Antiarrhythmic agent resident survival guide

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c Template:Antiarrhythmic agent Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Priyamvada Singh, M.D. [2]



Life Threatening Causes

Common Causes


Vaughan-Williams classification of antiarrhythmic agents

Vaughan-Williams classification of antiarrhythmic agents
Class IA
Class IB
Class IC
Class II
Class III
Class IV
Predominantly sodium
channel blocker with some
potassium channel blocking activity
Sodium channel blocking activity
Sodium channel blocking activity
*Pure α1 agonist(Vasoconstrictive)
*No β1
*Predominant β1 agonist (↑contractility)
*β2 arterial smooth muscle (Hypotensive)
Quinidine, procainamide, disopyramide
Lidocaine, mexiletine, phenytoin
Flecainide, propafenone
1st line Neurogenic shock
3rd-4th line septic shock
*1st line cardiogenic shock
* low output septic shock
Slows conduction, & prolongs repolarization
Slow conduction in diseased tissues, shorten repolarization
0.03 unit/min
20-300 mcg/kg/min
2.5-20 mcg/kg/min
Pre-excited atrial arrhythmias
PSVT, Ventricular tachycardia
Ventricular arrhythmia
*Coronary spasm
*Splanchnic vasoconstriction
Reflex bradycardia
(only α1)
Hypotension (β2)
Quinidine - abdominal cramping, diarrhea, rash, cinchonism (hearing decrease, tinnitus, and blurred vision), thrombocytopenia, hemolytic anemia, lupus syndrome , granulomatous hepatitis, QRS widening and ventricular arrhythmias.
CNS side-effects such as peri-oral numbness, tremors, paraesthesia, diplopia, hyperacusis, slurred speech, altered consciousness, seizures, and coma can be seen. Proarrhythmia and gi side-effects are common.
*Ischemic heart
*Gut ischemia
*Heart block
*Hypotension (add α1 agonist)


  • Class IA agents are proarrhythmogenic and are associated with increased incidences of Torsade de Pointes, ventricular tachycardia or ventricular fibrillation. If arrhythmia are observed with one class 1A agent all other class 1A agents should be avoided. Due to risk of proarrhythmia all class 1A drugs should be initiated in hospital. If QTC > 500 msec the drug should be stopped.
  • Disopyramide side-effects include anticholinergic effects (30%) including dry mouth, blurred vision, constipation, and urinary retention. Pyridostigmine (90 mg twelve hourly to 180 mg every eight hours) prevents or diminishes the anticholinergic effect of disopyramide and allows high tolerated doses of the drug.
  • Disopyramide-induced hypoglycemia has been noted. Other reported side effects includes nausea, vomiting, rash, cholestatic jaundice, and agranulocytosis. It prolongs repolarization and may cause proarrhythmia (VF, Torsade de Pointes)
  • Procainamide has side-effects similar to Quinidine.


  • Do not start with low dose Dopamine dose to perfuse the kidney.


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