ECG: the first step / Outline of the normal ECG

ECG: the first step

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Outline of the normal ECG

In a normal ECG, because the "cardiac vector loop during ventricular depolarization" mainly spreads left-inferior-posteriorly, when the loop is projected to lead I, lead aVF, and lead V2, the deflection of the QRS wave is mainly positive, positive and negative, respectively.

Let's consider the direction of the deflection in the representative leads in a normal ECG.

Summary
  Cardiac vector loop during ventricular depolarization Actual ECG recording
condition of the heart the direction the loop mainly spreads projection to leads
normal left-inferior-posterior I aVF V2 I aVF V2 all leads

Achievement Quiz

  1. In a normal heart, the direction that the "cardiac vector loop during ventricular depolarization" mainly spreads, which is towards the area the ventricle is relatively thick, is , , .
  2. Lead is the lead in which the direction is positive, so the deflection of the QRS wave of a normal heart that is formed by the projection of the "cardiac vector loop during ventricular depolarization", which spreads mainly to the left/right, is basically .
  3. Lead is positive in the direction. When the "cardiac vector loop during ventricular depolarization" of a normal heart, which spreads mainly superiorly/inferiorly, is projected to this lead, the QRS that is formed is mainly .
  4. Lead is positive in the directon. When the "cardiac vector loop during ventricular depolarization" of a normal heart, which spreads mainly anteriorly/posteriorly, is projected to this lead, the QRS that is formed is mainly .