anti aritmia-ijo-a.ppt

7/28/2019 anti aritmia-ijo-a.ppt

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Depart. Of Pharmacology & Therapy

Medical Faculty Padjadjaran University

Dr. Rovina Ruslami SpPD


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Antiarrhythmia 2 goals :

Arrhythmia :

asymptomatic life threatening

Termination of an ongoing Arrhythmia

Prevention of a recurrence

Control arrythmia

Proarrhythmic effect


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Cardiac cycle : automaticity rhythmic AP

SA node AV node HIS-purkinje

system


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0

2

0 mV

-85 mV

3

1

4

eff refractory period

Action Potential


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Mechanisms of Cardiac Arrhythmia

1. Enhanced automaticity / abnormal automaticity

2. Triggered automaticity

3. Block

4. Reentry

Tools

ECG

DC-cardioversion

ICDs (Implantable cardioverter defiblillators)


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Mechanisms of AAD actions :

suppressing the initiating mechanism

slow automaticity

altering the reentrant circuit

1. phase 4 slope2. threshold

3. max. diastolic potential

4. AP duration

-blockersblock of Na+, Ca++

adenosine

block of K+


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Normal Undirectional block

altering the reentrant circuit


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Principles in the clinical use of AADs

Identify & remove precipitating factors

Establish the goals of treatment

- some arrhythmias shouldnt be treated

- symptoms due to arrhythmia

- choosing among therapeutic approach

Minimize risks

- proarrhythmic effect

- monitoring of plasma concentration

- patient-specific contra indication

The electrophisiology of the heart as a moving target


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IA Na+ channel blocker

IB Na+ channel blocker

IC Na+ channel blocker

II -adrenoceptor blocker

III K+ channel blocker

IV Ca++ channel blocker

Classification of AADs :

class mechanism comment

slow phase 0 depol

shorten phase 3 repol

markedly slow phase 0 depol

suppress phase 4 depol

prolongs phase 3 repol

shorten action potential


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Class I AADs

Na channel blocker slow phase 0 depol

excitability

conductivity

Use-dependence tachycardiaClass IA: bind to Na channel in intermediate speed

quinidine, procainamide, disopyramide

Class IB: bind rapidly to Na channellidocaine, mexiletine, tocainide

Class IC: bind slowly to Na channel

flecainide, propafenone


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QUINIDINE

inhibits arrhythmia caused by hyperautomaticityPrevent reentry arrhythmia

Indications :

Wide variety of arrhythmia

A, AV, V - arrhythmia

Maintain SR after DCFK : p.o

Adverse effects : exacerbate arrhythmia--- blockproarrhythmic effect

CI : heart block, liver disease


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PROCAINAMIDE

Analog of local anesthetic

Indications :

VT that non responsive to lidocaine

FK : p.o liver kidney

Adverse effects :inotropic negative, hypotensiondrug induced SLE (long-term therapy)

Intoxication : asystole, CNS depression

quinidine like effect


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LIDOCAINE

Inhibits arrhythmia caused by abnormal automaticity

Indications :

Arrhythmia related to myocardial ischaemia

FK : iv excretion : liver

Adverse effects :inotropic negative (-); CNS effects, tremorproarrhythmic effects

CI : block, bradycardia

rapidly bind to Na channel


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-blocker slow phase 4 depol

Class II AADs

automaticity

AV conduction

Arrhythmia due to :- sympathetic activity

- AF, SVT

- post AMI prevent suddent death

Inotropic (-) CI for HF

HR & contractility

Propranolol, metoprolol, esmolol, carvedilol


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K channel blockers prolong phase 3

Class III AADs

AP duration

eff. Refractory period

sotalol, bretylium, amiodarone

SOTALOL

-blocker that has antiarrhythmia class III activity

Indications : sustained VT, long-term : mortality

Proarrhythmic effect torsade de pointes


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iv excretion : kidney

BRETYLIUM

Indications : life threatening VT , recurrent VF

FK :

AMIODARONE

Indications : severe refractory SVT, VT

Class I, II, III & IV action mainly class III

FK : p.o, EMG case :iv (bolus drip)

clinical effect is achieved in 6 weeks (po)

Adverse effects :

vary toxicity effect, withdrawl effect

liver toxicity, hyper-hypothyroidsm, muscle weaknessCI : block, bradycardia


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Ca channel blocker shorten AP

Class IV AADs

AV conduction

Inotropic (-) CI for HF

HR & PR interval

Verapamil, diltiazem

Vasodilatoranti hypertension, anti anginal

Indication : tachy-arryhthmia: SVT, VT

FK : p.o, iv ( !! hypotension) liver


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refractory period, conductivity, automaticity

Shorten refractory period; AP; conductivityIndications : controll ventr respons to AF

FK : p.o; iv

Adverse effects : intoxication : VES VT / VF

Indications : acute SVT

FK : iv, short d.o.a

Adverse effects : flushing, hypotension, chest pain

ADENOSIN

DIGOXIN


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