Class IV Anti-arrythmics

[spartan564]

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According to FA, Class IV drugs increase the ERP. As such, why do they not prolong the QT interval? Is this not the same effect as class Ia and class III which also prolong the ERP?

 

[ChessMaster3000]

I believe class IV only works at nodal tissues, which would be the reason why it doesnt prolong qt internal nor cause torsade.

 

[Fatalis]

yup!
odds: work at ventricles/atrial [think phase 4,0,1,2,3]
evens: work at SA/AV node [think phase 4,0,3]
also anything that messes with the QT interval: associate it with K+ channels, anything with the PR interval, think Na+
it is what I do when I have to answer those questions and it hasn't failed me since.

 

[alicealicealice]

Nice, I like that. Also when answering questions I always remember AV node = ABCD = Adenosine, Beta Blocker, CCB/Carotid massage, Digoxin. Usually you can immediately rule in/rule out a bunch of answer choices by figuring if blocking the AV node would be good or bad in a given vignette.

 

[Fatalis]

Nice, I like that. Also when answering questions I always remember AV node = ABCD = Adenosine, Beta Blocker, CCB/Carotid massage, Digoxin. Usually you can immediately rule in/rule out a bunch of answer choices by figuring if blocking the AV node would be good or bad in a given vignette.

so would you say it has a high sensitivity and specificity *laughs* lame I know lol
Cant wait to be done with this test!