Antiarrhythmic Drugs

Question 1

what is the major side effect that is used to stop arrythmias?

Answer 1

arrythmia - yes the drugs used to treat it are proarrythmatic

Question 2

if you stimulate the sympathetic nervous systme, what is the effect on the heart?

Answer 2

increase heart rate

Question 3

what occurs to the heart beat signals during an arrythmia?

Answer 3

there is a focused region in the left ventrical that turns the signal around backwards - something that can cause this is heart attack

Question 4

when someone goes into arrythmia - what do you do immediately?

Answer 4

defribrillate

Question 5

Normal sinus rhythm is a complex process where each ion

moves primarily through its own ion-specific channel.

Why is this important?

Answer 5

In patients at risk for an arrhythmia, drugs that alter

electrolyte balance may precipitate arrhythmias.

Ions that are important in the “complex process” of

maintaining normal sinus rhythm are:

Na+

K+

Cl-

Mg++

Ca++

Note: drugs that deplete K+ are of particular concern

Question 6

what are the ions involved in the normal sinus rhythm?

Answer 6

Na+

K+

Cl-

Mg++

Ca++

Note: drugs that deplete K+ are of particular concern

Question 7

describe the classifications of arrhythmias

Answer 7

classic

ventricular vs. super-ventricular

*the majority of the world uses ventricular and super-ventricular (superventricular won’t kill you, ventricular will)

Question 8

what occurs when someone says “my heart skipped a beat when I got scared”

Answer 8

you have preterm ventricular contraction, then a compensatory pause, then consequently a larger preload and larger ‘heart beat’

Question 9

how do you diagnose a cardiac arrhythmia?

Answer 9

• History and Exam
• ECG
• Exercise Testing- b/c most arrhythmias are a consequence of ischemia - therefore you bring one on where you can see it
• Holter
• Loop recorder
• Heart Rate Variability, Late Potentials

Tilt Table

Question 10

What is Wolfe Parkinson White Syndrome

Answer 10

accessory system bypassing the AV node - going straight from the SA node to the ventricle - therefore your heart is beating crazy fast- there is no flat line delay between atrium and ventricle -

to cure you go in an do a catheter ablation

Question 11

what is atrial fibrillation?

Answer 11

irregularly irregular heartbeat - totally chaotic -

Question 12

why do you get arrhythmias?

Answer 12

usually associated with structural abnormality of myocardium - ischaemia, heart failure, or hypertrophic obstructive cardiomyopathy (where the septum is massively hypertrophic)

Question 13

What is long QT syndrome?

Answer 13

• Inherited arrhythmogenic disease characterised by life threatening ventricular arrhythmia
• Autosomal Dominant; Romano-Ward
• Recessive assoc with deafness; Jervell Lange-Nielsen
• NOTE. DRUGS THAT PROLONG THE QT INTERVAL CAN PRECIPITATE ARRHYTHMIAS
• Rx with beta blocker, left cardiac sympathetic denervation or ICD

Question 15

when do we use drugs vs. defribrillator?

Answer 15

in people who have common onsets of arrythmia = use drugs to prevent their onset

Question 16

what are the Vaughan Williams drug classification?

Answer 16

• Class Ia: Disopyramide, Quinidine, Procainamide
• Class Ib: Lignocaine, Mexiletine
• Class Ic: Propafenone, Flecainide (“don’t even think about putting someone on one of these, they kill people”)
• Class II: Beta blockers (propranolol, atenolol )
• Class III: Amiodarone, Bretylium, Sotalol
• Class IV: Calcium Channel Blockers

Question 17

what are Class Ia drugs?

Answer 17

“JUST AWFUL DRUGS - you might see them in people hwo have been on them a long time and no one wants to take them off- you may see an electrophysiologist use them but otherwise they’re awful “

Quinidine: administered orally, GI side effects.

Cinchonism CNS S/E tinnitus, hearing loss, visual disturbances, confusion and psychosis.

Antibody induced thrombocytopenia

Disopyramide: Anticholinergic effects: Nausea, vomiting, dry mouth, urinary retention

Procainamide: Given PO, IV or IM. Associated with N+V, Rash, Arthralgia

Lupus like syndrome occurs more frequently and earlier in patients who are slow acetylators of procainamide

Question 18

What are Class Ib drugs?

Answer 18

• Lignocaine- sedattive for the ‘focused’ region of the ventricle causing the arrythmia
• Standard treatment for Ventricular arrhythmias associated with AMI and cardiac surgery.
• Acts preferentially on ischaemic myocardium
• Lignocaine: Administered IV only
• Rapidly metabolized /Half life = 30 mins
• Side effects: High plasma levels cause drowsiness, paraesthesia and seizure activity
• Mexiletine, oral treatment of ventricular arrhythmia

Question 19

What is Flecanide used for?

Answer 19

use in life threatening VT and SVT - given orally

it supresses the PVC- but it is HIGHLY pro arrythmic - so don’t use clinically

Question 20

What is the primary Class 3 agent antiarrythmic drug?

Answer 20

Amiodarone - it is highly lipophilic so it takes them an awful long time to be excreted - it does suprress ventricular arrythmia but it can cause thyroid disorders, photosensitivity (like suburn in December in Dublin),

Therefore it causes more damage than good - but that’s up to you -

its major problem is it’s lipophilicity, it is excreted by the lachrymal glands

Question 21

What do we need to know about Sotalol?

Answer 21

it is the one beta blocker that causes a prolonged QT

Question 22

What are Class 4 drugs?

Answer 22

Ca++ channel blockers)

Question 23

what does ICD stand for?

Answer 23

implanted cardio defribrillator - recommended if patient is expected to survive for at least 1 year with acceptable funcitonal capacity -

mortality from complications of it’s placement is less than 1% which is quite incredible considering your implanting them in people who are very very sick

Question 24

what is the first line treatment for the arrythmias?

Answer 24

beta blockers, safe and effective

then cathetar ablation

then ICD

then amioderone for patients who are not candidates for ICD

Question 25

“this is the whole lecture in one slide”