Table 1: Normal values and limits of the main ECG features.

Feature Normal Value Normal Limit
P width (Pf - Pi) 110ms +20ms
PQ/PR interval (Qi - Pi) 160ms +40ms
QRS width (J - Qi) 100ms +20ms
QT interval (Tf - Qi) 400ms +40ms
ST segment (Ti - J) 150ms -
T width (Tf - Ti) 150ms -
P amplitude 0.15mV +0.05mV
QRS height 1.50mV +0.50mV
ST level 0.00mV +0.10mV
T amplitude 0.30mV +0.20mV

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