QRS complex

QRS complex

n.

The principal deflection in the electrocardiogram, representing ventricular depolarization.

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QRS complex, QRS wave

a group of waves depicted on an electrocardiogram; it actually consists of three distinct waves created by the passage of the cardiac electrical impulse through the ventricles and occurs at the beginning of each contraction of the ventricles. In a normal electrocardiogram the R wave is the most prominent of the three; the Q and S waves may be extremely weak and sometimes are absent.