A QRS complex is a combination of the three electrocardiographical measurements of the Q, R and S waves in the heart's electrical cycle. It corresponds to the depolarization of the right and left ventricles of the human heart. The QRS complex can be further classified into a set of parameters, including QRS duration, QRS amplitude and ventricular activation time (VAT). The trait is QRS complex (EFO_0005054, an Experimental Factor Ontology identifier).