ECGs

Question 1

What position must patient be in to perform an ECG?

Answer 1

Lying on bed at 30-40 degrees with one or two pillows supporting neck

Question 2

Electrodes should be applied over bone or muscle to limit interference?

Answer 2

Bone

Question 3

Explain placement of the limb electrodes?

Answer 3

RA = red
LA = yellow 
LL = green
RL = black (earthed)

Ride, your, green, bike (clockwise starting at right hand)

Question 4

Explain placement of chest electrodes?

Answer 4

V1 - 4th ICS on right
V2 - 4th ICS on left
V3 - midway between V2 and V4
V4- 5th ICS midclavicular line
V5- same level as V4 anterior axillary line
V6 - same level as V4 and 5, mid axillary line

Question 5

1 large box on an ECG is worth?

Answer 5

0.2 seconds (200 ms)

Question 6

5 large boxes on an ECG are worth?

Answer 6

1 second

Question 7

1 small box on an ECG is worth?

Answer 7

0.04 seconds (40 ms)

Question 8

How do you calculate rate on an ECG?

Answer 8

Regular - large number of squares between 2R waves and divide into 300
Irregular - count the number of QRS complexes in 6 seconds

Question 9

Lead 1 is positive and AVF is positive?

Answer 9

Normal axis

Question 10

Lead 1 is positive and AVF is negative?

Answer 10

left axis

Question 11

Lead 1 is negative, AVF is positive?

Answer 11

Right axis

Question 12

Lead 1 is negative and AVF is negative?

Answer 12

Indeterminate axis

Question 13

Define the PR interval and give normal length?

Answer 13

onset of P to onset of QRS, represents AV node delay, normal if 120-200 ms (3-5 small squares)

you should look at it and ask does the PR measure 1 big square or less

Question 14

What is normal length of QRS?

Answer 14

120 ms or less (3 small boxes or less)

Question 15

Define the QT interval and give normal length?

Answer 15

Start of QRS until end of T wave - 8-12 small boxes (varies a lot though and there can be formulas to work out what should be normal

Question 16

Define a supra ventricular rhythm and list some examples

Answer 16

Supraventricular rhythms - originate above the AV node whether conducted through it or not

E.g. Sinus rhythm, sinus arrhythmia, AF, atrial flutter, AVNRT (WPW), wandering atrial pacemaker, SVT/ AVNRT

Question 17

ECG meets all the criteria of sinus rhythm but the rhythm itself is irregular, the irregularity is caused by physiological changes in the cardiac timing caused by respiration, it is considered a normal variant

Answer 17

Sinus arrhythmia

Question 18

Disorganised electrical activity in the atria, irregularly irregular QRS complexes and absent P waves

Answer 18

Atrial Fibrillation

Question 19

Regular usually narrow complex tachycardia, saw tooth baseline, F waves, regular QRS complexes, rate divisible into 300

Answer 19

Atrial flutter

Question 20

Rhythm originates at the AV junction, retrograde p waves can be seen, normal QRS morphology

Answer 20

Junctional rhythm

Question 21

Sinus rhythm with differing morphologies of P waves on beats

Answer 21

Supraventricular ectopics

Question 22

Define ventricular rhythms? are they ever normal? give some examples?

Answer 22

rhythms that originate in the ventricle - always pathological, always broad complexes QRS > 120 ms

E.g. ventricular premature complexes, ventricular tachycardia (monomorphic), polymorphic ventricular tachycardia (torsades de pointes), ventricular escape rhythm, ventricular fibrillation

Question 23

Regular broad complex tachycardia with QRS > 120 ms

Answer 23

Ventricular tachycardia

Question 24

What is torsades de pointes and what is it often associated with?

Answer 24

Polymorphic VT often associated with long QT interval and R on T phenomenon

Question 25

Irregular random baseline with no discernible waveforms

Answer 25

VF

Question 26

Define heart block?

Answer 26

Term given to a block in conduction between the atria and ventricle
Not to be confused with bundle branch block
Due to AV nodal dysfunction (drugs, ischaemia, age)

Question 27

Define first degree heart block?

Answer 27

PR interval > 200 ms, no progressive lengthening, stable rhythm

Question 28

Define Mobitz 1 second degree heart block?

Answer 28

mobitz 1 - progressive PR prolongation until a missed beat - not treated unless severe or HD compromise

Question 29

Define mobitz 2 second degree heart block?

Answer 29

constant PR interval but every nth beat is dropped - always abnormal

Question 30

Define 3rd degree heart block?

Answer 30

no relationship between P wave and QRS

Question 31

Lateral leads?

Answer 31

1, AVL, V5, V6

Question 32

Inferior leads?

Answer 32

2,3 and AVF

Question 33

Anterior leads?

Answer 33

V1 V2 V3 V4

Question 34

ST elevation?

Answer 34

More than 1mm in 2 contiguous limb leads
More than 2mm in two contiguous limb leads

contiguous = leads next to each other

Question 35

Evolution of ST changes in MI?

Answer 35

Normal > Peaked t wave > ST segment elevation that gradually increases > Q wave formation and loss of R wave > T wave inversion

Question 36

What is pericardial inflammation usually secondary to?

Answer 36

MI or Viral infection

Question 37

Symptoms of pericarditis?

Answer 37

• Pleuritic chest pain (worst on inspiration)
  
  • Fever
• Pericardial friction rub

Question 38

ECG changes in pericarditis?

Answer 38

• Upward concave ST elevation
  
  • Changes do not evolve (unlike MI)
  • Widespread changes involving > 1 vascular territory e.g. inferior and anterior ST elevation
  • Can be difficult to differentiate from ST elevation MI
• PR Depression is a useful diagnostic tool

Question 39

How is ventricular hypertrophy shown on ECG?

Answer 39

increased height of QRS complexes

Question 40

Left bundle branch block will be shown in ?

Answer 40

V5 and V6

QRS will be more than 0.12 secs

Question 41

Right bundle branch block will be shown in ?

Answer 41

V1 and V2

QRS will be more than 0.12 secs