Antiarrythmics Flashcards
1
Q
Conduction pathway
A
SA, atria
AV, bundle of his, bundle branches, purkinje, ventricles
2
Q
Where is SA node located
A
Right atria, posterior wall, by SVC
3
Q
Where is AV node
A
Septal wall near coronary sinuses
4
Q
Phase 0
Phase 1
A
Rapid depolarization
Partial repolarization
5
Q
Phase 2
Phase 3
A
Plateau
Repolarization
6
Q
Phase 4
Refractory period
A
Pacemaker potential
Phases 1-3
7
Q
What occurs in phase 0
A
Rapid depolarization, fast na channels open, inward Na movement
8
Q
What happens phase 1
A
Begin repolarization, na channels close
9
Q
What happens phase 2
A
Plateau, slow ca ch open, slow inward ca
10
Q
What happens phase 3
A
Repolarization, ca channels close, k channels open, slow outward k
11
Q
What happens phase 4
A
Pacemaker potential. Return to RMP
12
Q
SA node rate controlled by
A
ANS
13
Q
SNS stim
Receptors
What happens
A
B1.
Inc: catecholamines, hr (chronotropy), automaticity
Facilitation of conduction of AV node
14
Q
PNS ___
Receptors
What they do
A
Predominates
M2 muscarinic
Decreases HR, inhibits AV conduction, reduced automaticity
15
Q
Arrhythmias classified by
A
Site of origin (atrial, junctional, ventricular)
Wide or narrow ecg
Rhythm
HR inc or dec
16
Q
4 mechanisms of arrhythmia production
A
Altered automaticity
Delayed after depolarization
Re entry
Conduction block
17
Q
Altered automaticity
A
Latent pacemaker cells take over SA node role, escape beats
18
Q
Delayed after depolarization
A
Normal action potential of cardiac cell triggers abn depolarizations
19
Q
Re entry
A
Refractory tissue reactivated repeatedly and rapidly d/t unidirectional block, continuous circuit
20
Q
Conduction block
A
Impulse fail to propagate in nonconducting tissue
21
Q
Factors underlying cardiac arrhythmias
8
A
Arterial hypoxemia, electrolyte abn, acid base abn, myo ischemia, alt SNS activity, bradycardia, drugs, enlargement/failing ventricle
22
Q
When arrhythmias require tx
A
Can’t be corrected by removing cause
Hemodynamic compromise
Predisposes to more serious arrhythmias
23
Q
Non pharm prophylaxis
A
Radio frequency catheter ablation
Implantable defibrillator
24
Q
Class and phase they tx
Class I drugs
Class II
A
Na channel blockers, phase 0
BB, phase 4
25
Class and phase tx
Class III
Class IV
K ch blockers, phase 1 and 2
Ca ch blockers, phase 2
26
Class and phase tx
| V
Unclassified drugs
27
Effects of class I agents
Phase 0 depresses vmax velocity, dec in AP propagation, slows conduction velocity
28
IA agents
Dissociation
4 effects
Intermediate
| Decrease: depolarization rate phase 0, decrease conduction velocity. Prolong repolarization phase 3. Inc AP duration
29
IA drugs 3
Quinidine (prototype)
Procainamide
Disopyramide
30
Disopuramide
Indic
Route
SE
Suppresses vent tachyarrythmias. PO. Myocardial depressant, potentiates HF/hypotension. Atropine like effects.
31
IB agents
Dissociation
How they work
Fast na channel block. Alt AP by inhibit na influx, bind to na ch. little effect on max velocity, shortens ap duration and refractory period. Dec automaticity.
32
IB agents
| 4
Lidocaine (prototype)
Mexiletine
Tocainide
Phenytoin
33
Lidocaine
Class
Action
IB antiarrythmic
| Na fast ch blocker
34
Lidocaine
| Indic
Acute tx and prevention of v dysrhythmias, immeadiate aftermath of MI. V tach, v fib, pvcs
35
Lidocaine
Dose
Protein binding
1-1.5 mg/kg IV, then 1-4 mg/min gtt, max 3 mg/kg
| 50% binding
36
Lidocaine
Metabolism
Slowed by
Active metabolite prolongs 1/2t. Impaired by drugs: cimetidine, propranolol, or CHF, MI, liver dysfunc, GA.
37
Lidocaine
Metab induced by
Elim
Barbs, phenytoin, rifampin
10% renal elim
38
Lidocaine
E 1/2t
Therapeutic plasma level
2 hrs
| 1-5 mcg/ml
39
Lidocaine
| AE
Low bp and hr, seizure, drowsy, dizzy, lightheaded, tinnitus, confusion, apnea, myo, cns, and vent depression, sinus arrest, heart block, cv arrest, augment Nm blockade
40
Phenytoin
Class
Indic
IB agent
| Suppression of ventricular arrhythmias, assoc w dig toxicity (torsades)
41
Phenytoin
Give how
What happens in PIV
IV, ppt in D5W mix in NS
| Pain or thrombosis
42
IC agents
| What they do
Slow na ch blocker. Doesnt vary in cv cycle. Potent dec depolarization rate phase 0 and conduc rate w inc AP. Inhib thru his/purkinje.
43
IC agents 2
Flecainide prototype
| Propafenone
44
Flecainide
Indic
Sf
Duration
Tachyarrythmias w abn conduction pathways, WPW
Proarrythmic SE
Long acting
45
```
Propafenone
Indic
Properties
Route
SE
```
Vent and atrial tachyarrythmias.
Weak BB and ca block. PO.
Proarrythmic SE
46
Class II agents
What they are, phase
How they act
BB. Depress phase 4 depolarization, dec SA node discharge. Slows HR and dec myo 02 reqs, good for CAD. Slows AV conduc, prolongs PR. Dec automaticity.
47
Class II
| Indications
Tx SVT, atrial, and vent arrhythmias (esp post MI and reperfusion). Tx tachyarrythmias assoc w dig toxicity and SVT (afib or flutter)
48
Class II
| Prevents binding of what
Catecholamines to beta receptors
49
Class II agents
| 4
Propranolol- prototype
Metoprolol
Esmolol
Labetolol- off label use
50
Propranolol
Class
Indic
Beta adrenergic agonist, nonselective.
| Prevents reoccurrence of supra and ventricular tachyarrythmias ppt by SNS stim
51
Propranolol
| Dose
1 mg/min (total 3-6 mg) IV or 10-80 mg po
52
```
Propranolol
Onset
Peak
Duration
E 1/2
```
2-5 min
10-15 min
3-4 hrs
2-4 hrs
53
Propranolol
Protein binging
Metabolism
Therapeutic level
90-95%
Hepatic, weak metabolite
10-30 Ng/ml
54
Propranolol
Cv effects
Caution with
Bradycardia and myocardial depression
Reactive a/w disease, hypovolemia, CHF, AV block
55
Metoprolol
Class
Dose
B adrenergic antag, selec B1
| 5 mg IV over 5 min, max dose 15 mg over 20 min
56
```
Metoprolol
Onset
1/2 life
Metab
Can be used in
```
2.5 min
1/2 life 3-4 hrs
Liver
Mild CHF
57
Esmolol
Class
Dose
Beta adrenergic Antag, b1 selec
| 0.5 mg/kg iv over 1 min, then 50-300 mcg/kg/min
58
Esmolol
Duration
Effects what w/o effecting what
<15 min. Hr w/o dec bp significantly in small doses
59
Esmolol
Metab
No effect on
Hydrolyzed by plasma esterases
| Not same esterases as cholinesterase, so no effect on sux
60
Class III
| Action
Prolongs cv depolarization and inc AP duration, lengthens repolarization. Dec proportion of cycle when myo cells excitable, susceptible to triggering event
61
Class iii
| Indications
Suppressing supra and ventricular arrhythmias. Prophylaxis cv surgery for afib. Preventative for pts posT CV death not candidate for ICD. Controls rhyth afib.
62
Class iii drugs 3
Amio- prototype
Dronedarone
Sotalol
63
Amio
| Which class
III. But has I, II, and IV properties
64
Amio
| Blocks what
K, na, ca channels. Alpha and beta adrenergic antagonist
65
Amio
| Indic
Prophylaxis or tx atrial and vent arrhythmias (refractory SVT/VT/VF/AF), 1st line w VT/VF resistant to defibrillation
66
Amio
| Dose
150-300 mg iv over 2-5 min. Up to 5 mg/kg. Then 1 mg/min x.6 hrs, 0.5 mg/min 18 hrs
67
Amio
E 1/2 t
Metabolism and excretion
10-100 days (long)
Hepatic, active metabolite
Biliary and intestinal excretion
68
Amio
Therapeutic level
Protein binding
Vd
1-3.5 mcg/ml
Extensive. 96%
Large
69
Amio
| AE
Pulm toxicity/fibrosis/edema. ARDS. Photosensitive rash, grey/blue skin. Thyroid abn. Corneal deposits. CNS/GI disturb. Can cause torsades. Heart block. Low bp. Nightmares. Abn LFT. Inhibits -450
70
Sotalol
| Class
Class II and III. Nonselective beta adrenergic antag.
71
Sotalol
| Indic
Severe sustained vtach and vfib, prevents reoccurrence of tachyarrythmias, esp aflutter and Afib
72
Sotalol
SE
Cation
Excretion
Prolongs QTi, bradycardia, myoc depression, fatigue, dyspnea, AV block
Asthma pts
Urine
73
Ibutilide
Class
Indic
```
Pure class III
Conversion afib/flutter, control rate. Prolongs AP duration and increases refractory period.
```
74
Dofetilide
Class
Route
Indic
Class III. Oral. Maintenance NSR after afib or conversion.
75
Dofetilide
SE
Ok in who
Proarrythmic
| Post MI pts
76
Class IV agents
| Primary site/action
Blocks slow ca ch. primary site at AV node. Dec conduction thru AV, shortens phase 2 (plateau), of AP in ventricular myocytes. Contractility dec.
77
Class iv
Indications
Not used in
SVT, ventricular rate control in afib/aflutter.
Prevents reoccurrence SVT
Not used in ventricular arrhythmias
78
Class IV agents
| Ex
Ca ch blockers
Verapamil- prototype
Diltiazem
79
Verapamil
| Dose
2.5-10 mg iv over 1-3 min. Max dose 20 mg.
| Continuous gtt 5 mcg/kg/min
80
Verapamil
Dont use iv w/what
1/2 life
B blocker, heart block
| 6-8 hrs
81
Verapamil
Highly what
Metab
Excretion
Protein bound
Hepatic w active metabolite
Urine and bile
82
Verapamil
| SE
Myocardial depression, hypotension, constipation, bradycardia, nausea, prolongs NMB
83
Verapamil
| Caution
Myo dep and vasodil w inhalational drugs. Pot NMB. LA toxicity inc risk. Hyperkalemia w dantrolene. Dec dig clearance. Contraindication in WPW. Caution w BB
84
Dilt
Class
Dose
IV, Ca ch blocker
5-20 mg iv (0.25-0.35 mg/kg) over 2 min
Gtt 10 mg/hr
85
```
Dilt
1/2 life
Highly what
Metab
Excretion
```
4-6 hrs
Protein bound
Hepatic
Urine
86
Dilt
| SE
Myocardial depression, hypotension, constipation, bradycardia, nausea, prolongs NMB
87
Class V drugs 3
Adenosine, digoxin, atropine
88
Adenosine
| Action
Binds to A1 purine nucleotide receptors, opens K channels. Slows AV nodal conduction
89
Adenosine
| Indic `
Acute rx, terminated SVT or dx of VT
90
Adenosine
Dose
Duration
Elim
6 mg IV fast bolus. Repeat in 3 min, 6-12 mg iv
20-30 secs
Vascular endothelial enzymes
91
Adenosine
SE
Contraindicated in
AV/SA node inhib, flushing, HA, dizzy, SOB, CP, nausea, bronchospasm
Contra: asthma and heart block
92
Digoxin
What it is
Action
Cardiac glycoside
Inc vagal activity, dec SA node activity and prolongs conduction thru AV node. Dec HR, preload, and afterload. Inc contractility in CHF
93
Dig
| Indication
Manage afib or flutter, controls ventricular rate, esp w imp heart func
94
Digoxin
Dose
Onset
t 1/2
0.5-1 mg divided doses over 12-24 hrs
Onset 30-60 min
36 hrs
95
Digoxin
Therapeutic index
Weak what
Excretion
Narrow, 0.5-1.2 ng/ml
Protein binding
90% kidneys, reduce in elderly and renal impaired
96
Digoxin
| AE
Arrhythmias, heart block, anorexia, nausea, diarrhea, confusion, agitation
97
Digoxin
Potentiated by
Toxicity tx
Hypokalemia and hypomagnesemia
| Phenytoin (vent arrhythmias), pacing, atropine, antidote: immune fab
98
Atropine
Class
Indic
Muscarinic receptor antag
| Unstable bradyarrythmias
99
Atropine
Dose
Onset
Duration
0.4-1 mg IV
1 min
30-60 min
100
Atropine
Metab by
Cation dosing less than what, why
Liver.
| 0.4 mg, paradoxical response, penetrates BBB and CNS fx
