Example of a normal ECG

ECG basics Example of a normal ECG Intervals

Large square: 200ms

Small square: 40ms, 1mm x1mm

1.Heart rate: Number of QRS complexes * 6 (Count in the rhythm strip)

Irregular: QRS complex in 30 small squares

2.Sinus rhythm

P wave upright: Lead II

P wave inverted: Lead aVR

Each P wave looks the same (within the same lead) oCheck in the rhythm strip 1 / 2

3.Heart axis

Assess whether QRS complex is positive or negative:

Always compare to the T-P segment oThe part between the T wave of the last beat and the P wave of the next beat Heart Axis assesment Intermediate

oLead I: Positive

oLead II: Positive

Left

oLead I: Positive

oLead II: Negative

Right

oLead I: Negative

oaVF: Positive

Extreme

oLead I: Negative

oaVF: Negative

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