Cardio-Antiarrhythmics Flashcards Preview

BIOM*3090. UOG > Cardio-Antiarrhythmics > Flashcards

Flashcards in Cardio-Antiarrhythmics Deck (17):
1

what is the result of depolarizaiton in terms of AP?

Depolarization opens ion-specific channels which creates an Action Potential

2

what are the 3 phases of the Action potential?

0) depolarization proceeds rapidly due to na+ influx through rapidly opening Na+ channels.
1-2) plateau phase due to Ca2+ influx through more slowly opening Ca2+ channels.
3) repolarization due to closure of Ca2_ channels, K+ efflux through K+ chennels.
the membrane gradient is restored by Na+/K+ ATPase

3

what is the excitation-contraction coupling:

1) A.P. -> ^ Ca2+
2) ^ Ca2+, binds troponin C and & uncovers myosin binding site on actin
3) actin & myosin cross-linkages form -> contraction

-relaxation = Ca2+ released from troponin & pumped back into sarcoplasmic reticulum & out of cell, actin & myosin no longer cross-linked

4

what is Arrhythima?

electrical alterations -> abnormalities in heart rhytm. this may not affect the CO.

5

what is altered initiation?

SA node, altered rate, altered site

6

what is altered conduction?

heart block (bradyarrhythmias)
reentry conduction (tacharrhythmias)

7

what is ventricular fibrillation?

its irrgular rapid contraction of ventricles -> cannot pump blood properly. if not treated immediately it could be fatal.

8

how do defibrillators work?

they stop fibrillation by temporarily stopping all electrical activity to allow normal rhythm to resume.

9

where are 4 classes of antiarrhythimic agents.

class 1: Na+ channel blockers
class 2: beta-blockers
Class 3: Prolonged action potential/K+ channel blaocks
class 4: Ca2+ channel bloackers

10

what do Na+ channel blockers do?

reduce recovery of Na+ channels, therefore reduce conduction and excitation

11

what do K+ channel blockers?

prolong the Action Potential therefore refractory period.

12

describe the Na+ channel blocker 1A- Quinidine:

prototypical drug in this class, now less frequency used due to side-effects.

13

describe the Na+ channel blocker 1B- Lidocaine

most commonly used IV anti-aahythmic

14

describe the Na+ channel blocker 1C

also affect K+ channels- only used for severe ventricular arrhythmias

15

describe the class 2 beta bloackers.

propranolol, metropriolol
inhibits SNS effects & slows HR
most useful antiarrhythmics currently available

16

describe the class 3 K+ channel blockers

prolong action potential duration
also affect beta receptors & Na+ & Ca2+ channels

17

describe the class 4

Ca2+ channel blockers verapamil
decreases cardiac contractility.