Electrocardiogram (ECG): Purpose, Types, and What to Expect

An electrocardiogram (ECG or EKG) is one of the first tests performed especially when you present with symptoms such as chest pain, palpitations, or shortness of breath. This procedure, which takes only a few minutes, is a simple, fast, and painless test that records the electrical activity of your heart. It provides very valuable information about your heart’s working pattern.

What Is an Electrocardiogram?

An electrocardiogram is a medical test that enables the recording of electrical signals that occur with each beat of your heart. A natural electrical system within your heart ensures that muscles contract and relax in a regular manner. The ECG device, which captures the small changes these electrical signals create on the body surface, converts this data into a graphic curve. The shape, size, and intervals between these waves in this graph show whether your heart’s electrical activity is normal. This way, information can be obtained about conditions such as heart rhythm disorders, heart attack, or heart muscle thickening.

What Are the Types of ECG?

ECG not only examines your heart at rest but can also monitor your heart’s electrical activity through different methods. The most commonly used ECG type is the standard (12-lead) ECG taken in hospitals or clinics. Besides this, there are other ECG types used for long-term monitoring or evaluating your heart during exercise.

The main types of ECG are:

• Standard (12-Lead) ECG: This is the most frequently used ECG type in hospitals and outpatient clinics. It is an instant recording that records your heart’s electrical activity from 12 different angles (leads) through 10 electrodes placed on your body. This gives the most basic information about your heart’s current rhythm, rate, and electrical condition.
• Holter ECG: This is a portable ECG device that enables continuous monitoring of your heart rhythm for 24, 48 hours, or longer. With small electrodes attached to your chest and a recording device attached to your belt, rhythm changes in your heart are recorded while you perform your daily activities. It is especially used to find the cause of irregular and intermittent palpitations.
• Stress (Exercise) ECG: This involves monitoring the heart rhythm while the patient exercises on a treadmill or bicycle to detect vessel narrowing that does not show symptoms on resting ECG. ECG changes that occur when the heart’s oxygen need increases play an important role in evaluating suspected coronary artery disease.
• Event Recorder: This is a device that can be used for longer periods (several weeks or months) than Holter ECG. When the patient feels symptoms such as palpitations or dizziness, they press a button to record the heart rhythm at that moment. This makes it easier to find the cause of rarely occurring complaints.
• Ambulatory Blood Pressure Holter: Although not an ECG type, this is a device that works on similar principles to Holter ECG and performs 24-hour blood pressure monitoring of the patient. It is a frequently used method for determining the current situation in delayed ECG recordings.

How Is an ECG Taken?

Electrocardiogram recording is a quite simple and comfortable procedure. During the procedure, a total of 10 small, adhesive electrodes (pads) are placed on your chest, arms, and legs. These electrodes record your heart’s electrical activity from different parts of your body. The ECG device captures these signals and reflects them on paper or screen. The procedure takes approximately 5-10 minutes, and you lie motionless during this time.

When Is an ECG Needed?

ECG is usually performed when you experience symptoms of heart disease or when you have a risk of heart disease. When you present with complaints such as chest pain, palpitations, shortness of breath, dizziness, or fainting, your doctor will first request an ECG recording. Besides this, ECG recording may be needed for routine pre-operative checks or to monitor your heart health at regular intervals.

The main situations requiring electrocardiogram recording are:

• When you experience symptoms such as chest pain, palpitations, shortness of breath
• If you have heart disease risk factors such as high blood pressure, diabetes, high cholesterol
• When there is suspicion of heart attack
• If you have a pacemaker or implantable device, to check the device’s function
• As a routine evaluation before surgery
• To monitor arrhythmias

What Diseases Does ECG Show?

ECG can reveal much information related to your heart’s electrical organization. It helps diagnose many diseases such as heart attack, arrhythmias, heart muscle thickening, and heart failure. However, electrocardiogram alone may not be sufficient to make a definitive diagnosis and is usually evaluated together with other tests.

The main diseases that electrocardiogram shows are:

• Arrhythmias: Shows that your heart beats too fast (tachycardia), too slow (bradycardia), or irregularly. It can detect common arrhythmias such as atrial fibrillation.
• Heart Attack: In a heart attack, blood flow to the heart muscle is suddenly cut off. ECG can show distinct changes indicating the damage or oxygen deficiency caused by this condition.
• Heart Muscle Thickening (Hypertrophy): Heart muscle thickening due to causes such as high blood pressure appears as special wave changes on ECG.
• Heart Failure: Heart failure is a condition where the heart’s pumping power decreases. ECG can show heart muscle damage or electrical changes caused by this condition.
• Electrolyte Imbalances: Imbalances of important minerals in the body such as potassium and calcium can cause abnormal waves on ECG.

What Findings Are Significant on ECG?

Significant findings on ECG are deviations from normal in your heart’s electrical activity. Heart rate falling below 60 or rising above 100 per minute, abnormal rhythms, or changes in the shape of electrocardiogram waves are important findings. For example, elevation or depression of a section called the “ST segment” may be a sign of oxygen deficiency in the heart muscle or heart attack.

Examples of significant electrocardiogram findings:

• Abnormal Rhythm: Irregularity of the normally regular heart rhythm (for example, atrial fibrillation).
• Abnormal Rate: Your heart rate being outside the normal range (60-100 beats/min).
• ST Segment Changes: Elevation or depression of the ST segment is a sign of heart attack or heart muscle ischemia (oxygen deficiency).
• QRS Complex Widening: Widening of the QRS wave that occurs during your heart’s contraction may indicate intracardiac conduction problems.
• T Wave Changes: Flattening or inversion of the T wave may show problems such as electrolyte imbalance or oxygen deficiency in the heart muscle.

What Do ECG Results Mean?

Electrocardiogram results gain meaning through your doctor’s interpretation of your heart’s electrical activity. Results are usually expressed with terms such as “normal sinus rhythm.” Normal results show that your heart’s electrical activity is healthy. Abnormal results may indicate a heart disease and may require further investigations.

How Is Heart Attack Understood with ECG?

In a heart attack, blood flow to a part of the heart is suddenly cut off and the heart muscle in that area is deprived of oxygen. This situation immediately creates distinct changes on the electrocardiogram. The most commonly seen electrocardiogram finding is elevation or inversion of the ST segment. These changes are one of the most important indicators for your doctor that a heart attack has occurred and indicate a situation requiring emergency intervention.

What Should Be Considered Before ECG Recording?

Some simple points you should pay attention to before ECG recording ensure that the test gives more accurate results. Before the procedure, you should avoid very heavy exercise or excessive caffeine consumption. Wearing comfortable clothes and having your skin clean and dry to facilitate the adhesion of electrodes on your chest is important.

What you should pay attention to before ECG recording:

• Wear Comfortable Clothes: Prefer comfortable clothes without metal zippers or jewelry that can be easily removed and put on.
• Avoid Caffeine and Cigarettes: Do not drink coffee, tea, or smoke right before the procedure, as these can increase your heart rate and affect ECG results.
• Keep Your Chest Area Clean: Especially in men, chest hair may prevent electrodes from adhering well to the skin. In this case, shaving the areas where electrodes will be attached may be necessary.
• Inform Your Doctor: Tell your doctor about all medications you use, any allergies you have, and symptoms you experience.

Is ECG Safe? Are There Side Effects?

Yes, ECG recording is a completely safe procedure with no side effects. The ECG device does not give any electrical current to your body; it only detects electrical signals coming from your heart. Therefore, you should not expect any side effects during or after the procedure. The only possible situation is mild irritation or redness in the areas where electrodes are attached, which passes quickly.

Is ECG Alone Sufficient for Diagnosis?

ECG is a very important first step for heart diseases, but it may not always be sufficient alone to make a definitive diagnosis. Especially in conditions such as coronary artery disease, ECG may give normal results. Therefore, your doctor evaluates your ECG results together with your physical examination, blood tests, and other imaging methods (such as echocardiography, stress test).

Reference: Electrocardiogram