Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
Corresponding Author:
June Soo Kim ,Tel: +82-10-9933-3414, Fax: +82-2-3410-3849, Email: juneskim@skku.edu
Received: January 23, 2017. Accepted: April 5, 2017.
Abstract
QRS complex is a group of waves in the ECG and represents ventricular activation. It usually consists of three wave forms. Q wave is an initial negative wave at the onset of the QRS complex. R wave is the first positive wave in a QRS complex and appears at the onset of the QRS complex or following a Q wave. S wave is a second negative wave in a QRS complex. The morphology of QRS complex is useful in interpreting 12-lead ECG because it provides us clinical information regarding heart rate, QRS axis, heart position, rotation, and abnormal conductions in ventricle and so on.