Pharmacology-Antiarrhythmic Flashcards
Anti-arrhythmic drugs are often used to treat
atrial arrhythmias
Anti-arrhythmic drugs have a potential to affect______ and may produce _______side effects
LV function
Pro-dysrhythmic
From Class 1-4, name the classes in order
Sodium
Beta
Potassium
Calcium
(shay better pass this class)
List subclass Sodium Channel Blockers in order from most potent to least
1C
1A
1B
Class 1 Sodium blockers are
negative Inotropes
MOA of Sodium Blockers
Bind to and block fast Na+ channels (keeps them in an inactive state)
decrease the slope of phase 0
decrease size of AP
decrease conduction velocity
cells have a harder time depolarizing
Negative Inotropes
decrease LV function
Some Na+ blockers act on _____channels
K+
With Na+channel blockers, class 1A prolongs phase_____, the refractory period
Class 1B shortens phase ____, the refractory period
3
Nodal cells are NOT dependent on
Fast Na+ channels
Class 1A drugs slows conduction velocity by prolonging _____ and __________
repolarization; duration of action potential
Class 1A often treats
Afib, Aflutter, SVT and VT
Class 1A have ______________effects, which can cause tachycardia
Anticholinergic
What are common Class 1A drugs
Quinidine
Procainamide
Disopyramide
Quinidine, a class 1A Na+ blocker slows the _____rate and is an ___________, which can cause vasodilation and HOTN
atrial rate; alpha 1 antagonist
What are the side effects of Quinidine, a class 1A Na+ blocker?
Anticholinergic
Torsades
Cinchonism (blurred vision, HA, tinnitus)
prolongs QT & QRS
Quinidine, a class 1A Na+ blocker is used to treat acute/chronic ______________ & ____________
SV arrhythmias
New onset Afib
Procainamide, a class 1A Na+ blocker slows __________rate and prolongs______
Ventricular; QRS
What are side effects of Procainamide?
HOTN
Myocardial depression
Vfib
SLE, leukopenia, thrombocytopenia (w/chronic administration)
Watch renal function
Drug fever/rash
N/V
Potential for Ventric asystole/fib
What is the metabolite of Procainamide?
NAPA metabolite
Disopyramide, a class 1A Na+ blocker slows_____&______ and can precipitate _____&______
atrial and ventricular rate;
CHF & HOTN
What are the side effects of disopyramide, a class 1A Na+ blocker?
Myocardial Depression
Anticholinergic
Prolong QT
Vtach
Dry Mouth
Urinary hesitancy
Blurred vision
Nausea
What are the medications that are 1B Na+ blockers
Lidocaine
Mexiletine
Tocainide
Phenytoin
When are class 1B drugs best used
work better in ischemic cells
Class 1B drugs have minimal effect on conduction velocity in normal cells and shortens _____&______
repolarization & AP duration
MOA of Class 1B Na+ blockers
bind inactivated Na+ channels in ischemic cells and maintain state
1B Na+ blockers treat
V-tachyarrhythmias associated w/MIs
All 1B Na+ blockers slow_________rate
Ventricular
What is the dose of Lidocaine?
2mg/kg IV
1-4mg/min IV
What are the side effects of Lidocaine?
Assess for LAST
What are side effects of Tocainide & Mexiletine, class 1B Na+ blockers
synergistic effects w/BB
Pulmonary fibrosis w/toc
Phenytoin act similar to
Lidocaine
What are side effects of Phenytoin
CNS related (vertigo, sedation, confusion, nystagmus, and ataxia)
Class 1C Na+ blockers slows conduction velocity and treats
life-threatening ventricular & SVT
Class 1C Na+ blockers can cause
other dysrhythmias
pro-dysrhythmic effects
Examples of 1C Na+ blockers
Flecainide
Propafenone
Moricizine
Flecainide, 1C Na+ blocker, slows______ and treats________
atrial; PVCs and SVT
What are side effects of Flecainide, a class 1C Na+ blocker
Negative Inotrope
Depressed SA node
Vtach
Blurred Vision
Propafenone and Moricizine, class 1C Na+ blockers, slow_______
Ventricular rates
What are side effects of Propafenone
Dysrhythmias
CHF exacerbation
Blurred Vision
Side effects of Moricizine
Increased mortality post-MI
Dysrhythmias
Na+ channel blockers slow_______, effect __________Na+channels, and some have effects on phase ______
tachyarrythmias
fast
3 repolarization
What are the 2 common Class II beta blockers in the OR
Metoprolol
Esmolol
Class II Beta Blockers work on the _______action potential and slows down the ______cells
nodal
pacemaker
MOA of Class II Beta Blockers
Bind to and block Beta-1 receptors
Decreases conduction velocity, cAMP, Ca+ currents and slope of phase 4
Slows spontaneous depolarization
Prolonged repolarization/refractory period at AV node
Class II Beta Blockers slows_____&_____ and treats_______,_______and_______
atrial & ventricular rate
treats SNS induced arrhythmias
ectopic beats
tachyarrhythmias
Non-nodal: prolongs AP duration and refractory period
What are side effects of Class II BETA BLOCKERS
Myocardial Depression
HOTN,bradycardia, AV block
Increased airway resistance
Depression
Fatigue
Upregulation of beta receptors in
chronic therapy
Non-selective: Hypoglycemia, hyperkalemia, bronochoconstriction
Class III potassium blockers prolong
Phase III
MOA of Class III Potassium blockers
bind to and block K+ channels
decrease K+ currents
slows repolarization
increases effective refractory
period
Class III potassium blockers prolongs cardiac __________, action potential _________, and effective ________period
depolarization
duration
refractory
What is the prodrug of Class III potassium blockers
Amiodarone
Amiodarone exhibits what blockades
Na+, BB, and Ca+
Amio has anti-anginal effects by ______coronary arteries and ______coronary blood flow
dilating; increasing
Amio affects what classes
Class I, II, III, IV
Amio treats
ventricular and atrial tachyarrhythmias
Amio has both _____&____receptoor blockade, making it a negative ______& ______
alpha & beta (anti-adrenergic effects)
inotrope & vasodilation
prolongs QT
Amio is ______, which is why it often needs a loading dose
lipophilic
(PO may take days to week)
What is the active metabolite of Amio
Desmethylamiodarone
(slow effects and lingers)
Dosage of Amio
Loading 150mg over 10min
Maintenance 1mg/min over 6hrs
0.5mg/min over 18hrs
What are the side effects of Amio
Alveolar Pneumonitis
Pulm Edema
ARDS
HOTN
AV/SA node block
Decreased response to
catecholamines
Increases free O2 radicals=cellular destruction
Inhibits CYP450
Photosensitivity
What are other Class III drugs
Sotalol
Ibutilide
Dofetilide
Class III Potassium blockers Ibutilide and Dofetilide treat Afib/flutter with these side effects
Prolonged QT
Life-threatening V-arrhythmias
Torsades
Sotalol, a Class III Potassium blocker treats_____&_____ tachyarrhythmias and is a _______beta blocker at low doses
Atrial & Ventricular
Non-selective
Sotalol, a Class III potassium blocker has what side effects
Prolonged QT
Bradycardia
Torsades
Decreased MI Contractility
Delayed Conduction
Class IV CCB MOA
Bind to and block Ca+ channels
Maintains inactivate/closed states
Inhibits slow inward Ca+ currents
Decreases/flatten slope of phase 0 and 4
slows conduction velocity
Prolongs repolarization in AV node
Class IV CCB can be subdivided into
Dihydropyridines and non Dihydropyridines
Non-dihydropyridines are
cardiac selective
Non-dihydropyridines medications are
Diltiazem
Verapamil
Non-dihydropyridines treat
SVT, VTs (reentry)
early/delayed afterdepolarizations
CCB and BB should
NOT be administered together due too exaggerated effects
What are the side effects of Class IV Non-dihydropyridines
negative inotropy (MI depression and decreased CO)
bradycardia
AV nodal block
Vasoodilation and HOTN
Class I Na+ channel blockade can cause
reentry mechanism
v-tachyarrhythmias, wide-complex
common w/1C
Class III Potassium can
Prolong repolarization, refractory, and QT interval
Torsades is Common!!
Exacerbated by hypokalemia/magnesemia
Adenosine is made by our bodies by
breakdown of ATP
Adenosine MOA
Stimulates cardiac A1 (adenosine) receptors, which increases K+ conductance (hyperpolarization) & inhibits L-type Ca+ influx in nodal cell
Decreases slope of phase 0 & 4
Decreases conduction velocity & automaticity
Adenosine can treat
acute PSVT, WPW
Additional actions of adenosine include
Stimulates vascular A2 adenosine receptors, which increases cAMP in smooth muscle and causes vasodilation
Also blocks NE release from presynaptic SNS terminals
increased cAMP has a negative effect on kinase
What is the dosage of Adenosine
6mg IV initial
6mg or 12 mg IV after 3min
rapid flush 10-20 mL NS due to rapid transport into RBC (give close to heart)
What are side effects of Adenosine
AV block (pause common)
Vasodilation (rapid arterial HOTN, flushing, HA)
Digitalis Glycosides (Digoxin) is used to
Slow down atria arrythmias
What is the MOA of Digoxin
Na/K/ATPase potent inhibitor
Reduced activity of Na/Ca+ exchanger
Digoxin _____slope of phase 4 and _______slope of phase 0
Increases __________&__________
positive inotropy
increases; decreases
depolarization & automaticity
Digoxin is used to treat_______inotropy in _______patient
increased; HF
Digoxin treats_________ and is known to be a________
atrial tachyarrhythmias and HF
parasympathomimetic, which increases vagal activity, decreases SA firing and AV conduction (prolongs PR) and suppresses ectopic PMs
Digoxin will show these ECG changes
ST depression
Shorter QT
Inverted T waves
What are the therapeutic levels of digoxin
0.5-2ng/mL
Digoxin uses what as a resivoir
muscle
may be floating around in the elderly
cleared by the kidney
What are the toxic levels of digoxin
> 2-3 ng/mL
3.5ng/mL in PEDS
What are the causes of dig toxicity
*Hypokalemia
Hypomagnesemia
Impaired renal function
Decreased muscle mass
What are the early manifestation of digitalis toxicity
anorexia
N/V
trigeminal neuralgia
What are the cardiac effects of digitalis toxicity
atrial & ventricular dysrhythmias
delayed AV conduction
*AT w/block
*VF most common cause of death
What is the treatment of digitalis toxicity
treat underlying cause
lidocaine or class I for ventricular
atropine for excess vagal activity
propranolol or class II to
suppress increased
automaticity
When would a patient need a pacemaker
CHB
What is the ultimate treatment for digitalis toxicity
Digibind and Digifab: which decreases plasma concentration (antigen binding abx)
What are the H&Ts of arrhythmias
HYPO/HYPERthermia
Hypovolemia
Tension PTX
Tamponade
Toxins/Drugs
Thromboembolism
Atropine dose
0.02mg/kg
How to treat AFIB (ABCD)
Anticoag
BB
CCB/cardiovert
Digoxin
prevent w/procainamide
How to treat SVT (ABC)
Adenosine
BB
CCB
(Mg sulfate, Class 1A or 1C III)
How to treat PVCs
BB
Non-dihydropyridine CCB
Class I
Mg
Lidocaine
How to treat Vtach/fib
Lidocaine
Amio
Mg
BB
tx polymorphic w/Mg
prevention w/amio and lidocaine