Anti Aarhythmias Flashcards by Dewakar Gurung

what is the problem in atrial arrhythmia ?

the artium (not SAN) produces random impulses leading to random heart beats

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what does the P wave represent ?
QRS ?
T?

P = Atrial contraction 
QRS = Ventricle contaction
T = Ventricle repolarisation

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what can cause arrhythmias ?

why are they dangerous ?

pacemaker impulse formation (SAN or AVN)- more likely bradycardia
Contraction impulse conduction
or combination

rate / timing of contraction not enough to maintain normal CO

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what is happening phase 0 of Cardiac AP ?

Na + influx
lads to depolarisation
get graph out

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what is happening phase 1 ?

K+ Efflux leading to transient repolarisation

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what is happening phase 2 ?

Ca2+ influx leading to plateau due to K+ Efflux

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what is happening phase 3 ?

VG calcium channels close and therefore only K+ Efflux leads to repolarisation

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what is happening phase 4?

Na+/k+ ATPase is leading maintaining of RMP at -90mV

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What do Class 1 drugs do ?

Block Na+ channels leading to mark slowing of conduction but little on APD

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What do class 2 drugs do ?

Beta blockers

diminish phase 4 depolarisation and automaticity

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Name 2 class 1 drug ?

Flecainide, Lidocaine

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Name 2 class 2 drug ?

Labetalol, Propranolol, Bisoprolol

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What do class 3 drugs do?

block K+ Channels leading to a longer plateau phase (3) which leads to longer APD

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Name 2 class 3 drugs

Amiodarone, Sotalol

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What do class 4 drugs do?

block calcium channels leading to decrease of plateau phase leading to decreased phase 4 depolarisation

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what is happening in phase 0/2 of slow cardiac AP?

Look up graph

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what do calcium channels blockers do to slow cardiac AP?

decreases slope of phase 0 = reduce conduction velocity

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name 2 Class 4 drugs

Diltiazem, Verapamil

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what do Beta agonist do on the slow cardiac AP?

increase slope of If = increased conduction velocity

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What do musurarinic / Adenosine agents do to slow cardiac AP?

Decrease If slope

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what is the pathophysiology of Wolf/ Parkinson white syndrome?

Excessive conductive tissue leading to re-entry circuit from retrograde backflow

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how can the AVN cause re-entry loops?

fast pathway and slow pathway both present and different conduction times lead to repolarasiotn of fast pathway in node = Tachy

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how can infracts causes Re-entry ?

functional re-entry =

= abnormal channels caused by scar tissue

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Name 3 ways heart can cause abnormal impulse generation

Enhanced normal automaticity (AP increase from SAN)
Ectopi foci
Triggered rhythms -
Delayed After depolarisation 
Early after depolarisation

Name 2 ways the heart can cause abnormal conduction

Conduction block - (1st , 2nd and 3rd) | Reentry loops

What is the 2 main MOAs for treating abnormal generation of impulses?

Decrease slope of Phase 4 in pacemaker cells (CCBs or beta blockers) Raise the threshold

What is the 2 main MOAs for abnormal conduction of HBs?

``` Decrease conduction velocity (class 1) Increase end refractory period ```

what is Atropine ? what is it used for ?

Muscarinic antagnoists | used for Bradycardia as it competitively inhibits M2 Parasympathetics on the heart

What are Class 1A drugs used for ?

wide use - A fib/flutter and Brugada's acute SVTs and Ven arrhythmia's

What are Class 1A drugs side effects?

hypotension, reduced CO, Seizures, GI effects, Proarrhythmia

Name a class 1B drug what is it used for ? Why is it used for this ?

Lidocaine - IV only acute ischaemic VT only works on fast beating or ischaemic tissue (decrease phase 0)

what are the side effects of 1B drugs ?

dizziness, drowsiness and GI symptoms

``` Name a class 1C drug what is the major difference in these drugs ? ```

Flecainide | substantially decrease phase 0 in normal

What must you use flecanide with ? why is this

AVN blockers | as the flutter in atrium can transfer to ventricles

what is class 1C drugs used for ?

SVT ectopic ventricular foci WPW syndrome

``` What are some side effects of class 1C drugs ? what mustn't a patient have? ```

proarrhythmia and sudden death, GI and CNS effects due to anesthetics cardiac myopathy , ischemia

what are ECG effects of class 2 drugs ?

increase PR | decrease HR

``` What are the side effects of class 2 drugs? when should you not sue them ? ```

Bronchospasm Hypotension partial AVN block or acute HF

What are the cardiac effects of Class 3 drugs?

``` increase Refractory period decrease phase 0 increase threshold decrease phase 4 decrease speed of AV conduction ```

what are the effects on the ECG?

Increase PR, QRS and QT | decrease HR

What are the side effects of class 3 drugs ?

``` pulmonary fibrosis hepatic injury increased LDL thyroid disease photosensitivity optic neuritis - transient blindless ```

what must you do with patients on Amidarone ?

CYP3A4 Inhibtor - | adjust dose of digoxin and monitor warfarin

what are side effects of sotalol ?

Proarrthythmia | fatigue and insomnia

what is the main difference in solatol and amiodarone ?

sotalol is a partial beta blocker

``` what is the side effects of class 4 drugs ? what must you look out for in patients ? ```

hypotneison , decreased CO or sick sinus , constipation | Asytole if beta blocker is present

How does adenosine work and how is it given ?

Nucleoside binds to A1 receptors and activated K+ currents in AV and SAN decreasing APD = hyper polarisation IV bolus - t1/2 = seconds

when is adenosine given ? what is a major side effect of adenosine ?

convert reentry SVTs diagnosis of coronary artery diseases - ischeamia bronchopasm

what is vernakalant used for ? | MOA?

AFib that has just started - slows atrial conduction = potency at higher rates Blocks atrial specific K+ channels

what are the side effects of vernakalant ?

Hypotension, AV block | sneezing and taste disturbance

how does ivabradine work ? | what is special about this drug ?

blocks Ifunny in SAN | slows sinus node without affecting BP

What is the use of ivabradine ? | side effects ?

Reduce sinus tacy , HR in HF and angina- avoids BP drops | Flashing lights - tetragenic

how does digoxin work ? | what is it used with ?

block Na/K+ ATPase , decreasing activty of Na/Ca2+ exchanger leading to more calcium in cells = slows down AV conduction and HR beta blockers or CCBs

What is digoxin used for ?

Reduce Ventricular rates in AFib

what drugs are used in AF?

``` Rate = CCBs, bisoprolol and digoxin rhythm= sotalol, flecainide with bisoporlol and amiodarone ```

what drugs should you use for VT?

Depends what drugs Lignocaine amiodarone

what should be used for WPW?

flecainide | amiodarone

what drugs for acute reentry SVT?

adenosine , verapamil | flecainide , vagal manoeuvres

what drugs for chronic reentry SVT?

Bisoprolol , verapamil | sotalol

what drugs for ectopic beats ?

beat blocker first line | flecainide