Electrocardiogram (ECG)

An electrocardiogram, also known as an ECG or EKG, is a medical test that measures the electrical activity of the heart. It is a non-invasive and painless procedure that records the electrical signals produced by the heart as it beats.

How it Works

The ECG uses electrodes placed on the skin to detect the electrical signals produced by the heart. These signals are then transmitted to a machine that records them on graph paper or displays them on a screen. The recorded signals are called waves, and they provide information about the heart's rhythm and function.

Components of an ECG

An ECG consists of several components, including:

• P Wave: represents the electrical signal that triggers the contraction of the atria (upper chambers of the heart)
• QRS Complex: represents the electrical signal that triggers the contraction of the ventricles (lower chambers of the heart)
• T Wave: represents the electrical signal that occurs as the ventricles recover electrically and prepare for the next beat
• PR Interval: measures the time between the onset of the P wave and the start of the QRS complex, indicating the time it takes for the electrical signal to travel from the atria to the ventricles
• QT Interval: measures the time between the start of the QRS complex and the end of the T wave, indicating the time it takes for the ventricles to recover electrically

Types of ECG

There are several types of ECG, including:

• Resting ECG: a standard ECG that is performed while the patient is at rest
• Stress ECG: an ECG that is performed while the patient is exercising or under physical stress
• Ambulatory ECG: a portable ECG that is worn by the patient for an extended period, usually 24 hours, to monitor the heart's activity during daily activities
• Event Monitor ECG: a small device that is worn by the patient to record the heart's activity over a short period, usually 30 days, to capture intermittent symptoms or arrhythmias

Indications for ECG

An ECG may be ordered for various reasons, including:

• Chest pain or discomfort
• Shortness of breath
• Dizziness or lightheadedness
• Fainting or near-fainting episodes
• Palpitations or irregular heartbeat
• High blood pressure
• Heart failure
• Cardiac arrhythmias

Interpretation of ECG Results

The results of an ECG are interpreted by a healthcare professional, who looks for patterns and abnormalities in the waves and intervals. Abnormalities may indicate:

• Atrial fibrillation or other arrhythmias
• Ventricular tachycardia or ventricular fibrillation
• Heart block or conduction disorders
• Myocardial infarction (heart attack)
• Cardiomyopathy or heart muscle disease

Risks and Limitations of ECG

The ECG is a safe and non-invasive test, but it may have some limitations and risks, including:

• False negatives or false positives: the ECG may not always detect underlying heart conditions or may indicate abnormalities that are not present
• Interference from external sources: electrical interference from nearby devices or equipment may affect the accuracy of the ECG reading
• Patient movement or muscle activity: patient movement or muscle activity may cause artifacts on the ECG tracing, leading to inaccurate readings