Yang Yang AP and Antiarrhythmics Flashcards

1
Q

Important ion channels in the heart

A

-Sodium channels
-Calcium channels
-Potassium channels
-HCN channels
-hERG channels (avoid targeting when developing new drugs)

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2
Q

Potassium concentration outside the cell

A

5 mM

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3
Q

Sodium concentration outside the cell

A

142 mM

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4
Q

Calcium concentration outside the cell

A

5 mM

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5
Q

Chloride concentration outside the cell

A

103 mM

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6
Q

Potassium concentration inside the cell

A

148 mM

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7
Q

Sodium concentration inside the cell

A

10 mM

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8
Q

Calcium concentration inside the cell

A

<1 uM

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9
Q

Chloride concentration inside the cell

A

4 mM

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10
Q

Voltage value inside the cell

A

-70 mV

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11
Q

Voltage value outside the cell

A

0 mV

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12
Q

What are pacemaker cells?

A

-Specialized, non-contractile cells
-Physiologically depolarized
-High automaticity
-Ca2+-dependent spikes

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13
Q

What are ventricular myocytes?

A

-Contractile cells
-Hyperpolarized
-Low automaticity
-Na+-dependent spikes

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14
Q

Common arrhtyhmias

A

-Atrial sinus arrhythmia
-Re-entry arrhythmias
-Atrial fibrillation
-Wolf-Parkinson White
-Monomorphic ventricular tachycardia
-AV nodal re-entrant tachycardia
-Premature ventricular complexes

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15
Q

Re-entry arrhythmia requirements

A

-Multiple parallel pathways
-Unidirectional block
-Conduction time greater than ERP (effective refractory period)

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16
Q

What are class 1 antiarrhythmic drugs?

A

Na+ channel blockers

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17
Q

What are class 2 antiarrhythmic drugs?

A

Beta-adrenergic antagonists

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18
Q

What are class 3 antiarrhythmic drugs?

A

Agents that prolong refractory period (K+ channel blockers)

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19
Q

What are class 4 antiarrhythmic drugs?

A

Ca2+ channel blockers

20
Q

Class 2 antiarrhythmic drug mechanism of action

A

-Beta adrenergic blockers
-Slows pacemaker and Ca2+ currents in SA, AV node
-Increase refractoriness of SA, AV node
-Increase P-R interval
-Arrhythmias involving catecholamines (epinephrine, norepinephrine, etc . . .)

21
Q

Class 4 antiarrhythmic drug mechanism of action

A

-Ca2+ channel blockers
-Frequency-dependent block
-Increase refractoriness of AV node and P-R interval
-Protect ventricular rate from atrial tachycardia

22
Q

Beta blockers used as antiarrhythmics

A

-Esmolol
-Acebutolol
-Propranolol

23
Q

Beta blocker clinical use as antiarrhythmics

A

-Arrhythmias involving catecholamines
-Atrial arrhythmias (protect ventricular rate)
-Post-MI prevention of ventricular arrhythmias
-Prophylaxis in Long QT syndrome (catechol.-sens)

24
Q

Calcium channel blockers used as antiarrhythmics

A

-Verapamil
-Diltiazem

25
Q

Calcium channel blocker clinical use as antiarrhythmics

A

-Block re-entrant arrhythmias involving AV node
-Protect ventricular rate in atrial flutter and atrial fibrillation

26
Q

Class 1A antiarrhythmic effect on action potential

A

-Mixed block: Na+ and K+ channels
-Blocks open state
-Moderate, incomplete dissociation
-Widen QRS
-Prolonged QT

27
Q

Class 1B antiarrhythmic effect on action potential

A

-Na+ channel block
-Blocks open and inactivated state
-Rapid, complete dissociation
-Slight narrowing of action potential
-No clinically significant effect on ECG

28
Q

Class 1C antiarrhythmic effect on action potential

A

-Strong Na+ channel block
-Blocks open state
-Very slow, incomplete dissociation
-Widen QRS

29
Q

Class 1A antiarrhythmic drugs

A

-Quinidine
-Procainamide
-Disopyramide

30
Q

Class 1B antiarrhythmic drugs

A

-Lidocaine
-Mexiletine
-Tocainide
-Phenytoin

31
Q

Class 1C antiarrhythmic drugs

A

-Flecainide
-Propafenone
-Moricizine

32
Q

Quinidine clinical pearls

A

-2-8% risk of torsades de pointes
-Aniti-muscarinic activity

33
Q

Procainamide clinical pearls

A

-Lupus-like syndrome
-Ganglionic blocker

34
Q

Disopyramide clinical pearls

A

-Anti-muscarinic activity

35
Q

Lidocaine clinical pearls

A

-IV only; not effective orally
-Among top choices for rapid control of ventricular arrhythmias
-Only ventricular, not atrial

36
Q

Mexiletine clinical pearls

A

-Orally available, similar to lidocaine in efficacy

37
Q

Flecainide clinical pearls

A

-Ventricular and supraventricular
-Orally available

38
Q

Propafenone clinical pearls

A

-Ventricular and supraventricular
-Beta receptor blocking activity
-Orally available

39
Q

Class 3 antiarrhythmics mechanism of action

A

-Block IKr, prolong action potential duration and Q-T interval
-Increases effective refractory period
-In re-entrant circuit, increased ERP above conduction time around circuit will terminate re-entry

40
Q

Why can class 3 antiarrhythmics cause TDP?

A

-IKr block induces EADs and triggered upstrokes
-Multifocal/polymorphic ventricular tachycardia
-Can degenerate into ventricular fibrillation

41
Q

Class 3 antiarrhythmic drugs

A

-Amiodarone
-Dronedarone
-Ibutilide
-Sotalol
-Dofetilide

42
Q

Amiodarone clinical use

A

-Top choice for rate control in A-fib, suppression of post-MI ventricular arrhythmias

43
Q

Dronedarone clinical use

A

A-fib

44
Q

Sotalol clinical use

A

Prevent A-fib re-occurrence

45
Q

Ibutilide clinical use

A

Convert A-fib to sinus rhythm