Antarrhythmics Flashcards
All antiarrhythmics can precipitate _______
Lethal arrhythmia
All class I drugs do what
Block sodium channels
Which sodium channels do Class IA drugs block?
Effect on refractory period and action potential?
Open and activated Na+ channels
AP lengthened
RP lengthened
Which sodium channels are blocked by Class IB Drugs?
Effect on action potential and refractory period?
Inactivated Na+ channels
Shorten AP
Shorten RP
Which sodium channels are blocked by class I C drugs?
Effect on refractory period and Action potentiak?>
ALL sodium channels
No effect on AP
No effect on RP
What are the 2 class IA drugs
Quinidine
Procainamide
Which drug is class IB drug
Lidocaine
What drug is class I C
Flecainide
What is the MOA of Class II drugs
Reduce adrenergic activity on the heart
Which drugs are class II
Beta blockers
What is the MOA of Class III drugs?
Effect on action potential?
Effect on refractory period?
Blocks K+ channels
AP lengthened**
No effect on RP
What drugs are Class III
Amiodarone
Sotalol
What is the MOA of Class IV drugs
Calcium channel blockers: decrease HR and contractility
Which drugs are Class IV
Verapamil
Diltiazem
(Non-dihydropyridine CCBs)
How do you treat Torsades
Magnesium
What drug is the “broad spectrum” antiarrhtyhmic because it treats supraventricular and ventricular arrhythmias
Quinidine
What are the adverse effects of quinidine
Cardiac toxicity: SA block, AV block, ventricular arrhythmia
Blocks alpha receptors= hypotension and reflex tachycardia
Paradoxical tachycardia
Torsade de pointes
Diarrhea** big deal!
Cinchonism: hearing loss, angioedema vertigo, tinnitus, etc
Any drug that _______________ has the potential to cause Torsade de pointes
Prolongs QT interval
What is the adverse effect of Procainamide?
Drug induced Lupus in slow acetylators
What is the MOA of lidocaine
Blocks ~inactivated~ Na+ channels
=preferentially affects damaged tissue= more receptors are inactivated
What is the DOC for acute VENTRICULAR arrhythmias?
Lidocaine****
If you see VENTRICULAR arrhythmia on a question the answer is lidocaine
What is the main adverse effect of lidocaine
Seizures/convulsions
What is the MOA of Flecainide?
Strongly blocks all Na+ channels
No effect on ERP due to indiscriminate binding to ALL Na channels
Which antiarrhytmic is a last ditch effort drug
Flecainide
What is the adverse effect of flecainide
STRONG pro-arrhythmic effect
What is Esmolol used for?
Emergency treatment (Short half life, IV only)
Are acebutolol and esmolol non-specific B blockers?
No, B1 only
What is the MOA of amiodarone
Blocks K+ channels
Extends length of AP*****!!!
Other mechanisms:
Blocks Na+ channels (Class I)
B blocker (Class II)
CCB effect (Class IV)
Alpha blocker
What kind of arrhythmias can be treated with Amiodarone
Supraventricular
Ventricular
What is the DOC for supraventricular arrhythmias
Amiodarone
Amiodarone prolongs QT. Can it cause torsades?
No!!**
What drug can cause pulmonary fibrosis after a long term high dose?
Amiodarone*****
This is probably a test q
(Ground glass appearance)
What are the adverse effects of amiodarone
Pulmonary fibrosis
Turns cornea yellowish-brown and skin turns grayish blue
Thyroid dysfunction (iodine derivative)
What is the MOA of Sotalol
K+ blocker= prolongs AP
Non selective Beta blocker**
What kind of arrhythmia can be treated with Sotalol
Ventricular
Supraventricular
Who can NOT be given Sotalol
Asthmatics!** NON SPECIFIC B-BLOCKER WITH K+ CHANNEL BLOCKING PROPERTIES
What are the adverse effects of Sotalol
Torsades
B-receptor blockade= not for asthmatics
What kind of arrhythmias are treated with verapamil and diltiazem
Reentrant SUPRAventricular tachycardia ***
PSVT
AFib and flutter
What part of the heart is affected the most by CCBs
atria!!
NOT THE VENTRICLES
What is the order of treatment for Acute PSVT
- Adenosine
- Esmolol
- CCBs (via IV!)
What is the order of treatment for chronic PSVT?
B-Blockers (oral)
CCBs (oral)
What is the DOC for acute PSVT and WPW syndromes
Adenosine
What is the MOA of adenosine
Enhanced K+ conductance and inhibition of Calcium influx=
Hyperpolarized everything and resets the heart!*
What is the half life of adenosine
10 seconds
Stops the heart for 10 seconds!
Adenosine is only effective for _________arrhythmias
Reentry
Most PSVTs are
What is the MOA of magnesium
Unknown
What is IV magnesium used for
Torsade de Pointes*****
Digitalis induced arrhythmias
Anything that increases action potential duration will also increase ________
QT interval
Anything that increases QT interval has a chance of causing ____________ except for _________
Torsade de pointes
Amiodarone
Route of administration for lidocaine, adenosine and mangneisum?
IV only…. used only in acute therapy
The stronger or broader a drug is in its effects, the more potential for causing ____________
Arrhythmias
Lidocaine vs flecainide for example
Class IV can only be used for (ventricular/supraventricular)
Supraventricular
Class 1B can only be used for (supraventricular/ventricular)
Ventricular
Why are Class IV only effective in supraventricular arrhythmias
Because thats where Calcium is important for rate
Why does class 1B (Lidocaine) only work for ventricular arrhythmias?
Thats the only place where there is a plateau phase where the “window” current is functioning
