Anti-Arrhythmic Drugs - Howlett 4 Flashcards Preview

Pharmacology 3001 > Anti-Arrhythmic Drugs - Howlett 4 > Flashcards

Flashcards in Anti-Arrhythmic Drugs - Howlett 4 Deck (16)
Loading flashcards...
1

Arrhythmia

Disruption in the rate, rhythm, origin or conduction of the heartbeat
Causes include myocardial infarction, drug toxicity, electrolyte imbalance
Reduces ability of heart to pump blood
Can originate in any part of the heart

2

Supraventricular arrhythmias

Arise in atria or AV node

3

Ventricular arrhythmias

Arise in ventricles and are lethal

4

Bradycardias

Slow heart rate
Too few beats per minute
Lower CO

5

Tachycardias

Fast year rate
Too many beats per minute
Lower CO because ventricles cannot fill

6

Non-pharmacological means to treat arrhythmias

1. Remove abnormal tissue
2. Pacemaker
3. Implantable cardioverter-defibrillator

7

Treatment of tachycardias

Atrial or ventricular can be treated with anti arrhythmic drugs
1 + 3 are pro arrhythmic
Increase APD and increase refractory period

8

Class 1

Na channel blocker
Lidocaine
Preferentially bind to and block Na channels in cardiac tissue that is damaged
Prevent reentry

9

Class 2

Beta-blocker
Metoprolol
Block beta receptors in SNS in heart to decrease Ca overload
(Pain and stress causes SNS to increase Ca influx into heart, which can promote Ca overload which triggers DADs and EADs)
Slow HR, slow conduction velocity through the AV node and increase AV node refractory period

10

Class 3

Increase APD
Amiodarone
Prolong ADP and prolong refractory period mainly by blocking K channels responsible for depolarizing the heart
Even in normal tissue

11

Class 4

Ca channel blocker
Diltiazem, verapamil
Decrease Ca overload
Slow conduction velocity through AV node and increase AV node refractory period

12

Other

Digoxin, adenosine

13

Enhanced automaticity

Can occur in cells that show spontaneous depolarization (SA and AV nodes)
Increased SNS activity
Increased slope of spontaneous depolarization
Increased firing rate in AV node
Can also occur in muscle cells that do not show spontaneous depolarization
Can cause ectopic pacemaker: tachycardias when it is faster than SA node

14

Triggered automaticity

Abnormal AP following normal AP when heart is overloaded with Ca
EADs
or DADs

15

Reentry

AP activates heart more than once
Normal heart tissue with obstacle to conduction
Ischemic area, damage
AP cannot go through damaged area and goes wrong way, which can cause it to roll through again

16

Digoxin

Mimics effects of PNS in heart, especially at the AV node
Acts like beta-blockers and Ca channel blockers
Slows AV conduction and decreases ventricular rate