Class 7 Deck 1 Flashcards
Antiarrhythmic drugs in class 1 do what?
-Block fast Na channels with or w/o K channel block
Name 2 class 1A antiarrhythmics.
- Quinidine
- Procainamide
Class 1A antiarrhythmics do what?
- Lengthen AP duration & effective refractory period (Na channel blockade)
- Lengthen repolarization (K channel blockade)
What is procainamides MOA?
- Na & K channel blocker
- Decrease automaticity by decreasing phase 4 (depolarization)
- Prevent reentry by converting unidirectional to bidirectional block
What are the indications for procainamide?
- Ventricular tachydysrhythmias
- Atrial tach w/ accessory pathways
- SVT, AFib, PVCs, VT
Rapid infusion of procainamide can result in what?
-Severe hypotension from myocardial depression and vasodilation
Chronic use of procainamide can cause what?
-Lupus like symptoms
Procainamide toxicity can cause what?
- Mycardial depression
- Hypotension
- QRS and QT prolongation
- Heart block
- Ventricular ectopy
Name the 2 main class 1B antiarrhythmic drugs.
- Lidocaine
- Phenytoin
How do class 1B antiarrhythmics work?
- Less powerful Na channel blocker
- Shorten AP duration and refractory period in normal ventricle
What is lidocaine’s (class 1B) MOA?
- Na channel blocker
- Decrease slope of phase 4 (depolarization) in purkinje fibers
- Reduce automaticity
What are the indications for lidocaine?
- First choice ventricular arrhythmias (particularly reentry)
- PVC’s Vtach
- Will not work for SVT
Lidocaine toxicity can cause what?
- CNS depression or stimulation (convulsions)
- Depress LV performance
What is Phenytoin (class 1B) MOA
- Na channel blocker
- Depress phase 4 (depolarization)
- Abolishes activity triggered by digitallis
What are phenytoin’s indications for use?
- Suppress ventricular dysrhythmias associated with digitalis toxicity
- Paradoxical VTach or Torsades associated with prolonged QT interval
Phenytoin administration tidbits.
- Use with centeral line
- Dilute in NS
- Highly alkaline and can cause phlebitis
Phenytoin toxicity problems.
- Rapid admin can cause respiratory arrest, hypotension, ventricular ectopy and death
- Cerebellar signs (Drowsiness, nystagmus, nausea, vertigo)
Name 2 class 1C antiarrhythmic drugs
- Flecanide
- Propafenone
What is Flecainide’s (class 1C) MOA
- Depress AP of phase 0
- Prolong QRS and PR
- May suppress SA node (like BB and CCB)
When should Flecainide be used?
- Suppress PVC’s and VTach
- Atrial tachydysrhythmias including WPW
What are the side effects of flecainimide?
- Negative inotropic effect
- Vertigo
- Difficulty in visual accommodation
Class 2 antiarrhythmic drugs are called what?
-Beta Blockers
What is propanolol (class 2 BB) MOA
- Slowing of SA node
- slowing ectopic pacemakers
- Prolong AV conduction
- Increased refractory of AV node
What are the indications for propanolol use?
- SVT
- Convert atrial tachyarrhythmias to sinus rythm
- Slow ventricular response to AFib and flutter
Propanolol toxicity can cause what 3 things?
- Bradycardia/asystole
- LV failure
- Bronchospasm
antiarrhythmic drugs in class 3 are known as what?
-K channel blockade
In addition to class 3 effects amiodarone has what other effects?
- Class 1 = Na channel
- Class 2 = Beta blockade
- Class 4 = Ca channel
Amiodarone is a structural analog of _______
-Thyroid hormone
What is Amiodarone MOA
- Potent inhibitor of abnormal automaticity
- Prolongs refractory period and AP duration
- Antiadrenergic effects
- Prolong PR,QT, and QRS
- May slow SA and AV conduction
what are amiodarone’s indications for use?
- Termination of Ventricular tachycardias
- VFib or Vtach in patients unable to tolerate other agents
- Maintaining SR in patients w/ AFib
- WPW
What drug is considered an alternative to amiodarone (multi-channel blocking agent)? and how is it different?
- Dronedarone
- Structurally non-ionated
- Less efficacious but less side effects
What is the indication for dronedraone use?
-AFib to maintain NSR
What are the contraindications of dronedarone?
- Increased risk in patients w/ heart failure or afib
- 2nd/3rd degree heart blocks
- Meds that inhibit CYP3A4 can prolong QT
- Pregnancy
- Liver disease
What is Sotalol MOA?
- Oral non-selective beta
- Lowers BP
When is sotalol used?
- PSVT
- VTach/VFib
- Antihypertensive
What are class 4 antiarrhythmic drugs and name 2.
- Calcium channel blockers
- Verapamil and diltiazem
What is verapamil’s MOA?
- Blocks slow Ca influx to cell
- Prolongs AV conduction
- Depresses SA node discharge
What are the indications for Verapamil use?
- SVT
- Slow ventricular rate in AFib and A flutter
What is the major side effect in verapamil use?
-Hypotension
When is diltiazem used?
-Slow ventricular rate in AFib/Flutter
what is the MOA for digoxin?
- Inhibits Na/K ATPase
- Slows ventricular response in afib
Digoxin will indirectly _______ vagal activity and ______ sympathetic activity.
- Increase
- Reduce
Digoxin indications
-Ventricular rate control in AFib, AFlutter, SVT
What will digoxin toxicity do?
- Alterations in cardiac rate and rhythm may stimulate almost every known rhythm disturbance
- PVCs most common
- Enhanced by hypokalemia
