Arrhythmia Flashcards

1
Q

What do class 1 drugs do?

A
  • block Na channels
  • as a result upward curve of AP is shifted to right
  • slow conduction within cardiac tissue (phase 0)
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2
Q

What is the effect of class 2 drugs?

A
  • beta blockers
  • affects calcium inflow to heart
  • slightly increases AP duration
  • diminishes phase 4 depolarisation and automaticity
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3
Q

What is the effect of class 3 drugs?

A
  • blocks K channels
  • phase 3 and 4 occur later
  • refractory period is extended
  • so QT interval is extended
  • increases action potential duration
  • potential of causing pro-arrhythmia
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4
Q

What is the effect of class 4 drugs?

A
  • calcium blockers
  • decreases phase 4 spontaneous depolarization
  • affects plateau phase of AP
  • slows cardiac action potential
  • changes slope of phase 0
  • increases refractory period
  • slows conduction
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5
Q

What drugs affect automaticity (ability of heart cells to spontaneously depolarize and generate AP)?

A
  • B agonist
  • muscarinic agonists
  • adenosine
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6
Q

Procainamide

A
  • rarely used
  • decreased conduction (phase 0 decreased)
  • increases refractory period (increases action potential duration)
  • decreases automaticity (decreases slope of phase 4)
  • increases threshold
  • uses: acute IV treatment of supraventricular and ventricular arrhythmia
  • lupus-like syndrome and other 1A side effects
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7
Q

Quinidine

A
  • oral or IV
  • same effects as procainamide
  • has anticholinergic action to speed AV conduction used with digitalis, B blocker or Ca channel blocker
  • effects on ECG: increased QRS and QT
  • uses: maintain sinus rhythm in AF and atrial flutter and to prevent recurrence, Brugada syndrome
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8
Q

What are the side effects of class 1A drugs?

A
  • rarely used
  • hypotension, reduced CO
  • proarrhythmia (ex. Torsades de Points)
  • dizziness, confusion, insomnia, seizure (high dose)
  • GI effects (common)
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9
Q

Lidocaine

A
  • iv only
  • affects phase 0 and conduction in fast beating or ischaemic tissue
  • fast binding offset kinetics
  • no change in phase 0 in normal tissue
  • ADP slightly decreased in normal tissue
  • increases threshold (Na)
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10
Q

Mexiletine

A
  • given orally
  • fast binding offset kinetics
  • no changes in phase 0 in normal tissue
  • decreases phase 0 conduction in fast beating or ischaemic tissue
  • increases threshold (Na+)
  • ADP slightly decreased in normal tissue
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11
Q

What are the uses,side effects, and effects on ECG of class 1B drugs?

A
  • uses: acute ventricular tachycardia (esp. during ischaemia)
  • not used in atrial arrhythmias or AV junction along arrhythmias
  • side effects: less proarrhthymic than class 1A (less QT effect), CNS effects (dizziness, drowsiness), abd upset
  • ECG effects: none in normal, in fast beating or ischaemic
  • increases QRS width
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12
Q

Flecainide and propafenone (class 1C)

A
  • oral or IV
  • very slow binding offset kinetics
  • substantially decrease phase 0 in normal tissue
  • decreases in automaticity
  • increase in APD and refractory period

Effects on ECG
-increase PR, QRS, QT

Uses

  • wide spectrum
  • used for atrial fibrillation and flutter
  • premature ventricular contraction
  • WPW

Side effects

  • proarrhythmias and sudden death especially with chronic use and in structural heart disease
  • increased ventricular response to atrial flutter
  • CNS and GI effects like other local anesthetics
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13
Q

Propranolol

A
  • oral or iv
  • long-acting
  • class 2
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14
Q

Bisoprolol

A
  • class 2

- oral only

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15
Q

Metoprolol

A
  • class 2
  • 5mg IV or oral
  • shorter acting
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16
Q

Esmolol

A
  • class 2
  • IV only
  • very short acting
17
Q

What are the cardiac effects, effects on ECG, uses and side effects of class 2 agents (propranolol, bisoprolol, metoprolol, and esmolol)

A
  • increases APD and refractory period in AV node to slow AV conduction
  • decreases phase 4 depolarisation

Effects on ECG
-increase PR and decreases HR

Uses

  • treating sinus and catecholamine dependant tachycardia
  • converting re-entrant arrhythmias at AV node
  • protecting the ventricles from high atrial rates (slow AV conduction) in atrial flutter or atrial fibrillation

Side effects

  • bronchospasm
  • hypotension
  • don’t use in partial AV block or acute heart failure
18
Q

Amiodarone

A
  • class 3
  • oral or IV (central line because thrombophlebotic)
  • half life is 3 months

Cardiac effects

  • increases refractory period and APD
  • decreases phase 0 and conduction
  • increases threshold
  • decreases phase 4 (B and Ca block)
  • decreases speed of AV conduction

Effects on ECG

  • increases PR, QRS and QT
  • decreases HR

Uses
-very wide spectrum: effective for most arrhythmias especially ventricular tachycardia

Side effects

  • very serious that increase with time
  • pulmonary fibrosis
  • hepatic injury
  • increase LDL cholesterol
  • thyroid disease
  • photosensitivity
  • optic neuritis (transient blindness)
  • must look at benefit-to-risk ration
19
Q

Sotalol

A
  • class 3
  • oral

Cardiac effects

  • increased APD and refractory period in atrial and ventricular tissue
  • slow phase 4 (B blocker)
  • slow AV conduction

ECG effects
-increases QT and decreases HR

Uses
-wide spectrum: supraventricular and ventricular tachycardia

Side effects
-proarrhythmia, fatigue, insomnia

20
Q

Describe class 4 agents (Verapamil and diltiazem)

A
  • verapamil: oral or iv
  • diltiazem: oral

Cardiac effects

  • slow conduction through AV (Ca)
  • increases refractory period in AV node
  • increases slope of phase 4 in SA to slow HR

Effects on ECG

  • increases PR
  • increase or decrease HR depending on BP response and baroreflex

Uses

  • control ventricles during supraventricular tachycardia
  • converts supraventricular tachycardia (re-entry around AV)

Side effects

  • caution when partial AV block is present, can get asystole from B blocker
  • caution when hypotension, decreased CO or sick sinus
  • some GI problems (constipation)
21
Q

Adenosine

A
  • rapid iv bolus, very short half-life
  • natural nucleoside that binds A1 receptors and activates K+ currents in AV node and SA node
  • decreases APD
  • hyperpolarization causes decrease in HR
  • decreased Ca currents and increased refractory period in AV node
  • slows AV conduction

Uses

  • converts re-entrant supraventricular arrhythmia s
  • diagnosis of coronary artery disease (scans)
22
Q

Vernakalant

A
  • iv bolus over 10 min
  • blocks atrial specific K+ channels (outward channel class 3)
  • slows atrial conduction
  • increases potency with higher heart rates
  • used for termination of new onset AF

Side effects

  • hypotension, AV block
  • sneezing and taste disturbances

Uses
-convert recent onset AF to normal sinus rhythm

23
Q

Ivabradine

A
  • orally in 2.5mg bd dosing up to 10mg bd
  • blocks If ion current highly expressed in sinus node
  • slows the sinus node but doesn’t affect BP

Side effects

  • flashing lights
  • teratogenicity not known (avoid in pregnancy)

Uses

  • reduce inappropriate sinus tachycardia
  • reduce HR in heart failure and angina (avoid BP drops)
24
Q

Digoxin (cardiac glycoside)

A
  • enhances parasympathetic activity
  • last resort drug
  • slows AV conduction and slow HR

Uses
-treatment to reduce ventricular rates in AF and flutter

25
Q

Atropine

A
  • selective muscarinic antagonist
  • block parasympathetic activity to speed AV conduction and increase HR
  • treat parasympathetic bradycardia
  • give pacemaker for a more long-term plan
26
Q

Which drugs are used in AF?

A
  • rate control (slow conduction through AV node to reduce heart back to normal levels): bisoprolol, verapamil, diltiazem, maybe digoxin
  • rhythm control: sotalol, flecainide with bisoprolol, amiodarone
27
Q

Which IV drug for VT?

A
  • depends on what drugs already prescribed: metoprolol/bisoprolol, lidocaine/mexiletine, amiodarone
  • IV metoprolol/lidocaine or amiodarone
28
Q

Should flecainide be used alone in atrial flutter?

A
  • no

- give AV nodal blocking drugs to reduce ventricular rates in atrial flutter

29
Q

Best drug for treatment WPW?

A
  • flecainide

- amiodarone

30
Q

List drugs that could be used in re-entrant NCT?

A
  • acutely IV: adenosine, verapamil, flecainide

- chronic (repeated episodes, orally): bisoprolol, verapamil, sotalol, flecainide, procainamide, amiodarone

31
Q

Which drugs for ectopic beats?

A
  • bisoprolol first line

- flecainide, sotalol or amiodarone

32
Q

Which drugs to treat sinus tachycardia?

A
  • ivabradine (no drop in BP)

- bisoprolol, verapamil