Hi all,
So obviously we know the various mechanisms and side effects of these drugs, but are we expected to differentiate between them for certain situations? For example, 3 different classes could be used for Afib...
In terms of differentiating, I know that class IB is best post-MI (lidocaine), adenosine is the DOC for SVTs if no other info given, but are there any other 'must-know' associations?
Well the issue is that in many circumstances you have many options. In tests, the times they would ask you abt drugs would be to differentiate which ones not to use because of side effects or co-morbid conditions. So know the side effects because this is testable.
Otherwise, it is tough to test drug of choice when there are a few options. Below is more clinical and probably won't be tested, but is useful for the wards.
Treatment:
Narrow complex, regular supraventricular tachycardias are usually treated in the following order:
1) Vagal maneuvers- in my experience these work infrequently
2) Adenosine- if it terminates great, if it doesn't usually nodal blockade with beta blockers, dilt or dig
3) True anti-arrhythmics are rarely used unless the above don't work
4) Recurrent/long term- often ablation is the treatment chosen b/c success rate is very high and can avoid symptoms and the side affects associated with antiarrhythmics
Narrow complex, irregularly irregular
1) MAT- Dilt often used but can use other nodal blocking agents
2) AF- this is a bit of a debate and will depend on a handful of things one of which is who you talk to. It will also depend on structural heart disease, h/o heart failure, length of the QT and whether you choose a rate or rhythm control strategy
- First presentation we will often give people a chance at sinus rhythm- so either anti-arrhythmics (flec, propafenone amio) followed by cardioversion or just cardioversion
- Those who have infrequent AF that can be terminted- pill in pocket Flec or propafenone (ie PRN)
- Heart failure- Amio, Dofetilide, sotalol (or rate control with Metop; those with low EF we tend not to use Dilt)
- For AF, we will use ablation but unlike AT, AVNRT and AFL, atrial fibrillation doesn't have a great longterm success rate.
Unstable VT: Amio 300 and shock. Followed by amio drip and 10g amio load over the course of ~8 days
Recurrent VT- similar to AF has a ton of options:
- Outpt/oral management- Beta blockers, Sotalol, Dofetilide, Mexiletine, Amio
In the hospital we often use Amio first unless ischemic (when we will sometimes use Lido first). If there is breakthrough we add lidocaine. This is often with background metop therapy. If this fails sometimes quinidine, sometimes ablation. Again there is a lot of variability.
