Antiarrhythmic Drugs Flashcards
what is the major side effect that is used to stop arrythmias?
arrythmia - yes the drugs used to treat it are proarrythmatic
if you stimulate the sympathetic nervous systme, what is the effect on the heart?
increase heart rate
what occurs to the heart beat signals during an arrythmia?
there is a focused region in the left ventrical that turns the signal around backwards - something that can cause this is heart attack
when someone goes into arrythmia - what do you do immediately?
defribrillate
Normal sinus rhythm is a complex process where each ion
moves primarily through its own ion-specific channel.
Why is this important?
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
what are the ions involved in the normal sinus rhythm?
Na+
K+
Cl-
Mg++
Ca++
Note: drugs that deplete K+ are of particular concern
describe the classifications of arrhythmias
classic
ventricular vs. super-ventricular
*the majority of the world uses ventricular and super-ventricular (superventricular won’t kill you, ventricular will)
what occurs when someone says “my heart skipped a beat when I got scared”
you have preterm ventricular contraction, then a compensatory pause, then consequently a larger preload and larger ‘heart beat’
how do you diagnose a cardiac arrhythmia?
- 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
What is Wolfe Parkinson White Syndrome
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
what is atrial fibrillation?
irregularly irregular heartbeat - totally chaotic -
why do you get arrhythmias?
usually associated with structural abnormality of myocardium - ischaemia, heart failure, or hypertrophic obstructive cardiomyopathy (where the septum is massively hypertrophic)
What is long QT syndrome?
- 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
when do we use drugs vs. defribrillator?
in people who have common onsets of arrythmia = use drugs to prevent their onset
what are the Vaughan Williams drug classification?
- 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
what are Class Ia drugs?
“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
What are Class Ib drugs?
- 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
What is Flecanide used for?
use in life threatening VT and SVT - given orally
it supresses the PVC- but it is HIGHLY pro arrythmic - so don’t use clinically
What is the primary Class 3 agent antiarrythmic drug?
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
What do we need to know about Sotalol?
it is the one beta blocker that causes a prolonged QT
What are Class 4 drugs?
Ca++ channel blockers)
what does ICD stand for?
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
what is the first line treatment for the arrythmias?
beta blockers, safe and effective
then cathetar ablation
then ICD
then amioderone for patients who are not candidates for ICD
