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Flashcards in Antiarrhythmics Deck (47)
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1

What are the 5 phases of fast response action potentials?

Phase 0: opening of sodium channels in the membrane
Phase 1: Repolarization
Phase 2: Influx of Ca into the cell
Phase 3: Opening of K channels
Phase 4: Resting membrane potential

2

Where do the fast response action potentials occur? Are they Ca or Na dependent?

Atrial tissue, His-purkinje tissue system, and ventricle tissue; Na dependent

3

Where do the slow response action potentials occur? Are they Ca or Na dependent?

Those that occur in S-A, A-V nodes ; Ca dependent

4

What are the 4 classes of anti-arrhythmic drugs? What are the "others" in anti-arrhythmic drugs?

(1) Sodium channel blockers
(2) Beta-blockers
(3) K channel blockers
(4) Ca channel blockers
Others- digoxin, adenosine

5

What are the sodium channel blockers? Are they mild, moderate, or high blockers?

(1) Procainamide- moderate
(2) Lidocaine- minimum
(3) FLecainide- strong

6

What does Procainamide do?

- Moderate Na channel blocker
~ Decreases conduction which decreases reentry (of the fast action potentials)
~ Decreases automaticity which decreases ectopic beats (in low doses)
- Moderate K channel blocker
~increases APD which decreases reentry
~ excessive increase in APD= EAD and Torsade de Pointe (10-20% of patients)

7

T/F Procainamide is not dose dependent.

FALSE; at high doses it becomes pro-arrhythmic

8

Procainamide- Uses

(1) Atrial, ventricular premature beats
(2) Atrial flutter, fibrillation (prevents re-occurrence by suppressing reentry that causes them)
(3) Ventricular tachycardia/fibrillation (prevents the re-occurrence)

9

Procainamide- Adverse Effects

(1) Cardiac suppression
(2) Ganglion block (hypotension)
(3) Lupus-like syndrome (fever, joint pain)

10

What does Lidocaine do?

- Minimal sodium, channel blockade and phase 0 depression
~ decreases automaticity (selectively decreases ventricular abnormal pacemakers)

11

Lidocaine- Uses

(1) Ventricular arrhythmias only (fast action potentials)
(2) VPC, Vent. Tachyardia: associated with MI
(3) Digoxin-induced ventricular arrhythmias

12

T/F Lidocain is ineffective against atrial arrhythmias

TRUE

13

Lidocaine- Adverse Effects

High doses causes CNS symptoms (agitation, convulsions)

14

How is Lidocaine given?

IV only due to rapid first pass metabolism int he liver

15

What dose Flecainide do?

- Strong Na channel blocer (decreases phase 0)
~ decreases conduction (fast action potentials)
~ decreases automaticity

16

Flecainide: Uses

(1) Atrial tachyarrythmias in the absence of heart disease

17

Who is contraindicated to use Flecainide?

Patients with ventricular heart disease

18

Flecainide: Adverse Effects

(1) Cardiac suppression: bradycardia
(2) Pro-arrhythmic

19

What are the Beta blockers?

Propranolol, Metoprolol

20

What do Beta blockers do?

- Decrease automaticity and decrease conductino in A-V node
~blocks sympathetic tone int he A-V node

21

Beta blockers- Uses

(1) Supraventricular tachyarryhtmias
(2) Catecholamine induced arrhythmias
(3) Slows ventricular rate during atrial tachycardias (by decreasing conduction of A-V node)
(4) post MI patients because it increases the sympathetic drive which lowers the chance of other arrythmias

22

Beta blockers- Adverse Effects

(1) Bradycardia
(2) decrease contractility (C.O)
(3) Decrease BP

23

What are the K channel blockers?

Amiodarone

24

What does Amiodarone do?

- K-channel block which increases APD which suppresses reentry
- Na-channel block which decreases conduction which suppresses reentry
- decreases automaticity which decreases ectopic beats

25

Which drug has a low potential for EAD and Torsade de Point: Procainamide or Amiodarone?

Amiodarone

26

Amiodarone: Uses

(1) Suppress atrial and ventricular premature beats
(2) Suppress atrial fibrillation and ventricular tachycardias

27

Amiodarone: Adverse Effects

(1) T1/2 13-103 days; pulmonary fibrosis
(2) Tremor
(3) Thyroid dysfunction
(4) Photosensitivity

28

What are the Ca channel blockers?

Verapamil, Diltiazem

29

Why is Nifedipine not used for anti-arrhythmic drugs?

It has no direct effect on the heart

30

What Ca channel blockers do?

- Decrease Ca entry which decreases automaticity (S-A, A-V node) and decreases conduction in A-V node