Step I drug selection for arhythmia/tachy/SVT/etc
Started by axeon123
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I don't know if there's any good way to memorize but here's a little simplified version.
If it's SVT, close your eyes and use Adenosine for acute management. (There is no other correct answer on step 1). Second line for chronic: Calcium Channel Blockers (NOT dihydropyridines like nifedipine!).
Post MI anti-arrhythmia prophylaxis: Beta Blockers, Class 1A.
Refractory arrhythmias: Amiodarone, Class 1C.
Various ventricular tachyarrhythmias: Amiodarone, Class 1A.
Atrial Fibrillation: Digitalis can be used.
Digitalis induced arrhythmias: Use Lidocaine.
Anything else someone can add? This isn't a complete list but should serve the purpose. Uworld frequently tests on Supraventricular tachycardias. Know Adenosine very well, plus its side effects.
If it's SVT, close your eyes and use Adenosine for acute management. (There is no other correct answer on step 1). Second line for chronic: Calcium Channel Blockers (NOT dihydropyridines like nifedipine!).
Post MI anti-arrhythmia prophylaxis: Beta Blockers, Class 1A.
Refractory arrhythmias: Amiodarone, Class 1C.
Various ventricular tachyarrhythmias: Amiodarone, Class 1A.
Atrial Fibrillation: Digitalis can be used.
Digitalis induced arrhythmias: Use Lidocaine.
Anything else someone can add? This isn't a complete list but should serve the purpose. Uworld frequently tests on Supraventricular tachycardias. Know Adenosine very well, plus its side effects.
Thanks for sharing. I have found that while answering some Qbank questions, there occurs some confusion between procain and lidocaine (i.e. which one is which).
Easy way to remember: Procaine (Although known as procainamide) has only one "i" so it's Class 1A whereas Lidocaine has two "i's" so it's Class 1B. Might look like a silly mnemonic but for me personally, it has worked almost every time while answering questions.
Adding to the list of drugs, Magnesium is also antiarrhythmic and is used to treat Torsade de Pointes.
Easy way to remember: Procaine (Although known as procainamide) has only one "i" so it's Class 1A whereas Lidocaine has two "i's" so it's Class 1B. Might look like a silly mnemonic but for me personally, it has worked almost every time while answering questions.
Adding to the list of drugs, Magnesium is also antiarrhythmic and is used to treat Torsade de Pointes.
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I wrote a post about this in my blog. My solution was to use the diagram in Lippincott's Pharmacology. It's amazing. If you don't have it, pm me.
send me your email in a private message.
that is what i thought too.
I'm pretty sure 1As and 1Cs are contraindicated in patient's depressed ventricular function, e.g. post-MI.
Class 1Bs, usually Lidocaine, decrease the probability of arrhythmia. Something in the back of my mind is telling me re-entrant circuits, but I haven't actually done my review of cardiology yet, so I'm not sure.
1st line management of Tachyarrhythmias:
1) Ventricular tachycardia/Ventricular fibrillation:
(i) No pulse = 1st line therapy is defibrillation --> If still no pulse then give epinephrine or vasopressin --> if pulseless VT despite defibrillation X 2 and a couple rounds of epinephrine/vasopressin can given amiodarone
(ii) Pulse = Amiodarone (2nd line is lidocaine)
2) Atrial flutter/atrial fibrillation:
(i) Unstable = emergent cardioversion (note that difference between cardioversion and defibrillation is that you sync the shock to the QRS complexes)
(ii) Stable = both rate control and rhythm control are associated with similar outcomes. In clinical practice rate control with a beta-blocker or calcium channel blocker is first line. Selecting which agent for pharmacologic rhythm control is a little more complex:
a) No heart disease: sotalol, flecainide, or propefenone
b) HTN + Left ventricular hypertrophy: amiodarone
c) Congestive heart failure: amiodarone or dofetilide
d) Coronary artery disease: dofetilide or sotalol
(note that propafenone and flecainide are contraindicated in coronary artery disease)
3) Supraventricular tachycardia:
(i) Unstable = cardiovert
(ii) Stable = 1st try vagal manuevers --> if persistent give adenosine
Bradyarrhythmias:
Main treatment for Mobitz type 2 block and complete heart block is pacemaker. While awaiting a pacemaker can treat with atropine.
Post-MI beta-blocker use: indication is not primarily arrhythmia prophylaxis. Rationale for beta-blockers is that they reduce heart rate and contractility --> reduced work performed by heart --> reduced oxygen demand. NOTE that primary post-MI arrhythmia prophylaxis is not utilized any longer in clinical practice (in the past lidocaine was routinely prescribed for this indication but this practice was subsequently shown to actually increase mortality).
Hope that helps
1) Ventricular tachycardia/Ventricular fibrillation:
(i) No pulse = 1st line therapy is defibrillation --> If still no pulse then give epinephrine or vasopressin --> if pulseless VT despite defibrillation X 2 and a couple rounds of epinephrine/vasopressin can given amiodarone
(ii) Pulse = Amiodarone (2nd line is lidocaine)
2) Atrial flutter/atrial fibrillation:
(i) Unstable = emergent cardioversion (note that difference between cardioversion and defibrillation is that you sync the shock to the QRS complexes)
(ii) Stable = both rate control and rhythm control are associated with similar outcomes. In clinical practice rate control with a beta-blocker or calcium channel blocker is first line. Selecting which agent for pharmacologic rhythm control is a little more complex:
a) No heart disease: sotalol, flecainide, or propefenone
b) HTN + Left ventricular hypertrophy: amiodarone
c) Congestive heart failure: amiodarone or dofetilide
d) Coronary artery disease: dofetilide or sotalol
(note that propafenone and flecainide are contraindicated in coronary artery disease)
3) Supraventricular tachycardia:
(i) Unstable = cardiovert
(ii) Stable = 1st try vagal manuevers --> if persistent give adenosine
Bradyarrhythmias:
Main treatment for Mobitz type 2 block and complete heart block is pacemaker. While awaiting a pacemaker can treat with atropine.
Post-MI beta-blocker use: indication is not primarily arrhythmia prophylaxis. Rationale for beta-blockers is that they reduce heart rate and contractility --> reduced work performed by heart --> reduced oxygen demand. NOTE that primary post-MI arrhythmia prophylaxis is not utilized any longer in clinical practice (in the past lidocaine was routinely prescribed for this indication but this practice was subsequently shown to actually increase mortality).
Hope that helps
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in 10 days. No I'm still on my first pass through UW.
