AF and Arrythmias

Question 1

How does electrical conduction spread through the heart?

Answer 1

The cardiac conduction system begins in the sinoatrial (SA) node

This signal travels down through the right atrium to the atrioventricular (AV) node

From here, the action potential travels via the bundle of His to the bundle branches (left and right) onwards to the Purkinje fibres

The Purkinjee fibres infiltrate the walls of both the left and right ventricles to cause contraction of the ventricles

Question 2

What is an arrhythmia?

Answer 2

disturbance of the electrical rhythm of the heart
- characterised by an irregular and often fast heartbeat that results in uncoordinated contraction of the atrium of the heart

Question 3

What are the different types of arrhythmias? How are they categorised?

Answer 3

by heart rate
- tachycardia, bradycardia

by origin
- supra ventricular (atria), ventricular (ventricles)

by time course
- paroxysmal (intermittently and spontaneously terminating), persistent (do not spontaneously terminate), permanent (continue despite intervention)

Question 4

What is the role of the atrioventricular node?

Answer 4

the AV node limits the number of irregular impulses that go to the ventricles
- they terminate the spontaneous impulses
= therefore ventricular rate is not as fast as atrial rate

Question 5

What are the causes of arrhythmias?

Answer 5

cardiac causes
- post MI, valvular disease

drugs
- thyroxine, alcohol, caffeine

non-cardiac causes
- anaemia, hyperthyroidism, acute infection, electrolyte imbalances

Question 6

What are the modifiable and non-modifiable risk factors for arrhythmias?

Answer 6

modifiable
- obesity, alcohol consumption, risks for CVD (smoking, stress, caffeine), activity level, hypertension, sleep apnea, diabetes, thyroid problems

non-modifiable
- age, male sex, family history, congenital heart defects

Question 7

What are the symptoms of arrhythmia?

Answer 7

• fatigue
• reduced exercise tolerance
• palpitations
• dyspnoea
• dizziness
• chest pain/tighness
• anxiety
• malaise

can be asymptomatic

Question 8

What are the risks associated with arrhythmias?

Answer 8

risk of stroke and systemic embolisms
hospitalisations
congestive heart failure

Question 9

What are the classes of treatment for arrhythmias?

Answer 9

rate control
- beta blockers = bisoprolol
- calcium channel blockers = diltiazem, verapamil
- digoxin
- amiodarone

rhythm control
- pill in pocket = flecainide (if paroxysmal)
- beta blocker = metoprolol
- amiodarone
- electrical cardioversion = ablation with amiodarone