Electrocardiogram Summary 1986.2.25

Electrocardiogram Summary 1986.2.25

1. Electrical axis

Focusing on standard leads, lead I shows an upward wave pattern, while lead III shows a downward wave pattern, indicating a leftward electrical axis; conversely, a rightward electrical axis is indicated.

2. Cardiac position

Focusing on leads aVL and aVF, if aVL shows an upward wave, it indicates a transverse cardiac position; if aVF shows an upward wave, it indicates a vertical cardiac position; if both show upward waves, it indicates an intermediate cardiac position.

3. Rotation

Focusing on lead V3, if V3 shows a downward wave, it indicates clockwise rotation; if V3 shows an upward wave, it indicates counterclockwise rotation.

4. Upright and inverted forms of each wave, regular internal variations

P-QRS-T waves are all inverted in lead aVR, while upright in all other leads. P waves are upright in all leads; if inverted, it indicates an ectopic P wave, which may be caused by atrioventricular node impulses or atrial impulses. The direction of the QRS complex varies significantly on the ECG depending on cardiac position, electrical axis, and rotation, but overall, qR and Rs represent left ventricular membrane potential, while rS and QS types represent right ventricular membrane potential. All lead complex waveforms are influenced by these factors. These points should be kept in mind when analyzing ECGs.