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High - Cardiovascular system > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

How does the heart work?

A
  • Sinoatrial node fires electrical impulse (Sets normal pace of heart rhythm)
  • Atrial depolarisation (Impulse travels through atria, contracts + empty blood into ventricles)
  • AV node funnels impulse (Slows or blocks impulse too closely spaced giving time for blood to fill ventricles)
  • Ventricular depolarisation (Impulse travels through ventricles + Contracts - pump blood to lungs + body)
  • Atrial repolarisation (Atria recharge + refill w blood)
  • Ventricular repolarisation (Ventricles recharge + refill w blood)
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2
Q

What are the types of arrhythmias?

A

Supraventricular:
- AF
- Atrial flutter
- Paroxysmal SV tachycardia

Ventricular:
- Ventricular tachycardia + fibrillation
- Torsade de pointes

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3
Q

What are the symptoms of AF?

A
  • Palpitations
  • Dyspnoea
  • Dizzy
  • Tired
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4
Q

What are the types of AF?

A
  • Paroxysmal: episodes last <7 days
    Usually stops w/in 48h
  • Persistent: episodes last >7 days
  • Permanent: present all the time
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5
Q

What is the treatment for AF?

A

First line: Rate control:
- Beta-blocker (not sotalol)
- Rate limiting CCB (diltiazem, verapamil)
- Digoxin (sedentary patient + non-paroxysmal)

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6
Q

What is the treatment for AF if rate control is ineffective?

A

Offer dual therapy (AVOID beta-blocker + verapamil)

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7
Q

What is the treatment for AF in reduced LVEF?

A

Beta-blocker + digoxin
- Avoid CCB: may worsen condition
- BBlockers red sympathomimetic activity

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8
Q

What are the exeptions for rate control as first line for AF?

A
  • New onset
    <48h rate or rhythm >48h rate
  • HF (avoid diltiazem + verapamil)
  • Reversible cause
  • Atrial flutter suitable for ablation
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9
Q

What is used for rhythm control in AF?

A

Anti-arrhythmic drugs:
- Amiodarone
- Flecainide
- Propafenone (avoid in IHD (angina))
- Standard beta-blocker (1st line post-cardioversion)

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10
Q

What is used for stroke prevention?

A

Calculated using CHADsVASc
2+ (high risk): Offer warfarin or DOAC (non valvular)

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11
Q

What is the treatment for paroxysmal supraventricular tachycardia?

A

Reflex vagal nerve stimulation (parasympathetic NS activated)

  • Face in ice cold water
  • Valsalva manoeuvre - motion used when straining on defecation

If ineffective: IV adenosine, verapamil

Recurrent episodes: catheter ablation OR anti-arrhythmic drugs

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12
Q

What is the treatment for ventricular arrhythmias?

A

Pulseless or fibrillation: CPR + defibrillator

Maintenance: high risk of cardiac arrest:

  • Cardioverter defibrillator implant OR
  • Anti-arrhythmic drug

Haemodynamic instability: Direct current

  • Stable + sustained: IV anti-arrhythmic drug
  • Non-sustained: beta blocker
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13
Q

What is tosade de pointes caused by?

A
  • Drugs that prolong QT prolongation
  • Hypokalaemia
  • Bradycardia (severe)
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14
Q

What are the symptoms of torsade de pointes?

A
  • Syncope
  • Seizures
  • Palpitations
  • Dyspnoea
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15
Q

What is the treatment for torsade de pointes?

A

IV magnesium sulphate

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16
Q

What is in Class I of the vaughn william classification?

A

Na+ channel blockers
- Flecainide (avoid in structural/IHD + CI in asthma)

17
Q

What is in Class II of the vaughn william classification?

A

Betablockers

18
Q

What is in Class III of the vaughn william classification?

A

K+ channel blockers
- Amiodarone
- Sotalol
- Dronedarone (hepatotoxicity and HF side effects)

19
Q

What is in Class IV of the vaughn william classification?

A

Rate limiting Ca2+ channel blockers
- Diltiazem
- Verapamil

20
Q

Which anti-arrhythmic drug is CI in asthma/COPD?

A

Adenosine + flecainide

21
Q

What is the MOA of amiodarone?

A

Blocks K+ channels that repolarise heart during phase 3 of cardiac action potential

22
Q

What is the indication of amiodarone?

A
  • Arrhythmias
  • CPR: revive pts w pulseless ventricular tachycardia/fibrillation
23
Q

What is the oral loading dose of amiodarone?

A
  • 200mg TDS - 1 week, BD - 1 week,
  • OD maintenance
24
Q

What are the side effects of amiodarone?

A

Corneal micro-deposits - crystals form in outer layer of eye causing glares + halos

Optic neuropathy

Grey skin

Phototoxicity
- broad spec SPF sunscreen for several months after stopping

Pulmonary toxicity

Thyroid dysfunction

Hepatotoxicity
- Monitoring: LFTs. Stop if 3x AST + ALT

Peripheral neuropathy - pins + needles. Numbness

QT prolongation

25
Q

What is the MHRA alert for amiodarone?

A

Serious side effects may persist for a month/longer after stopping (long HL). Regular reviews. Monitor: LFT + TFT. CT scan if pulmonary toxicity suspected

26
Q

What are the interactions of amiodarone?

A
  • Enzyme inhibitors → inc amiodarone levels, risk of toxicity
  • Amiodarone is an enzyme inhibitor → inhibits metabolism of other drugs (Digoxin - half dose of digoxin)
  • Beta-blockers, digoxin → bradycardia
  • Rate limiting CCB → cardio depression
  • Statins → rhabdomyolysis (Simvastatin: max dose 20mg)
  • QT prolongation - Drugs that cause hypokalaemia inc risk of torsade de pointes
  • Isoniazid, metronidazole, nitrofurantoin, phenytoin, vinca alkaloid → peripheral neuropathy
27
Q

What is the MOA of digoxin?

A
  • Derived from fox glove plant
  • Inc force of contraction by inhibiting Na+/K+ ATPase in myocardium
  • Dec HR + SA node automaticity + AV node conductivity
28
Q

What is the indication of digoxin?

A
  • Sedentary patients with non paroxysmal atrial fibrillation
  • Heart failure
29
Q

What is the therapeutic index of digoxin and when should you monitor digoxin levels?

A

0.8 - 2MCG/L
- Samples taken 6 hours after dose
- If stable: no regular monitoring unless: Suspected toxicity OR RI (digoxin renally cleared)

30
Q

What is the dose for digoxin?

A

Determined by RI + lower in elderly

Loading - rapid treatment in AF to restore sinus rhythm

Maintenance: OD

  • Non-paroxysmal AF in sedentary patients: 125 - 240mcg
  • Worsening or severe HF: 62.5 - 125mcg
  • Switching from IV to oral: inc dose by 20% - 33% to maintain same digoxin levels
31
Q

What are the signs of digoxin toxicity?

A
  • Acute: N+V, diarrhoea, abdominal pain
  • Chronic: yellow halos, confusion, delirium, arrhythmias
32
Q

What increases the risk of digoxin toxicity?

A

Hypokalaemia: acts on same site as K on Na/K ATPase pumps, when potassium levels are low digoxin combined more easily inc effect

  • Co-prescribe: potassium sparing diuretic

Renal impairment

Hypomagnesia

Hypercalcaemia

33
Q

What are the interactions of digoxin?

A
  • Hypokalaemia → predisposes digoxin toxicity
  • Dose adjustment: 1/2 digoxin dose: amiodarone, quinine, dronedarone
  • Inducers → RED digoxin levels = therapeutic failure
  • ACEi/ARB, NSAIDs → RED renal excretion = toxicity
  • Beta-blockers, rate limiting CCB → bradycardia
  • Hypercalaemia (Vit D + calcium supplement) → predispose to digoxin toxicity

High - Cardiovascular system (7 decks)

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