Arrhythmias - Therapy Flashcards
What is an arrhythmia?
–Any deviation from the normal rhythm of the heart
•Sinus arrhythmia
•Supraventricular arrhythmia
–Atrial fibrillation
–SVT (junctional)
•Ventricular arrhythmia
–Ventricular tachycardia
–Ventricular fibrillation
•(Heart block)
What is heart block?
Heart block is an abnormal heart rhythm where theheart beats too slowly (bradycardia). In this condition, the electrical signals that tell the heart to contract are partially or totally blocked between the upper chambers (atria) and the lower chambers (ventricles).
How are the electrical signals different in atrial fibrillatino?
Electrical signals are disorganised in atrial fibrillation
What is the pathology associated with this ECG?
Vntricular fibrillation
Note - P waves are absent
What is the pathology associated with this ECG?
Ventricular tachycardia
What is the pathology associated with this ECG?
Atrial fibrilaltion
What is responsible for the uneven distribution of ions which accounts for the uneven resting membrane potential?
•Sodium-potassium ATPase pump
What causes myocardial muscle to contract?
Movement of ions across the myocyte cell membrane - propagation of an electrical impulse - leads to myocardial muscle contraction
What are the different phases of the action potential?
What are the different classes of drugs that are used to treat arrhythmias?
•Class 1
–Class Ia
–Class Ib
–Class Ic
- Class II
- Class III
- Class IV
- Other
What are class 1 anti arrhythmic drugs?
What is the action of Class 1 a drugs?
Block sodium channels
Delay repolarisation
Increase action potential duration
What can class 1 a drugs be used for?
AF
Premature atrial/ventricular contractions
Ventricular tachycardia
Wolff-Parkinson-white syndrome
Name some class 1 a drugs
Disopyramide
What are the actions of 1 b drugs?
Block sodium channels
Accelerate repolarization
Decrease the action potential duration
What can class 1 b drugs be used for?
Used for ventricular dysrhythmias only (premature ventricular contractions, ventricular tachycardia, ventricular fibrillation)
What are the common type 1b drugs?
phenytoin, lidocaine
What is the effect of class 1c drugs?
- Block sodium channels (more pronounced effect)
- Little effect on action potential duration or repolarization
What are class 1 c drugs used for?
Severe ventricular dysrhythmias
May be used in atrial fibrillation/flutter
Give an example of a class 1 c drug
Flecainide
What are the Class 2 drugs?
Beta Blockers
What stage of the heart cycle do beta blockers act on?
Phase 4 depolarisation
What is the effect of beta blockers on the transmission of impulses in the heart?
Reduces the transmission of impulses in the heart’s conduction system
What type of heart dysrhythmia are beta blocers used for?
- General myocardial depressants for both supraventricular and ventricular dysrhythmias
- Now first line for atrial fibrillation (Bisoprolol)
What are examples of beta blockers?
Atenolol and Bisoprolol
What are class 3 drugs?
Amiodarone and sotalol
What stage of the action potential do amiodarone and sotalol funciton in?
- Increase action potential duration
- Prolong repolarization in phase 3
What type of dysrhythmia is amiodarone and sotalol used for?
- Used for dysrhythmias that are difficult to treat
- Life-threatening ventricular tachycardia or fibrillation, atrial fibrillation or flutter—resistant to other drugs
Sustained ventricular tachycardia
What are type 4 drugs?
Calcium channel blockers
What stage of the actionpotential do calcium channels function in?
Depress phase 4 depolarisation
What type of dysrhythmia are CCB’s used for?
•Used for paroxysmal supraventricular tachycardia; rate control for atrial fibrillation and flutter