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Q2 antiarrhythmic drugs
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Most common arrhythmia
Atrial fibrillation
How many fascicles do the LBB and RBB have?
LBB
: 2 (anterior, posterior)
RBB
: 1
Is RBBB clinically significantly?
No
Is LBBB clinically significant?
Yes - indicates that both fascicles knocked out --> extensive myocardial damage
Often seen in advanced HF, coronary disease, MIs
What phases of the AP are repolarizing phases?
1 (K+ out)
3 (K+ out rapidly)
What phase of the AP is the depolarizing phase?
Phase 0
What phase of the AP is the plateau phase?
Phase 2
What is response for maintenance of phase 4?
Na+/K+ ATPase pump
Na+ out
K+ in
What phases of the AP are associated with Ca2+ coming into the cell?
What ion enters the cell rapidly in phase 0 of AP?
Na+
Cause of early afterdepolarizations
QT prolonging drugs
Cause of late afterdepolarization
Digitalis toxicity
3 mechanisms of cardiac arrythmias
Enhanced automaticity
Afterdepolarizations
Re-entry
Atrial re-entry arrhythmia associated with multiple reentry circuits and the one with one large big reentry circuit in atrium
Multiple reentry circuits
: atrial fibrillation
One big circuit
: atrial flutter
Early afterdepolarization affects what phase?
Phase 3
Late afterdepolarization affects what phase?
Phase 4
QT intervals begins where and ends where?
Beginning of QRS complex
End of T wave
3 mechanisms of anti-arrhythmic drugs
Slowing or abolition of automatic rhythms
Blocking of impulse propogation in re-entry
Prevention or blocking of EADs and DADs
Vaughan Williams Classification of Antiarrhythmic Drugs
I
: Na+ channel blockade
II
: β blockade
III
: K+ channel blockade
IV
: Ca2+ channel blockade
Action of class I (Na+ channel blockade) on phase 0
Reduces phase 0 slope and peak of action potential
Action of class II (β blockade)
Block sympathetic activity --> reduction of rate and conduction
Action of class III (K+ channel blockade)
Delay phase 3 --> increase of action potential and increases refractory period (QT prolongation)
Action of class IV (Ca2+ channel blockade)
Blocks L-type channels
Reduces rate and conduction
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Author
Anonymous
ID
55001
Card Set
Q2 antiarrhythmic drugs
Description
Q2 antiarrhythmic drugs
Updated
2010-12-11T19:56:46Z
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