Antiarrhythmics Flashcards
which class of drugs decreases cardiac automaticity?
B-blockers
which class of drugs decreases AV conduction?
Ca channel blockers
natural pacemaker in the heart
SA node
Fast AP occurs in … and …
purkinje fibers and muscle fibers
the … is determined by the steepness of phase 0
conduction velocity (Vmax)
phase 2 also constitutes the … during which another impulse cannot be generated
effective refractory period
the steeper the slope of phase 4, the higher the rate of …
automaticity
… is the time that the cell is depolarized
action potential duration
… protects heart against arrhythmias
effective refractory period
slow AP occurs in … and …
SA and AV nodes
increased/decreased SA node firing
altered automaticity
abnormal generation of impulses; spontaneous depolarization in another portion of heart leading to generation of AP
ectopic pacemaker
a unidirectional conduction block
reentrant arrhythmia
Class IA: Na channel blockers
disopryamide, quinidine, procainamide
Class IA blockers are most effective with …
atrial arrhythmias
IA blockers are myocardial depressants that reduce … and … and increase …
reduce automaticity and responsiveness (Vmax) and increase ERP
most important Class IA Na channel blocker
disopryamide
Class IA Na channel blockers block … and inhibit rabid inward Na current
rapid Na channels
Class IA Na channel blockers slow … thereby abolishing ectopic foci
phase 4 depolarization (decreases automaticity)
Class IA Na channel blockers depress … in slow and fact action potentials
the rate of phase 0 depolarization
side effects of which drug?: anticholinergic action (urinary retention, dryness of mouth, constipation); generalized cardiac depression; reduction in myocardial contractility
disopyramide
which class IA Na channel blocker?: IV administration only
procainamide
Class IB Na channel blockers
lidocaine and mexiletine
Class IB Na channel blocker used for ventricular arrhythmias in ICUs that arise from myocardial infarctions or digitalis toxicity
lidocaine
lidocaine is effective only on … and is not effective in the treatment of atrial arrhythmias
ventricular arrhythmias
Lidocaine will suppress ventricular ectopic foci and will decrease … by decreasing slope of phase 4
automaticity of purkinje fibers
lidocaine shortens duration of … and …
AP and ERP
Class IC Na channel blockers
flecainide and propafenone
Class IC Na channel blockers used for ventricular arrhythmias
propafenone
Class II B1 Blockers
metoprolol, acebutolol, esmolol, propranolol
B-blockers are utilized to treat:
arrhythmias (heart rate)
B1 blockers are used primarily with …
atrial arrhythmias
Bl blockers reduce … by slowing the transmission of impulses through the AV node
ventricular rate
B blockers will decrease … of discharge and the conduction velocity
the SA node rate
primary effect of B blockers is to decrease rate of conduction through … (increases ERP)
the AV node
B-blockers and … slow conduction through AV node
verapamil
Class III K channel blockers
amiodarone, sotalol, dofetilide, ibutilide
K channel blockers prolong the AP and ERP of …
purkinje and muscle fibers
what has replaced lidocaine as drug of choice in cardiac resuscitation?
IV amiodarone
Unlike amiodarone and sotolol, … and … are “pure” class III with no Class I, II or IV activity
ibutilide and dofetilide
Class IV Ca channel blockers
verapamil and diltiazem
Ca channel blockers used to treat …
atrial arrhythmias
verapamil is used to reduce ventricular response to atrial flutter or fibrillation by slowing … through AV node
conduction
Verapamil will depress …
Ca dependent action potentials
the key effect of verapamil is to … conduction velocity through the AV node
depress
Verapamil will also slow … of SA and AV nodes
slow pacemaker activity (automaticity)
both verapamil and diltiazem reduce
HR, SA node automaticity, AV conduction, myocardial contractility
side effects of which class?: severe bradycardia stemming from AV block, depressive effect on myocardial contractility, contraindicated in patients with sick sinus syndrome, AV block and CHF
Class IV Ca channel blockers
verapamil and … together may cause AV block
Bl Blockers
verapamil can increase blood levels of …
digoxin
Adenosine is a
Ca blocker
elimination half life of amiodarone is …
25 to 100 days
digoxin useful for atrial …, … or … because it slows conduction through AV node
tachycardia, flutter or fibrillation
MoA: digoxin inhibits … and increases intracellular Ca concentration
Na/K ATPase
Digitalis increases …
cardiac contractility
direct effects of digoxin on AV node: will have increased … and decreased conduction velocity
ERP
indirect effects of digoxin: will increase … to the heart and slow HR by increasing baroreceptor firing
the vagal activity
MoA of digoxin is increased … for muscle contraction and enhanced contractility
intracellular Ca availability
the other clinical use of digoxin is to reduce …
atrial arrhythmias
side effect of digoxin increased automaticity of purkinje fibers and elevated risk of …
ventricular arrhythmias
T1/2 of digoxin is …
1.5 days
cardiac side effects of digoxin: abnormalities in the cardiac rhythm including …, slowing of the heart rate and …
AV block
Ventricular arrhythmias
hypercalcemia will … digoxin effects
enhance
old age will … digoxin clearance
decrease
hypokalemia … sensitivity to digoxin
increases
myocardial infarction- digoxin should …
not be used