the heart is working, identifies problems within the heart and allows for procedures to open blocked arteries. During the procedure, a small tube, or catheter, is inserted into a blood vessel in the arm or leg that leads to the heart. Contrast dye may be injected into the bloodstream through the catheter. The dye is visible through x-ray images, which shows the dye as it flows through the heart and blood vessels. If blockages are observed, they may be opened with a percutaneous coronary intervention (PCI) during a procedure. 

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