How is Heart Disease Diagnosed? Learning about the Pumping Capacity of the Heart

One of the biggest questions we hear is “how is heart disease diagnosed?” It helps to start at the beginning. The heart is a muscle that provides the force needed to move blood around your entire body and return back to the heart. The standard measure of how well each side of your heart pumps blood is called the ejection fraction, and a normal heart’s ejection fraction is typically between 55 and 70%. An ejection fraction between 36 and 49% indicates the heart muscle is pumping below normal, and an ejection fraction below 35% suggests the heart is having trouble pumping blood.

How is Ejection Fraction Measured?

The ejection fraction is measured by several imaging techniques, which are called echocardiogram (ECG), magnetic resonance imaging (MRI), cardiac computed tomography (CT), nuclear imaging tests and cardiac catheterization. The type of test requested by your doctor will depend on your specific medical condition and test results. Let’s explore each of these techniques in more detail.


An echocardiogram (ECG) is also called echocardiography or diagnostic cardiac ultrasound. ECG uses sound waves to make pictures of your beating heart—the atria, ventricles, valves, aorta, arteries, and veins attached to your heart. From the ECG, your cardiologist can see the size and shape of your heart, thickness and movement of your heart muscle, how well the chambers and valves in your heart are working, and the force with which your heart contracts. This information allows your cardiologist to determine if your heart and valves are working correctly and shows the health of your heart muscle and blood vessels in and around the heart. Your cardiologist will calculate the ejection fraction and identify any problems with your 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 your beating heart and blood vessels. The MRI shows your cardiologist the structures of your heart including the heart muscle, valves, the chambers of the heart, and how well blood flows through your heart and blood vessels. This information is used to determine heart function and how much blood is pumped from your left ventricle to your aorta, which is your left ventricular ejection fraction.

Cardiac Computed Tomography (CT)

A CT scan uses x-rays to take pictures of your beating heart from many angles. Your cardiologist will be able to view your entire heart, its structures, and its pumping ability. Your cardiologist will calculate your ejection fraction and determine what parts of your heart are healthy or diseased. Sometimes the cardiac CT is done using contrast dye. The dye enables your cardiologist to see the blood flow in your arteries and to see if coronary artery bypass grafts are open.

Nuclear Imaging Tests

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

Cardiac Catheterization

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

Next Steps:

  • Read more about each procedure mentioned above to learn more about how heart disease is diagnosed:

About Impella

The Impella 2.5 system is a temporary (<6 hours) ventricular support device indicated for use during high risk percutaneous coronary interventions (PCI) performed in elective or urgent, hemodynamically stable patients with severe coronary artery disease and depressed left ventricular ejection fraction, when a heart team, including a cardiac surgeon, has determined high risk PCI is the appropriate therapeutic option. Use of the Impella 2.5 in these patients may prevent hemodynamic instability which can result from repeat episodes of reversible myocardial ischemia that occur during planned temporary coronary occlusions and may reduce peri- and post-procedural adverse events.

Protected PCI and use of the Impella 2.5 is not right for every patient. Patients may not be able to be treated with Impella if they have certain pre-existing conditions, which a cardiologist can determine, such as: severe narrowing of the heart valve, severe peripheral artery disease, clots in blood vessels, or a replacement heart valve or certain heart valve deficiencies. Additionally, use of Impella has been associated with risks, including, but not limited to valvular and vascular injury, bleeding, and limb ischemia in certain patients. Learn more about the Impella devices’ approved indications for use, as well as important safety and risk information at