antidysrhythmias2

Question 1

2 major mechanisms antidysrhythmics

Answer 1

reentry, enhanced automaticity

Question 2

factors assoc with dysrhythmias

Answer 2

arterial hypoxia, electrolyte and acid/base balance abnormalities, myocardial ischemia, altered sympathetic activity, bradycardia, dilated cardiomyopathy, prolonged qt (acquired), r on t phenomenon

Question 3

class 1 antidysrhythmics

Answer 3

all sodium channel blockers and decrease rate phase 0 depolarization
-all depress automaticity and decrease rate of conduction

Question 4

class IA drugs

Answer 4

quinidine, procainamide, disopyramide

Question 5

class IA speed of action

Answer 5

intermediated

Question 6

class IA actions

Answer 6

depress phase 0 depolarization
prolong action potential duration
slow conduction velocity

Question 7

class IB action speed

Answer 7

most rapid binding and dissociation

Question 8

class IB drugs

Answer 8

lidocaine, mexiletine, phenytoin

Question 9

class I B action

Answer 9

shorten action potential duration,
little effect phase 0 depolarization
bind in inactive state
most effective on tacy arrhythmias

Question 10

class I C speed-

Answer 10

slowest of class I

Question 11

class I C drugs

Answer 11

flecainide

propafenone

Question 12

class I C actions

Answer 12

markedly decreased phase 0 depolarization
minimal effect on phase 0 depolarization
profoundly decreased conduction velocity
best on tachy arrhythmias

Question 13

class II drugs

Answer 13

beta blockers- propanolol, esmolol

Question 14

class II mech action

Answer 14

inhibit sympathetic activity
beta block
-decrease rate of discharge sinus and ectopic pacers and increase effective refractory period of AV node

Question 15

carvedilol

Answer 15

class II, alpha and beta block, can also block K, CA, NA current and prolong action potential duration

Question 16

class III drugs

Answer 16

amiodarone, ibutiide, sotalol (II and III)

Question 17

Class III action

Answer 17

block K channels and prolong depolarization, prolong action potential duration and prolong refractory period, prolong QT.

Question 18

Class IV drugs

Answer 18

calcium channel blockers- verapamil, diltiazem

Question 19

action class IV drugs

Answer 19

decreased conduction through SA and AV node. (negative chronotropy and dromotropy)

Question 20

procainamine treats

Answer 20

IA- treats reentry and automaticity (a tach, V tach, prolong QT, QRS and cause ST-T changes

Question 21

excretion procainamide

Answer 21

renal excretion. active metabolite- NAPA contributes to effects

Question 22

dosage procainamide

Answer 22

100mg every 5 minutes up to 15mg/kg

Question 23

lidocain treats

Answer 23

(IB) reentry- vent. dysrythmias, pvcs, v tach

Question 24

metabolism lidocaine

Answer 24

hepatic metabolism with active metabolities

Question 25

side effects lidocaine

Answer 25

seizures with plasma conc>5mcg/ml, cns depression, apnea, arrest >10mcg/ml

Question 26

dose of lidocaine

Answer 26

1-2mg/kg | infuse at 1-4mg/mmin

Question 27

phenytoin treats

Answer 27

(IB) reentry and automaticity, ventricular dysrhythmias

Question 28

metabolism phenytoin

Answer 28

hepatic metabolism 1/2 time 24 hours

Question 29

side effects phenytoin

Answer 29

ataxia, nystagmus, vertigo, slurred speech, sedation, confusion, hyperglycemia, leukopenia, thrombocytopenia

Question 30

beta blockers causes

Answer 30

(II) decreased conduction velocity, increased refractory period, increased PR duration, decreased QT duration

Question 31

Class III antidysrhythmics treats

Answer 31

reentry and automaticity SVT, a fib, VT

Question 32

amiodarone action

Answer 32

block alpha and beta, calcium and potassium blocking effects. dilates coronary arteries.

Question 33

metabolism amiodarone

Answer 33

hepatic, 1/2 time 29 days

Question 34

s/e amiodarone

Answer 34

pulmonary alveolitis, prolonged QT, bradycardia, block, decreased cardiac output, decreased vitamin K rash, cyanosis, peripheral neuropathy, weakness, increased dig level

Question 35

sotalol at high dose

Answer 35

prolongs action potential all tissues

Question 36

sotalol at low doses

Answer 36

nonselective beta antagonist

Question 37

dig what treats

Answer 37

a tach, heart failure

Question 38

digoxin mech action

Answer 38

+ inotrope- inhibits sodium potassium atpase ion transport system. slow conduction through AV node, increase stroke volume, decrease LV end diastolic pressure, positive lusitrope, negative chronotrope, enhance conduction

Question 39

s/s hypokalemia induced dig toxicity

Answer 39

anorexia, nausea, vomiting, pain, prolonged PR, degrading block, a tach, v fib