antiarrhythmics

Question 1

class I drugs

Answer 1

sodium channel blockers
block the influx of Na+ into the cell during phase 0 of the action potential
the cells take longer to reach its threshold potential
also reduce the speed of diastolic depolarization (Phase 4)

Question 2

Class I-a drugs

Answer 2

depress phase 0 depolarization
are more cardiodepressant than class 1B or class 1C drugs

Question 3

Class I-b drugs

Answer 3

slow phase 0 depolarization
supress ventricular excitability
shorten phase 3 of AP

Question 4

Class I-c drugs

Answer 4

slow phase 0 of action potential
reduce conductivity
might lengthen refractory periods

Question 5

Class 1a antiarrhythmics

Answer 5

quinidine
procainamide (pronestyl)
disopryamide (rythmodan)
phenytoin (dilantin)

Question 6

Quinidine cardiac uses

Answer 6

SVT (e.g. a fib , a flutter, PAT)
ventricular arrhythmias (PVCs)

Question 7

Quinidine adverse effects

Answer 7

hypotension, syncope
wide QRS, prolong PR, QT intervals
VT or Torsades de pointes
AV heart block

Question 8

Important when using quinidine

Answer 8

monitor the QT interval
avoid in high degree AV block
potentiates the effect of digoxin
concurrent use with amiodarone can widen the QRS complex

Question 9

procainamide (pronestyl) cardiac uses

Answer 9

SVT (A fib, PAT)
ventricular arrhythmias (PVC, VT)

Question 10

procainamide adverse cardiac effects

Answer 10

hypotention
bradycardia, AV heart block
VT, Torsade de pointes, VF, asystole

Question 11

important points using procainamide

Answer 11

monitor QT interval
avoid in high degree AV block
potentiates the effect of digoxin
conceurrent use with amiodarone can cause procainamide toxicity
concurrent use with beta blockers potentiates the cardiac depressant effect

Question 12

d/c IV procainamide if one of the four following

Answer 12

• the arrhythmia is supressed
  QRS widens by 50% of its original width
  hypotension
  a total of 500 mg administered

Question 13

e.g. of Class 1b drugs

Answer 13

lidocaine
tocainide (tonocard)
mexiletine (mexitil)

Question 14

lidocaine’s half life is ____, so to maintain serum levels and ____

Answer 14

short
IV bolus after maintenance infusion

Question 15

NEVE administer lidocaine to control

Answer 15

symptomatic IVR,
it would suppress the heart’s only pacemaker

Question 16

Tocainide use cautiously with

Answer 16

beta blockers
in the presence of heart failure

Question 17

avoid use of tocainide with

Answer 17

known sensitivity to local amide-type anesthetics (e.g. lidocaine)

Question 18

class Ic drugs (e.g.)

Answer 18

flecainide (tambocor)
propafenone (rythmol)
moricizine( ethmozine)

Question 19

flecainide should be avoided

Answer 19

following recent MI
high degree AV blocks, chronic A. Fib
known heart failure

Question 20

concurrent use of flecainide with ___ may potentiate the action of both drugs

Answer 20

beta blockers

Question 21

Propafenone (rythmol) avoid use with

Answer 21

AV blockers, BBBB
hypotension, heart failutre

Question 22

concurrent use with quinidine cans______

Answer 22

slow the metabolism of propafenone

Question 23

propafenone may potentiate the action of

Answer 23

beta blockers
warfarin

Question 24

propafenone with permanent pacemaker

Answer 24

reassess thresholds

Question 25

CLASS II (beta-blockers, -lol)

Answer 25

impede catecholamine stimulation
lower BP, HR, speed of conduction, contractility

Question 26

2 common use of beta blockers

Answer 26

HTN
long term management of agina pectoris

Question 27

side effects of beta blockers

Answer 27

dyspnea, cough bronchospasm
heart failure, palpitations, hypotension, syncope
AV heart block, bradycardia, sinus arrest

Question 28

beta blockers use caution with

Answer 28

asthmatics and patents with bronchospastic disease

Question 29

beta blockers mask signs of

Answer 29

hypoglycaemia, use cautiously in diabetics

Question 30

atenolol concurrent use with ____ increase the risk of heart failure, bradycardia, heart block

Answer 30

calcium channel blockers

Question 31

to manage HTN, atenolol is often use with _____

Answer 31

thiazide diuretic therapy

Question 32

metoprolol can enhance the effects of class __ antiarrhythmics

Answer 32

1a

Question 33

avoid use of sotalol with

Answer 33

prolong QT interval
hypokalemia, potassium depleting diuretics

Question 34

class III antiarrhythmics

Answer 34

potassium channel blockers affect repolarization
lengthen the AP
e.g. amiodarone

Question 35

cardiac use of amiodarone

Answer 35

SVT, tachycardia secondary to Wolff-Parkinson-White syndrome
life-threatening arrhythmias (VT, VF)

Question 36

oral amiodarone used with IV administration b/c

Answer 36

oral amiodarone has a long half life of 45 days

Question 37

adverse effects of amiodarone

Answer 37

can increase resistance to cardioversion
pulmonary toxicity

Question 38

amiodarone interacts with ___
monitor

Answer 38

warfarin
PT and INR

Question 39

amiodarone is contraindicated in patients with

Answer 39

acute hepatitis

Question 40

_____ commonly occur with use of amiodarone

Answer 40

photosensitivity and corneal deposits

Question 41

class IV antiarrhythmics

Answer 41

calcium channel blockers
depress phases 2 and 3 of the action potential
can interrupt circus movements in tachy caused by AV nodal reentry
e.g. verapamil
diltiazem

Question 42

avoid calcium channel blockers with

Answer 42

beta blockers
contraindicated in acute MI, advanced HF, pulmonary edema, hypotension, cardiogenic shock, AV block

Question 43

adenosine

Answer 43

produces transient AV node block and interrupts reentry pathways
very short half life (10 second)
most patients develop a short-lived (<10 seconds) sinister rhythm e.g. asystole or 3 av block

Question 44

atropine

Answer 44

sympathetic nervous sytem to gaind control

Question 45

epinephrine
avoid use

Answer 45

patient with sulfite allergies
incompatible with alkaline solution (e.g. sodium bicarb)

Question 46

digoxin strengthens

Answer 46

myocardial contractility

Question 47

d/c digoxin ___ pre cardioversion

Answer 47

48 hours

Question 48

avoid use of digoxin in

Answer 48

wolff-parkinson -white syndrome, AV block, VT

Question 49

magnesium sulfate ___ muscle cell excitability

Answer 49

decreases

Question 50

use magnesium sulfate cautiously with

Answer 50

renal disease

Question 51

______ conteracts magnesium toxicity

Answer 51

calcium