Arrythmias

Question 1

What is an arrhythmia/dysrhythmia and name some of the types

Answer 1

An abnormality of heart rate or rhythm

Bradycardia, atrial flutter, atrial fibrillation, tachcardia (ventricular and supraventricular), ventricular fibrillation

Question 2

What are the causes of arhythmias

Answer 2

Tachycardia

• Ectopic pacemaker activity
• Afterdepolarisations
• Atrail flutter/atrial fibrillation
• Re-entry loop

Bradycardia

• Sinus bradycardia (problem with sinus node)
• Conduction block

Question 3

What happens in a delayed after-depolarisation

Answer 3

There is depolarisation of myocytes after the original depolarisation

More likely if intracellular calcium is high which can be high enough to trigger a depolarisation

Question 4

What happens in an early after-depolarisation

Answer 4

There is depolarisation during the repolarisation of the membrane, can lead to oscillations

More likely if AP is prolonged

Question 5

What is long QT syndrome

Answer 5

Condition affecting repolarisation of the heart after a heart beat

In it, the ion channels are affected so they do not behave normally and the patient can develop a fast and chaotic heart beat

Associated with torsades de pointes and early after-depolarisations

Question 6

What might multiple re-entrant circuits cause in the atria

Answer 6

Atrial fibrillation

Question 7

Give some examples of re-entrant loops

Answer 7

AV nodal re-entry

Ventricular pre-excitation - Wolff-Parkinson White syndrome