ECG Analysis

Question 1

Steps of ECG analysis

Answer 1

Patient details

1. Rate
2. Rhythm
3. Axis
4. P waves
5. QRS (normal <120ms)
6. PR interval (120-200ms)
7. QTc (380-420ms)
8. ST segments
9. T waves
10. Extras

Question 2

What do you look for in 2. Rhythm?

Answer 2

Look for P waves followed by QRS complexes

Question 3

What are the ECG characteristics of atrial flutter?

Answer 3

Saw-tooth baseline

Question 4

What are the ECG characteristics of nodal rhythm?

Answer 4

Regular QRS complexes but no P waves

Question 5

In 3. Axis, what is a normal axis?

Answer 5

Leads I & II positive (-30 - +90)

Question 6

In 3. Axis, what is a normal axis?

Answer 6

Leads I & II positive

-30 –> +90

Question 7

In left axis deviation, what happens in leads I and II?

Answer 7

Lead I positive
Lead II negative
(Leaving each other)
-30 –> -90

Question 8

In RAD what happens to leads I and II?

Answer 8

Lead I negative
Lead II positive
Reaching each other
+90 –> +180

Question 9

Causes of RAD >+90

Answer 9

Anterolateral MI
RVH 
PE
L. posterior hemiblock
WPW 
ASD secundum

Question 10

Causes of LAD

Answer 10

Inferior MI
LVH
L. posterior hemiblock
WPW 
ASD primum

Question 11

What are the causes of absent P waves on ECG?

Answer 11

AF
SAN block
Nodal rhythm

Question 12

What causes dissociated P waves and QRS complexes?

Answer 12

Complete heart block

Question 13

What is P.mitrale, what is it associated with and what causes it?

Answer 13

P mitrale = bifid P waves
Associated with LA hypertrophy
Causes: HTN, AS, MR, MS

Question 14

What is P. pulmonale, what is it associated with and what causes it?

Answer 14

P pulmonale = peaked P waves
Associated with RA hypertrophy
Causes: pulmonary hypertension, COPD

Question 15

What are the causes of a wide QRS (>120ms)?

Answer 15

Ventricular initiation
Conduction defect
WPW

Question 16

What is a pathological Q wave?

Answer 16

> 1mm wide and >2mm deep

Full thickness MI

Question 17

What does RVH look like on ECG

Answer 17

R wave in V6 >25mm

R wave in V5/ V6 + S wave in V1 >35mm

Question 18

What is PR interval?

Answer 18

From the start of the P wave to start of QRS

Question 19

What is a normal PR interval?

Answer 19

120-200ms

Question 20

Cause of a long PR interval?

Answer 20

Heart block

Question 21

Causes of short PR interval?

Answer 21

Accessory conduction e.g. WPW
Nodal rhythm
HOCM

Question 22

Cause of a depressed PR interval?

Answer 22

Pericarditis

Question 23

What is a normal QTc?

Answer 23

380-420ms

Question 24

Causes of long QTc?

Answer 24

TIIMME >420

Toxins
- Macrolides
- Anti-arhythmics (Ia/III) e.g. amiodarone
- TCAs
- Histamine antagonists
Inherited e.g. Romano-Ward, Jervell with SNHL
Ischaemia
Myocarditis
Mitral valve prolapse
Electrolytes - hypomagnesaemia, hypokalaemia, hypocalcaemia and hypo