Arrhythmias

Question 1

Treatment of VT - Haemodynamically Compromised

Answer 1

Emergency DC Cardioversion

Question 2

Treatment of VT - Haemodynamically Stable

Answer 2

IV lidocaine or IV amiodarone

May need DC cardioversion if unsuccessful

Question 3

Treatment of Bradycardia - Rate >40bpm and Asymptomatic

Answer 3

No treatment needed

Look for a cause and stop any drugs which could be contributing

Question 4

Presentation of Sick Sinus Syndrome

Answer 4

Sinus node dysfunction 
Bradycardia +/- arrest 
Sinoatrial block 
SVT alternating with bradycardia/asystole 
AF and thromboembolism may occur

Question 5

Treatment of Symptomatic Sick Sinus Syndrome

Answer 5

Pacing

Question 6

Acute Management of SVT

Answer 6

Vagotonic manoeuvres
IV adenosine or verapamil
DC shock if compromised

Question 7

Maintenance Therapy of SVT

Answer 7

Beta blockers or verapamil

Question 8

Maintenance Therapy of AF/flutter

Answer 8

Beta blocker or verapamil
Alternatively, digoxin or amiodarone
Flecanide for pre exited AF

Question 9

Causes of First and Second Degree Heart Block

Answer 9

Normal variant 
Athletes
Sick sinus syndrome 
Ischaemic heart disease 
Acute myocarditis 
Drugs (beta blockers, digoxin)

Question 10

Treatment of First Degree Heart Block

Answer 10

None needed

Follow up recommended to monitor development to ore advanced block

Question 11

Causes of Mobitz Type I Block

Answer 11

Vagal in origin

Usually block in AV node

Question 12

Treatment of Mobitz Type I Block

Answer 12

Generally only requires monitoring

Question 13

Causes of Mobitz Type II Block

Answer 13

Block at infranodal level (e.g. Bundle of His)

Question 14

Treatment of Mobitz Type II Block

Answer 14

Permanent pacing due to higher risk of progression to complete heart block

Question 15

Causes of Third Degree Heart Block

Answer 15

Ischaemic heart disease 
Idiopathic (fibrosis)
Congenital 
Digoxin toxicity 
Aortic valve calcification 
Cardiac surgery/trauma 
Infiltration

Question 16

Treatment of Third Degree Heart Block

Answer 16

Dependant on cause, but ventricular pacing generally needed

Question 17

Treatment for Bradycardia - Symptomatic or Rate below 40bpm

Answer 17

IV Atropine
No response = temporary pacing wire
If needed = Isoprenaline infusion, or external cardiac pacing

Question 18

What is the most common childhood arrhythmia?

Answer 18

Supraventricular re-entry tachycardia

Question 19

How does IV Adenosine slow the heart rate?

Answer 19

Block the secondary circuit at the AV node to return the heart to sinus rhythm

Question 20

What are the two main mechanisms of arrhythmia production?

Answer 20

Defects in impulse formation

Defects in impulse conduction

Question 21

How does pathological altered automaticity lead to arrhythmias?

Answer 21

A latent pacemaker subverts the SA node’s function as the heart’s normal pacemaker

Question 22

How does triggered activity lead to arrhythmias?

Answer 22

Afterpolarisations are triggered by a normal AP

Can get early after depolarisation or late depolarisation

Question 23

When do Early Afterdepolarisations occur?

Answer 23

During the inciting AP within Phase 2 and Phase 3

Associated with prolongation of AP and drugs prolonging QT interval

Question 24

When do Late Afterdepolarisations occur?

Answer 24

After complete depolarisation

Associated with Ca2+ overload provoked by catecholamines, digoxin, heart failure

Question 25

What defects in impulse formation lead to arrhythmias?

Answer 25

Altered automaticity | Triggered activity

Question 26

What defects in impulse conduction lead to arrhythmias?

Answer 26

Re-entry Conduction block Accessory tracts

Question 27

How does re-entry lead to arrhythmias?

Answer 27

Re-entry occurs when a self sustaining current occurs which stimulates and area of myocardium repeatedly/rapidly Re-entrant circuits require: Unidirectional block Slowed retrograde conduction velocity

Question 28

How do accessory tract pathways lead to arrhythmias?

Answer 28

Electrical pathways that bypass AV node (e.g. Bundle of Kent) Ventricles receive impulses from both normal and accessory pathways

Question 29

Sudden onset tachycardia with recovery of normal sinus rhythm after carotid sinus massage or adenosine is characteristic of which arrhythmia?

Answer 29

Paroxysmal Supraventricular Tachycardia

Question 30

What is the most common cause of Paroxysmal Supraventricular Tachycardia?

Answer 30

Atrioventricular nodal reentrant tachycardia

Question 31

What are the three kinds of atrial fibrillation?

Answer 31

Paroxysmal Persistent Permanent

Question 32

What is paroxysmal atrial fibrillation?

Answer 32

Episodes of AF terminate spontaneously

Question 33

What is persistent atrial fibrillation?

Answer 33

Episodes are non self terminating

Question 34

What is permanent atrial fibrillation?

Answer 34

Continuous AF which cannot be cardioverted | Treatment centres on rate control and anticoagulation