ECG Waves

An ECG (electrocardiogram) is a medical test that measures the electrical activity of the heart. It is typically represented as a waveform with several key components, each corresponding to different phases of the heart's electrical cycle. Here are the main components of an ECG waveform:

P Wave:

• Description: The P wave represents atrial depolarization, which is the electrical impulse that causes the atria (the heart's upper chambers) to contract.

• Appearance: A small, smooth, upward deflection.

QRS Complex:

• Description: The QRS complex represents the depolarization of the ventricles, which is the electrical impulse that causes the ventricles (the heart's lower chambers) to contract. This is the most prominent part of the ECG waveform.

• Components:

  • Q Wave: The initial negative deflection.

  • R Wave: A sharp positive deflection.

  • S Wave: A negative deflection after the R wave.

• Appearance: A quick, sharp, large wave.

T Wave:

• Description: The T wave represents the repolarization of the ventricles, which is when the ventricles recover after contraction and prepare for the next heartbeat.

• Appearance: A broad, upward deflection (sometimes inverted depending on the condition).

U Wave (sometimes present):

• Description: The U wave is not always visible but, when it is, it represents the repolarization of the Purkinje fibers or possibly the recovery of the papillary muscles.

• Appearance: A small, smooth upward deflection that follows the T wave.

PR Interval:

• Description: The PR interval measures the time taken for the electrical impulse to travel from the atria to the ventricles. It spans from the beginning of the P wave to the beginning of the QRS complex.

• Normal range: 120 to 200 milliseconds.

QT Interval:

• Description: The QT interval represents the total time for ventricular depolarization and repolarization, from the beginning of the QRS complex to the end of the T wave.

• Normal range: Varies with heart rate but typically 350 to 450 milliseconds.

ST Segment:

• Description: The ST segment represents the period between ventricular depolarization and repolarization, often used to assess if there is any ischemia or injury to the heart tissue.

• Appearance: It is typically a flat line between the end of the QRS complex and the start of the T wave.