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Management of Arrhythmias
Agents classified according
•Mode of action
Anti arrhythmic drugs
• Acts principally by suppressing excitability
and slowing down conduction in atrial or
• Blocks Na+ channels
• Contraindicated in patients w/ heart failure as
they depress myocardial function.
Class 1 drugs
Class 1a drugs:
• Prolongs cardiac action potential
• ↑ tissue refractory period
• Uses: atrial and ventricular arrhythmias
• E.g. Disopyramide:
• Causes anticholinergic side effects- urinary
retention, ppts glaucoma.
• Depresses myocardial function n hence
avoided in cardiac failure
• E.g. Quinidine:
• Rarely used as it increases mortality n causes
Class 1b drugs:
They shorten the AP and tissue
Acts on ventricles so used in Ventricular
tachycardia and ventricular fibrillation.
E.g. Lidocaine, Mexiletine
Affects slope of AP w/o altering duration or
Uses: prophylaxis of AF, SVA, VA.
Contraindicated in patients w/ previous MI-
leads to pro- arrhythmias
Given w/ AV node blocking drugs- β
blockers to prevent pro-arrhythmias
Class 2 drugs
Group comprises of β blockers
These drugs diminish Phase 4
depolarization, thus depresheart rate and
contractility. sing automaticity, prolonging
AV conduction, and decreasing
These reduce the rate of SA node
depolarization and causes a relative block
in AV node.
Uses: Rate control in Atrial Flutter, AF, SVA,
Reduces myocardial excitability and risk of
arrhythmic death in patients w/ CHD &
Cardio selective β blockers:
Acts on myocardial β1 receptors
E.g. Atenolol, Bisoprolol, Metoprolol
Non selective β blockers:
Acts on β1 & β2 receptors
Β2 blockade- bronchospasm and peripheral
E.g. Propranolol, Nadolol, Carvedilol
Causes torsade de pointes
Class 3 drugs
o Acts by prolonging plateau phase of AP.
o Hence lengthens refractory period
o Effective- atrial & ventricular tachyarrhythmia
o Causes QT prolongation and predisposes to torsade
de pointes and VT
o E.g. Amiodarone
o Principal drug
o Also has class 1, 2, 4 activity
o Most effective drug- paroxysmal AF
o Uses: to prevent recurrent episodes of VT
o Side effects: photosensitivity, skin discoloration,
thyroid dysfunction, nausea, vomiting etc
Class 4 drugs
Blocks the slow calcium channels(
important for impulse generation and
conduction in atrial and nodal tissues
Acts at the AV node
E.g. Verapamil, Diltiazem
Other anti- arrhythmic drugs
Atropine Sulphate (0.6 mg i.v., repeated
if necessary- maximum of 3 mgs)
↑ sinus rate and SA, AV conduction
Best choice- severe bradycardia or
hypotension due to vagal over activity.
Side effects: dry mouth, thirst, blurred
vision, atrial and ventricular extra
Given i.v. bolus, initially 3mg over 2 sec. If
no response after 1-2 mins, 6mg should be
given; and if needed after 1-2 mins, max
dose 12mg may be given.
Uses: terminate SVT when AV node is part
of re-entry circuit or in Atrial Flutter with 2:1
AV block or broad complex tachycardia.
Side effects: flushing, dyspnea, chest pain
Slows conduction and prolongs
refractory period in AV node.
Controls ventricular rate in AF & SVT of
Shortens refractory period and
enhances conduction and excitability in
other parts of the heart.
Side effects: GI disturbances,