How to read an Electrocardiogram (ECG) - Part 1, PQRST Waves

The electrocardiogram (ECG) is a diagnostic tool that measures and records the electrical activity of the heart in detail.

The ECG records the electrical activity that results when the heart muscle cells in the atria and ventricles contract.

• Atrial contractions show up as the P wave.

• Ventricular contractions show as a series known as the QRS complex.

• The third and last common wave in an ECG is the T wave. This is the electrical activity produced when the ventricles are recharging for the next contraction (re-polarizing)

Interestingly, the letters P, Q, R, S, and T are not abbreviations for any actual words but were chosen many years ago for their position in the middle of the alphabet.

The electrical activity results in P, QRS, and T waves that are of different sizes and shapes. When viewed from different leads, these waves can show a wide range of abnormalities of both the electrical conduction system and the muscle tissue of the hearts 4 pumping chambers.

Part 1 PQRST Waves
Part 2 ECG Graph Interpretation
Part 3 The P Wave
Part 4 The PR Interval
Part 5, The QRS Complex
Part 6, The ST Segment