Cardiac Arrythmia Drugs Flashcards
How do arrhythmias occur?
- abnormal impulse generation e.g. Ectopic, delayed or early afterdepolarisations
- abnormal conduction e.g. Conduction block or re-entry
What is re-entry in the heart?
When an impulse fails to die out after normal activation of the heart and returns to its site of origin and re-excites the heart - can lead to arrhythmias.
Name 2 class I antiarrhythmics.
Lidocaine - IB
Flecanide - IC
What is the MOA of class I antiarrhythmics?
Block Na+ channels, which decreases slope of depolarisation and leads to slower conduction.
What is Wolff Parkinson White Syndrome? What can be used to treat it?
Congenital problem with extra tissue between atria and ventricles that allows spread of conduction in either direction - can lead to arrhythmias.
Treatment: Flecanide (IC)
Name a class II antiarrhythmic.
Bisoprolol
What is the MOA of class II antiarrhythmics.
Block beta-adrenoceptors, which decreases slope of depolarisation and slows conduction.
Name 2 class III antiarrhythmics.
Amiodarone
Sotalol
What is the MOA of class III antiarrhythmics?
Block K+ channels, leading to prolonged repolarisation and increased refractory period.
Name 2 class IV antiarrhymics.
Verapamil
Diltiazem
What is the MOA of class IV antiarrhythmics.
Blocks Ca2+ channels, slowing conduction through AVN and increasing refractory period.
Name some common side effects of antiarrhythmics.
- headache
- GI upset
Which class of the Vaughn Williams classification is both antiarrhythmic and proarrhythmic?
Class I - can occasionally lead to sudden death.
What is Torsades de pointes? Which class of antiarrhythmics can cause it?
Specific form of ventricular tachycardia in patients with long QT interval. Characterised by rapid, irregular QRS complexes that appear to twist around ECG baseline. Increased risk with class III.
What is long QT syndrome?
Condition which affects repolarisation of the heart - results in an increased risk of irregular heartbeat, palpitations, fainting or sudden death.
