Drugs Used in Cardiac Arrhythmias Lecture - Konorev

Question 1

which cells have fast action potential

Answer 1

ventricular contractile cardiomyocytes
atrial cardiomyocytes
purkinje fibers

Question 2

which cels have slow (pacemaker AP)

Answer 2

SA node cells

AV node cells

Question 3

class 1a drugs

Answer 3

quinidine
procainamide
disopyramide

Question 4

class 1B drugs

Answer 4

lidocaine

mexiletine

Question 5

class 1C drugs

Answer 5

flecainide

propafenone

Question 6

class 2 drugs- beta blockers

Answer 6

esmolol

propranolol

Question 7

class 3 drugs

Answer 7

potassium channel blocking drugs

amiodarone
dronedarone
sotalol
dofetilide
ibutilide

Question 8

class 4 drugs

Answer 8

cardioactive CCB

verapamil
diltiazem

Question 9

miscelaneous agents

Answer 9

adenosine

Question 10

class 1 drugs sodium channel blocker
-state dependent block

Answer 10

most useful drugs block open activated or inactivated Na+ channels, with very little affinity towards channels in a resting state

Question 11

class 1A drugs and channels

Answer 11

block sodium channels, slow impulse conduction, reduce automatism of ectopic pacepaker

-use dependent block- preferentiallhy bind to open sodium channels (ectopics with faster rhythms targeted)

• block postassium channels
  
  • prolong AP duration, prolong QRS and QT

Question 12

class 1A drugs kinetics

Answer 12

dissociate with intermediate kinetics

Question 13

class 1B drugs and channels

Answer 13

block sodium channels - bind to inactivated sodium channels (preferentially bind to depolarized cells)

-do not block potassium channels, no prolonged AP, QT, or ARS

Question 14

class 1B drugs and kinetics

Answer 14

dissociate from channel with fast kinetics

-may shorten AP

Question 15

class 1C drugs and channels

Answer 15

block sodium channels, slow impulse conduction (bind open/activated channels)

block certain potassium channels but not ones responsible for repol

• no proloned AP, or QT
• prolong QRS interval duration

Question 16

class 1C drugs and kinetics

Answer 16

dissociate from channel with slow kinetics

Question 17

class 2 drugs effects

Answer 17

slow action potential
SA node decrease HR, increase RR

• AV node - decrease AV conducatance (increase PR)
• ventricular myocardium - decrease Ca2+ overload, prevent delayed afterdepol

Question 18

class 2 drug effects on ecg

Answer 18

decreased slope due to effects on If and T type ca chanels

increased threshold due to effect on L type Ca channels

Question 19

class 3 drugs

Answer 19

potassium channel blockers

inwardly rectifying K+ channels are open in resting state
no current in these channels
-limit frequency of AP (regulate duration of refractory period)

-prolong AP duration and QT

Question 20

class 4 drugs

Answer 20

block both activated and inactivated L type calcium channels

decrease slope of phase 0 depol

slow SA node depol
prolong AP duration and refractory period in AV node
prolong AV node conducation time

-may be effective in DAD-incuded ventricular arrhythmias