ECG Interpretation

Question 1

order of systematic approach

Answer 1

calibration. rate. rhythm. axis. intervals. hypertrophy. infarcts. ST elevation/depression. T wave abnormalities

Question 2

calibration of ECG (time and voltage)

Answer 2

25 mm (5 big boxes) = 1s. each mm = 0.04s, each box = 0.2 s. 10mm = 1 mV.

Question 3

how to make sure leads not reversed?

Answer 3

I should have positive P wave; aVR should see negative waves (negative p and qrs)

Question 4

count off method for rate

Answer 4

300 150 100 75 60 50

Question 5

10 second method for rate

Answer 5

printoff is 10s long. count full cardiac cycles (R-R intervals) –> multiply by 6

Question 6

sinus rhythm is present if?

Answer 6

every p wave followed by QRS, every QRS preceded by 1 P. P wave upright in I, II, III

Question 7

how does the P wave normally spread? so which leads are good to see them?

Answer 7

starts at top of RA, goes down and left. best leads: inferior (II, III, aVF) and V1 (closest to RA)

Question 8

quick trick for normal axis?

Answer 8

if leads I and II are positive, then it’s normal

Question 9

axis: def? look at which leads (plotting method)?

Answer 9

average QRS vector in LIMB leads. look at I and aVF –> plot on X Y graph to estimate angle