Antiarrhythmics Flashcards
Class 1 drugs cause a longer time to get thru phase 0 and longer ERP means a longer time between depolarization. This causes a faster or slower HR?
slower
Class 1 drugs are good for what 2 SVTs? (AF, W)
A fib, WPW (reentry tachycardia)
Do class 1 work on cardiac or nodal APs?
cardiac
where in the heart do class 1C meds shorten the AP? (PF)
purkinje fibers
Class 2 drugs decrease the spontaneous rate of what phase in what cell’s AP?
phase 4 in nodal cells
Class 2: decreasing rise of phase 4 decreases the firing frequency of what and slows the conduction thru where?
SA node firing, conduction thru AV node
Is the DOA of the cardiac AP in ventricular myocardium (cardiac cells) altered by class 2 drugs?
no
class 2: slowing the conduction speed of the cardiac impulses thru atrial tissues results in prolongation of what interval?
PR interval
class 2 drugs are good for supraventricular and ventricular arrhythmias. Name the 2 SVTs and the 1 VT.
a fib, a flutter, V tach
sympathetic stimulation increases the slope of what phase, which hits threshold sooner causing more frequent depolarization and HR
nodal phase 4
by decreasing phase 4 slope, class 2 meds causes the nodal cell to reach what longer and thus decreases HR?
threshold
drug induced slowing of HR by class 2 meds results in a decrease in myocardial O2 requirements, which is desirable for pts with what?
CAD
class 2 meds may be important in suppressing ventricular arrhythmia during myocardial what and what? (I,R)
ischemia, reperfusion
class 2 drugs are effective in decreasing what 2 things related to arrhythmias? (M,M)
mortality, morbidity
class 3 meds block what phase in what cells?
phase 3 in cardiac cells
what 3 things do class 3s increase? (E, A, TBCD)
ERP, AP duration, and time between cardiac depolarization
class 3s prevent cardiac arrythmias by decreasing the portion of the cardiac cycle during which the myocardial cells are what? (E)
excitable
by decreasing the portion of the cardiac cycle that myocardial cells are excitable, class 3 meds make them less susceptible to what? (TE)
triggering event
phase 3 of the myocardial cells corresponds to what interval on the ECG
QT
class 3 meds slow HR by elongating what interval in the ECG and what period in the cardiac AP, thus creating more time between depolarizations
QT interval, effective refractory period
what type of tachycardias may class 3 drugs suppress if the AP duration becomes longer than the cycle length of the tachycardia circuit? (R)
reentrant tachycardias
by elongating the QT interval, class 3s put the heart at risk for what rhythm?
Torsade’s
why shouldn’t pts with prolonged QT intervals be given class 3 meds?
increases the risk of torsades
torsades can deteriorate to which rhythm?
V fib
class 4 meds are useful in the treatment of what 2 arrhythmia?
Supraventricular and idiopathic ventricular tachycardia
what channel does class 4 drugs block?
calcium
class 4 meds reduce the slope in what 2 phases in nodal cells?
phase 4 and phase 0
by reducing the slope of phase 4 in nodal cells, CCBs decrease the rate of what (SD), which reducing the rate of pacemaker what? (F)
spontaneous depolarization, firing
by delaying the slope of phase 0, CCBs decreasing the what in the SA node (F) and slow down the conduction where?
firing, av node
do nondihydropyridine or dihydrpyridine CCBs work on the SA and AV node?
nondihydropyridine
do nondihydropyridine or dihydrpyridine CCBs work on blood vessels?
dihydropyridine
do class 3 or class 4 drugs do a better job treating V tach?
class 3
do class 1 and 3 drugs work on cardiac or nodal APs?
cardiac
do class 2 and class 4 drugs work on cardiac or nodal APs?
nodal
proarrhythmic effects are bradyarrhythmias or tachyarrhythmias that represent a new cardiac arrhythmia associated with what therapy? (A)
antiarrhythmic therapy
what is the most common proarrhythmic effect rhythm?
Torsades
torsades is triggered by an early depolarization in a setting where what 2 things are delayed?
repolarization, ERP
what interval is prolonged for torsades to occur?
QTc interval
what two med classes increase the QTc interval and thus make the heart prone to torsades?
class 1A and class 3
incessant ventricular tachycardias (reentry arrythmias) are caused by meds that hasten or slow the conduction of cardiac impulses?
slow
what 2 med classes cause incessant ventricular tachycardias?
class 1A and 1C
class 1A and 1C can slow the conduction of cardiac impulses long enough to create a continuous what? (VTC)
ventricular tachycardia circuit
AKA for a continuous ventricular tachycardia circuit? (R)
reentry
what med class can cause wide complex ventricular rhythms in the setting of structural heart disease?
class 1c
wide complex ventricular rhythm reflects a what tachycardia and easily degenerates to what rhythm?
reentrant tachycardia, V fib
pts taking what drug class experience a higher incidence of sudden cardiac arrest d/t arrhythmic effects?
class 1c
what 2 drug classes increase mortality in pts with previous MI and ventricular arrhythmia?
class 1a and class 1c
what 1 drug and 1 drug class decrease mortality in pts with previous MI and ventricular arrhythmia?
amiodarone, beta blockers
what one drug and one class of med are not longer recommended in treatment of pts with early stages of acute MI?
lidocaine, class 4
what is the drug of choice for pts in torsades?
mg
what med can be sued solo or in adjunct with an ICD for the treatment of pts with arrythmias d/t heart failure?
amiodarone
what 1 med class and 3 drugs can be used to treat A fib after heart surgery? (B, A, S, M)
beta blockers, amiodarone, sotalol, magnesium
what med class is quinidine?
class 1a
quinidine is used for supraventricular or ventricular arrythmias?
supraventricular
quinidine prevents the recurrence of what tachyarrhythmia?
supraventricular
quinidine suppresses what ventricular contractions? (P)
premature ventricular conctractions
quinidine slows ventricular rate in the presence of what rhythm?
a fib
quinidine can possibly convert which rhythm to NSR?
a fib
quinidine can suppress SVTs associated with what syndrome?
Wolf-Parkinson-White
quinidine decreases the slope of what phase in nodal AP?
phase 4
quinidine increases fibrillation threshold in what 2 areas?
atria and ventricles
quinidine stops reentry arrythmias by doing what to the conduction of cardiac impulses in the area of injury? (P)
prolonging conduction of cardiac impulses
quinidine is eliminated by the liver how? (H)
hydroxylation
what 3 reasons is quinidine rarely used? (S, LTI, NA)
SEs, low TI, newer agents
quinidine do not use in pts with preexisting what 2 things?
heart block, prolonged QTc
quinidine may cause HR increase by what 2 actions? (AA, RSA)
anticholinergic action, reflex SNS activity increase
quinidine also has what blocking properties that can be an additive matter with vasodilating drugs?
alpha blocking
quinidine may increase or decrease the effects of NMBs?
increase
quinidine has a low TI with what 3 AEs? (HB, H, P?
heart block, hypotension, proarrythmic
what med class is procainamide?
class 1a
procainamide effective at treating what type of tachyarrhythmias, but less effective at treating what type of tachyarrhythmias?
ventricular, atrial
procainamide effective at treating what 2 rhythms?
PVCs, paroxysmal VT
procainamide is the analogue of which LA?
procaine
does procainamide or quinidine prolong the QTc interval more?
quinidine
does procainamide have vaoglytic effects?
no
since no vagolytic effects procainamide can be used in pts with A fib to suppress ventricular irritability without increasing what? (VR)
ventricular rate
what is procainamide’s cardio active metabolite? (N)
N-acetyl-procainamide (NAPA)
N-acetyl-procainamide (NAPA) can build up and reach dangerous levels in what pts?
renal failure pts
procainamide not used as much because of what profile?
SE profile
SE of procainamide: causes what d/t direct myocardial depression? (H)
hypotension
SE of procainamide: causes what in the presence of a heart block?
V fib and asystole
SE of procainamide: causes a syndrome that resembles what with chronic use?
SLE
Procainamide may prolong what and cause what wave changes?
prolong QRS, ST-T wave changes
what class of med is disopyramide
class 1a
disopyramide is comparable to what other med in effectively suppressing atrial and ventricular tachyarrhythmias
quinidine
disopyramide’s elimination is prolonged if what organ is dysfunctioning
kidneys
disopyramide has what SEs from its anticholinergic activity (DM, UH)
dry mouth, urinary hesitancy
what med class is moricizine
class 1a
what class 1 drug is reserved for treatment of life-threatening ventricular arrhythmias when other meds are not available? (M)
moricizine
what class is lidocaine?
class 1b
Does lidocaine principally suppress ventricular or supraventricular arrhythmias?
ventricular
in one word, how does lidocaine effect supraventricular arrhythmias? (M)
minimally
lidocaine delays the rate of spontaneous depolarization of what phase in ventricular cardiac cells?
phase 4
lidocaine delays the rate of spontaneous depolarization in ventricular cardiac cells by preventing the decrease of what ion permeability?
potassium
lidocaine is effective at suppressing what type of cardiac arrhythmias such as PVCs and VT?
reentry cardiac arrhythmias
What is bolus dose of lidocaine (mg/kg)? What is continuous infusion after the bolus (mg/min)?
2 mg/kg; 1-4 mg/min
What are the 4 advantages of lidocaine over quinidine and procainamide? (RO, RO, GTI, LSE)
rapid onset, rapid offset, greater TI, less SEs
where is lidocaine metabolized?
liver
lidocaine’s metabolites may possess what type of cardiac activity? (A)
antiarrhythmic
lidocaine may also block ATP-dependent channels preventing ischemia-mediated shortening of ventricular what? (D)
depolarization
decrease lidocaine dose in pts with what 2 heart conditions?
acute MI, CHF
decrease lidocaine dose in pts with decreases in what two blood flows situations?
decreased CO, decrease hepatic BF
At therapeutic levels, lidocaine has no significant effects on what 2 parts of the heart rhythm and conduction where?
QRS, QTc interval; AV node conduction
at hi doses, lidocaine can decrease conduction in what 2 places?
AV node, purkinje fibers
Unlike quinidine and procainamide, lidocaine does not alter the duration of what or the activity of what system?
QRS complex, SNS
At what plasma concentration does lidocaine not have effects on ECG, CV system or CNS?
<5 mcg/mL
What 6 lidocaine toxicity effects are seen at plasma concentrations of 5-10 mcg/mL? (PV, MD, B, PPRI, WQC, S)
peripheral vasodilation, myocardial depression, bradycardia, prolonged PR interval, wide QRS complex, seizures
what 3 lidocaine toxicity effects are seen at plasma concentrations of >10 mcg/mL? (CD, A, CA)
CNS depression, apnea, cardiac arrest
Decreased convulsion threshold related to lidocaine toxicity in what 3 conditions? (H, H, A)
hypoxemia, hyperkalemia, acidosis
Mexiletine is what class of drug?
class 1b
Mexiletine and tocainide are oral analogues of what drug?
lidocaine
Mexiletine is used for chronic suppression of ventricular or supraventricular tachyarrhythmias?
ventricular
Mexiletine should be used in combo with beta blockers or other antiarrhythmic drugs for synergistic effect to decrease incidence of what at higher doses?
side effects
Mexiletine has an amine side group allowing it to avoid significant what? (part of metabolism)
liver first pass effect
does lidocaine have this amine side group that Mexiletine has to avoid a significant first pass effect?
no
what class is phenytoin?
class 1b
