Antiarrhythmics Flashcards
(291 cards)
1
Q
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?
A
slower
2
Q
Class 1 drugs are good for what 2 SVTs? (AF, W)
A
A fib, WPW (reentry tachycardia)
3
Q
Do class 1 work on cardiac or nodal APs?
A
cardiac
4
Q
where in the heart do class 1C meds shorten the AP? (PF)
A
purkinje fibers
5
Q
Class 2 drugs decrease the spontaneous rate of what phase in what cell’s AP?
A
phase 4 in nodal cells
6
Q
Class 2: decreasing rise of phase 4 decreases the firing frequency of what and slows the conduction thru where?
A
SA node firing, conduction thru AV node
7
Q
Is the DOA of the cardiac AP in ventricular myocardium (cardiac cells) altered by class 2 drugs?
A
no
8
Q
class 2: slowing the conduction speed of the cardiac impulses thru atrial tissues results in prolongation of what interval?
A
PR interval
9
Q
class 2 drugs are good for supraventricular and ventricular arrhythmias. Name the 2 SVTs and the 1 VT.
A
a fib, a flutter, V tach
10
Q
sympathetic stimulation increases the slope of what phase, which hits threshold sooner causing more frequent depolarization and HR
A
nodal phase 4
11
Q
by decreasing phase 4 slope, class 2 meds causes the nodal cell to reach what longer and thus decreases HR?
A
threshold
12
Q
drug induced slowing of HR by class 2 meds results in a decrease in myocardial O2 requirements, which is desirable for pts with what?
A
CAD
13
Q
class 2 meds may be important in suppressing ventricular arrhythmia during myocardial what and what? (I,R)
A
ischemia, reperfusion
14
Q
class 2 drugs are effective in decreasing what 2 things related to arrhythmias? (M,M)
A
mortality, morbidity
15
Q
class 3 meds block what phase in what cells?
A
phase 3 in cardiac cells
16
Q
what 3 things do class 3s increase? (E, A, TBCD)
A
ERP, AP duration, and time between cardiac depolarization
17
Q
class 3s prevent cardiac arrythmias by decreasing the portion of the cardiac cycle during which the myocardial cells are what? (E)
A
excitable
18
Q
by decreasing the portion of the cardiac cycle that myocardial cells are excitable, class 3 meds make them less susceptible to what? (TE)
A
triggering event
19
Q
phase 3 of the myocardial cells corresponds to what interval on the ECG
A
QT
20
Q
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
A
QT interval, effective refractory period
21
Q
what type of tachycardias may class 3 drugs suppress if the AP duration becomes longer than the cycle length of the tachycardia circuit? (R)
A
reentrant tachycardias
22
Q
by elongating the QT interval, class 3s put the heart at risk for what rhythm?
A
Torsade’s
23
Q
why shouldn’t pts with prolonged QT intervals be given class 3 meds?
A
increases the risk of torsades
24
Q
torsades can deteriorate to which rhythm?
A
V fib
25
class 4 meds are useful in the treatment of what 2 arrhythmia?
Supraventricular and idiopathic ventricular tachycardia
26
what channel does class 4 drugs block?
calcium
27
class 4 meds reduce the slope in what 2 phases in nodal cells?
phase 4 and phase 0
28
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
29
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
30
do nondihydropyridine or dihydrpyridine CCBs work on the SA and AV node?
nondihydropyridine
31
do nondihydropyridine or dihydrpyridine CCBs work on blood vessels?
dihydropyridine
32
do class 3 or class 4 drugs do a better job treating V tach?
class 3
33
do class 1 and 3 drugs work on cardiac or nodal APs?
cardiac
34
do class 2 and class 4 drugs work on cardiac or nodal APs?
nodal
35
proarrhythmic effects are bradyarrhythmias or tachyarrhythmias that represent a new cardiac arrhythmia associated with what therapy? (A)
antiarrhythmic therapy
36
what is the most common proarrhythmic effect rhythm?
Torsades
37
torsades is triggered by an early depolarization in a setting where what 2 things are delayed?
repolarization, ERP
38
what interval is prolonged for torsades to occur?
QTc interval
39
what two med classes increase the QTc interval and thus make the heart prone to torsades?
class 1A and class 3
40
incessant ventricular tachycardias (reentry arrythmias) are caused by meds that hasten or slow the conduction of cardiac impulses?
slow
41
what 2 med classes cause incessant ventricular tachycardias?
class 1A and 1C
42
class 1A and 1C can slow the conduction of cardiac impulses long enough to create a continuous what? (VTC)
ventricular tachycardia circuit
43
AKA for a continuous ventricular tachycardia circuit? (R)
reentry
44
what med class can cause wide complex ventricular rhythms in the setting of structural heart disease?
class 1c
45
wide complex ventricular rhythm reflects a what tachycardia and easily degenerates to what rhythm?
reentrant tachycardia, V fib
46
pts taking what drug class experience a higher incidence of sudden cardiac arrest d/t arrhythmic effects?
class 1c
47
what 2 drug classes increase mortality in pts with previous MI and ventricular arrhythmia?
class 1a and class 1c
48
what 1 drug and 1 drug class decrease mortality in pts with previous MI and ventricular arrhythmia?
amiodarone, beta blockers
49
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
50
what is the drug of choice for pts in torsades?
mg
51
what med can be sued solo or in adjunct with an ICD for the treatment of pts with arrythmias d/t heart failure?
amiodarone
52
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
53
what med class is quinidine?
class 1a
54
quinidine is used for supraventricular or ventricular arrythmias?
supraventricular
55
quinidine prevents the recurrence of what tachyarrhythmia?
supraventricular
56
quinidine suppresses what ventricular contractions? (P)
premature ventricular conctractions
57
quinidine slows ventricular rate in the presence of what rhythm?
a fib
58
quinidine can possibly convert which rhythm to NSR?
a fib
59
quinidine can suppress SVTs associated with what syndrome?
Wolf-Parkinson-White
60
quinidine decreases the slope of what phase in nodal AP?
phase 4
61
quinidine increases fibrillation threshold in what 2 areas?
atria and ventricles
62
quinidine stops reentry arrythmias by doing what to the conduction of cardiac impulses in the area of injury? (P)
prolonging conduction of cardiac impulses
63
quinidine is eliminated by the liver how? (H)
hydroxylation
64
what 3 reasons is quinidine rarely used? (S, LTI, NA)
SEs, low TI, newer agents
65
quinidine do not use in pts with preexisting what 2 things?
heart block, prolonged QTc
66
quinidine may cause HR increase by what 2 actions? (AA, RSA)
anticholinergic action, reflex SNS activity increase
67
quinidine also has what blocking properties that can be an additive matter with vasodilating drugs?
alpha blocking
68
quinidine may increase or decrease the effects of NMBs?
increase
69
quinidine has a low TI with what 3 AEs? (HB, H, P?
heart block, hypotension, proarrythmic
70
what med class is procainamide?
class 1a
71
procainamide effective at treating what type of tachyarrhythmias, but less effective at treating what type of tachyarrhythmias?
ventricular, atrial
72
procainamide effective at treating what 2 rhythms?
PVCs, paroxysmal VT
73
procainamide is the analogue of which LA?
procaine
74
does procainamide or quinidine prolong the QTc interval more?
quinidine
75
does procainamide have vaoglytic effects?
no
76
since no vagolytic effects procainamide can be used in pts with A fib to suppress ventricular irritability without increasing what? (VR)
ventricular rate
77
what is procainamide's cardio active metabolite? (N)
N-acetyl-procainamide (NAPA)
78
N-acetyl-procainamide (NAPA) can build up and reach dangerous levels in what pts?
renal failure pts
79
procainamide not used as much because of what profile?
SE profile
80
SE of procainamide: causes what d/t direct myocardial depression? (H)
hypotension
81
SE of procainamide: causes what in the presence of a heart block?
V fib and asystole
82
SE of procainamide: causes a syndrome that resembles what with chronic use?
SLE
83
Procainamide may prolong what and cause what wave changes?
prolong QRS, ST-T wave changes
84
what class of med is disopyramide
class 1a
85
disopyramide is comparable to what other med in effectively suppressing atrial and ventricular tachyarrhythmias
quinidine
86
disopyramide's elimination is prolonged if what organ is dysfunctioning
kidneys
87
disopyramide has what SEs from its anticholinergic activity (DM, UH)
dry mouth, urinary hesitancy
88
what med class is moricizine
class 1a
89
what class 1 drug is reserved for treatment of life-threatening ventricular arrhythmias when other meds are not available? (M)
moricizine
90
what class is lidocaine?
class 1b
91
Does lidocaine principally suppress ventricular or supraventricular arrhythmias?
ventricular
92
in one word, how does lidocaine effect supraventricular arrhythmias? (M)
minimally
93
lidocaine delays the rate of spontaneous depolarization of what phase in ventricular cardiac cells?
phase 4
94
lidocaine delays the rate of spontaneous depolarization in ventricular cardiac cells by preventing the decrease of what ion permeability?
potassium
95
lidocaine is effective at suppressing what type of cardiac arrhythmias such as PVCs and VT?
reentry cardiac arrhythmias
96
What is bolus dose of lidocaine (mg/kg)? What is continuous infusion after the bolus (mg/min)?
2 mg/kg; 1-4 mg/min
97
What are the 4 advantages of lidocaine over quinidine and procainamide? (RO, RO, GTI, LSE)
rapid onset, rapid offset, greater TI, less SEs
98
where is lidocaine metabolized?
liver
99
lidocaine's metabolites may possess what type of cardiac activity? (A)
antiarrhythmic
100
lidocaine may also block ATP-dependent channels preventing ischemia-mediated shortening of ventricular what? (D)
depolarization
101
decrease lidocaine dose in pts with what 2 heart conditions?
acute MI, CHF
102
decrease lidocaine dose in pts with decreases in what two blood flows situations?
decreased CO, decrease hepatic BF
103
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
104
at hi doses, lidocaine can decrease conduction in what 2 places?
AV node, purkinje fibers
105
Unlike quinidine and procainamide, lidocaine does not alter the duration of what or the activity of what system?
QRS complex, SNS
106
At what plasma concentration does lidocaine not have effects on ECG, CV system or CNS?
<5 mcg/mL
107
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
108
what 3 lidocaine toxicity effects are seen at plasma concentrations of >10 mcg/mL? (CD, A, CA)
CNS depression, apnea, cardiac arrest
109
Decreased convulsion threshold related to lidocaine toxicity in what 3 conditions? (H, H, A)
hypoxemia, hyperkalemia, acidosis
110
Mexiletine is what class of drug?
class 1b
111
Mexiletine and tocainide are oral analogues of what drug?
lidocaine
112
Mexiletine is used for chronic suppression of ventricular or supraventricular tachyarrhythmias?
ventricular
113
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
114
Mexiletine has an amine side group allowing it to avoid significant what? (part of metabolism)
liver first pass effect
115
does lidocaine have this amine side group that Mexiletine has to avoid a significant first pass effect?
no
116
what class is phenytoin?
class 1b
117
phenytoin is useful in treating VT or torsades that is associated with what type of heart rhythm?
prolonged QTc interval
118
is phenytoin effective at treating atrial tachyarrhythmias?
no
119
what is the dose of IV phenytoin that is administered every 5 minutes until the arrhythmia is controlled? (mg/kg)
1.5 mg/kg
120
phenytoin is administered at a dose of 1.5 mg/kg every 5 minutes until what dose range is administered? (mg/kg)
10-15 mg/kg
121
phenytoin's effects on automaticity and conduction velocity of cardiac impulses resembles what other drug?
lidocaine
122
what does phenytoin shorten more than any other antiarrhythmic drug?
QTc interval
123
what 2 parts of the heart rhythm does phenytoin not effet?
QRS complex, ST-T waves
124
Does phenytoin depress the myocardium?
no
125
phenytoin improved conduction in what node?
AV node
126
phenytoin depresses activity in what node?
SA node
127
phenytoin metabolism: phenytoin is what (H) and then conjugated with what (GA) for excretion in the urine
hydroxylated, glucuronic acid
128
phenytoin blood levels may be increased in what organ dysfunction?
liver
129
what are the 3 phenytoin SEs? (H, BMD, PIIS)
hypotension, bone marrow depression, partially inhibits insulin secretion
130
with its effect on the pancreas, does phenytoin increase or decrease blood glucose?
increases blood glucose
131
phenytoin toxicity manifests as what disturbances and especially in what area?
CNS disturbances; especially cerebellar
132
what are the 6 CNS disturbances of phenytoin toxicity? (A, N, V, SS, MS, C)
ataxia, nystagmus, vertigo, slurred speech, mental sedation, confusion
133
what does phenytoin suppress with digitalis toxicity?
ventricular arrhythmias
134
do you use D5W or NS with phenytoin?
NS
135
what class of med is flecainide?
class 1c
136
flecainide is a fluorinated LA analogue of what med? (P)
procainamide
137
flecainide is more effective than quinidine and disopyramide at suppressing what 2 rhythms?
PVCs, VT
138
flecainide is effective in treating what type of tachyarrhythmias?
atrial tachyarrhythmias
139
Because flecainide delays conduction in the bypass tracts, flecainide can treat what mechanism of arrhythmias? (R)
reentry mechanism arrhythmias
140
flecainide can treat the reentry mechanism of what syndrome?
Wolff-Parkinson-White syndrome
141
flecainide is reserved for treatment of what arrhythmias? (LT)
life-threatening arrhythmias
142
flecainide elimination is decreased in pts with what 2 conditions?
CHF, renal failure
143
flecainide increases the plasma concentration of what 2 drugs? (D, P)
digoxin, propranolol
144
flecainide SEs: in one word, describe its negative inotropic effects. (M)
moderate
145
does flecainide increase or decrease pacemaker capture threshold?
increase
146
flecainide depresses what nodes function?
SA node
147
does flecainide have proarrhythmic effects?
yes
148
what drug class is propafenone?
class 1c
149
Is propafenone an effective oral antiarrhythmic for suppression of ventricular tachyarrhythmias, atrial tachyarrhythmias or both?
both
150
propafenone possesses weak blocking of what other channels?
beta, calcium
151
where is propafenone extensively metabolized?
liver
152
Does propafenone have principally active metabolites?
yes
153
how potent is propafenone's active metabolites?
equal potent to the parent drug
154
what are the 2 slowing SEs of propafenone? (MD, SANS)
myocardial depression, SA node slowing
155
what are the 2 blocking SEs of propafenone involving the heart?
AV node block, BBB
156
propafenone interferes with the metabolism of what 3 meds causing their plasma concentrations to increase? (P, M, W)
propranolol, metoprolol, warfarin
157
propafenone is especially a proarrhythmic in pts in what sustained rhythm and with what condition?
sustained VT, poor LV function
158
Beta blockers are what class?
class 2
159
Class 2 meds are effective at treating cardiac arrhythmias related to enhanced activity of what?
SNS
160
class 2 meds can be used control ventricular response in what 2 rhythms?
a fib, a flutter
161
what are the 4 class 2 meds? (MAPE)
metoprolol, acebutolol, propranolol, esmolol
162
what is the mg range of IV metoprolol to give over 20 minutes?
5-15 mg
163
how many hours (range) does 5-15 mg of IV metoprolol given over 20 minutes?
5-7 hours
164
what class 2 med is effective in treating frequent PVCs?
acebutolol
165
what class 2 med may be effective in controlling torsades in pts with a prolonged QTc interval?
propanolol
166
what 3 class 2 meds are approved for preventing of sudden death following MI?
metoprolol, acebutolol, propranolol
167
class 2 meds decrease the depolarization rate in what phase in nodal cells?
phase 4
168
class 2 meds decrease conduction in what 2 sites of the heart?
SA node, AV node
169
Do class 2 meds shorten or prolong the PR interval?
prolong
170
do class 2 meds have a lot or little effect on the ST-T wave?
little
171
do class 2 meds shorten or prolong overall QTc interval?
shorten
172
what are the 4 SEs of class 2 drugs related to inhibiting SNS? (B, H, MD, B)
bradycardia, hypotension, myocardial depression, bronchospasm
173
What are the 2 most common CNS SEs of class 2 meds? (MD, F)
mental depression, fatigue
174
class 2 meds make what disease worse?
raynaud disease
175
do class 2 meds make extremities warm or cold?
cold extremities
176
class 2 meds interfere with glucose metabolism resulting in hyperglycemia or hypoglycemia in DM pts?
hypoglycemia
177
Chronic use of class 2 meds cause a downregulation or upregulation of beta receptors?
upregulation of receptors
178
pts taking class 2 meds will be unresponsive to what med that is used to treat low HR or BP? (E)
ephedrine
179
Upregulation of beta receptors with chronic class 2 med use can lead to what type of rhythm with abrupt discontinuation?
supraventricular tachycardias
180
class 2 meds have depressant effects on myocardium d/t what blockade and what direct effects on the cardiac muscle
beta blockade, depressant effects
181
what drug class is amiodarone?
class 3
182
what 4 places does amiodarone block?
potassium channels, calcium channels, beta receptors, sodium channels
183
amiodarone potent against what 2 tachyarrhythmias? (RS, V)
refractory supraventricular tachyarrhythmias, ventricular tachyarrhythmias
184
what is the IV dose (mg) of amiodarone for VT or V fib resistant to defibrillation?
300 mg
185
amiodarone is effective in suppressing tachyarrhythmias associated with what?
WPW syndrome
186
what is the PO maintenance dose (mg) of amiodarone of ventricular tachyarrhythmias?
400 mg
187
what is the PO maintenance dose (mg) of amiodarone for suppression of supraventricular tachyarrhythmias?
200 mg
188
what is the IV dose (mg/kg) of amiodarone that is administered over 2-5 min?
5 mg/kg
189
amiodarone decreases mortality after what similar to beta blockers?
MI
190
preop oral amiodarone decreases the incidence of what rhythm after cardiac surgery?
A fib
191
after initiation of oral therapy, amiodarone decreases in ventricular tachyarrhythmias within how many hours?
72 hours
192
amiodarone prolongs what in all cardiac tissues?
ERP
193
is amiodarone a major or minor negative inotrope?
minor
194
amiodarone is a minor negative inotrope that may be offset by its potent what properties?
vasodilating
195
amiodarone: competitive or noncompetitive blockade of alpha/beta receptors?
noncompetitive blockade
196
amiodarone: constricts or dilates coronary arteries and increases or decreases coronary BF
dilates, increases
197
amiodarone: small or large Vd?
large
198
amiodarone: elimination half-life is how many days?
29 days
199
amiodarone: chronic oral therapy results in effects up to how many days after discontinuation?
60 days
200
amiodarone: minimal or extensive protein binding?
extensive
201
amiodarone has extensive protein binding making it not easily removed by what?
HD
202
amiodarone displaces what drug from protein-binding sites?
digoxin
203
what is the active metabolite of amiodarone that accumulates with chronic therapy? (D)
desethylamiodarone
204
Desethylamiodarone is active or inactive and has a shorter or longer elimination half life than amiodarone?
active; longer elimination half life
205
amiodarone inhibits P450 resulting in increased plasma concentrations of what 6 drugs? (D, P, Q, W, P, C)
digoxin, procainamide, quinidine, warfarin, phenytoin, cyclosporine
206
amiodarone potentiates warfarin by depressing clotting factors dependent on what?
vitamin K
207
amiodarone SEs are especially seen if daily maintenance dose is > how many mg?
>400 mg
208
what is the most serious SE of amiodarone?
pulmonary toxicity (alveolitis)
209
what can you consider restricting in pts who are on amiodarone?
oxygen
210
how does restricting oxygen in pts on amiodarone help with pulmonary toxicity?
decreases production of free oxygen radicals
211
what 2 tests a pt a on amiodarone have before GA?
PFTs, chest x ray
212
pts with preexisting amiodarone induced pum toxicity are at an increased risk of developing what postop?
ARDS
213
acute onset of pulm toxicity is manifested as how postop?
pulm edema
214
what other test is recommended for pts on amiodarone?
liver function tests
215
amiodarone increases what enzyme concentration and what liver infiltration?
transaminase, fatty liver infiltration
216
where can microdeposits occur in pts on amiodarone?
cornea
217
amiodarone can cause neuropathy where resulting in a mild degree of visual loss?
optic neuropathy
218
amiodarone can cause neurologic toxicity resulting in what 5 symptoms? (PN, T, SD, HA, PSMW)
peripheral neuropathy, tremors, sleep disturbances, HA, proximal skeletal muscle weakness
219
what does amiodarone contain that can affect thyroid metabolism?
iodine
220
what level should be checked to ensure amiodarone hasn't caused hypo or hyperthyroidism?
TSH
221
amiodarone causes a block at what node?
AV node
222
amiodarone prolongs what interval?
QTc
223
because amiodarone prolongs QTc, there is an increased risk of what type of tachyarrhythmias?
VTs (including torsades)
224
amiodarone decreases HR with a resistance to what med? (A)
atropine
225
amiodarone causes a decrease responsiveness to SNS d/t blocking what 2 receptors?
alpha and beta
226
amiodarone's negative inotropic effects enhanced by what 3 types of meds? (G, B, C)
GA, beta blockers, CCBs
227
amiodarone can accentuate the effects of lidocaine which can increase the likelihood of what condition?
sinus arrest
228
chronic amiodarone pts may need what intervention and/or what medication intraop? (TAP, I)
temporary artificial pacemaker; isoproterenol
229
what class is dronedarone?
class 3
230
dronedarone is a derivative of what med?
amiodarone
231
dronedarone is recommended for treatment of A fib/flutter in pts who will be undergoing drug therapy/cardioversion to get them back to what rhythm or in pts who are already in what rhythm?
NSR; NSR
232
dronedarone is contraindicated for pts with what 2 conditions? (AHF, PAF)
advanced heart failure, permanent atrial fibrillation
233
dronedarone blocks multiple sites like amiodarone, but is stronger at blocking which 2?
Na channels, adrenergic receptors
234
dronedarone is a moderate inhibitor of CYP3A4 so avoid with what 3 meds? (A, MA, PIs)
antifungals, macrolide abx, protease inhibitors
235
lower dose of dronedarone with verapamil and diltiazem to avoid what 2 things? (SB, CB)
severe bradycardia, conduction block
236
what are the 2 most common SEs of dronedarone? (N, D)
nausea, diarrhea
237
in the ATHENA trial, pts on dronedarone did not have increased rates of what 3 things? (ILD, H, H)
interstitial lung disease, hypothyroidism, hyperthyroidism
238
what drug class is sotalol?
class 3
239
what type of blocker is sotalol? (acting, selectivity, receptor)
long-acting, noncardioselective beta blocker
240
how does sotalol act at low dosages?
like a nonselective beta blocker
241
at higher dosages, sotalol prolongs the cardiac AP in what 3 areas of the heart? (A, V, ABT)
atria, ventricles, accessory bypass tract
242
sotalol can treat what 2 sustained rhythms as well as what type of rhythm after cardiac surgery?
V Tach, V Fib; atrial tachyarrhythmia (A fib)
243
sotalol is not recommended in pts with what 3 conditions? (A, LVD, CCA)
asthma, LV dysfunction, cardiac conduction abnormalities (including prolonged QTc)
244
what is the most dangerous SE of sotalol?
Torsades
245
what organ excretes sotalol?
kidneys
246
should sotalol dose be adjusted for renal disease?
yes
247
which sotalol isomer is the beta antagonist?
L isomer
248
which sotalol isomer may increase mortality in pts with ventricular dysfunction and recent MI?
D isomer
249
What drug class is ibutilide, dofetilide and bretylium?
class 3
250
ibutilide is able to convert a recent onset of what 2 rhythms to NSR?
a fib, a flutter
251
what is rhythm SE of ibutilide?
polymorphic VT
252
Dofetilide is a potent, pure blocker of what channel?
potassium
253
Dofetilide prolongs the AP duration increasing what interval?
QT interval
254
Dofetilide is effective in converting pts to NSR who recently onset into what 2 rhythms?
A fib, A flutter
255
Dofetilide is also effective at maintaining NSR in pts who have been successfully what?
cardioverted
256
Dofetilide's dose should be adjusted if which organ isn't functioning?
kidneys
257
proarrhythmic effects occur if Dofetilide is administered with which other drug type?
CCBs
258
Dofetilide can cause dose-related Torsades in pts with preexisting what dysfunction?
LV dysfunction
259
does Dofetilide depress myocardial contractility?
no
260
Verapamil is effective at treating what 2 arrhythmias? (PST, RT)
paroxysmal SVT, reentry tachycardia (usually including the AV node)
261
What med effective controls ventricular rate in pts who develop A fib or A flutter?
Verapamil
262
Will Verapamil slow the ventricular response with WPW syndrome?
no
263
does Verapamil depress accessory tracts?
no
264
does Verapamil have some, little, or large efficacy in ventricular ectopic beats?
little
265
what is the IV dose range (mg or mcg/kg) of Verapamil given over 1-3 min followed by a continuous infusion of what rate (mcg/kg/min)?
5-10 mg or 75-150 mcg/kg; 5mcg/kg/min
266
What is the antiarrhythmic IV dose (mg) of diltiazem?
20 mg
267
Digoxin plays a role in what pt population? (CLOCHF)
chronic, low output CHF
268
Digoxin is a positive inotrope by increasing what intracellularly?
Ca
269
what does Digoxin inhibit to increase intracellular Na?
Na/K ATPase pump
270
what does this increased intracellular Na that Digoxin caused block which increases intracellular Ca?
Na/Ca exchanger
271
Digoxin decreases what 4 things in the failing heart without increasing what 1 thing? (LVP, A, WT, OC; H)
LV preload, afterload, wall tension, oxygen consumption; HR
272
in the absence of HF, Digoxin increases myocardial what?
contractility
273
Digoxin stabilizes what atrial activity thus preventing/treating atrial tachyarrhythmias?
electrical activity
274
What is Digoxin's vagolytic effect on the heart?
slowing impulse thru AV node
275
Digoxin's vagolytic effect causes what effect on ventricular response rate to a fib?
decreases it
276
What is the PO dose range (mg) of Digoxin that is divided over 12-24 hrs?
0.5 - 1 mg
277
why shouldn't Digoxin be used in WPW syndrome?
enhances conduction impulses thru accessory tracts and increases ventricular response rate
278
Digoxin toxicity can be any cardiac arrhythmia, however what is the most common one? (ATWB)
atrial tachycardia with block
279
Digoxin toxicity can be partially reversed giving what?
potassium
280
what 5 things contribute to Digoxin toxicity? (H, H, D, DSMM, RD)
hypercalcemia, hypomagnesemia, diuretics, decrease skeletal muscle mass, renal dysfunction
281
does an increased SNS from hypoxemia contribute to digoxin toxicity?
Yes
282
Adenosine slows conduction impulse thru where?
AV node
283
Adenosine is an effective alternative to CCBs for what rhythm?
paroxysmal supraventricular tachycardia (including WPW)
284
What is IV dose (mg) of Adenosine and if necessary repeat with what dose range (mg) 3 minutes later?
6 mg; 6-12 mg
285
By stimulating cardiac adenosine 1 receptors, Adenosine has what 3 effects? (increases what, shortens what, hyperpolarizes what)
increases K currents, shortens AP duration, hyperpolarizes cardiac cells
286
Adenosine decreases concentration of what, thus inhibiting L-type calcium channels?
cAMP
287
what are the 4 steps of Adenosine causing negative dromotropy?
1. decrease cAmp
2. inhibit L-type Ca channels
3. decrease Ca entry into cell
4. decrease conduction velocity in SA & AV node
288
what are the 3 steps of Adenosine causing negative chronotropy
1. inhibit pacemaker current
2. decrease slope of nodal cell phase 4
3. decrease rate of spontaneous firing
289
What is Adenosine's elimination half-time (seconds)?
10 seconds
290
What are 3 SEs of Adenosine? (FF, TAVB, B)
facial flush, transient AV block, bronchospasm
291
Adenosine is not effective in what 3 rhythms?
A fib, A flutter, VT
