ECG

Question 1

What does P wave represent

Answer 1

Atrial depolarisation (contraction)

Question 2

Normal parameters of P wave

Answer 2

3 small squares duration
2.5 small squares high
Upright in leads I, AvF, V3-V6

Question 3

What does PR segment represent and how high should it be

Answer 3

Delay at AV node

Should be 0. Should be on baseline

Question 4

PR interval represent?

what Duration normal?

Answer 4

Atrial depolarisation and delay at AV node

3-5 small squares

Question 5

What does qrs complex represent

Answer 5

Ventricular depolarisation

Question 6

What is the R wave

Answer 6

always the first positive deflection

Question 7

what is the q wave

Answer 7

Any negative wave before the R wave

Question 8

What is the S wave

Answer 8

Any negative wave that follows the R wave

Question 9

What is the R’ wave

Answer 9

Any subsequent positive wave that follows the R wave

Question 10

What does the QT interval represent

Answer 10

Whole ventricular action potential

Question 11

Normal duration of QT interval

Answer 11

males 2 big squares

Females 11 small or 2 big 1 small

Question 12

ST segment represent?

What elevation is normal

Answer 12

plateau phase of ventricular action potential

up to 2mm normal on chest leads

Question 13

T wave represent?

Answer 13

Ventricular repolatisation

Question 14

How to assess rate

Answer 14

Count the number of large squares between two peaks of R waves.

Divide 300 by this number

Question 15

How to assess rate when there are irregular rhythms

Answer 15

Count the number of QRS complexes on the entire rhythm strip and multiply this number by 6

Question 16

How to assess rhythm

Answer 16

Mark the R waves with a piece of paper and move this along the ECG to see if all the waves match up

Question 17

What would cause a regular irregular rhythm

Answer 17

2nd degree heart block

Question 18

What would cause an irregularly irregular rhythm

Answer 18

AF

Question 19

What is cardiac axis

Answer 19

The overall direction of electrical spread in the heart when the ventricles contract

Question 20

What is the normal direction of the cardiac axis

When can this axis be deviated

Answer 20

-30° ￫ 90°

Axis is deviated if electrical activity is stronger on one side - e.g. in Left Ventricular Hypertrophy

Question 21

what condition could P waves be absent

Answer 21

AF

Question 22

IN a normal axis, what will the QRS complexes look like in lead 1 and aVF

Answer 22

Both point up

Question 23

In a left axis deviation, what will the QRS complexes look like in lead 1 and aVF

Answer 23

LEad 1 the QRS will point up

aVF QRS will point down

Question 24

In a r axis deviation, what will the QRS complexes look like in lead 1 and aVF

Answer 24

Lead 1 the QRS will point down

aVF the QrS will point up

Question 25

In extreme axis, what will the QRS look like

Answer 25

Both point down

Question 26

What to assess in P waves

Answer 26

is each P wave followed by a QrS complex Is each QRS complex preceded by a P wave Do P wave look normal

Question 27

What conditions cause prolongation of PR interval

Answer 27

certain heart blocks (1st degree, 2nd degree Mobitz type 1)

Question 28

What does a shorted PR interval indicate

Answer 28

Pre-excitation syndromes

Question 29

What can cause a broad QRS

Answer 29

(i) Abnormal depolarisation (e.g. bundle branch blocks, ventricular ectopic beats) (ii) Pre-excitation (accessory pathways)

Question 30

Where is the ST segment supposed to be

Answer 30

On isoelectric line

Question 31

How elevated must ST segment be to be considered abnormal

Answer 31

by at ;east 1mm in limb leads 2mm in chest leads AND they must occur in 2+ adjacent leads e.g. leads v1,v2,v3 or leads 2, aVF and III

Question 32

What does elevated ST segment indicate

Answer 32

ST Elevation of >1mm (limb leads)/>2mm (chest leads) in adjacent leads indicates ST Elevation Myocardial Infarction (STEMI)

Question 33

What does depressed ST segment indicate

Answer 33

Ischaemia

Question 34

What does abrnoma T wave look like What would this indicate

Answer 34

Tall and tented Tall: At least ½ the amplitude of the preceding QRS complex) Tented: Look as if they’ve been pinched from above - i.e. a pointed peak, narrow base Hyperkalaemia

Question 35

When is T wave inversion normal

Answer 35

Lead aVR | normal variant in leads V1 and III

Question 36

What could t wave inversion indicate

Answer 36

non-specific sign for Ischaemia, Bundle Branch Blocks, Pulmonary Embolism (PE), Hypertrophic Cardiomyopathy (HCM) etc.

Question 37

What does a flattened T wave indicate

Answer 37

Non specific sign of ischaemia or electrolyte imbalance e.g. hypokalaemia

Question 38

What is there a risk of if the QT interval is prolonged

Answer 38

Life threatening arrhythmias