The Heart

Take a look at the picture above, it is a diagram of the human heart showing the build up of plaque inside the arteries.

If your doctor suspects you have this problem, he may send you for tests to help him better determine the seriousness of your condition.

Tests which involve very little pain and are low risk (ECG and echocardiogram) are used to help decide whether a more invasive test is needed.

Of all the low risk non-invasive tests available none gives more information than a myocardial perfusion scan (also called a cardiac scan).

Cardiac Scan

The coronary artery supplies the heart muscle with blood.

A cardiac scan is a picture of the blood flow in the heart muscle (myocardium).

Blockages in the coronary artery can result in a reduction of blood to areas of the myocardium. These areas if left unchecked can lead to serious complications.

The aim of a cardiac scan is to look for any areas of the myocardium suffering from reduced blood flow.

Coronary Artery Disease

CAD is a very serious condition and if left unchecked can result in heart attack. Early detection of CAD is important and a cardiac scan has become an important tool in the management of patients suffering with and at risk of developing this condition.

CAD complications, like heart attack, can be sudden because the effects of blockages to arteries sometimes pose no problems under normal conditions (rest) but only manifest themselves when the heart is required to pump more blood during stress or exercise.

Cardiac scans take two pictures of the heart muscle; one when the body is at rest and the other when it is under stress. The two pictures are then compared to make a diagnosis

Indications for a Cardiac Scan

Some of the reasons your doctor will request you have a cardiac scan are:

To diagnose CAD.

To assess the risk of possible complications during and after major surgery (non-cardiac).

To determine the extent of damage after heart attack.

To determine the functional significance of a blocked artery seen on another test.

For a more complete list of indications please follow the link.

More...

The Procedure

A cardiac scan has two phases, rest and stress:

REST:
You will be injected intravenously with a tracer that is absorbed by the heart muscle.

About 15 minutes after the injection you will be instructed to lie on a table under a special camera.

While the camera is taking pictures it is very important you lie still


STRESS:
This phase requires the heart be put under stress. The heart is stressed by either walking on the treadmill or by using drugs for those unable to exercise.

ECG leads will be placed on your body to monitor electrical signals from your heart while it is being stressed.

At the peak of stress the tracer is injected and a recovery phase follows where you are allowed to "catch your breath".

You are then instructed to lie on the table for pictures to be taken in the same way as the rest test.