ECG

An ECG (electrocardiogram) is a medical test that measures the electrical activity of the heart over a period of time. It is used to assess the heart’s rhythm, structure, and overall health. An ECG is a simple, non-invasive procedure that involves attaching electrodes (small sensors) to the skin, which then record the electrical impulses generated by the heart as it beats.

Key Points About an ECG:

  • How it Works: The heart generates electrical impulses that trigger heartbeats. These electrical signals spread across the heart muscle, causing it to contract and pump blood. The ECG records these electrical signals and shows them as waves on a graph.
  • Waveforms: The output of an ECG is a series of waves that represent different phases of the heart’s electrical cycle. The main components of an ECG waveform are:
    • P wave: Shows the electrical activity of the atria (upper heart chambers) as they contract.
    • QRS Complex: Represents the electrical activity that causes the ventricles (lower heart chambers) to contract.
    • T wave: Reflects the recovery phase as the ventricles relax.
  • Electrodes: Small adhesive electrodes are placed on the skin at specific points on the chest, arms, and legs to detect the electrical signals. There are typically 12 leads, which provide a comprehensive view of the heart’s electrical activity from different angles.

Why Is an ECG Done?

An ECG is often performed to:

  • Diagnose heart problems: Such as arrhythmias (irregular heartbeats), heart attacks, and heart disease.
  • Monitor heart health: It can help track changes in the heart’s electrical activity over time.
  • Evaluate symptoms: Like chest pain, palpitations, dizziness, or shortness of breath.
  • Check for heart abnormalities: Such as an enlarged heart, or electrolyte imbalances.

Types of ECG Tests:

  • Resting ECG: A standard ECG done while you are lying down and relaxed. It records the heart’s electrical activity at rest.
  • Stress Test ECG: Done while you are exercising (on a treadmill or stationary bike) to monitor how the heart responds to physical stress.
  • Holter Monitor: A portable ECG device worn for 24 to 48 hours to monitor the heart’s activity throughout the day and night.
  • Event Monitor: Similar to a Holter monitor, but used for a longer period, typically several weeks, to capture intermittent symptoms.

What Does an ECG Show?

An ECG can detect:

  • Irregular heart rhythms (arrhythmias), such as atrial fibrillation or ventricular tachycardia.
  • Heart attacks (myocardial infarctions), both ongoing and past.
  • Electrolyte imbalances, such as low potassium or calcium levels, which can affect heart rhythm.
  • Signs of heart enlargement or other structural problems.
  • Ischemia (lack of blood flow) to the heart muscle.

Advantages of an ECG:

  • Non-invasive: No needles or surgery.
  • Quick and painless: It typically takes just a few minutes to perform.
  • Immediate results: The ECG is recorded in real time and can be analyzed by a doctor right away.

Limitations:

  • Doesn’t Detect All Heart Issues: It may not identify every heart condition, especially if the issue isn’t occurring while the test is happening.
  • Interference: Certain conditions, like movement or poor electrode contact, can interfere with the results.