ECG

Question 1

What indicates left axis deviation on an ECG?

Answer 1

Lead 1 is positive and avF is negative

Question 2

What indicates right axis deviation on an ECG?

Answer 2

Lead 1 is negative and avF is positive

Question 3

What would a normal axis show on an ECG?

Answer 3

Both lead 1 and avF would be positive

Question 4

What would the ECG axis be if both lead 1 and avF are negative?

Answer 4

Indeterminate

Question 5

How can the heart rate be calculated when rhythm is regular?

Answer 5

300/the number of large boxes between the top of each QRS complex.

Question 6

How can the heart rate be calculated when rhythm is irregular?

Answer 6

Count the number of QRS complexes in the rhythm strip x 6

i.e. 14 QRS complexes x 6 = 84 bpm

Question 7

Normal duration of PR interval?

Answer 7

Normally 0.12-0.2s

Question 8

Normal length of QRS complex?

Answer 8

Usually less than 0.1s

Question 9

Heart rate in atrial fibrillation?

Answer 9

300bpm

Question 10

Rhythm of atrial fibrillation?

Answer 10

Irregularly irregular rhythm

Question 11

P waves are present in atrial fibrillation. True/false?

Answer 11

False P waves are absent

Question 12

What is the characteristic P wave pattern in atrial flutter?

Answer 12

“Saw tooth” pattern

Question 13

QRS complexes are normal in atrial fibrillation. True/false?

Answer 13

False

Narrow QRS complexes typically present in atrial fibrillation.

Normal QRS complexes in atrial flutter.

Question 14

What is the typical appearance for ventricular fibrillation?

Answer 14

Bizarre irregular waveform

No recognisable QRS complexes

Random frequency and amplitude

Unco-ordinated electrical activity

Question 15

What is the main difference between monomorphic and polymorphic ventricular tachycardia?

Answer 15

In polymorphic VT, the QRS complex amplitude varies whereas in monomoprhic VT, it remains the same.

Question 16

What are the 2 main features of torsades de pointes?

Answer 16

A specific polymorphic VT associated with a long QT interval.

QRS complexes appear to twist around the isoelectric line.

Question 17

Characteristic feature of 1st degree heart block?

Answer 17

PR interval greater than 0.2s (5 small squares) - not usually serious and can be found in healthy patients.

Question 18

Characteristic feature of 2nd degree heart block - Mobitz type 1?

Answer 18

Progressive lengthening of the PR interval, eventually resulting in a dropped beat (P wave with no QRS).

Question 19

Characteristic feature of 2nd degree heart block - Mobitz type 2?

Answer 19

Each P wave is associated with a QRS complex until there is 1 atrial conduction (atrial depolarisation) or P wave that is not followed by a QRS complex.

Tends to happen in a specific pattern i.e. every 3 waves.

Question 20

Characteristic feature of 3rd degree heart block?

Answer 20

No relation between P wave and QRS complexes but both are present.

Question 21

Characteristic feature of Wolff-Parkinson-White syndrome?

Answer 21

Sloping QRS complex (delta wave) - pre-excitation

Question 22

What are the 2 main AV nodes?

Answer 22

Left bundle branch

Right bundle branch

Question 23

How to distinguish between RBBB and LBBB (use WiLLiaM MoRRoW)?

Answer 23

Look at the QRS morphology in V1 and V6.

If the QRS looks like W in V1 and M in V6 it is LBBB. (WiLLiaM)

If the QRS looks like M in V1 and W in V6 it is RBBB. (MoRRoW)

If both leads V1 and V6 don’t have these then can assume normal

Question 24

LBBB is ALWAYS pathological. True/false?

Answer 24

True

RBBB on the other hand can be physiological e.g. if young and growing

Question 25

When QRS complexes are narrow, where is the origin of the tachycardia typically and what is an example?

Answer 25

Above the AV node

Example: supraventricular tachycardia

Question 26

When QRS complexes are wide, where is the origin of the tachycardia typically and what is an example?

Answer 26

Below the AV node

Example: VT (ventricular tachycardia)

Question 27

Ventricular tachycardia is a medical emergency. True/false?

Answer 27

True

VT until proven otherwise. Associated with cardiac arrest.

Question 28

First line treatment for SVT?

Answer 28

Vagal manoeuvres are a first-line (first choice) treatment for supraventricular tachycardia (SVT) (fast heart rate) because they’re a low-risk, low-cost way to slow down a heart rate that’s too fast.

Question 29

What is carotid sinus massage?

Answer 29

Gentle pressure is applied to the carotid sinus, a small area located on either side of the neck where the carotid artery splits into two branches.

This technique is used to slow down the heart rate and can help diagnose or treat certain types of abnormal heart rhythms, such as supraventricular tachycardia (SVT).

Question 30

What is the valsalva manoeuvre?

Answer 30

A breathing technique that involves a person trying to exhale forcefully with a closed mouth and nose.

Can be used to stop episodes of supraventricular tachycardia (SVT) by stimulating the vagus nerve, which helps slow down the heart rate.

Question 31

What is adenosine used for?

Answer 31

Adenosine is primarily used to treat and diagnose certain types of supraventricular tachycardias (SVTs), which are abnormal fast heart rhythms originating above the ventricles.

Question 32

Why is adenosine ineffective for VT?

Answer 32

It is not effective for arrhythmias that originate in the ventricles (ventricular tachycardia)

Adenosine primarily affects the atrioventricular (AV) node, slowing conduction through this node and interrupting re-entrant circuits that involve it.

VT originates in the ventricles, below the AV node, so adenosine’s effects on the AV node do not influence the ventricular tissue directly where VT occurs.

Question 33

Why is it risky to give adenosine for wide-complex tachycardias i.e. ventricular tachycardia?

Answer 33

In cases of wide-complex tachycardia where the diagnosis is uncertain, using adenosine can be risky because it may cause adverse effects without treating the arrhythmia if it turns out to be VT.

Question 34

Adenosine is reserved for use in SVT. True/false?

Answer 34

True

Question 35

First line treatment for VT in haemodynamically unstable patients (i.e. low blood pressure, chest pain, altered mental status, signs of shock)?

Answer 35

Immediate Synchronized Cardioversion - delivers a shock timed with the QRS complex to restore normal rhythm safely.

Question 36

Treatments for VT in haemodynamically stable patients ?

Answer 36

anti-arrhythmic medications:

Amiodarone: Often the first-line drug due to its efficacy in converting VT to sinus rhythm and preventing recurrence.

Lidocaine: Another option, particularly in cases related to acute myocardial ischemia.

Procainamide: Sometimes used as an alternative, especially in cases of monomorphic VT.

Question 37

Treatment options for patients with recurrent VT or high risk of recurrence?

Answer 37

ICDs - can detect and terminate VT episodes with pacing or shocks.

Catheter ablation - Ablation targets the areas of the heart responsible for the abnormal rhythms.

Beta-blockers - Used in patients with underlying structural heart disease or after myocardial infarction to prevent VT.

Addressing underlying causes - identifying and treating reversible causes like electrolyte imbalances, ischemia, or drug toxicity.

Question 38

Which one SVT or VT has narrow QRS complexes and typically originates above the AV node?

Answer 38

SVT (supraventricular tachycardia)

Question 39

What areas of the heart do the chest leads look at?

Answer 39

V1 Septal view of the heart
V2 Septal view of the heart
V3 Anterior view of the heart
V4 Anterior view of the heart
V5 Lateral view of the heart
V6 Lateral view of the heart

Remember: SSAALL