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Crrab 1 > intro to arrhythmias > Flashcards

intro to arrhythmias Flashcards

1
Q

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

A

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

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2
Q

What are ions flow controlled by?

A

Gates

  • voltage sensitive
  • Can be modulated by ion conc. and metabolic conditions
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3
Q

Which parts of the heart are sodium dependent?

A

Atrial, Purkinje and ventricular cells

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4
Q

Which cells of heart are calcium dependent?

A

SA and AV node

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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

What is I(K)?

A

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

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8
Q

What is considered the refractory period?

A

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

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9
Q

What happens when you black Na channels?

A

Number of channels available at optimal conditions are decreased

  • unavailable due to inactivation gate closure and drug blockage
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10
Q

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

A

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

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11
Q

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

A

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

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12
Q

What are the factors that can lead to arrhythmias?

A 
Ischemia 
Drug tox
Hypoxia
Acidosis/Alkalosis
Electrolyte abnormalities
Overstretching of cardiac fibers
Excessive catecholamine exposure
Autonomic influences
Scarred or diseased tissue
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13
Q

What are the 2 factos that lead to arrhythmias?

A

Impulse formation

Impulse conduction problems

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14
Q

What are the 2 characteristics of impulse formation?

A

Diastolic and action potential interval

  • diastolic is more important
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15
Q

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

A

Alter slope
Hyperpolerize

Achetylcholine and B-Adrenorecptor blocking drugs

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16
Q

What can increase slope of diastolic interval?

A 
Hyperkale
B-adrenoceptor stimulation
Positive chronotropic drugs
Fiber stretch
Acidosis
17
Q

What is afterdepolarization?

A

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

Early and Delayed

18
Q

What happens in early afterdepolarization? Consequences?

A

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
Q

What happens in delayed afterdepolarization? Conseqences?

A

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

Exacerbated by fast heart

20
Q

What is reentry?

A

Impulse reenters and excites areas of the heart more than once

can be called circus movements

21
Q

What needs to happen for reentry to occur?

A
  • some type of block’

- Conduction time must exceed refractory period

22
Q

What is the bundle of Kent?

A

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
Q

name some Class 1A drugs?

A

Quinidine
Procainamide
Disopyramide

24
Q

Name some Class 1B drugs?

A

Lidocaine

Mexilitine

25
Q

Name some class 1C drugs?

A

Flecainide

Propafenone

26
Q

What are the K channel blockers?

A

Amiodarone
Defetilide
Ibutilide

27
Q

What er the Ca channel blockers?

A

Verapamil

Diltiazem

28
Q

What are the B-Adrenergic blockers?

A

Propranolol
Acebutolol
Esmolol
Satalol

29
Q

What are state dependent drugs?

A

Only bind in activated or inactivated but not RESTED channels

30
Q

What is inversely related to dose?

A

Channel specificity

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

Crrab 1 (27 decks)

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