ECG

Question 1

what is an electrocardiogram?

Answer 1

a graphical representation of the electrical activity of the heart

10 electrodes, 12 traces obtained

Question 2

which leads are bipolar and orientated in the coronal plane?

Answer 2

standard leads I, II, and III

Question 3

which leads are unipolar and orientated in the coronal plane?

Answer 3

augmented leads aVR, aVF, aVL

Question 4

which leads are unipolar and orientated in the horizontal plane?

Answer 4

V1 to V6

Question 5

bipolar leads =

Answer 5

utilise a single positive and a single negative electrode between which electrical potentials are measured

Question 6

unipolar leads =

Answer 6

single positive recording electrode and utilise a combination of the other electrodes to serve as a composite negative electrode

Question 7

Eindhoven’s triangle

Answer 7

aVR, aVL, aVF readings made from signals from leads I, II, and III

Question 8

P wave

Answer 8

atrial depolarisation

Question 9

QRS complex

Answer 9

ventricular depolarisation

Question 10

T wave

Answer 10

ventricular repolarisation

Question 11

duration of PR interval

Answer 11

120-200ms

3-5 small squares

Question 12

duration of QRS

Answer 12

80-120ms

2-3 small squares

Question 13

duration of QT

Answer 13

350-450ms

Question 14

how do you calculate QTc

Answer 14

QTC = QT / √ RR

Question 15

duration of QTc

Answer 15

<350ms is short

for men, >440ms is long

for women, >480ms is long

Question 16

what is the direction of travel of electrical impulses in the heart?

Answer 16

SA node → AV node → Bundle of His → Bundle branches → Purkinje fibres

Question 17

ECG territories: which leads are lateral?

Answer 17

lead I, aVL, V5, V6

Question 18

ECG territories: which leads are inferior?

Answer 18

lead II, lead III, aVF

Question 19

ECG territories: which leads are septal?

Answer 19

V1, V2

Question 20

ECG territories: which leads are anterior?

Answer 20

V3, V4

Question 21

how to calculate heart rate from ECG?

Answer 21

if heart beat is regular, 300 divided by no. of big squares between QRS complexes

if heart beat is irregular, number of QRS complexes on rhythm strip multiplied by 6

Question 22

types of irregular heart rhythm

Answer 22

regularly irregular

irregularly irregular

Question 23

what causes right axis deviation?

Answer 23

right ventricular hypertrophy

Question 24

what causes left axis deviation?

Answer 24

conduction defects

Question 25

left axis deviation on ECG

Answer 25

Look at Leads I, II, aVF.

Left Axis Deviation =
Leaving each other

Question 26

right axis deviation on ECG

Answer 26

Look at Leads I, II, aVF.

Right Axis Deviation =
Reaching towards each other

Question 27

no p waves?

Answer 27

atrial fibrillation

Question 28

no QRS complex?

Answer 28

heartblock

Question 29

sawtooth baseline is a sign of

Answer 29

atrial flutter

Question 30

chaotic baseline is a sign of

Answer 30

atrial fibrillation

Question 31

left atrium enlargement on ECG

Answer 31

P mitrale

Question 32

right atrium enlargement on ECG

Answer 32

P pulmonale (tall P wave)

Question 33

what does prolonged PR interval suggest?

Answer 33

AV block

Question 34

ECG sign of first degree heart block

Answer 34

fixed prolonged PR interval

Question 35

ECG sign of second degree heart block

Answer 35

Mobitz type 1: PR interval increases then dropped beat

Mobitz type 2: PR interval fixed with dropped beats (2:1, 3:1, 4:1)

Question 36

ECG sign of third degree heart block

Answer 36

complete heart block OR AV dissociation - no relation between P waves and QRS

Question 37

what can torsades de pointes develop into?

outline looks like a party streamer

Answer 37

ventricular fibrillation

Question 38

management of ventricular fibrillation

Answer 38

Oxygen, IV access, Cardiac monitor, ECG

Drugs: Amiodarone

Electricity: DC Cardioversion

Question 39

management of torsades de pointes

Answer 39

IV magnesium sulfate

Stop drugs causing prolonged QTc

Question 40

examples of narrow complex tachycardia

Answer 40

Atrial Fibrillation
Atrial Flutter
Re-entry (AVRT or AVNRT)
Atrial Tachycardia
Multifocal Atrial Tachycardia

Question 41

SVT treatment

Answer 41

Vagal manouevres (e.g. Valsalva, carotid sinus massage, head in ice-cold water)
Adenosine
DC Cardioversion
AF or Flutter: Beta blockers, amiodarone or digoxin. (Rate + rhythm control)
Rate control prophylaxis thereafter +/- catheter ablation

Question 42

treatment of bradycardia

Answer 42

atropine

pacemaker

Question 43

treatment of tachycardia

Answer 43

adenosine, amiodarone, beta blockers, verapamil, digoxin

DC cardioversion

Question 44

ECG sign for pericarditis

Answer 44

widespread concave ST elevation (or saddle-shaped)

Question 45

causes of ST depression

Answer 45

Ischaemia – horizontal or downsloping ST-depression, de Winter’s sign
Digoxin – generalised ST depression with curved ST segment
Hypokalaemia – typically <0.5mm
Heart Failure – may be seen in left lateral leads (I, aVL, V5, V6)
SVTs – typically V5, V6
Physiologial – seen during exercise

Secondary ST Depression
LVH or RVH
LBBB or RBBB
Pre-excitation
Pacemaker stimulation in left ventricle

Question 46

sign of hyperkalaemia on ECG

Answer 46

tall T waves

Question 47

T wave inversion may be a sign of:

Answer 47

previous episode of ischaemia
acute ischaemia
cerebrovascular insult
hypertrophic cardiomyopathy

Question 48

causes of prolonged QTc

Answer 48

Drugs – Antipsychotics, Tricyclic antidepressants, chloroquine, hydroxychloroquine, quinine, macrolides, some anti-arrythmics.
Hypokalaemia
Hypomagnesaemia
Hypocalcaemia
MI
Hypothermia
Raised intra-cranial pressure
Congenital Long QT syndrome

Question 49

what does a delta wave indicate?

Answer 49

Wolff-Parkinson-White syndrome