Question

Which of the following correctly explains a phase/ event in the cardiac cycle in a standard electrocardiogram?

• A. Time between S and T represents the atrial systole.
• B. QRS complex indicates ventricular contraction.
• C. QRS complex indicates atrial contraction.
  
• D. P-wave indicates the beginning of ventricular contraction.

Answer 1

The correct option is B QRS complex indicates ventricular contraction.

Introduction to ECG :

Electrocardiogram (ECG) it is a graphical representation of the electrical excitation of the cardiac muscles.The Instrument is called electrocardiograph.

Components of ECG:

A normal electrocardiogram consists of the P wave, QRS complex and aT wave.
P wave represents atrial depolarisation as a result of this the atria contract and pumps the blood into the ventricles.
QRS wave represents the ventricular depolarisation which leads to the contraction of the ventricles.
The T wave represents ventricular repolarization, during this period the ventricles relax.

Final answer
b. QRS complex indicates ventricular contraction.