Arrhythmias Flashcards
What is an arrhythmia?
Abnormality of the heart’s rhythm
What is tachycardia?
Fast heart rhythm, heart rate > 100/min
What is bradycardia?
Slow heart rhythm, heart rate < 60/min
What is a premature heartbeat?
Extra beat
Usually harmless
What is a supraventricular arrhythmia and what are some types of this?
Tachycardias that occur in the atria or AV node
Atrial fibrillation (AF) = irregular, rapid heartbeat
Atrial flutter = regular, rapid heartbeat
PSVT = regular, rapid heartbeat which begins and ends suddenly
Wolff-Parkinson-White syndrome = disrupts the timing of electrical signals –> ventricles beat too fast
What is a ventricular arrhythmia and what are some types of this?
Tachycardias that begin in the lower chambers of heart, which can be life threatening and require immediate medical attention
Ventricular tachycardia (VT) = rapid, regular heartbeat which lasts for a few seconds or longer and increases the risk of VFib
Ventricular fibrillation (Vfib) = rapid, irregular heartbeat which can lead to sudden cardiac arrest
What are some drugs to treat bradycardias?
Atropine
Isoproterenol
Describe atroprine
Blocks vagal inhibition of sinus and AV node, which blocks the parasympathetic activity on the heart
IV bolus administration
Short half life
Anticholinergic side effects (dry mouth, pupil dilation, low BP when standing)
What is a type of class I drug to treat tachycardia?
Na channel blockers
Name a Na channel blocker to treat tachycardia
Lidocaine
Describe lidocaine
Blocks Na channels
Slows initial depolarisation
Shortens action potential duration
This slows the heart rate down
Short half life
IV bolus administration
Side effects of hypotension
What is a type of class II drug to treat tachycardia?
Beta blockers
Describe beta blockers
Can be beta 1 or beta 2
They dampen the SA nodes, which means the sympathetic nerves no longer have an affect, i.e. the release of adrenaline and noradrenaline is blocked
Can be taken oral or IV
What are the side effects of beta 1?
Bradycardia
Heart failure
What are the side effects of beta 2?
Muscle aches
Asthma gets worse
What can be some other side of effects of beta blockers?
Fatigue
Sleep disturbances
What is a type of class III drug to treat tachycardia?
K channel blockers
What is a class III drug to treat tachycardia?
Amiodarone
Describe amiodarone
Prolongs action potential duration which prevents the conduction of any unwanted electrical activity
Long half life
Serious side effects which limits use to high risk patients
What is a type of class IV drug to treat tachycardia?
Ca channel blockers
What is class IV drug to treat tachycardia?
Verapamil
Describe verapamil
Prevents calcium entry into the heart and arteries which reduces rate and conduction velocity in sinus and AV nodes
Oral and IV use
Side effects = hypotension, constipation, flushing
How does adenosine treat tachycardia?
Hyperpolarises the SA node
Slows down the rate of firing of the SA node
Describe drug treatment of cardiac arrest
For asystole:
- adrenaline
For VFib:
- amiodarone
- lignocaine
Describe an ECG in cardiac arrest
Completely random - there is no baseline
Ventricular muscle randomly switches on and off, so randomly contracts rather than coordinated contractions –> collapse of cardiac output
