ECG interpretation

Question 1

How do you calculate HR on an ECG?

Answer 1

If regular:
count squares in R-R interval
Divide 300 by this number

If irregular:
Count number of of complexes in one rhythm strip (10s)
Multiply this by 6

Question 2

Normal HR range?

Answer 2

60-100

Question 3

Normal cardiac axis

Answer 3

Lead 2 most positive deflection compared to leads 1 and 3

-30 to +90

Question 4

Right axis deviation

Answer 4

Lead 3 is the most positive, lead 2 and AVF also positive, and lead 1 is negative
+90 to +180
Common in right ventricular hypertrophy

Question 5

Left Axis deviation

Answer 5

Lead 1 most positive deviation
Leads 2 and 3 are negative
-30 to -90
Common in heart conduction defects

Question 6

What pathologies (and their parallel signs) might no P-wave indicate?

Answer 6

Sawtooth baseline - Atrial Flutter
Chaotic waves - fibrillation
Flat line - no atrial activity?

Question 7

Define prolonged PR and what can it show?

Answer 7

PR interval >0.2 seconds (5 squares)

Heart block

Question 8

How would 1st degree heart block manifest?

Answer 8

fixed prolonged PR (>0.2s)

Occurs between SAN and AVN (in atrium)

Question 9

How would 2nd degree heart block (Mobitz type 1) manifest?

Answer 9

Increased PR interval until there is a dropped QRS

Occurs in AVN
https://geekymedics.com/wp-content/uploads/2017/01/MobitzType1-1.jpg

Question 10

How would 2nd degree heart block (Mobitz type 2) manifest?

Answer 10

Fixed PR, with dropped QRS beats (within a fixed ratio)

Occurs after AVN in bundle of his or purkinje

Question 11

How would 3rd degree heart block manifest?

Answer 11

Complete dissociation between P waves and QRS complexes

Occurs from AV node down

Question 12

What does a shortened PR indicate?

Answer 12

P-wave initiated closer to AVN - smaller atria

or - There is an accesory pathway (may be associated with a delta wave - for example in WPW syndrome

Question 13

What might a broad (>0.12s) QRS indicate?

Answer 13

Abnormal sequence
eg ventricular ectopic
Bundle branch block

Question 14

What might an abnormally narrow QRS indicate?

Answer 14

atrial ectopic

Question 15

define a small complex

Answer 15

Small complexes are defined as < 5mm in the limb leads or < 10 mm in the chest leads

Question 16

What can a tall complex indicate?

Answer 16

LVH

Question 17

What does a Delta wave indicate?

Answer 17

WPW syndrome

Question 18

What does a pathological Q-wave look like?

Answer 18

> 25% size of following R-wave, or >2mm height + >40ms in width

Question 19

What does a pathological Q wave indicate?

Answer 19

If diffuse, previous MI

Question 20

What does poor R-wave progression indicate?

Answer 20

Previous MI or large patient

Question 21

What can ST elevation indicate?

Answer 21

Anterior MI
LVH
Pericarditis

Question 22

What can ST depression indicate?

Answer 22

Myocardial ischaemia

Question 23

What do T-waves represent?

Answer 23

Ventricle repolarisation

Question 24

What are “Tall T waves”?

Answer 24

> 5mm in limb leads and >10mm in chest leads

Question 25

What may “Tall tented T waves” indicate?

Answer 25

Hyperkalaemia

Tall T waves indicate hyper acute STEMI

Question 26

When is inverted T waves a sign?

Answer 26

when in leads other than V1 and Lead III

Question 27

Give some examples of Inverted T wave associated pathology

Answer 27

Ischaemia
PE
LVH (lateral leads)
Hypertrophic cardiomyopathy (widespread)
L/RBBB

Question 28

What can a Biphasic T-wave indicate?

Answer 28

Hypokalaemia

Ischaemia

Question 29

What is the J point?

Answer 29

Where the QRS complex becomes the ST segment.

Question 30

How long should QT interval be?

Answer 30

0.35 - 0.45 seconds