Week 4 - Arrhythmia Therapies - anti arrhythmics Flashcards
What is vaughan william’s classification of anti-arrhythmics?
5 classes based on which receptor they act upon
What are class I anti arrhythmics? give an example.
Na+ channel blockers. flecainide.
How do Na+ channel blockers treat arrhythmias?
act on fast Na+ channels on myocytes. slows depolarisation of myocyte, shortens plateau phase, doesnt afect repolarisation. they reduce speed of conduction and excitability of myocytes.
What are class II anti arrhythmics? give 2 examples.
beta blockers. atenolol and bisoprolol.
How do beta blockers work to treat arrhythmias?
block b1 receptors on SA and AV nodes, slowing HR .
reduce contractility by reducing plateau phase of myocyte so less Ca+ gets in
What are class III anti arrhythmics? give an example.
k+ channel blovckers. amiodarone.
How do k+ channel blockers work?
prolongs repolarisation of myocyte, so theres a longer refractory period.
When would you give beta blockers?
first line for atrial fibrillation. suppresses ventricular ectopies
When would you give k+ channel blockers? What are the negatives?
life threatening ventricular tachycardia or fibrillation. also atrial fibrillation or flutter.
has many drug interactions and negative side effects
What are class IV anti arrhythmics? give 3 examples.
CCB’s.
verapamil
diltiazem
felodipine
How do CCB’s work?
decrease depolarisation in SA and AV nodes. slows HR down. shortens plateau phase, reducing Ca+ intake, reducing contractility.
When would you use CCB’s?
rate control in atrial fibrillation and flutters. also for SVT.
What are class V anti arrhythmics? give examples.
‘other’ category. have properties of multiple other classes. digoxin and adenosine.
How does digoxin work?
positive inotrope. blocks Na+/K+ase pump. increases vagal tone so decreases SA and AV conduction.
When would you give digoxin?
hard to control atrial fibrillation and flutters, and SVT. alongside CCB and B blocker.
