Antiarrhythmic agent resident survival guide

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

Vaughan-Williams classification of antiarrhythmic agents

Vaughan-Williams classification of antiarrhythmic agents

Class IA

Class IB

Class IC

Class II

Class III

Class IV

Mechanism

Predominantly sodium channel blocker with some potassium channel blocking activity

*Mainly predominant β1 agonist (↑ cardiac contractility) * some α1 agonist(Vasoconstrictive)

*V1 receptor of GIT vasculatures *Antidiuretic effects

*Pure α1 agonist(Vasoconstrictive) *No β1

*Predominant β1 agonist (↑contractility) *β2 arterial smooth muscle (Hypotensive)

Agents

Quinidine, procainamide, disopyramide

2nd line septic shock

2nd line septic shock

1st line Neurogenic shock 3rd-4th line septic shock

*1st line cardiogenic shock * low output septic shock

Effect

Slows conduction, & prolongs repolarization

2-20 mcg/min

0.03 unit/min

20-300 mcg/kg/min

2.5-20 mcg/kg/min

Indications

Pre-excited atrial arrhythmias PSVT, Ventricular tacchyarrhythmia

Arrhythmia (more β1)

*Coronary spasm *Splanchnic vasoconstriction

Reflex bradycardia (only α1)

Hypotension (β2)

Complications

Arrhythmia

*Not in cardiogenic shock *Arrhythmia *Ischemia induced cardiotoxicity

*Ischemic heart *Gut ischemia

*Bradycardia *Heart block

*Hypotension (add α1 agonist)

Do's

• Assess the cause of shock
• Always volume fluid resuscitation first
• Norepinephrine in undifferentiated shock.
• Titrate dobutamine according to clinical response slowly ( 2-20 ug/kg/min ) to avoid tachycardia (10% increase from the baseline). The benefit that dobutamine has as minimal effect on myocardial oxygen demand is lost if it is not well titrated.

Don'ts

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