Anti-arrhythmic mechanisms

[donkeykong1]

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Anyone know why Antiarryhmtic class 1b which slows phase 3, decreases ERP, by shortening Action potential duration is used just for V-tach and not svt or afib/flutter?

 

[Charles_Carmichael]

Atrial cells have shorter action potential durations, so class Ib drugs don't work as well at therapeutic levels (IIRC, I think Lilly mentioned something like there's less time for the drug to bind and block the Na+ channel due to the shorter APD).

That's why class Ib drugs aren't effective for treating SVTs. Hope that helps.

 

[donkeykong1]

Atrial cells have shorter action potential durations, so class Ib drugs don't work as well at therapeutic levels (IIRC, I think Lilly mentioned something like there's less time for the drug to bind and block the Na+ channel due to the shorter APD).

That's why class Ib drugs aren't effective for treating SVTs. Hope that helps.

thanks

that makes sense if u look at the ekg the qrs complex would be thinner in width in svt than vt,