ECG Basics my Brain Rejects x

Question 1

What are the two things you need to be in sinus

Answer 1

Every p wave is followed by a QRS

The PR interval is less than 200ms

Question 2

What is normal axis

Answer 2

Net + QRS in I and II/aVF

Question 3

What is right axis deviation

Answer 3

Net - QRS in I and + QRS in II/aVF

Question 4

What is left axis deviation

Answer 4

Net + QRS in I and - QRS in II/AVF

Question 5

Normal p wave duration

Answer 5

0.12s/120ms

Question 6

Normal p wave amplitude

Answer 6

<2.5mm (2 lil squares)

Question 7

Normal PR interval

Answer 7

0.12-0.22s

Question 8

Normal QRS duration

Answer 8

<0.12

Question 9

How does the R wave progress

Answer 9

Should be small in V1 and get bigger through precordial leads

Question 10

Normal QTc interval:

Answer 10

Men: <0.45
Women: <0.46

Question 11

What is a shortened QTc interval

Answer 11

<0.32

Question 12

Where can you most easily see a U wave

Answer 12

V3/4

Question 13

Normal U wave characteristics

Answer 13

<1-2mm amplitude or <25% t wave’s amplitude

Question 14

1st Degree Heart Block

Answer 14

PR interval >0.22

Causes:
- Degenerative fibrosis!
- Ischaemia
- Beta Blockers

Prognosis:
- Benign

Question 15

2nd Degree Heart Block Mobitz Type 1 (Wenckebach)

Answer 15

Longer, longer, longer drop

Gradually increasing PR interval until the atrial impulse (p wave) is blocked at the AV node and no QRS happens

Prognosis:
- Usually benign and asymptomatic
- Pts respond well to atropine
- Don’t usually need pacing

Question 16

2nd Degree Heart Block Mobitz Type 2

Answer 16

If some Ps don’t get through then you have mobitz 2

Intermittent blockage of the atrial impulse (no QRS) but with constant PR interval

Causes:
- Mostly due to structural damage to the conduction system (infarction, fibrosis, necrosis)

Prognosis:
- Likely symptomatic bradycardia
- Possible progression to CHB

Question 17

3rd Degree Heart Block

Answer 17

If Ps and Qs don’t agree then you have a 3rd degree = Complete Heart Block

All atrial impulses (p waves) are blocked by the AV node until an escape rhythm happens which is either wide or narrow QRS –> NO relation between p waves and QRS complexes

Causes:
- Complete blockage at the AV node
- Inferior AMI
- AV nodal blocking drugs: Bblockers, digoxin

Prognosis:
- High risk of symptomatic bradycardias and death
- Requires a pacemaker

Question 18

Inferior limb leads

Answer 18

III, aVF, II

Question 19

Lateral limb leads

Answer 19

I, aVL, -aVR

Question 20

Septal chest leads

Answer 20

V1 V2

Question 21

Anterior chest leads

Answer 21

V3 V4

Question 22

Anterolateral chest leads

Answer 22

V5 V6

Question 23

RBBB

Answer 23

QRS >0.12

MaRRoW

M in V1
W in V6

Secondary ST changes: V1-2 have inverted t waves

Question 24

LBBB

Answer 24

QRS >0.12

WiLLiaM

W in V1 because R wave small or missing so can have just QS
M in V6

Secondary St changes: left sided (V5,V6) t wave inversions and ST depressions