A First Look at the ECG

Question 1

What do the separate components of the QRS complex correspond to?

Answer 1

Q – the interventricular septum depolarises from left to right
R – the bulk of the ventricle depolarises from the endocardial to epicardial surface
S – the upper part of the interventricular septum depolarises

Question 2

Largest R-wave?

Answer 2

SLII as main vector flow directly to the positive lead electrode.

Question 3

Negative R-wave?

Answer 3

aVR as the main vector flow downwards and towards the left and so results in negative deflections for all waveforms.

Question 4

Smallest R-wave?

Answer 4

aVL as the main vector approaches at a broad angle so results in the least upright QRS complex.

Question 5

What is “progression” of the chest leads?

Answer 5

The R-wave should become larger going from V1-V6 until the R-wave is bigger than the S-wave in V4 (= neg. to pos.)

Question 6

Explain the ARI BAR system

Answer 6

A – electrical Activity
R – Rate
I – Irregular or regular

B – Broad QRS complex
A – Atrial activity
R – Relationship between P wave and QRS complex

Question 7

Which leads look at the heart in the frontal/coronal plane?

Answer 7

SLI, SLII, SLIII, aVR, aVL, and aVF give six different views of the heart in the coronal plane.

Question 8

Which leads look at the heart in the horizontal/transverse plane?

Answer 8

The precordial chest leads.