Electrocardiogram (ECG)

I had a fantastic tutorial on ECG in St.Mary's Hospital from Dr.forget-the-name. This is just for my own reference when I get 'demented' every time I get asked to interpret an ECG.

1) Make sure you start by mentioning the details of the patient. U can easily obtain this from the ECG strip.

This is the ECG for Mr/Mrs/Ms_(px name)_, _(px age)_ years old, taken on _(date of ECG done)__.

2) Look at the rhythm lines at the bottom of the ECG.

1- RATE (beats per minute/bpm)
Rate can be calculated depending on the rhythm :
a. If regular : 300/(number of small boxes in R-R)
b. If irregular : (number of R-R in 6 secs/30 small boxes) X 10

a. sinus rhythm : there is P wave before every QRS complex
b. irregular : no P wave before QRS complex -> consistent with Atrial Fibrillation

a. normal : Both lead I and AVF are +ve
b. right axis deviation : Lead I -ve, AVF +ve
c. left axis deviation : Lead AVF -ve, I +ve (hypertrophy)

4- P-R interval
a. normal : <0.2sec (1 big box)
b. prolonged : >0.2sec (1 small box) -> consistent with atrioventricular (AV) block /drugs-beta blocker,digoxin

5- QRS complex
a. normal : <0.12 secs (3 small boxes)
b. widen : 2 possibilities ;
*(1) conduction delay : bundle branch block (BBB) - look at V1 and V6
-right BBB (RBBB) - MarroW : M shape in V1, W shape in V6
-left BBB (LBBB) - WilliaM : W shape in V1, M shape in V6
*(2)hypertrophy : height [(R wave in V5 or V6) + (S wave in V1)] > 35mm

6- S wave
a. normal
b. invertion : infarction (myocardial infarction)
c. depression : ischaemia

7- T wave
a. tall tented T-wave : hyperkalaemia
b. inverted T wave : ischaemia
*peak T wave over infarcted area = early MI

*I,AVL,V1,V2 : superior
*V3,V4 : anterior
*V5,V6 : lateral
*II,III,AVF : inferior
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