Centurion Healthcare

Electrocardiograms and Stress Tests

What is an electrocardiogram (ECG)? 

An electrocardiogram (ECG) is a non-invasive, painless test that records the electrical activity of the heart. A stress test is an ECG performed while the heart is being stressed by medications or exercise.

Who needs an ECG?

Doctors may suggest an ECG to measure:

An ECG is also useful for determining whether a patient has heart disease. A doctor may request this test for a patient who complains of chest pain or palpitations. The test may be included as part of a routine examination in patients over the age of 40 as the risk of heart-related health complications tends to increase with age.

What preparation is required for the test?

Before the test, the doctor will need to be informed of all non-prescription and prescription medicines taken, as some medicines can distort the ECG results. The doctor will specify how heart medications should be taken before the test.  All jewellery should be removed before beginning the test. Men usually perform the test bare-chested, whilst women may wear a bra, T-shirt or gown. A cloth or paper covering will also be provided, as stockings should be taken off.

What are the risks?

An ECG is a safe procedure. Minor discomfort may be experienced only when electrodes are removed, similar to the removal of a band-aid. In some rare cases, electrodes may cause redness or swelling of the skin.

When an ECG is performed during a stress test, the exercise or medication that mimics the effects of exercise, may cause irregular heartbeats. This side effect is caused by the exercise or medication, not the ECG itself.

The risk of electrocution during an ECG is nil. Electrodes placed on the body only record the electrical activity of the heart. They do not emit electricity.

What to expect during the test

Holter monitor – also known as an ambulatory ECG monitor, a holter monitor records heart rhythms for an entire 24-hour period. Wires from electrodes on the chest are attached to a battery-operated recording device carried in a pocket or worn on a belt or shoulder strap. Whilst wearing the device, patients must keep a diary of activities and symptoms. This diary is compared with the electrical recordings to determine the cause of symptoms.

Event recording – a doctor might suggest this device if symptoms are infrequent. It is similar to a holter monitor, except that it allows the patient to record an ECG just when the symptoms occur.

What happens after the procedure?

If the ECG results are normal, no further testing may be needed.  If abnormalities are found, a repeat ECG or other diagnostic test, such as an echocardiogram may be required. Treatment will depend on the causes of the signs and symptoms.

The results

A consistent, even heart rhythm and a heart rate between 50 and 100 beats a minute is considered healthy. Variations provide clues about heart health including:

Heart rate – checking pulse is generally a sufficient measure of heart rate, however, an ECG may be helpful in cases where a pulse is difficult to feel or too fast or irregular to count accurately.

Heart rhythm – when the heart’s electrical system malfunctions, an ECG can help a doctor to identify an unusually fast heartbeat (tachycardia), an unusually slow heartbeat (bradycardia) or other heart rhythm irregularities (arrhythmias). In other cases, medications such as beta blockers, psychotropic drugs or amphetamines can trigger arrhythmias.

Heart attack – an ECG can often identify evidence of a past heart attack or one that is in progress. The ECG patterns may also indicate which part of the heart has been damaged, as well as the general extent of the damage.

Insufficient blood and oxygen supply to the heart – an ECG conducted whilst having symptoms can help a doctor to determine whether the chest pain is caused by inadequate blood flow to the heart muscle.

Structural abnormalities – an ECG can provide clues about enlargement of the chambers or walls of the heart, heart defects and various other health problems.

What is a Stress Test? 

A stress test helps determine how well the heart works under stress. The test involves exercise on either a treadmill or bicycle. During difficult exercise, the body needs more oxygen, so the heart needs to pump harder to provide it. By showing whether the blood supply is reduced in the arteries that supply the heart, a doctor can use a stress test to determine whether there is coronary artery disease present, and if so, the severity.

Who needs a Stress Test?

Doctors may recommend a stress test in order to:

What Preparation is Required Before the Test?

What to Expect During the Test?

A technician will be present throughout the test to closely monitor patient wellbeing.

ECG electrodes will be attached to the chest, arms and legs. The recording will show how fast the heart beats, its rhythm (steady or irregular), as well as the strength and timing of electrical signals as they pass through each part of the heart.

A blood pressure cuff will be wrapped around the arm to monitor blood pressure during the test. In addition, patients may be asked to breathe into a special tube so the exhaled gases can be monitored.

During the test, the exercise level will get progressively harder. However, patients can stop at any time, if they feel the exercise is too much. At the end of the test, normal activities may be resumed.

What is Monitored During the Test?

The following measures will be taken during the stress test:

What are the Risks?

There is very little risk - no more than walking fast or jogging up a big hill. At all times, a doctor will be available in the event anything unusual occurs during the test.