Normal values

Heart rate     60 - 100 bpm
PR interval     0.12 - 0.20 s
QRS interval     ≤ 0.12 s
QT interval     < half RR interval (males < 0.40 s; females < 0.44 s)
P wave amplitude (in lead II)     ≤ 3 mV (mm)
P wave terminal negative deflection (in lead V1)     ≤ 1 mV (mm)
Q wave     < 0.04 s (1 mm) and < 1/3 of R wave amplitude in the same lead