Question

Given below is the ECG of a normal human. Which one of its components is correctly interpreted below?

• A. Peak T - Initiation of total cardiac contraction
• B. Peak P - Initiation of atrial contraction
• C. Complex QRS - One complete pulse
• D. All the above

Answer 1

The correct option is B Peak P - Initiation of atrial contraction

A normal ECG shows PQRST graph which represent one complete pulse.

The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria.

The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction.

The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole (contraction).