Electrocardiogram
ECG/EKG: Non Invasive Heart Tests

Electrocardiogram

Contents

• What Is An Electrocardiogram?
• What Does An ECG Show?
• Who Should Have An ECG?
• How Is It Done?
• What Do The Results Mean?
• Are There Limitations To The Test?
• How Much Does An ECG Cost?

An electrocardiogram (ECG) is a safe and inexpensive way for a doctor to monitor a person's heart rate and rhythm. It can also help diagnose if a heart attack has occurred or whether there is a potential problem with blood supply to the heart. It is also used to study other problems such as cardiac arrhythmia and congestive heart failure as well as to diagnose cardiomyopathy (heart muscle disorders), aneurysms, blood clots in the heart and pericarditis (inflammation of the heart membrane). It can also help with the diagnosis of chest pain if the underlying cause is not clear. The test is sometimes called an EKG, electrocardiography and a 12-lead EKG/ECG (because the heart's electricity activity is monitored in 12 parts of the body). The printout after the test shows a graph of the electrical activity and rhythm of each heartbeat over the time of the test. The results of the test will help a doctor determine the best course of treatment if a problem is uncovered.

What Does An ECG Show?

1. If a heart attack has occurred. The results of an ECG help determine if clot busters should be given.
2. Helps predict if a heart attack is developing.
3. A heartbeat that's too slow, too fast or irregular (arrhythmia).
4. Reduced blood flow to the heart muscle, i.e.: coronary heart disease (CHD).
5. If the heart is not pumping forcefully enough (helps in the diagnosis of heart failure).
6. If the heart's muscle is too thick or if parts of the heart are too big (cardiomyopathy).
7. Heart valve problems (heart valve disease).
8. Signs of abnormal blood electrolytes (calcium, magnesium, potassium).
9. Heart birth defects (congenital heart defects).
10. Any inflammation in the membrane surrounding the heart (pericarditis).

Who Should Have An ECG?

Both men and women who display symptoms of a heart problem. Those signs include:

1. Fluttering heartbeat or sensation that the heart is pounding or beating irregularly.
2. Chest pain.
3. Unusual fatigue and weakness.
4. Breathing problems.
5. Unusual sounds when the doctor listens to the heart with a stethoscope.

An ECG may also be carried out as part of a routine health exam. It can also be used to test for early signs of heart disease in those with a family history of the condition. It may also be used to monitor those taking heart medications or with medical devices such artificial pacemakers to check that they are working. An ECG is also commonly used to test the health of a person's heart before any major surgery or starting a cardiac rehab exercise program.

How Is It Done?

Patients do not have to prepare in any special way for the test although you should avoid drinking cold water or exercising directly before the test as this may alter the results. You will also be asked to remove all jewelry. The ECG may be carried out in a doctor's office or at a hospital. You may be asked to change into a hospital gown and lie on an examination table. Next electrodes (soft sticky patches) will be attached to various parts of the body - the chest, wrists, ankles and back. These patches will conduct the electrical impulses. The nurse or technician will apply a conducting gel to ensure a good connection. They will then hook the electrodes up to the machine and the test begins. It usually lasts less than one minute. No electricity is passed into the body so there is no need to worry about an electrical shock. The ECG simply records the heart's electrical activity. The entire procedure takes about 10 minutes. To locate the heart, see pictures of the human body.

What Do The Results Mean?

In a healthy person the electrical impulses recorded will show a heartbeat with a regular sequential path. The results can be printed on graph paper - the more spikes in the graph, the more likely there is to be a problem. At a basic level the test records the heart rate. This can also be done by taking a person's pulse, but an ECG will give a more accurate measurement. A normal heart rate ranges between 60 and 100 beats a minute. The ECG can also monitor a person's heart rhythm, whether the heart is beating too fast (tachycardia) or too slow (bradycardia). It can also trace any electrical blockage in the heart that is causing this irregularity. Each type of arrhythmia has it owns distinctive appearance on a chart.

The ECG can also tell if a person has had a heart attack - the patient may not even be aware they have had one. Damaged muscle or scar tissue which results from a previous heart attack does not transmit electrical impulses in the same way as healthy tissue. An ECG will pick this up, as well as indicating where approximately in the heart ventricle the damage has occurred.

An ECG can also give information about the effects of medications on the heart that the patient may be taking. It can also indicate other health conditions which can affect the heart's wave patterns such as hormonal problems, diabetes and:

• Anorexia nervosa.
• Complicated alcohol abstinence (delirium tremens).
• Digitalis toxicity (overdose of a certain medication).
• Drug-induced lupus erythematosus (autoimmune disorder).
• Familial periodic paralysis (rare condition which causes temporary paralysis).
• Guillain-Barre (condition which attacks the body's immune system).
• Hyperkalemia (high levels of potassium in the blood).
• Hypoparathyroidism (endocrine disorder which causes brittle nails, dry hair and sometimes seizures).
• Insomnia (sleep disorder).
• Lyme disease (bacterial infection caused by a tick bite).
• Narcolepsy (falling asleep or extreme drowsiness every 3 to 4 hours during the day).
• Obstructive sleep apnea (breathing difficulties while sleeping).
• Primary hyperaldosteronism (causes secondary hypertension).
• Primary hyperparathyroidism (endocrine disorder which causes fatigue, fractures and depression).
• Sick sinus syndrome (heart rhythm disorders).
• Wolff-Parkinson-White syndrome (heart condition).

Are There Limitations To The Test?

A standard ECG only records a brief period of the heart's activity (about 6 seconds) so it may not reflect heart problems if the patient's symptoms are intermittent. The most common example is where a patient is suffering intermittent chest pains, a common symptom of CHD. This patient may end up with a normal ECG result if they are not experiencing pain on the day of the test. In such instances a special ECG called ambulatory electrocardiography (AECG) will be used. AECG’s are portable devices which can be worn over a period of 24 or 48 hours to monitor the heart's rhythm (such as a Holter Monitor), or for longer periods like weeks and months (such as event monitors or transtelephonic monitors). The Holter will monitor the heart continuously and is used when symptoms are likely to occur in a 24-48 hour timeframe. An event monitor makes intermittent recordings to investigate 'events' or symptoms which occur less frequently. It can be taken off to bathe or for other brief periods but it is best to wear it as much as possible. Alternatively an exercise stress test using an ECG can be performed. This shows how the heart performs during exercise. It is also referred to as the treadmill test.

Some abnormalities indicated by an ECG may be non-specific and observed in several different types of conditions. However this can normally be further investigated by a detailed examination of the patient and by carrying out other cardiac tests (exercise stress test, echocardiogram etc).

Occasionally an ECG will report that a patient is entirely normal despite there being an underlying cardiac problem. This is why any patient who shows symptoms of heart disease should be further investigated, regardless of the ECG result. A heart catheterization or coronary angiography may be necessary.

How Much Does An ECG Cost?

The average cost of a routine ECG is between $150 and $200. An exercise stress test is more expensive, and averages between $250 and $300. An echocardiogram costs on average about $1400. All these costs should include the test itself and the cost of the technician's reading and interpretation of the results.

Other Types of Heart Testing

• Nuclear Heart Scan
• Chemical Stress Test
• Calcium Score Test

For more heart problems, see the following:

• Heart Disease in Pregnancy
• What Are The Risks? Heart Disease Risk Factors
• Stats: UK heart disease statistics and American heart disease statistics.

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