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Flashcards in intro to arrhythmias Deck (30):
1

What are the 3 ways of which depolarizations deviate from normal?

Rate of impulse
Impulse site of origin
Conduction (transport of impulse)

2

What are ions flow controlled by?

Gates
- voltage sensitive
-Can be modulated by ion conc. and metabolic conditions

3

Which parts of the heart are sodium dependent?

Atrial, Purkinje and ventricular cells

4

Which cells of heart are calcium dependent?

SA and AV node

5

Is the SA node repolarization controlled by I(k)?

Nope its controlled by different potassium channels and thus drugs that Block I(k) tend to have no affect on SA node

6

What is the key factor of pathophysiology of arrhythmias and drugs to treat them?

relation between resting potential of a cell and the number of the action potential that can be evoked

7

What is I(K)?

Its rapid I(kr) and Slow I(Ks) added to one another.

8

What is considered the refractory period?

The time between the end of phase 0 and the end of phase 3

9

What happens when you black Na channels?

Number of channels available at optimal conditions are decreased

- unavailable due to inactivation gate closure and drug blockage

10

What is the resting membrane potential of after Na channel blockers?

-55
which All Na+ channels are inactivated
- Increase refractory period of cell
- prolongs recovery time

11

What is the resting membrane potential of Av and Sa nodes?

-50-- (-70) which is why they can depolarize even with a Na channel blocker

12

What are the factors that can lead to arrhythmias?

Ischemia
Drug tox
Hypoxia
Acidosis/Alkalosis
Electrolyte abnormalities
Overstretching of cardiac fibers
Excessive catecholamine exposure
Autonomic influences
Scarred or diseased tissue

13

What are the 2 factos that lead to arrhythmias?

Impulse formation
Impulse conduction problems

14

What are the 2 characteristics of impulse formation?

Diastolic and action potential interval

- diastolic is more important

15

Vegal discharge and what other drug will do what to diastolic interval?

Alter slope
Hyperpolerize

Achetylcholine and B-Adrenorecptor blocking drugs

16

What can increase slope of diastolic interval?

Hyperkale
B-adrenoceptor stimulation
Positive chronotropic drugs
Fiber stretch
Acidosis

17

What is afterdepolarization?

Membrane voltage oscillations that result in transient abnormal depole of cardiac myocytes during phase 2,3,4,

Early and Delayed

18

What happens in early afterdepolarization? Consequences?

Open Ca channel Last phase 2
Open Na channel Early phase 3
Inhibit K channel

Exacerbated by slow heart.

- Torsades des pointes or tachys

19

What happens in delayed afterdepolarization? Conseqences?

Elevated cytosolic Ca when cell is almost completely repolarized. Overloads SR and release Ca to cause depole.

Exacerbated by fast heart

20

What is reentry?

Impulse reenters and excites areas of the heart more than once

can be called circus movements

21

What needs to happen for reentry to occur?

-some type of block'
-Conduction time must exceed refractory period

22

What is the bundle of Kent?

Called Wolff-Parkinson-White syndrome

Abnormal electrical accessory connection between atria and ventricle.

allows impulse to be conducted without going through the AV node

23

name some Class 1A drugs?

Quinidine
Procainamide
Disopyramide

24

Name some Class 1B drugs?

Lidocaine
Mexilitine

25

Name some class 1C drugs?

Flecainide
Propafenone

26

What are the K channel blockers?

Amiodarone
Defetilide
Ibutilide

27

What er the Ca channel blockers?

Verapamil
Diltiazem

28

What are the B-Adrenergic blockers?

Propranolol
Acebutolol
Esmolol
Satalol

29

What are state dependent drugs?

Only bind in activated or inactivated but not RESTED channels

30

What is inversely related to dose?

Channel specificity
- More drug you give the more spillover there is to secondary channels