Flashcards in Anti-arrhythmics Deck (122):
Caused by abnormalities in the formation and/or conduction of these electrical impulses
What's heart rate (u)
HR describes the frequency of depolarization of the ventricles
What's the normal resting HR (normal sinus rhythm - NSR)? (U)
60-100 beats per minute
Can Arrythmias be silent? (U)
In most pts that experience sx, what do they experience?
Palpitations (feeling like there's fluttering or racing)
In severe cases, what sx may one experience?
What's the most common etiology of arrhythmias?
Infarction secondary to coronary artery dx
List the non-cardiac conditions that may trigger arrhythmias.
Electrolyte imbalances especially those involving potassium, magnesium, sodium and calcium
Elevated sympathetic states such as hyperthyroidism and infection
List the electrolytes that may trigger arrhythmias when they are out of balance
What's QT prolongation?
Drug- induced slowing of repolarization, which can result in a particularly dangerous ventricular tachyarrhythmia called Torsade de Pointes (TdP)
What's the resting value?
What happens in phase 0 of action potential?
Depolarization (determines conduction velocity)
Na channels OPEN (entering cell)
What determines conduction velocity?
What's the value of phase 1 of action potential?
What happens in phase 1 of action potential?
Na channels CLOSE
What happens in phase 2 (plateau)?
Ca channels OPEN (entering cell)
K channels OPEN (EXITING cell)
What happens in phase 3?
Ca2+ channels CLOSE
K channel stays open (continue exiting cells)
Na may enter cell (late inward Na current)
What happens in phase 4?
Slow increase in potential
When is refractory period of action potential?
Phase 1 to end of phase 3
How's arrhythmias classified?
Based on their location of origin into:
What's Supraventricular arrhythmias?
Arrhythmias originating ABOVE atrioventricular node
What's ventricular arrhythmias?
Originating BELOW the atrioventricular node
What's the most common Supraventricular arrhythmias? (U)
Atrial fibrillation (AFib)
Results from multiple waves of electrical impulses in the atria, resulting in an irregular and usually RAPID VENTRICULAR RESPONSE
Why does the mgt of AFib involve anticoagulation?
Due to disorganized depolarization of the atria, coordinated atrial contraction is impaired, which increases the risk of thromboembolism and stroke
What type of ventricular tachycardia is a medical emergency?
Ventricular tachycardia without a pulse
What's a risk factor for Torsade De Pointes (TdP)? (U)
Prolongation of the QT prolongation
What's Torsade de Pointes (TdP)? What can it result in?
TdP is a particularly lethal ventricular tachyarrhythmia which is most commonly ass. with drugs and can result in SUDDEN CARDIAC DEATH
How is QT interval measured? What's the measured space define?
From beginning of the QRS complex to the end of the T wave
Reflect ventricular depolarization and repolarization
What pre-existing condition may cause additive QT prolongation?
Any pre-existing cardiac condition
What class of antiarrhythmics also result in additive QT prolongation? (U)
Class Ia (Disopyramide, Quinidine, Procainamide) double quarter pounder
Class III (Amiodarone, Ibutilide, Dofetilide, Dronedarone, Sotalol) AIDDS
Name main antibiotics that may cause additive QT prolongation. (U)
Quinolones (Ciprofloxacin, Levo, Moxi, Nor, Ofloxacin, Gemi, Spar)
Macrolides (Azithromycin, Erythromycin, Clarithromycin, Telithromycin)
Which Azole antifungal is most responsible for causing additive QT prolongation? (U)
Which anticancer is most responsible for causing additive QT prolongation? (U)
Which SSRI is most responsible for causing additive QT prolongation? (U)
What's the max dose of citalopram to prevent additive QT prolongation?
When is 20mg citalopram the max dose to prevent additive QT prolongation?
2C19 poor metabolizer
Pt on 2C19 inhibitors
Taking QT prolonging drugs
Whats the max dose in for Escitalopram (Lexapro) to prevent additive QT prolongation?
In the elderly?
Don't exceed 10mg/d
What's the preferred antidepressant in cardiac pts to prevent QT prolongation?
What antidepressant should be avoided if pt has cardiac risk?
Which antiemetic agent is most responsible for causing additive QT prolongation? (U)
5-HT3-receptor antagonists (Dolasetron, Ondansetron, Granisetron, Palonosetron)
Which antipsychotic is most responsible for causing additive QT prolongation? (U)
Which other agent is most responsible for causing additive QT prolongation? (U)
What's the 2 main reasons antiarrhythmic drugs are used?
Class I and III (used to terminate arrhythmias and restore and maintain normal sinus rhythm)
Class II and IV and Digoxin (used to slow ventricular rate during a Supraventricular arrhythmias)
What class of antiarrhythmic drugs is used to terminate arrhythmias and restore and maintain normal sinus rhythm?
Class I and III
Disopyramide, Quinidine, Procainamide,
Lidocaine, Mexiletine, Phenytoin,
Amiodarone, Ibutilide, Dofetilide, Dronedarone, Sotalol (AIDDS)
What class of antiarrhythmic agent is used to slow ventricular rate during a Supraventricular arrhythmias?
Beta-blockers e.g. Esmolol, Propranolol)
What must be done prior to starting any medication for NON-LIFE-THREATENING arrhythmia? (U)
Check pts electrolytes
Run a toxicology screen
What's the Vaughan Williams classification of antiarrhythmics?
Class I a, b, c
List drugs that are listed as class Ia.
Double Quarter Pounder
List drugs that are listed as class Ib
Lettuce, Mayo, Pickles
List drugs that are listed as class Ic
List drugs that are listed as class II
Beta-blockers e.g. Esmolol, Propranolol
List drugs that are listed as class III
List drugs that are listed as class IV
How are class I antiarrhythmics sub-classified?
They are Na channel blockers.
They are divided based on the DURATION of time they bind to Na channel
Ia - Intermediate Na channel blockers and they also block K channel
Ib - Fast Na channel blockers
Ic - Long Na channel blockers
Define class Ia antiarrhythmics
INTERMEDIATE Na + K channel blockers
Double Quarter Pounder
Define class Ib antiarrhythmics
FAST Na channel blockers
Lettuce, Mayo, Pickles
Define class Ic antiarrhythmics
LONG Na channel blocker
Which class I sub- Grp especially have a black box warning?
Class Ic (fries pls - Flecainide, Propafenone)
MOA of class Ia antiarrhythmics?
REDUCE conduction velocity and automaticity
INCREASE refractory period
What's the black box warning associated with Quinidine (class Ia)? (U)
Control AV conduction BEFORE initiating
SE of quinidine (class Ia)? (U)
Stomach cramping (22%)
Cinchonism (tinnitus, hearing loss, blurred vision, headache, delirium)
Are the different salts of quinidine interchangeable
267mg of gluconate = 200mg of sulfate form
What's unique about Procainamide injection metabolite? (U)
Has a active metabolite - N-acetyl Procainamide (NAPA)
What's the black box warning associated with Procainamide injection?
Fatal blood dyscrasias e.g. Agranulocytosis
Long-term use -> Positive antibody (ANA) in 50% of pts which may result in DRUG-INDUCED LUPUS ERYTHEMATOSUS-like syndrome
SEs of Procainamide injection?(u)
What's the SE of Disopyramide?
Anticholinergics effect (xerostomia, constipation, urinary constipation)
Effect of class Ia agents (double quarter pounder) on QT prolongation?
ALL class Ia can have additive QT prolongation with other agents that also prolong the QT interval
What are class Ib agents (Mayo, Lettuce, Pickles) ONLY used for?
Ventricular arrhythmias (no efficacy for Supraventricular arrhythmias such as AFib)
T/F? All class Ib antiarrhythmics can't cross the blood-brain barrier.
All can cross the blood-brain-barrier
When are class Ic agents absolutely contraindicated?
Patients with heart failure (HF)
Those who just experienced an acute myocardial infarction (MI)
MOA of class II antiarrhythmics (Esmolol, Propranolol)?
Indirectly block Ca channels in the SA and AV nodes
What are class II antiarrhythmics (Esmolol, Propranolol) used for? (U)
To slow the ventricular rate in Supraventricular tachyarrhythmia (eg. AFib)
MOA of class III agents? (AIDDS)
Blocks K channels -> significant increase in refractory period
What's the exception to the MOA of class III agents?
Ibutilide - works by activating the late inward Na current which also results in increased refractory period
In addition to blocking K channel, what other channels/receptors do Amiodarone and Dronedarone act on?
They also block
In addition to blocking K channel, what other channels/receptors do Soltalol act on?
Significant B-adnerergic receptor blocker
What's the class of amiodarone? And brand name?
What's the black box warning of amiodarone?
Pts should be hospitalized when therapy is initiated becuz of (pulmonary toxicity, liver toxicity, proarrhythmic)
SE of amiodarone (cordarone/pacerone/nexterone)
Hypotension (IV only)
Hypo/hyperthyroidism (more hypo than hyper)
Corneal microdeposits, Optic neuritis
Slate blue (blue-grayish) skin discoloration
What considerations are taken when amiodarone (cardarone, pacerone, nexterone) will be infused over 2 hrs?
Should be admin in a non-polyvinyl chloride (non-PVC) container should as polyolefin or glass
Recommended to be added to D5W
What's the advantage of premixed IV bag? (U)
PVC bag not an issue
Available in most commonly used conc
If hypotension occurs, can slow rate or d/c
What's the half- life of amiodarone?
When's amiodarone recommended? (U)
Drug of choice I pts with concomitant heart failure
Which is the class III agent has to be given with meals?
Dronedarone - 400mg PO BID with meals
What's the black box warning of Dronedarone?
HF (class IV or any class with a recent hospitalization)
In pts with permanent AFib
SE of Dronedarone? (U)
Increased SCr (and possibly BUN)
What's the pregnancy cat. of Dronedarone?
When's Dronedarone used?
Only in pts who can be converted to normal sinus rhythm
Which class III agent requires a REMS program?
Tikosyn (Dofetilide) in pharmacy system - allows retail pharmacies to stock and dispense Tikosyn
What's the monitoring parameters for Tikosyn (Dofetilide)?
In the first few days
What's the effect of ALL class III agents on QT prolongation?
Can have additive QT prolongation with other agents that also prolong the QT interval
What should be considered wrt to electrolytes and ALL anti-arrhythmic?
Electrolyte abnormalities (k, Na, Ca, Mg) should be corrected before any antiarrhythmics is initiated
What's the consequence of not correcting electrolyte before initiating antiarrhythmics?
Risk of arrhythmia is increased
What should be avoided with use of class III antiarrhythmics?
St. John's wort (P-glycoprotein inducer)
What meds should be reduced when starting amiodarone? By how much?
Digoxin (reduce by 50%) and Warfarin (reduce by 30%-50%)
What class of drugs should use lower doses with amiodarone?
Simvastatin, Lovastatin, Atorvastatin
T/F? Monitor INR after initiating Dronedarone in pts with Warfarin
MOA of class IV agents?
They block L-type Ca channels, slowing SA and AV nodal conduction velocity
Uses of class IV agents?
Used to slow ventricular rate in Supraventricular tachyarrhythmia
List agents under class IV antiarrhythmics?
Verapamil (Calan/ Verelan/ Covera HS)
What type of CCBs are used in antiarrhythmics?
Only non-dihydropyridine CCBs are used
When is CCB is preferred over b-blocker in pts with arrhythmias?
If co- existing asthma/COPD in pts
Other antiarrhythmics not included in Vaughan Williams classification?
MOA of adenosine?
Slows conduction through the AV node via activation of adenosine-1 receptors
Uses of adenosine in arrhythmias?
Used to restore normal sinus rhythm in Supraventricular re-entrant tachyarrhythmia
Effects of digoxin?(u)
Digoxin enhances vagal tone, resulting in decrease ventricular rate in atrial tachyarrhythmia
What's the brand name of digoxin? (U)
What's the therapeutic range of digoxin (lanoxin) for AFib?
What's the antidote for Digoxin (lanoxin)?
Whats the first signs of digoxin (lanoxin) toxicity? (U)
Loss of appetite
Other signs of digoxin (lanoxin) toxicity? (U)
Blurred/ double vision
Altered color perception
Greenish-yellow halos around lights or objects
Arrhythmia (prolonged PR interval, accelerated junctional rhythm, bidirectional ventricular tachycardia)
Is digoxin (lanoxin) used alone?
Used in combo with b-blockers or CCB
Since digoxin is mostly renally cleared, whats the concern with digoxin (lanoxin) use here?
In decreased renal fxn -> reduce digoxin dose
In acute renal failure -> hold digoxin
What increases risk of digoxin (lanoxin) toxicity?
Hypokalemia (K < 3.5 mEq/L)
Role of medication guide in amiodarone dosing?
Dispense medication guide with amiodarone
Should amiodarone be taken with food?
Amiodarone can be taken with/ without food.
BUT, if you should stick to which ever method you use e.g. If you start taking amiodarone with food, then you need to continue taking it with food, while on the med
What body organs need to be monitored while in amiodarone?
Eyes - vision should be checked before and during the time you're using amiodarone
Blood - blood should be checked regularly
Chest x-ray during tx
Photosensitivity and amiodarone?
Amiodarone may cause your skin to be more sensitive to the sun.
Stay out of the sun
What's the brand name for Dronedarone?