SM 140a - Pharmacology of Anti-Arrhythmic Drugs Flashcards
Procainamide, Quinidine, and Disopyramide are Class ___ anti-arrhythmic agents that block _____
Procainamide, Quinidine, and Disopyramide are Class IA** agents that block **Na+ and K+ channels
Slow AP upstroke, prolong AP duration
Problems with ________ usually cause Ventricular Fibrillation
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
Most drugs that block _______ channels are proarrythmic for Torsades de Pointes.
Why?
Most drugs that block potassium channels are proarrythmic for Torsades de Pointes
Blocking potassium channels increases the length of the action potential (phases 2 and 3). Anything that prolongs phases 2 and 3 has the potential to cause Early After Depolarizations (EADs), which is the triggered activity that leads to Torsades de Pointes
Which agents can be used to suppress symptomatic PVCs and VT in the setting of MI?
- Class II
- Class III: Amiodarone only
- Class IB
- Class IA: Procainamide occasionally
Lidocaine, Mexelitine, and Phenytoin are Class ___ anti-arrhythmic agents that block _____
Lidocaine, Mexelitine, and Phenytoin are Class IB** agents that block **Na+ channels moderately (No K+ blocking action)
Slow AP upstroke
What are the general treatment principles for treating an arrhythmia that is caused by triggered activity?
(Ex: Monomorphic VT, Polymorphic VT)
- Cause: Early After Depolarizations (Phase 2-3)
- Common if action potential is prolonged
- Ex: Torsades de Pointes
-
Treat by shortening the action potential
(without messing with Na+ or Ca2+ channels)
- Cause: Delayed After Depolarizations (Phase 4)
- Common if intracellular Ca2+ is too high
- Ex: Digitalis Toxicity
- Treat by reversing the underlying cause of high Ca2+
Procainamide is a class ____ anti-arrhythmic that blocks _________ channels.
It can be used to ___________, and ____________.
Procainamide is a class IA anti-arrhythmic that blocks Na+ and K+ channels.
It is used to treat Sustained VT , and Prevent VT after MI.
(But it is rarely used because amiodarone and lidocaine are more effective)
Which tachycardias can arise from triggered activity?
- Monomorphic Ventricular Tachycardia**
- Polymorphic ventricular tachycardia
** = Can also arise from reentry (major cause) or automaticity
Veramapil is a class ____ anti-arrhythmic that blocks ______ channels. It __creases conduction time and __creases the refractory period in the AV node
It can be used to _____________ and _____________..
Veramapil is a class IV** anti-arrhythmic that blocks **Ca2+ channels. It increases conduction time and increases the refractory period in the AV node
It can be used to control heart rate in A-fib and A-flutter** and **terminate supraventricular tachycardia.
What are the major side effects of disopyrimide?
Typical anti-muscarinic side effects
- Urinary retention
- Constipation
- Blurred vision
- Dry mouth
- Closed angle glaucoma
Proarrythmic -> Torsades de Pointes, heart block
(Disopyrimide = class IA)
Which subclass (A, B, or C) of Class I anti-arrythmic drugs has the greatest potassium channel blocking action?
Class IA (Moderate Na+ and K+ channel blocking)
(Procainamide, Quinidine, Disopyramide)
A heart patient on medications is experienceing yellow vision and nausea.
Which drug might be causing this?
Digoxin
What are the major side effects of procainamide?
Drug induced lupus
Proarrythmic -> Torsades de Pointes, heart block
(Procainamide = IA)
Problems with ________ usually cause monomorphic VT
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
(Although monomorphic VT can also be caused by automaticity or triggered activity)
Describe the mechanism of action of lidocaine
Lidocaine binds to the activated and inactivated Na+ channel, but not the resting channel
This means it has little effect on normal, healthy tissue, whose channels are normally in the resting state.
Sick myocardium, however, is partially depolarized, so the Na+ channels are more likely to be in the activated or inactivated state.
Therefore, Lidocaine binds preferentially to sick myocardium to decrease the strength of the phase 0 upstroke
Dofetilide is a class ____ anti-arrhythmic that blocks ______ channels. It __creases action potential duration in heart tissues.
It can be used to _____________.
Dofetilide is a class III** anti-arrhythmic that blocks **K+ (and some Na+) channels. It increases action potential duration in heart tissues.
It can be used to maintain sinus rhythm in A-fib and A-flutter.
Which treatment strategy for atrial fibrillation involves modifying the atrial electrical properties in the SA node?
Rhythm control
Problems with ________ usually cause AVRT
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
Which class of anti-arrhytmic drugs are considered Ca2+ channel blocker?
Class IV
(Verapamil, Diltiazem)
What are the major side effect of digoxin?
- Anorexia
- Nausea, vomiting
- Disorientation
- Hallucination
- Yellow vision
Proarrhythmic ->
- AV nodal block (due to vagal tone)
- Ventricular Premature Beats (due to increased Ca2+)
- VT (due to reeentry or premature beats)
What are the major side effects of Quinidine?
Nausea, vomit, diarrhea
Cinchoism: CNS toxicity (Tinnitus, hearing loss, delerium, psychosis)
Proarrythmic -> Torsades de Pointes, Heart block
(Quinidine = Class IA)
Problems with ________ usually cause Ventricular Premature Beats
A. Automaticity
B. Reentry
C. Triggered Activity
A. Automaticity, and B. Reentry
Quinidine is a class ____ anti-arrhythmic that blocks _________ channels.
It can be used to ___________, and ____________, but it is most useful as an anti-malarial agent.
Quinidine is a class IA** anti-arrhythmic that blocks **Na+ and K+ channels.
It can be used to convert atrial fibrillation or atrial fluttur to sinus rhythm** , and **maintain sinus rhythm in atrial fibrillation patients, but it is most useful as an anti-malarial agent
(Other agents are more effective for these arrhthmias)
What are the major side effects of amiodarone?
- Hypo- or hyper-thyroidism
- Pulmonary fibrosis
- Hepatotoxicity
- Gray/blue skin discoloration
Proarrythmic -> Sinus bradycardia, AV block
Note: the only K+ channel blocker that does not cause Torsades de Pointes
(Amiodarone = class III anti-arrythmic)
Problems with ________ usually cause Atrial Flutter
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
Verapamil and diltiazem are Class ___ agents that block _____
Verapamil and diltiazem are Class IV** anti-arrhythmic agents that block **L-type Ca2+ channels
Prolong conduction time, refractory period in the AV node
What are the major side effects of dofetilide?
Headache GI effects
Proarrythmic -> Increase risk of hypokalemia, new or worse VT (ex: Torsades de Pointes)
(Dofetilide = Class III anti-arrythmic)
Ibutilide is a class ____ anti-arrhythmic that blocks ______ channels. It __creases action potential duration in heart tissues.
It can be used for _____________.
Ibutilide is a class III** anti-arrhythmic that blocks **K+** channels. It **increases action potential duration in heart tissues.
It can be used for acute termination of A-fib and A-flutter.
Which antiarrythmic might be useful in a patient with a loud systolic murmur that gets louder when standing from a squatting position?
This murmer is present in hypertrophic cardiomyopathy.
Treat with disopyramide
[Thank you Nathin Shlobin!]
Sotalol is a class ____ anti-arrhythmic that blocks ______ channels. It __creases action potential duration in heart tissues.
It can be used to _____________, ____________ and _____________.
Sotalol is a class III** anti-arrhythmic that blocks **K+ channels (also has some beta-blocking activity). It increases action potential duration in heart tissues.
It can be used to maintain sinus rhythm in A-fib and A-flutter**, **prevent AVNRT, AVRT** and **treat ventricular tachyarrythmias.
A heart patient on medications has shortness of breath and increased patellar reflexes on physical exam.
What medication might be casuing this?
Procainamide
Side effect = drug induced lupus, which induces arthralgia, leading to increased patellar reflexes and pleuritis (-> shortness of breath)
[We (thank you Nathan Shlobin) are pretty sure about this, but if you know of another drug suggest an edit!]
Amiodarone, Dronedarone, Soltalol, Ibutilide, and Dofetilide are Class ___ anti-arrhythmic agents that block _____
Amiodarone, Dronedarone, Soltalol, Ibutilide, and Dofetilide are Class III** agents that block **K+ channels (primarily)
Increase AP duration, Increase effective refractory period
Which drug is considered the most effective anti-arrythmic agent?
Why isn’t it always used?
Amiodarone (class III anti-arrythmic)
It is not alwyas used because thee side effects can be severe
- Hypo- or hyper-thyroidism
- Pulmonary fibrosis
- Hepatotoxicity
- Gray/blue skin discoloration
What are the major side effects of lidocaine?
CNS toxicity
(Confusion, delerium, parasthesias, grand mal siezures)
(Lidocaine = Class IB)
Which agents can be used for rate control in atrial fibrillation and atrial flutter?
- Clas II
- Class IV
- Digoxin
Metoprolol and esmolol are Class ____ anti-arrhythmic agents that are ______ blockers
Metoprolol and esmolol are Class II** antiarrhythmic agents that are **beta blockers
Decrease slope of phase 4 depolarization(SA), decrease upstroke velocity (SA, AV)
What are the general treatment strategies to treat a tachyarrhythmia that arises from reentry?
(ex: A-fib, A-flutter, multifocal AT, AVRT, AVNRT, Ventricular premature beats, Monomorphic VT, V-fib)
- Increase the refractory period of the slow conducting tissue
- Slow down conduction even further
- Supress premature beats
Problems with ________ usually cause Atrial Premature Beats
A. Automaticity
B. Reentry
C. Triggered Activity
A. Automaticity
What are the major side effects of Sotalol?
Similar to beta blockers
- Bronchospasm
- Depression
- Cognitive impairment
- Hypotension
Sotalol = Class III anti-arrythmic
Proarrythmic -> New or worse VT (ex: Torsades de Pointes)
Amiodarone is a class ____ anti-arrhythmic that blocks ______ channels. It __creases action potential duration in heart tissues and __creases the effective refractory period
It can be used to _____________, ____________ and _____________.
Amiodarone is a class III** anti-arrhythmic that blocks **K+ (and some Na+, Ca2+) channels (also has some beta-blocking activity). It increases action potential duration in heart tissues and increases the effective refractory period
It can be used to suppress ventricular tachycardia (but defibrillator is more effective), maintain sinus rhythm in Afib and Aflutter** and **convert Afib to sinus rhythm.
A heart patient is recovering from MI but develops siezures and lethargy after 3 days in the intensive care unit.
What medication might be casuing this?
Lidocaine or Mexelitine (Class IB)
Propafenone is a class ____ anti-arrhythmic that blocks ______ channels. It __creases conduction time in heart tissues and __creases inotropy
It can be used for _____________, ____________ and _____________.
Propafenone is a class IC** anti-arrhythmic that blocks **Na+ (and some K+) channels. It increases conduction time in heart tissues and decreases inotropy
It can be used for acute conversion of atrial fibrillation**, **maintenence of sinus rhythm in atrial fibrillation, and treatment of ventricular arrhythmia.
Problems with ________ usually cause Multifocal AT
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
Flecainide and Proafenone are Class ___ anti-arrhythmic agents that block _____
Flecainide and Proafenone are Class IC** agents that block **Na+ channels strongly, and K+ channels very weakly
Prolong AP upstroke, decrease inotropy
What are the general treatment strategies to treat arrhythmias caused by automaticity?
(ex: Sinus tachycardia, atrial or ventricular premature beats, monomorphic VT)
- Hyperpolarize the membrane
- Decrease the slope of phase 4 depolarization
- Increase threshold potential
In general, make it more difficult for the automatic focus to reach threshold and initiate an action potential
What are beta-blockers used for in the context of arrythmias?
Beta blockers = class II anti-arrythmic agents
- Decrease the ventricular response in atrial fibrillation
- Disrupt reentrant arrythmias (AVRT, AVNRT, AT)
- Suprpresse premature ventricular contraction and atrial premature beats
- Decrease mortality & incidence of sudden death post-MI
Which class of anti-arrhytmic drugs are considered potassium channel blockers?
Class III
(Amiodarone, Dronedarone, Solalol, Ibutilide, Dofetilide)
Which tachycardias can arise from problems with reentry?
- Atrial fibrilation
- Atrial flutter
- Multifocal Atrial Tachycardia
- AVNRT
- AVRT
- Ventricular Premature Beats*
- Monomorphic Ventricular Tachycardia**
- Ventricular Fibrillation
* = Can also arise from automaticity
** = Can also arise from automaticityor triggered activity, but reentry is the main cause
Mexelitine is a class ____ anti-arrhythmic that blocks ______ channels.
It can be used for _____________.
Mexelitine is a class IB** anti-arrhythmic that blocks **Na+ channels.
It can be used for chronic suppression of ventricular arrythmias.
(Not first line, but used sometimes)
Which subclass (A, B, or C) of Class I anti-arrythmic drugs has no effect on potassium channels?
Class IB (Low Na+, No K+ blocking)
(Lidocaine, Melilotine, Phenytoin)
What are the major side effects of propafenone?
Bronchospasm
Proarrythmic -> Heart block due to slow conduction, exacerbation of ventricular arrythmia
(Propafenone = Class IC)
Lidocaine is a class ____ anti-arrhythmic that blocks ______ channels.
It can be used to treat ___________, and ____________.
Lidocaine is a class IB** anti-arrhythmic that blocks **Na+ channels.
It can be used to treat ventricular arrythmias (especially post-MI) , and myocardial ischemia.
Which agents can be used to treat Torsades de Pointes?
- Electrical cardioversion (first choice)
- Mg2+
- Stabilizes electrical membrane
- Isoproterenol, overdrive pacing
- Increase HR to decrease QT interval
- Phenytoin
Which class of anti-arrhythmic drugs are considered sodium channel blockers?
Class I
A: Moderate Na+ and K+ blocking
B: Low Na+ and no K+ blocking
C: High Na+ and v. low K+ blocking
What are the major side effects of using beta blockers to treat arrythmias?
Bronchospasm, depression, cognitive impariment, hypotension
Proarrythmic -> Bradycardia, heart block
Disopyrimide** is a class **IA anti-arrhythmic that blocks _________ channels and binds the ____ receptor.
It can be used to treat ___________.
It has negative ________ effects.
Disopyrimide** is a class **IA** anti-arrhythmic that blocks **Na+ and K+ channels and binds the M2 muscarinic receptor. (Therefore, it is anti-muscarinic)
It has negative** **inotropic effects.
It can be used to treat hypertrophic obstructive cardiomyopathy. (but it is not commonly used)
Which agents can be used for acute conversion of A-fib and A-flutter, as well as maintenenc of sinus rhythm?
- Class IC
- Flecanide
- Propafenone
- Class III
- Amiodarone
- Sotalol
- Dofetilide
- Ibutilide
What are the side effects of Adenosine?
- Flushing
- Chest burning
- Chest pressure
Proarrythmic -> Atrial fibrillation (occasional)
Problems with ________ usually cause sinus tachycardia
A. Automaticity
B. Reentry
C. Triggered Activity
A. Automaticity
Describe the mechanism of action of mexelitine
Mexelitine binds to the activated and inactivated Na+ channel, but not the resting channel
Therefore, it preferentially binds sick myocaridum over healthy myocardium, to inhibit the phase 0 upstroke
(Same mechanism as lidocaine, but mexelitine is orally available)
(Mexelitine = Class IB)
Which agents can be used to suppress symptomatic PVCs and VT?
- Class II
- Class IB
- Class IC
- Class III
- Sotalol and amiodarone only
- Class Ia (occasionally disopyramide)
Note: almost everything except Class IV
Which drug is the first choice for diagnosis and termination of SVT?
Adenosine
It gets rid of QRS complexes momentarily so A-fib and A-flutter are easier to see
A ________ QT interval can predispose a patient to Torsades de Pointes
A long QT interval can predispose a patient to Torsades de Pointes
Which subclass (A, B, or C) of Class I anti-arrythmic drugs has the greatest sodium channel blocking action?
Class IC (High Na+, very low K+ blocking)
(flecainide, propafenone)
What are the major side effects of Ibutilide?
GI effects (Few extracardiac effects)
Proarrythmic -> Increased risk of Torsades de Pointes in the first few hours
Flecainide is a class ____ anti-arrhythmic that blocks ______ channels. It __creases conduction time in heart tissues and __creases inotropy
It can be used for _____________, and _____________.
Flecainide is a class IC** anti-arrhythmic that blocks **Na+ (and some K+)** channels. It **increases** conduction time in heart tissues and **decreases inotropy
It can be used for acute conversion of atrial fibrillation**, and **maintenence of sinus rhythm in atrial fibrillation.
What is the mechanism of action of class II anti-arrythmic drugs?
What are they used for?
Class II anti-arrhythmic drugs are beta blockers
- Decrease slope of phase 4 depolarization in the SA node
- Decrease upstroke velocity in the SA and AV node
They are used to…
- Decrease the ventricular response in atrial fibrillation
- Disrupt reentrant arrythmias (AVRT, AVNRT, AT)
- Suprpresse premature ventricular contraction and atrial premature beats
- Decrease mortality & incidence of sudden death post-MI
Problems with ________ usually cause Polymorphic VT
A. Automaticity
B. Reentry
C. Triggered Activity
C. Triggered Activity
Which class of anti-arrhytmic drugs are considered beta-blockers?
Class II
(Metoprolol, Esmolol, many others)
Which anti-arrythmic drug is most likely to cause grand-mal siezures?
Lidocaine, Mexelitine
Problems with ________ usually cause Atrial Fibrillation
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
A heart patient on medications is experiencei tinnitus and delerium.
What medication might be casuing this?
Quinidine or Disopyrmide
Which anti-arrhythmic drugs are classified in the “miscellaneous” category?
Digoxin
Adenosine
Mg2+
Which treatment strategy for atrial fibrillation involves slowing down the AV node?
Rate control
What are the effects of digoxin on the heart?
What is it used for?
- Effects
-
Positive inotropy
- Digoxin blocks the Na+/K+ ATPase
- This increases the amount of Na+ in the cell
- This decreases the activity of the Na+/Ca2+ exhanger (which normally pumps Ca2+ out and Na+ in)
- Vagomimetic: slows conduction through SA node, Atria, AV node
-
Positive inotropy
- Uses
- Control ventricular response in A-fib and A-flutter
- Use with beta blocker, Ca2+ channel blocker
- Heart failure: Last resort agent to increase systolic function
*
- Control ventricular response in A-fib and A-flutter
What might cause the appearane of retrograde P waves on an ECG?
Retrograde P-wave = P-wave after the QRS complex
Due to reentry (AVNRT)
The two major treatment strategies to treat atrial fibrillation, atrial flutter, and atrial tachycardia are __________ control and ___________ control.
Describe each one briefly
The two major treatment strategies to treat atrial fibrillation, atrial flutter, and atrial tachycardia are (ventricular) rate control and rhythm control.
-
Rate control
- Slow down the AV node to control the ventricular rate
- Leave the atria in fibrillation
-
Rhythm control
- Modify the atrial electrical properties in the SA node to resotre sinus rhythm
What are the major side effects of mexelitine?
Nausea, vomiting, confusion, delerium, parasthesias, grand-mal siezures (same as lidocaine)
Proarrythmic: may exacerbate ventricular arrythmia, sinus bradycardia
(Mexelitine = class IB)
What agents can be used to disrupt SVT, such as AVNRT and AVRT?
- Adenosine (1st choice for diagnosis and treatment)
- Class II
- Class IV
- Class III (amiodarone, but rarely used becaues others are less toxic)
What are the effects of Adenosine on the heart?
What is it used for?
- Effects
- Binds A1 Adenosine receptors
- Causes hyperpolarization and heart block
- Activates K+ channels
- Blocks L-type Ca2+ channels
- Inhibits funny current
- Uses
- Diagnosis and treatment of SVT (1st choice)
- Terminates reentrant rhythms
Which classes of anti-arrythmic drugs can prolong the QT interval on the eletrocardiogram?
Class III: K+ channel blockers
Class IA: Na+ and K+ channel blocker
What are the side effects of flecainide?
Confusion, irritability
Proarrythmic -> Heart block due to slow conduction, may exacerabate ventricular arrythmia
(Flecainide = class IC)
Problems with ________ usually cause AVNRT
A. Automaticity
B. Reentry
C. Triggered Activity
B. Reentry
Which tachycardias can arise from problems with automaticity?
- Sinus tachycardia
- Atrial premature beats
- Ventricular premature beats*
- Monomorphic Ventricular Tachycardia**
* = Can also arise from reentry
** = Can also arise from reentry (major cause) or triggered activity
What are the major side effects of veramapil?
- Constipation
- Peripheral edema
- Hypotension
Proarrythmic -> Sinus bradycardia, heart block