Antiarrhythmics Flashcards
Na channel blockers type Ia
disopyramide
quinidine
procainamide
double quarter pounder
Prolong the AP
Na channel blockers type Ib
Lidocaine
Tocainamide
Mexiletine
Lettuce, tomato, mayo
Decreases AP duration, shortens phase 3 repolarization
Na channel blockers type Ic
Moricizine
Flecainide
Propafenone
More fries please
B blockers Type II
Metropolol
Esmolol
Propanolol
K channel blockers type III
amiodarone Bretylium Dofetilide Ibutilide Satalol
A big dog is scary
- Diminish outward K during repolarization
- Increase duration of AP
- Prolong effective refractory period
Ca channel blockers Type IV
verapamil
diltiazem
- Decrease inward Ca current
- Decrease rate of phase 4 spontaneous depolarization
- Slows conduction in Ca dependent tissues
- Use dependent
early afterdepolarization
interrupts phase 3
delayed after depolarization
interrupts phase 4
interval b/w depolarizations
duration of AP + duration of diastolic interval
Depressed conduction
simple block- AV nodal block, BBB
Reentry
- Impulse reenters/excites areas of heart more than once
- Must be an obstacle
- Must be unidirectional block
- Conduction time must be long enough that retrograde impulse does not encounter refractory tissues
how to depress autonomic properties of abnormal pacemaker cells
- Decrease slope of phase 4
- Elevate threshold potential
- Increase max diastolic potential
- Increase AP duration
effective in supraventricular and ventricular arrhythmias
Type Ia
Procainamide
Class 1a
Used for atrial and ventricular arrhythmias
Slows upstroke of AP, slows conduction, prolongs QRS, prolongs AP duration
PK: metabolite NAPA w class III activity
ADRs: excessive APD prolongation, QT prolongation, reversible lupus erythematosus
Used for ventricular arrhythmias
2b
Lidocaine
2B
DOC for termination of VT and prevention of VF after cardioversion in setting of acute ischemia
Decreases AP duration, shortens phase 3 repolarization
PK: extensive first pass metabolism
ADRs: least cardiotoxic but associated with neurological findings
Cannot be used in structural heart disease
1c
Flecainide
Used for supraventricular arrhythmias
Blocks both Na and K channels but does not prolong AP or QT interval
ADR: severe exacerbation of arrthymia
Propafenone
Similar to flecainide + beta blocking activity
Amiodarone
K channel blocker
Prolongs AP duration, significantly blocks Na channels, weak adrenergic and Ca channel blockade; broad activity
- Extracardiac effects- peripheral vasodilation
associated with many drug/drug interactions
Verapamil
Blocks activated and inactivated L-type Ca channels, slows SA node by direct action, suppresses both early and delayed afterdepolarizations
ADRs: hypotension and VF if given to a pt with a VT misdiagnosed as SVT; can induce AV block, constipation, lassitude, nervousness, peripheral edema
Adenosine
Nucleoside- activates inward rectifier K current and inhibits Ca current resulting in marked hyperpolarization and increased refractory period
ADRs: flushing, SOB, chest burning, high grade AV block, atrial fibrillation, headache, hypotension, nausea, paresthesias
DOC for conversion of paroxysmal SVT
Adenosine
Atropine
Blocks actions of AcH at parasympathetic sites, increases CO
Digoxin
Inhibits Na/K ATPase, results in increased intracellular Na, decrease Ca expulsion, increased free Ca.
Decreased HR
Increased refractory period
Decreased conduction velocity
ADRs: visual disturbances
Atrial fibrillation drugs
Acute: IV CCB- rapid effects
BB- 1st choice in high catecholamine states. Should not be used acutely in systolic heart failure
digoxin- slower onset, less effective
Chronic: oral BB, CCB
long term strategy of atrial fibrillation
Rate control > rhythm control
Direct current cardioversion most effective
Paroxysmal supraventricular tachycardia treatment
Acute: IV adenosine, verapamil, diltiazem
Chronic: radiofrequency catheter ablation potentially curative
Torsades de pointes treatment
magnesium
CYP inducer
rifampin
CYP blocker
cimetidine
adverse drug reaction of class IV
ventricular fibrillation
if given to a pt with ventricular tachycardia instead of supraventricular tachycardia
