Why are R waves (Figure) used to determine heart rate rather than T waves? Solution R wave: Mainly its represents first upwards deflection after P wave, Easiest wave form for detremaing the heart function R wave minaly represents the part of VENTRICULAR DEPOLARIZATION , its mainly enlarge with ventricular hypertrophy T wave; Represents the repolarization of the ventricles, this T wave inverted or flat in the condition of the mycordial ischemic and bundle branch block after ventriculr depolarisition the total heart rhytham will be completed so because R wave heart rate will be determains.