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4 Clinical Pharmacology and Intro to Prescribing > 13 Cardiac Arrhythmias > Flashcards

13 Cardiac Arrhythmias Flashcards

1
Q

What is a cardiac arrhythmia?

A
  • Disturbance in cardiac cycle where either:
    • Pacemaker (SAN) functions incorrectly or
    • Abnormal contraction/conduction in the heart

= insufficient to maintain cardiac output

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2
Q

Give some possible symptoms of cardiac arrythmias.

How is an arrythmia diagnosed?

A
  • Palpitations
  • Feeling dizzy
  • Fainting
  • Short of breath

Diagnosed:

ECG

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3
Q

How can bradycardic cardiac arrythmias be caused? (2)

A
  1. Conduction block in (may be due to ischaemia) :
    1. AV node
    2. Bundle of His
    3. Bundle branches
  2. Sinus bradycardia
    1. SAN- slower depolarisation
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4
Q

The following diagram shows a normal cardiac myocyte action potential. Describe what happens in phases 0-4 (in terms of ions).

A
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5
Q

Explain the action potential of the SAN in terms of the ions involved.

A
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6
Q

How can tachycardic cardiac arrythmias be caused? (4)

A
  1. Ectopic pacemaker activity - eg following ischaemia or mitral stenosis
    1. Supraventricular
    2. Ventricular
  2. After depolarisations - long QT/scarring
    1. Abnormal depolarisation of cardiac myocytes
      1. Early (phase2/3)
      2. Later (phase 4)
  3. Re-entry loops-eg due to ischaemia
    1. Impulse blocked- travels in retrograde way- re-excites area- another AP in quick succession
  4. Wolff-parkinson white syndrome
    1. Abnormal electrical conduction in heart- impulses travel down bundle of Kent –> faster HR
  5. (Tachycardia can be caused a fibrillations)
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7
Q

Give some causes of atrial/ventricular fibrillations.

A
  1. Ectopic focal points firing electrical impulses
    1. Tachycardia and irregular impulses
  2. High blood pressure
  3. Mitral valve disease
    1. Stenosis- dilation and damage to atria
    2. Regurgitation- irritation of atria
  4. Ischaemia
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8
Q

What is the most common arrhythmia? Why should a person with this type of arrhythmia be given anticoagulants?

A

Atrial fibrillation

  • Increased chance of clot formation- give anticoagulants
  • Causes: breathlessness and poor perfusion- prevents 10% of blood entering ventricles
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9
Q

What are the 4 classes of anti-arrhythmic drugs?

(Anti-arrhythmics work to reduce abnormal impulse generation or slow conduction through tissue)

A
  1. Sodium blockers
  2. Beta blockers
  3. Potassium blockers
  4. Calcium channel blocker (CCBs)
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10
Q

How do sodium blockers work to treat arrhythmias? (class 1)

A
  • Slow depolarisation= RHYTHM CONTROLLING
    • Decrease slope in phase 0
  • Doesn’t affect SAN Na as uses HCN channels
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11
Q

How do beta blockers work to treat arrhythmias? (class 2)

(DON’T give to asthmatics)

A
  • SAN- decrease slope of funny current = RATE CONTROLLING
    • (by blocking sympathetic nervous system)
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12
Q

Give 2 examples of class 2 antiarrhythmics.

A

Beta blockers

  1. Propanolol
  2. Bisoprolol
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13
Q

How do potassium blockers work to treat arrhythmias? (class 3)

A

Increase refractory period- RHYTHM CONTROLLING

  • Prevents early depolarisations
  • No potassium can leave
    • Prolongs phase 3/plateau
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14
Q

Give an example of a class 3 antiarrhythmic (potassium blocker) and give its potential side effects.

A

Amiodarone (wide spectrum- effective for most arrhythmias)

Can act on: sodium channels, potassium channels, calcium channels, &as non competitive beta blocker

Side effects:

Gets deposited everywhere

  • Pulmonary fibrosis
  • Hepatic injury
  • Increase LDL cholesterol
  • Thyroid disease
  • Photosensitivity
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15
Q

How do calcium channel blockers work to treat arrhythmias? (class 4)

A

Prevent calcium influx- slows heart rate - RATE CONTROLLING

Prolongs phase 2

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16
Q

Give 2 examples of calcium channel blockers used to treat arrhythmias.

A
  • Diltiazem
  • Verapamil
17
Q

Give an example of a Class IA antiarrhythmic.

  • How is it administered?
  • What types of arrhythmias might it be used for?
  • What are some of its side effects?
A

Quinidine

  • Oral/IV
  • Atrial fibrillation, atrial flutter, tachycardia, Brugada syndrome (irregular beats in ventricles)
  • Side effects: hypotension, pro-arrhythmic
18
Q

Give an example of a Class IB antiarrhythmic.

  • How is it administered?
  • What types of arrhythmias might it be used for?
  • What are some of its side effects?
A

Lidocaine

  • IV
  • Ventricular tachycardia due to ischaemic heart disease
  • Abdominal upset
19
Q

Give an example of a Class IC antiarrhythmic.

  • How is it administered?
  • What types of arrhythmias might it be used for?
  • Who is it contraindicated for?
  • What does it need to be used with?
A

Flecainide

  • Oral/IV
  • Used for:
    • Supraventricular fibrillation
    • Wolff-Parkinson-White syndrome
  • Contraindicated: ischaemic heart disease
  • Use with AVN blocker- can increase ventricular response
20
Q

What anti-arrhythmic would you prescribe for a patient with ectopic beats?

A

Beta blockers

21
Q

How would you go about managing a patient with atrial fibrillation/flutter pharmacologically?

A
  1. First= rate controlling drugs (+digoxin to enhance vagal activity)
    1. Beta blocker
    2. Calcium channel blocker
  2. Second= rhythm controlling drugs for Cardioversion (restore normal sinus rhythm)
    1. Sodium blockers
    2. Potassium blockers
  3. Consider anticoagulants
    1. Aspririn
    2. Heparin
    3. Warfarin

If ACUTE- electrical/pharmacological cardioversion to restore sinus rhythm first

(digoxin= increases force of contraction)

22
Q

What might we give to patients with tachycardic arrhythmias?

A
  1. Lidocaine is ischaemic heart disease (IB)
  2. Quinidine (IC)
  3. Beta blockers
  4. Calcium channel blockers
23
Q

What drug do we give to patients with Wolff-parkinson-White syndrome?

A

Flecainide (Class IC- sodium blocker)

24
Q

How does Ivabradine work as an anti-arrhythmic?

What are its specific indications?

Give a side effect of Ivabradine.

Who should Ivabradine NOT be given to?

A
  1. Blocks If (funny current)
    1. Slows sinus node
  2. Reduce HR in:
    1. Sinus tachycardia
    2. HF and angina
  3. Side effect: flashing lights
  4. AVOID in pregnancy = teratogenic
25
Q

Ivabradine is an iF blocker. It slows the heart rate through its affect in the iF current. What is it particularly useful in treating?

A
  • Heart failure
  • Managing angina

4 Clinical Pharmacology and Intro to Prescribing (27 decks)

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