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Angiography

What is it?

Angiography is a procedure in which the heart and it's blood vessels can be seen with x-rays.

In an x-ray, electromagnetic radiation (the "x"-rays) is projected towards your body. These rays are a lot like light, except they have higher energy. As a result of this, they are able to penetrate skin, whereas normal light cannot.

Dense materials (such as bone) tend to absorb or deflect these x-rays, while lighter materials (such as tissue) allow the x-rays through. The x-rays that pass through the body then strike a photographic film and turn it black. In an x-ray, dense materials (bones) appear white, air appears black and soft tissues appear as progressively lighter shades of grey, depending on their density.

Normally, the heart and vessels cannot be seen, since they are not dense enough to deflect the x-rays (these are so-called "soft" tissues). In order to see these structures, a chemical known as a "radio-opaque dye" must be injected via a cardiac catheter. This dye is a harmless chemical that travels in the blood vessels and heart chambers and is very effective at deflecting x-rays. With the aid of the radio-opaque dye, a chest x-ray will show the heart and major blood vessels. Angiography complements the information obtained with echocardiography.

Why is it necessary?

Angiography is necessary to get a picture of the heart and the major blood vessels attached to it. With this information, your physician can decide the heart is:

1. enlarged
2. small
3. malformed
4. improperly connected to the blood vessels

Your cardiologist can also determine if there are any communications ("holes") between the heart chambers. More often, angiography is used to assess the severity of the disease. The will allow the cardiologists to plan if and when surgery is necessary. On the day of the surgery, this information will be presented to the cardiac surgeon (Dr. John Lee) which gives him a good idea of how the heart looks and how the surgery should be performed.

Risks Involved

In this procedure, your child will be exposed to low doses of high-energy electromagnetic radiation. The amount is several times larger than a dental x-ray. Pregnant women and children have been found to be more sensitive to x-ray radiation. Very high doses of electromagnetic radiation has been linked to cancer, although most physicians believe that the benefits far outweigh the risks.

The radio-opaque dye used in Angiography is harmless. There is a small risk that your child will develop an allergy to the dye. If anyone in your family has become ill after a heart/kidney study, you should mention this to your cardiologist. However, the newer dyes have almost completely eliminated the risk of allergic reaction.

The most significant risks are those associated with the catheterization required to inject the dye.