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
