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Pharmacology > Lecture 11: Anti-Arrythmic Drugs (Part I) > Flashcards

Lecture 11: Anti-Arrythmic Drugs (Part I) Flashcards

1
Q

____: Any change from normal sequence of cardiac impulse (may be fast, slow, or erratic beat) that result in ineffective pumping of blood to vital organs

A

Cardiac Arrythmia

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2
Q

True or False: A change in beat velocity or rhythm is considered arrhythmic

A

True

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3
Q

_____ is made up of continuous cycles of depolarization and re-polarization of cardiac muscle tissue. During this period, cardiac muscle cells are refractory to any further stimuli, which is known as ____

A

Cardiac action potential; effective refractory period (ERP) /absolute refractory period (ARP)

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4
Q

Which AP corresponds to pacemaker cells (SA/AV Node) and which correspond to non-pacemaker cells?

A

Left = non-pacemaker
Right = pacemaker cells

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5
Q

How many phases are present in pacemaker cell action potential?

How many phases are present in non-pacemaker cell action potential?

A

Pacemaker cell action potential = three phase s(Phase 4, 0, and 3)

Non-pacemaker cell action potential = five phases (Phase 0, 1, 2, 3, and 4)

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6
Q

What initiates Phase 4 in pacemaker cell action potential?

A

Slow and spontaneous depolarization by:

1) inward pacemaker current (inward funny current) - maintains automaticity
2) HCN channels

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7
Q

By the end phase 4 of pacemaker cell action potential, there is an increase in ___ (influx), which stimulates ___ entry

A

Na; Ca2+

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8
Q

Phase 0 of pacemaker cell action potential is characterized by rapid ____. What causes this?

A

rapid depolarization
- cause: opening of VG Ca2+ channel

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9
Q

What causes phase 3 of pacemaker cell action potential (repolarization phase)?

A

1) Opening of K+ selective channels via: delayed rectifier outward current

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10
Q

During phase 3 of pacemaker cell AP, are Ca2+ channels open or closed?

A

Closed

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11
Q

Following repolarization (phase 3 of pacemaker cell AP) - once the membrane potential reaches ___, it triggers the opening of __, for the next slow and spontaneous depolarization

A

-60 mV; If

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12
Q

True or False: In pacemaker cell action potential, phase 4 is associated with Na influx, phase 0 is associated with Ca influx, and phase 3 is associated with K efflux

A

True

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13
Q

What is the order in which the pacemaker cell AP phases occur in?

What is the order in which the non-pacemaker cell AP phases occur in?

A

Pacemaker: Phase 4→Phase 0 →Phase 3

Non Pacemaker: Phase 4→ 0 → 1→ 2 → 3 →4

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14
Q

What happens in phase 4 (first stage of non-pacemaker cell AP)?

A

K+ ions efflux via: delayed rectifier outward K+ currents - IKs - maintains negative potential

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15
Q

Which stage of the non-pacemaker cell action potential is associated with rapid depolarization (and, ultimately, a shift from negative (-90 mv) to positive potential) ?
A. Phase 1
B. Phase 4
C. Phase 0

A

C. Phase 0

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16
Q

During phase 0 of non-pacemaker cell AP, there is fast influx of __ ions. Which channels are closed at this time?

A

Na; Outward K

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17
Q

Which stage of the non-pacemaker cell action potential is associated with a rapid, transient repolarization stage? Cause?

A

Phase 1 is the initial rapid transient repolarization stage in Non-Pacemaker Cell Action Potential
- Due to opening of transient outward K+ channels

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18
Q

What factors lead to Phase 2 (plateau phase) of non-pacemaker cell action potential?

A
  • Inward flow of calcium
  • Outward K+ current
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19
Q

IKr and Iks are rapid and slow acting delayed rectifiers that allows for K+ efflux at what phase of non-pacemaker cell action potential?

A

Phase 2 (plateau) and Phase 3

20
Q

By the end of phase 2 in the non-pacemaker cell action potential, the ___ channel closes and is following by steady and fast efflux of K+ via ___ and ___

A

Ca2+; IKr/IKs

21
Q

What happens in phase 4 of the non-pacemaker cell action potential? How it it achieved?

A

Re-establishment of resting membrane potential
- Achieved by opening of outward K+ currents (IKr/IKs*) - time independent, but depends on potential of -90 mV

22
Q

Which of the following corresponds to the following description?
“Atrial depolarization”

A. P wave
B. PR interval
C. QRS complex
D. ST segment

A

A. P wave

23
Q

Which of the following corresponds to the following description?

“Time between atrial depolarization and ventricular depolarization”
A. P wave
B. PR interval
C. QRS complex
D. ST segment

A

B. PR interval

24
Q

Which of the following corresponds to the following description?
“Ventricular depolarization”
A. P wave
B. PR interval
C. QRS complex
D. ST segment

A

C. QRS complex

25
Q

Which of the following corresponds to the following description?
“Time taken for both ventricles to get completely depolarization - corresponds to plateu phase)”
A. P wave
B. PR interval
C. QRS complex
D. ST segment

A

D. ST segment

26
Q

Which of the following corresponds to the following description?
“Ventricular repolarization”
A. P wave
B. PR interval
C. QRS complex
D. ST segment
E. T waves

A

E. T waves

27
Q

Two types of defects that can lead to arrythmia?

A

1) Defects in impulse formation
2) Defects in impulse conduction

28
Q

What are two factors that can cause defects in impulse formation?

A

1) Altered automaticity
2) Triggered activity

29
Q

What is the normal path taken by electrical activity?

A

SA Node→AV Node→Bundle of His→Purkinje

30
Q

____: a condition in which there is a defect in either pacemaker cells OR non-pacemaker cell activity, leads SA Nodal firing rate to become altered/impairs downstream conduction

A

Altered Automaticity

31
Q

____: Process by which the initial AP triggers an immediate and addition depolarization PRIOR to completion of one cycle, leads to arrythmia

A

Triggered activity

32
Q

What are the two types of triggered activity?

A

1) Early After Depolarization (EAD)
2) Delated After Depolarization (DAD)

33
Q

When does Delayed After Depolarization commonly occur? When does Early After Depolarization occur?

A

DAD = Phase 3 or end of Phase 3
EAD = End of Phase 2 or early part of Phase 3

34
Q

True or False: Early After Polarization is most likely to happen towards the enter of plateau or beginning of rapid repolarization

A

True

35
Q

If Early After Depolarization persists, what condition could it lead to?

How is this condition characterized?

A

Torsade de Pointes
- characterized by:
1) ventricular tachyarrythmia
2) prolonged QT intervals
3) heart rate (200-250 beats/min)

36
Q

What three drugs are known to induce Torsade de Pointes?

What three gene mutations are known to induce the condition?

A

Drugs: anti-arrythmic drugs; tricyclic antidepressants; anti-virals

Mutations: KCNQ1, HERG, SCN5A

37
Q

True or False: Digitalis can induce torsade de pointes (TdP)

A

True - can be treated by MgSO4 IV infusion

38
Q

Delayed After Depolarization typically occurs after repolarization (phase _) due to a rise in ___, leading another depolarization to occur before completion of one cycle

A

phase 3; Ca2+

39
Q

Three factors that can lead to defects in impulse conduction?

A

1) Re-entry
2 ) Conduction block
3) Accessory Tract Pathways

40
Q

What are two factors that lead to re-entry?

A

1) Uni-directional block
2) Slow retrograde conduction velocity

41
Q

_____ is due to failure to propagate impulses due to damage induced reduced excitability of cardiac tissue. Often results in decrease contractility of ___

A

Conduction Block; myocyte

42
Q

True or False: Accessory fibers, such as Bundle of Kent, can bypass SA-AV Path

A

True

43
Q

Supraventricular Tachyarrythmia (WPW Syndrome) could lead to ______ if it is AV Nodal in origin

A

Paroxysmal Supraventricular Tachycardia

44
Q

True or False: Impulses from accessory path and normal path can trigger impulses

A

True

45
Q

What four drug classes are associated with QT Prolongation and TdP?

A

1) Anti-arrhythmics
2) Anti-microbials
3) Anti-depressants
4) Anti-psychotics

Pharmacology (53 decks)

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