Drugs that slow/block conduction at the AV node and WPW

teedubbyaw said:
It then goes on to state in antidromic AVRT: "pharmacologic agents that slow conduction through the AV node but do not affect the accessory pathway are very dangerous in patients with accessory pathways. Administration of these drugs will cause the atrial impulses to travel preferentially down the accessory pathway and avoid the physiologic control exerted by the AV node...in a patient with WPW or a concealed pathway, these agents could turn a fairly stable arrhythmia into a very highly unstable disaster"

The way I read this was that it can terminate the loop in orthodromic, but don't give these drugs to anyone with WPW/accessory pathway. Contradiction is all I saw. I absolutely see the issue in aflutter or afib, but other than that...? Anyone care to clear that up in layman's terms?
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Book is wrong. It works anti- or orthodromic. Anytime the AVN is a required part of the circuit it is safe and efficacious to block it.
 
Thanks. That confused the ever living hell out of me.

In antidromic, can the AV node exert any control to the retrograde impulse? Assuming the answer is yes, if drugs work.
 
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teedubbyaw said:
Thanks. That confused the ever living hell out of me.
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Also, the terms ortho- and anti- apply to AVRT only and always involve an AP and the AVN.

AVNRT has the "Fast-slow", etc.
 
teedubbyaw said:
In antidromic, can the AV node exert any control to the retrograde impulse? Assuming the answer is yes, if drugs work.
Click to expand...

The AVN should still be exerting its delay whether it's conducting anterograde or retrograde.
 
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