Which of the following correctly explains a phase/event in the cardiac cycle in a standard electrocardiogram?
(a) QRS complex indicates atrial contraction.
(b) QRS complex indicates ventricular contraction
(c) Time between S and T represents atrial systole.
(d) P-Wave indicates the beginning of ventricular contraction.
Option (b) QRS complex indicates ventricular contraction
QRS Complex QRS wave (complex) begins after a fraction of second after the P wave. It begins as a small downward deflection (Q) and continues as a large upright (R) and triangular wave, ending as downward wave (S) at its base.
This represents ventricular depolarization (ventricular contraction). Thus, the other options are wrong.