Cardiac Diagnostics and Imaging

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What is cardiac diagnostics and imaging?

Cardiac diagnostics and imaging includes heart tests and imaging procedures to detect conditions and disorders of the heart and blood vessels, including heart attack, coronary artery disease, heart valve disease, and arrhythmia.

There are many cardiac tests. Here are some common ones:   

  • Echocardiogram is a heart ultrasound to look at its structure and function.
  • Electrocardiogram (ECG, or EKG) records your heart’s electrical activity as it pumps. It shows how fast and steadily the heart is beating as well as the strength of each beat.

  • Stress test combines an ECG with mild to moderate exercise so your cardiologist can examine the electrical activity of your heart when it is under stress. If you are not physically able to use a treadmill or exercise bike, your cardiologist will give you medicine that mimics stress. A stress echocardiogram is a heart ultrasound after exercise.

  • Nuclear stress test is a heart imaging procedure with a very small amount of radioactive material to detect even small changes in blood flow and heart function after exertion.

  • Ambulatory ECG, or Holter monitor is a portable ECG. It allows you to continue your regular activities at work and at home while the device you wear monitors your heart continually.

  • Cardiac CT (computed tomography), or heart scan, is like 3D X-rays that allow your cardiologist to see your heart’s anatomy and blood low. You may have a contrast dye—usually iodine—to highlight your blood flow.

  • Cardiac MRI (magnetic resonance imaging) also allows your cardiologist to see your heart’s structures and blood flow, but instead of radiation, an MRI machine uses a powerful magnetic field to produce the images.

  • Coronary angiogram with cardiac catheterization is a special type of X-ray procedure with a contrast dye to see how blood flows through your blood vessels.

Why are cardiac diagnostic and imaging procedures performed?

Your doctor may refer you to a cardiologist for cardiac diagnostics and imaging if you experience any of these signs and symptoms of a potential heart problem:

ECGs are also part of a routine health check before you have a surgical procedure, and sometimes as part of an annual exam. If you already have a heart disease diagnosis, your cardiologist will ask you to have one or more heart tests on a regular basis to monitor your condition or to see how well your current treatment plan is working.

Who performs cardiac diagnostic and imaging procedures?

A cardiac care nurse or other staff member may perform noninvasive tests, such as ECGs, but a cardiologist interprets the test results. A technologist performs CT scans and MRIs under the supervision of a radiologist. The radiologist will consult with the cardiologist in charge of your care. Your cardiologist will share the imaging test results with you over the phone or during a follow-up appointment to discuss next steps.

For invasive tests, such as coronary angiograms, a team of healthcare providers, including an interventional cardiologist, care for you while performing the test. An interventional cardiologist specializes in invasive diagnostic tests and cardiac imaging. Other heart specialists include cardiac electrophysiologists, who care for people with heart rhythm problems like atrial fibrillation.

How are cardiac diagnostic and imaging procedures performed?

Cardiac tests are often performed at a hospital. You may have an ECG at a doctor’s office or clinic, but you will most likely have a stress test and similar tests at a hospital under a doctor’s supervision. You will have cardiac imaging tests, such as angiography, at a specialized radiology clinic or hospital cardiac catheterization lab—cath lab for short.

Echocardiograms, ECGs, and stress tests

A sonographer performs heart ultrasounds, taking several pictures of your heart to share with your doctor. For tests that record your heart rhythm, a nurse places painless electrodes on your arms, legs and chest and attaches the ends to an ECG machine. It only takes a few minutes to record the rhythm.

For a stress test, you walk on a treadmill or cycle on a stationary bike while the ECG records your heart rhythm. You may receive instructions to not eat or drink before the procedure. If you need a Holter monitor, you’ll have electrodes attached to a small monitor you wear in a pouch, typically for 24 hours, but you may need to wear it longer.

Imaging Tests

If you are undergoing a heart imaging exam with dye or contrast, a nurse will start an intravenous (IV) line into a vein in your arm to administer the contrast agent. For an MRI, you lie on a narrow table that slides into the MRI machine. Some machines are fully enclosed and some are open on one end. The test takes 30 to 90 minutes. A cardiac CT scan is similar to a cardiac MRI, but the machine is open—shaped like a donut—and generally quicker than an MRI.

For an angiogram, a nurse will insert an IV to give you fluids and a sedative. You will lie on a table with an X-ray machine at the side. The cath lab team uses ECG to monitor your heart throughout the procedure. Your doctor makes a tiny incision in your groin or wrist, inserts a catheter (thin, hollow tube), and guides it through the artery to your heart. Your doctor administers contrast dye and X-rays track the dye’s flow through your heart. You may sleep through the procedure or drift in and out of sleep. It generally takes about an hour.

A nuclear stress test is like an imaging exam with radioactive material instead of a dye. You lie on a table next to a special camera that detects the radioactive tracer material. You repeat the imaging test after exercising or receiving medicine to make your heart beat fast. 

What are the risks and potential complications of cardiac diagnostic and imaging procedures?

Before having any cardiac diagnostic testing or imaging, ask your doctor why you need the test, what he or she expects to learn from it, and if there are alternatives to the test. Know your options ahead of time and learn about the benefits and potential complications of each test. Also, ask what other tests or treatments you might need based on the results.

There are no risks to an ECG or Holter monitor. However, there are some risks associated with stress tests. These include a sudden drop in blood pressure, irregular heartbeats, and heart attack. Your care team has access to emergency equipment for immediate care.

The risks of imaging tests are generally related to the dye or contrast if you are allergic to them or if they affect your kidney function. Your imaging team will monitor you for signs of a reaction and will give you medicine to treat it. The amount of radioactivity in a nuclear stress test is very small and poses little risk. It’s about the same amount of radioactivity as an X-ray.

An angiogram is a common heart diagnostic test, but serious risks and complications can occur, including arrhythmia, heart attack, and stroke. Your doctor will only perform an angiogram if the benefits—making a clear diagnosis and planning treatment—outweigh your personal risk of complications.

Reducing your risk of complications

You can reduce your risk of certain complications by:

  • Following fasting and medication instructions prior to the procedure

  • Informing your cardiologist about all medications you take and all allergies you have.

  • Make sure you know how to contact your doctor. Ask for numbers to call during and after regular business hours.

  • Notifying your doctor immediately of any concerns after the examination, such as bleeding, fever, or signs or a stroke

What can I expect after a cardiac diagnostic and imaging procedure?

In most cases, your doctor will contact you with the results of your test at a follow-up appointment. If you have an in-office ECG, your doctor will share the results with you immediately, so there is no waiting. If your doctor identifies a treatable condition during an angiogram, you may receive catheter-based treatment that same day, such as angioplasty for clogged arteries. Your doctor will discuss this possibility with you before the test.

You can generally go home after an echocardiogram, ECG, stress test, nuclear stress test, MRI or CT scan. After an angiogram, you will stay in a recovery room for observation. You have to lie flat for several hours to prevent bleeding at the catheter insertion site. Ask your doctor when to start taking your medications again. You may have some pain and bruising at the incision for several days. You also have to avoid strenuous activity and heavy lifting (such as a sack of groceries) for a several days following the procedure.

If you have an imaging test with contrast, dye, or radioactive tracer, your doctor may advise you to drink extra fluids to help flush it out of your system.

When should I call my doctor?

You will have a follow-up appointment to discuss your results but you should contact your doctor if you experience:

  • Continued bleeding from the incision if you had cardiac catheterization

  • Inability to urinate or difficulty urinating

  • Fever

  • Redness or discharge from the incision

You should seek immediate medical care or call 911 if you experience:

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Jan 23
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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