Question

Given here is ECG of a normal human. Which one of its components is correctly interpreted

• A. QRS complex - one complete pulse
• B. Peak T - initiation of total cardiac contraction
• C. Peaks P and R - systole and diastole blood pressure
• D. Peak T - initiation of left atrial contraction only.

Answer 1

Answer: (A)

QRS complex - one complete pulse

A) The QRS complex represents the electrical impulse as it spreads through the ventricles and indicates ventricular depolarization. The QRS complex starts just before ventricular contraction and is the complete pulse.

B) The T wave represents the repolarization of the ventricles. Cardiac relaxation takes place.

C) The P wave represents the depolarization of the atria This happens right before the atria contract and push blood into the ventricles. R represents the peak of the ventricular contraction. Systole corresponds to contraction while diastole corresponds to relaxation. The P and R peaks only signify a systole.

D) T wave signifies the relaxation of the whole heart (diastole).

So the correct answer is 'QRS complex - one complete pulse'.