Heart Scans Demystified

One problem with heart disease is that you can go for years without symptoms, while your condition steadily worsens. Often, by the time you have symptoms, your heart has been irreversibly damaged by the disease. Worse yet, it’s also possible to be unaware you have heart disease until you have a heart attack. For many people from families with a history of heart disease, a simple test called a heart scan can detect or diagnose the early stages of heart disease, and save lives.

What is a heart scan?

The heart scan is a non-invasive procedure, meaning nothing is inserted into your body to collect the data. There are two types of scans available:

  • A CT scan uses computed tomography to take multiple x-rays of your arteries and heart. The CT scan is slower, because it has to take multiple images, but can detect the presence of “soft plaque.”

  • An EBT uses electron-beam tomography to take pictures of the heart and arteries. The EBT is faster but it only shows “hard plaque” in your arteries.

Why get a heart scan?

A heart scan measures the amount and location of the plaque in your arteries, to determine your risk for (or degree of) cardiovascular disease.

Plaque is a fatty substance that builds up in the walls of the arteries. Over time, the arteries can become narrow and constrict blood flow. If this happens in the heart, it can cause a heart attack. Plaque can also cause the walls of the arteries to harden, making them more prone to rupture.

How a Heart Scan Is Done

  • Prior to the heart scan, a technician might inject a substance ("contrast") into your arteries to make them show up clearer on the scans.

  • You will then lie down on a table that slides into the scanning machine, and the machine will rotate around the table to get the images.

  • The process can take several minutes, and you will need to lie still while the machine takes the images.

  • Once the scan is over, the machine will calculate the amount of plaque present and assign what is called a calcium score. The score is between 1 and 1000, and the higher the number, the greater the amount of plaque present.

    • 0–10 = Minimal plaque
    • 11–100 = Moderate plaque
    • 101–400 = Increased plaque
    • Over 400 = Extensive plaque

Once you get the results of your heart scan, you can discuss your treatment options with your doctor.

How to Get a Heart Scan

Your doctor might request one or both types of heart scans depending on your condition, or based on what is available in your area. For example, if your doctor suspects the presence of plaque, he might order the EBT because it is a faster procedure. If the EBT does not show any plaque, he might order a CT scan to detect the presence of soft plaque, which can cause arteries to rupture.

Things to Consider Regarding Heart Scans

  • The CT scanner takes multiple images, or "slices," to get a full picture of your arteries. The latest machines take 64 slices, but older machines take fewer images. Currently, the 64-slice scanners are the best at detecting both “hard” and “soft” plaque.

  • Heart scans can determine if there is a blockage in an artery, but they can’t determine the extent of the blockage.

  • If the non-invasive scans show a blockage, you might need a more-invasive test--an angiogram--to determine the extent of the blockage.

  • The imaging dye that is used for "contrast" during your scan is iodine-based and made from shellfish products. Advise your doctor in advance if you are allergic to shellfish, or iodine, or if you have had a prior allergic reaction to medical contrast dyes.

  • Patients with kidney disease or diabetes should avoid the contrast dyes because they can damage the kidneys.

  • Pregnant women should avoid most scans, and should speak with a doctor about which types of scans might be safe, if needed.
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