S2W6 Arrythmias - causes and treatments (PD)

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What are arrythmias generated by?
Abnormal impulse formation or impulse propagation
Usually as a consequence of defective ion channels, exchangers or ion handling
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What are the types of arrythmia?
Bradycardia, Tachycardia and non-maintained skipped beat
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What are the different degrees of altered automaticity-block?
First degree - slowed conduction between AVN and ventricle
Second degree - intermittent failure of transmission from atria to ventricle
Third degree - complete loss of transmission, uncoordinated atria and ventricle
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What is wolf parkinsons white syndrome?
A condition where the heart beats abnormally fats for periods of time, this is caused by an extra coonduction pathway through the annulus fibrosis
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What are ectopic beats?
Early or extra heartbeats which cause heart palpitations.
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How are arrythmias maintained?
AP circulates with slowed conduction velocities
This may reflect altered ion channels which continues re-enterant excitation.
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What is reenterant excitation?
Rentry occurs when a propagating impulse fails to die out after normal activation of the haert and persists as aresult of continous activity. It is the electrophysiologic mechanism responsible for arrythmia.
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What are the classes of drugs by the vaughan williams classification (VWC)?
Class I - Sodium channel blockers
Class II - beta adrenoreceptor blockers
Class III - potassium channel blockers
Class IV - Calcium channel blockers
Other adenosine/digoxin
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What do class I drugs do?
Reduce etopic ventricu;ar/atrial automacity
Reduce DAD-induced triggered activity
Reduce reenterant tendency by converting unideirectional to bidirectional block
Block NaV1.5 Na Channels (1a)
Bind to inactive channel state (1b)
Depression of phase 0 by ac
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What are some problems of class I drugs
Can cause asystole
Can make healthy tissue ischaemic
Do not target healthy tissue
Class 1a can affect K channels - increased risk of torsade de pointes
commonly end in -ine
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What do class II drugs do?
Blosk B adrenoreceptors reducing abnormal automaticity
end in -olol
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What do class III drugs do?
Delay repolarisation anywhere in re-enterant pathway, this increases AP recovery time which increases refractory time and decreases re-entry tendency.
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Problems of class III drugs?
Possibility to percipitate LQT prolongation and torsade de pointes]
Amiodarone decreases thyroid fuction
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What do class IV drugs do?
Reduce conduction in AV node by blocking Ca channels
Reduce DADs leading to ectopic activity in atria/ ventricle (verapamil and dilitiazem)
bolus iv converts reentry in the AV node to sinus rhythm
Blocks conduction in damaged section
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Other cards in this set

Card 2

Front

What are the types of arrythmia?

Back

Bradycardia, Tachycardia and non-maintained skipped beat

Card 3

Front

What are the different degrees of altered automaticity-block?

Back

Preview of the front of card 3

Card 4

Front

What is wolf parkinsons white syndrome?

Back

Preview of the front of card 4

Card 5

Front

What are ectopic beats?

Back

Preview of the front of card 5
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