pharmacological treatment of arythmias

Question 1

what class of disrythmic drugs work to inhibit the propagation of sodium in the action potential and therefore work on phase 0 of the action potential?

Answer 1

class one

Question 2

what is class 1a drug which works by preventing ventricular dysrhythmias and preventing atrial fibrillation by over stimulation of the vagus? (moderate channel blockade)

Answer 2

disopyramide (resembles quinidine)

Question 3

what is the class 1b drug which is used to treat and prevent ventricular tachycardias and fibrillation during and after a myocardial infarction? (weak channel blocker)

Answer 3

lignocaine

Question 4

what is the class 1c drug used to treat ventricular ectopic beats and prevents paroxysmal AF? (strong channel blockade)

Answer 4

flecainide

Question 5

what stage of the cardiac action potential do beta blockers work on?

Answer 5

beta blockers block depolarisation of pacemaker cells (block stage 4) also block calcium entry in stage 2

Question 6

what are the main beta blockers used to reduce mortality following an MI and prevent recurrence of tachycardias provoked by sympathetic activity?

Answer 6

atenolol, bisoprolol and sotalol

Question 7

what is the 3rd class of drugs used to treat dysrhythmias?

Answer 7

potassium channel blockers

Question 8

which phase of the AP do potassium channel blockers work on?

Answer 8

phase 3

Question 9

what is the main type of class 3 drug used?

Answer 9

Amiodarone

Question 10

what type of tachycardias is amiodarone used to treat?

Answer 10

supra ventricular tachycardias and Wolf-Parkinson-White syndrome

Question 11

what is the name of the drug which combines the properties of class 2 and 3 drugs?

Answer 11

sotalol

Question 12

what is stall used to treat?

Answer 12

supra ventricular dysrhythmias and ventricular ectopic beats

Question 13

what type of channels do class 4 drugs act on?

Answer 13

voltage gated L type calcium channels (work on phase 2 of the AP and shorten the plateau phase)

Question 14

in which areas of the heart is conduction dependant on voltage gated L type channels?

Answer 14

in the SA and AV nodes

Question 15

what happens to the force of the contraction with the use of class 4 drugs?

Answer 15

it is reduced

Question 16

what type of tachycardias are the rate-limiting calcium channel blockers used to treat?

Answer 16

supra ventricular tachycardias

Question 17

what is the main class 4 drug used?

Answer 17

Verapimil

Question 18

what class of receptors does adenosine work on in the heart?

Answer 18

G1

Question 19

what do the G1 receptors eventually trigger which causes the HR to reduce and the pacemaker ability to decrease?

Answer 19

inhibits phosphorylation of calcium channel (therefore calcium cannot enter the cell) and also activates potassium channels to move more potassium out of the cell

Question 20

what type of tachycardias is adenosine used to treat?

Answer 20

SVTs