Drugs for Cardiac Arrhythmias Flashcards
1
Q
What are the class 1A drugs?
A
- Quinidine
- Procainamide
- Disopyramide
2
Q
What are the class 1B drugs?
A
- Lidocaine
- Mexiletine
3
Q
What are the class 1C drugs?
A
- Flecanide
- Propafenone
4
Q
What are the class 2 beta blockers?
A
- Esmolol
- Propranolol
5
Q
What are the class 3 potassium channel-blocking drugs?
A
- Amiodarone
- Sotalol
- Dofetilide
- Ibutilide
6
Q
What are the class 4 cardioactive calcium channel blocking drugs?
A
- verapamil
- Diltiazem
7
Q
What do class 1A drugs do?
A
- block Na+ channels: (preferentially bind to open Na+ channels)
- block K+ channels
- prolong QRS and QT intervals
8
Q
What does Procainamide do in addition to sodium channel block?
A
- directly depresses the activities of SA and AV nodes
- possesses antimuscarinic activity
- has ganglion-blocking properties (reduces peripheral vascular resistance)
9
Q
What are the adverse effects of Procainamide?
A
- QT interval prolongation
- induction of torsade de pointes arrhythmias and syncope
- excessive inhibition of conduction
- Lupus erythematosus syndrome with arthritis, pleuritis, pulm disease
- nausea, diarrhea
10
Q
What are the pharmacodymanics and clinical use of Quinidine?
A
- affords antimuscarinic effect on the heart
- beta-blocking activity
- may cause hypotension -> tachycardia
NOTE: rarely used d/t adverse effects
11
Q
What are the adverse effects of Quinidine?
A
- QT interval prolongation
- torsades de pointes arrhythmia
- excessive conduction slowing
- NVD
- HA, dizziness, tinnitus
12
Q
What is the clinical use of Disopyramide?
A
recurrent ventricular arrhythmias
- affords potent antimuscarinic effect on heart
13
Q
What are the adverse effects of Disopyramide?
A
- QT interval prolongation
- torsade de points
- negative inotropy
- atropine-like symptoms (urinary retention, dry mouth, blurred vision, constipation)
14
Q
What do class 1B drugs do?
A
- block sodium channels (**preferentially bind to depolarized cells/inactivated sodium channels)
15
Q
What class of drugs dissociates from the channels with fast kinetics?
A
class 1B
16
Q
What drug class has a more specific action on sodium channels, does not block potassium channels, and does not prolong action potential or QT duration?
A
class 1B
17
Q
What does Lidocaine do?
A
blocks inactivated sodium channels
18
Q
What drug selectively blocks conduction in depolarized tissue, making damaged tissue “electrically silent”?
A
Lidocaine
- fast kinetics of dissociation from sodium channel results in recovery from block between action potentials, with no effect on cardiac conductivity in normal tissue
19
Q
What is the clinical use of Lidocaine?
A
termination of ventricular tachycardia in the setting of acute myocardial ischemia
20
Q
What are the adverse effects of Lidocaine?
A
- it is the least toxic of all class 1 drugs **
- may cause hypotension in patients with heart failure by inhibiting cardiac contractility
- paresthesias, tremor, slurred speech, convulsions
21
Q
What drug is the orally active congener of lidocaine, and has similar electrophysiological/antiarrhythmic effects to lidocaine?
A
Mexiletine
22
Q
What is the clinical use of Mexiletine?
A
- ventricular arrhythmias
- relieves chronic pain, especially pain due to diabetic neuropathy and nerve injury
23
Q
What are the adverse effects of Mexiletine?
A
- tremor
- blurred vision
- nausea
- lethargy
24
Q
What do class 1C drugs do?
A
- block sodium channels (slow impulse conduction)
- state dependent (preferentially bind open sodium channels)
- blocks certain potassium channels
- prolong QRS interval
25
What drug blocks sodium and potassium channels, and has no antimuscarinic effects?
Flecainide
26
What is the clinical use of Flecainide?
in patients with otherwise normal hearts who have supraventricular arrhythmias
27
What are the adverse effects of Flecainide?
may be ver effective in supressing premature ventricular contractions
28
When might Flecainide cause severe exacerbation of ventricular arrhythmias?
when administered to patients with preexisting ventricular tachyarrhythmias
- patients with previous MI
- patients with ventricular ectopic rhythms
29
What drug class causes ventricular arrhythmias, such as PVCs and sustained VT and VF?
class 1C
NOTE: CAST trial was terminated early because 1C drugs were shown to increase mortality 2.5 fold
30
What drug has sodium blocking kinetics similar to flecaininde, and possesses weak beta-blocking activity?
propafenone
31
What is the clinical use of propafenone?
supraventricular arrhythmias in patients without structural disease
32
What are the adverse effects of propafenone?
- exacerbation of ventricular arrhythmias
- a metallic taste
- constipation
33
What is the sympathetic effect of class 2 drugs on SA nodal cells?
- lowers action potential threshold due to effect of L-type Ca channels
- increases slope due to effects on funny current and T-type Ca channels
34
What are the effects of propranolol and esmolol on SA and AV nodal cells?
- SA node: decreases HR (increasing RR interval)
| - AV node: decreases AV conductance (increasing PR interval)
35
What are the clinical uses of propranolol in cardiac arrhythmias?
- arrhythmias associated with stress and thyroid storm
- atrial fibrilation and flutter
- paroxysmal supraventricular arrhythmias
- arrhythmias associated with MI (it decreases mortality in pt with MI)
36
What short-acting selective beta-1 blocker has a half-life of 10 minutes (because of hydrolysis by blood esterases)?
Esmolol
37
What is the clinical use of Esmolol?
- supraventricular arrhythmias
- arrhythmias associated with thyrotoxicosis
- myocardial ischemia or acute MI with arrhythmias
- as an adjunct drug in general anesthesia to control arrhythmias during surgery
38
What are the adverse effects of beta-blockers?
- reduced CO
- bronchoconstriction
- impaired liver glucose metabolism
- increase VLDL, decrease HDL (unfavorable)
- sedation, depression
39
What are the contraindications of beta-blockers?
- asthma
- peripheral vascular disease
- Raynaud's syndrome
- T1DM on insulin
- bradyarrhythmias and AV conduction abnormalities
- severe depression of cardiac function
40
What do class 3 drugs block?
potassium channels
- calcium activated
- inward rectifying
- tandem pore domain
- voltage-gated
41
When are inwardly rectifying potassium channels open?
in the resting state
42
What contributes to the regulation of action potential?
- voltage-gated potassium channels
43
```
What class of drugs :
- block potassium channels
0 prolong action potential duration
- prolong QT interval
- prolong refractory period
```
class 3 drugs
44
What drug is used to treat recurrent ventricular tachycardia and atrial fibrillation?
Amiodarone (class 3)
45
What is Amiodarone metabolized by?
CYP3A4
- major metabolite is active, with very long elimination half-life (weeks-months)
NOTE: it inhibits many CYP enzymes, which may affect the metabolism of many other drugs, so all meds should be carefully reviewed, dose adjustments may be necessary
46
What are the adverse effects of Amiodarone?
- AV block and bradycardia
- low incidence of torsades de points
- fatal pulmonary fibrosis
- hepatitis
- photodermatitis
- optical neuritis
- hypo/hyperthyroidism (blocks peripheral conversion of T4->T3
47
What drug is considered a class 2 (non-selective beta-blocker) and a class 3 agent (prolongs APD)
Sotalol
48
What are the clinical uses of Sotalol?
- treatment of life-threatening ventricular arrhythmias
| - maintenance of sinus rhythm in patients with atrial fibrillation**
49
What are the adverse effects of Sotalol?
- depression of cardiac function
| - provokes torsades de pointes
50
What drug specifically blocks the rapid component of the delayed rectifier potassium current?
Dofetilide
NOTE: effect is more pronounced at lower heart rates)
51
What is the clinical use of Dofetilide?
- restore sinus rhythm in patients with atrial fibrillation
| - maintains sinus rhythm after cardioversion (restoring normal HR) in patients with atrial fibrillation
52
What are the adverse effects of Dofetilide?
QT interval prolongation and increased risk of ventricular arrhythmias
53
What drug slows cardiac repolarization (similar to dofetilide) by blocking the rapid component of the delayed rectifier potassium current?
Ibutilide
54
What is the clinical use of Ibutilide?
conversion of atrial flutter and atrial fibrillation to sinus rhythm
55
What are the adverse effects of Ibutilide?
QT interval prolongation and increased risk of ventricular arrhythmias
56
What drug class blocks both activated and inactivated L-type calcium channels?
class 4 drugs
57
What do class 4 drugs do?
- decrease the slope of phase 0 depolarization -> bradycardia
- increase L-type calcium channel threshold potential -> prolong AP duration
- prolong refractory period in the AV node
58
What are the two class 4 drugs mentioned?
Verapamil, Diltiazem
59
What is the clinical use of Verapamil and Diltiazem ?
- termination and prevention of paroxysmal supraventricular tachycardia
- ventricular rate control in atrial fibrillation and flutter
60
What are the adverse effects of Verapamil and Diltiazem?
- negative inotropy
- AV block
- SA node arrest
- bradyarrhythmias
- hypotension
NOTE: Verapamil also causes constipation
61
What drug activates potassium current and inhibits calcium and funny currents, causing hyperpolarization and suppression of action potentials in slow cells?
Adenoside
| - it also inhibits AV conduction and increases nodal refractory period
62
What is the clinical use of Adenosine?
conversion of sinus rhythm in paroxysmal supraventricular tachycardia
63
What are the adverse effects of Adenosine?
- shortness of breath
- bronchoconstriction
- chest burning
- AV block
- hypotension
