Arrhythmia - Therapy Flashcards
What is arrhythmia?
A deviation from the ‘normal’ rhythm of the heart
What is a deviation from the normal rhythm of the heart called?
Arrhythmia
What are examples of arrhythmias?
Sinus arrhythmia
Tachycardias
Bradycardias (heart block)
What are examples of tachycardias?
Supraventricular arrhythmia (atrial fibrillation and supraventricular tachycardia)
Ventricular arrhythmia (ventricular tachycardia and ventricular fibrillation)
What does STC stand for?
Supraventricular tachycardia
What are examples of supraventricular arrhythmias?
Atrial fibrillation
Supraventricular tachycardia
What are examples of ventricular arrhythmias?
Ventricular tachycardia
Ventricular fibrillation
What are bradycardias also known as?
Heart block
What does the P wave of the ECG correspond to?
Activation of the atria
What does the QRS complex of the ECG correspond to?
Activation of the ventricles
What does the T wave of the ECG correspond to?
Recovery wave
What is the charge inside a cell relative to the outside?
Negative
What is the charge inside a cell at rest known as?
Resting membrane potential
Why is the resting membrane potential of a cell negative?
Uneven distribution of ions across the cell membrane
Dependent on the sodium-potassium ATPase pump (needs energy)
Talk about the concentration gradients of potassium, sodium and calcium inside and outside a myocyte?
Potassium greater concentration inside the cell
Calcium and sodium greater concentration outside the cell
What is used to classify antiarrhythmias?
Vaughan-Williams classification
What are the different classifications of antiarrhythmics?
IA
IB
IC
II
III
IV
V
What are class I antiarrhythmias?
Membrane stabilising agents
How do class I antiarrhythmias work?
Acts on fast sodium channel responsible for phase 0
Decreases the amplitude size (size of action potential)
Reduces velocity of conduction/excitability
What are the different categories of class I antiarrhythmias?
Ia
Ib
Ic
How do class IA, IB and IC vary in effect?
Different effect on action potential duration and therefore effective refractory period
What is an example of a class IA antiarrhythmias?
Quinidine
How does a class Ia antiarrhythmias work?
Moderate sodium channel blockade
How does a class I antiarrhythmias affect the effective refractory period?
Increases it
What is an example of a class IB antiarrhythmias?
Lidocaine
How do class IB antiarrhythmias work?
Weak sodium channel blockade
How do class IB antiarrhythmias affect the effective refractory period?
Decrease effective refractory period
What does ERP stand for?
Effect refractory period
What is an example of a class IC antiarrhythmias?
Flecainide
How do class IC antiarrhythmias work?
Strong sodium channel blockade
How do class IC antiarrhythmias affect the effective refractory period?
Do not change effective refractory period
What class I antiarrhythmias is the most common?
IC (flecainide)
When are class I antiarrhythmias most effective?
At high heart rates
If the graph represented class I antiarrhythmias, what would be IA, IB and IC?
1 - class IC
2 - class IB
3 - class IA
What are class II antiarrhythmias?
Beta blockers
What are examples of class II antiarrhythmias?
Atenolol
Bisoprolol
Propranolol
How do class II antiarrhythmias work?
Acts via B1 receptors to block sympathetic stimulation of the heart:
Prolongs phase 4 depolarisation
Shortens phase 2
How do class II antiarrhythmias prolong phase 4 depolarisation?
Slows SA discharge and AV conduction
Reduces excitability in non-nodial cardiac tissue
What does class II antiarrhythmias shortening phase 2 mean for contractility?
Negative effect on contractility
What are class II antiarrhythmias the first line for?
Atrial fibrillation (bisoprolol)
What is the first line for atrial fibrillation?
Class II antiarrhythmias (bisoprolol)
How do class III antiarrhythmias work?
Prolong refractiveness (slows K flow out of cells):
Increase action potential duration
Prolong repolarisation in phase 3
Prolongs effective refractory period
What are examples of class III antiarrhythmias?
Amiodarone
Bretylium
Sotalol
How do class III antiarrhythmias prolong refractiveness?
Slows K flow out of cells
What is amiodarone used for?
Ventricular tachycardia and occasionally in supraventricular tachycardia