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Pharmacology > CVS: Anti-arrhythmics > Flashcards

CVS: Anti-arrhythmics Flashcards

1
Q

P wave represents the…

A

wave of depolarisation that spreads from the SA node throughout the atria

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2
Q

P-R interval represents the…

A

time between the onset of atrial depolarisation and the onset of ventricular depolarisation

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3
Q

QRS complex represents…

A

ventricular depolarisation

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4
Q

Q-T interval represents…

A

ventricular depolarisation and repolarisation, roughly estimates the duration of an average ventricular action potential

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5
Q

Class I drugs are all…

A

Na+ channel blockers.

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6
Q

What is the action of class IA drugs, and what will be their effect on the ERP?

A

Slows phase 0 depolarisation.

Increases the ERP.

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7
Q

What is the action of class IB drugs, and what will be their effect on the ERP?

A

Shortens phase 3 repolarisation and APD (action potential duration).

ERP unchanged.

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8
Q

What is the action of class IC drugs, and what will be their effect on the ERP?

A

Slows phase 0 depolarisation.

ERP unchanged.

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9
Q

Class II drugs are all…

A

B-adrenoreceptor blockers.

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10
Q

What is the action of class II drugs, and what will be their effect on the ERP?

A

Suppresses phase 4 depolarisation.

ERP unchanged.

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11
Q

Class III drugs are all…

A

K+ channel blockers.

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12
Q

What is the action of class III drugs, and what will be their effect on the ERP?

A

Prolongs phase 3 repolarisation.

Increases ERP.

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13
Q

Class IV drugs are all..

A

Ca2+ channel blockers.

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14
Q

What is the action of class IV drugs, and what will be their effect on the ERP?

A

Prolongs action potential.

Increases ERP.

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15
Q

A class IA drug is…

A

Procainamide.

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16
Q

Effect of procainamide on 1. conduction, 2. ERP/AED, 3. automaticity?

A
  1. conduction: decreases
  2. ERP/AED: increases
  3. automaticity: decreases
17
Q

A class IB drug is…

A

Lidocaine.

18
Q

Effect of lidocaine on 1. conduction, 2. ERP/AED, 3. automaticity?

A
  1. conduction: little effect
  2. ERP/AED: increases
  3. automaticity: decreases
19
Q

A class IC drug is…

A

Flecainide.

20
Q

Effect of flecainide on 1. conduction, 2. ERP/AED, 3. automaticity?

A
  1. conduction: suppresses phase 0 upstroke
  2. ERP/AED: has a minor effect on APD and refractoriness
  3. automaticity: decreases due to an increase in the threshold potential
21
Q

Clinical uses of flecainide?

A

Refractory ventricular tachycardias that tend to progress to VFib.

22
Q

Adverse effects of flecainide?

A

Increase mortality.

23
Q

A class II drug is…

A

Propanolol.

24
Q

What is the action of propanolol?

A

Diminishes phase 4 depolarisation, depressing automaticity, prolonging AV conduction, decreasing heart rate and contractility

25
Q

Uses of class II drugs?

A
  1. treat tachycardias caused by increased sympathetic activity
  2. for atrial flutter and fibrillation
  3. AV nodal reentrant tachycardia

It is the only class that reduces mortality after MI. Propanolol reduces the incidence of sudden arrhythmic death after MI.

26
Q

A class III drug is…

A

Amiodarone.

27
Q

What is the action of amiodarone?

A
  1. Blockade of Ikr and Iks channels in phase III, will not affect the K+ channels in phase 0 (Ito channels).
  2. Blockade of Na+ channels in phase I
  3. Blockade of adrenergic receptor in phase II
  4. Blockade of Ca2+ channels in phase IV
28
Q

Pharmacokinetics of amiodarone?

A

35-65% bioavailability
Hepatic metabolism into bioactive desethylamiodarone
Long elimination half life: 3-10 days for first t1/2, several weeks for second t1/2. Therefore, after discontinuation, effects will be maintained for 1-3 months.

29
Q

What are the clinical uses of amiodarone?

A
  1. Maintaining normal sinus rhythm in Afib patients

2. Effective in preventing recurrent ventricular tachycardia

30
Q

What is the adverse effect of amiodarone?

A

Symptomatic bradycardia and heart block

31
Q

Class IV drug are…

A

Verapamil

Adenosine

32
Q

What is the action of verapamil?

A
  1. Slowing conduction
  2. Prolonging APD and ERP
  3. Decreasing automaticity
33
Q

What are the uses of verapamil?

A

Supraventricular tachycardia
Hypertension
Angina

34
Q

Adverse effects of verapamil?

A

Hypotension

Contraindication: patients with preexisting depressed cardiac function

35
Q

What is the action of adenosine?

A

Suppression of AV node conduction, increases the AV nodal refractory period

Stimulates cardiac K+ channel, KAch

Inhibits calcium current

36
Q

What is the pharmacokinetics of adenosine?

A

Half-life in blood is <10s. Therefore, it is very useful as emergency treatment.

37
Q

What is the clinical use of adenosine?

A

Supraventricular tachycardia

38
Q

What are the adverse effects of adenosine?

A
  1. Flushing
  2. SOB/chest burning
  3. Induction of AV block/AF
  4. Headache
  5. Hypotension

Pharmacology (7 decks)

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