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Cardiovascular System > TORSADES DE POINTES [QT INTERVAL PROLONGATION] > Flashcards

TORSADES DE POINTES [QT INTERVAL PROLONGATION] Flashcards

1
Q

What is Torsades de pointes?

A

A type of arrhythmia.

This is where the heart beats in a very unusual way, typically very fast, causing not enough oxygen to be pumped around the body and the brain is starved of oxygen,
leading to blackouts, fainting, and even death.

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2
Q

Causes of Torsades De Pointes?

A
  • Stress
  • Strenuous exercise
  • Sudden noise
  • Drugs, e.g. sotalol
  • Hypokalaemia (low potassium)
  • Bradycardia
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3
Q

What is the drug treatment for Torsades De Pointes?

A

IV Magnesium Sulphide

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4
Q

What drugs cause QT Interval Prolongation?

A

ABCs of QT Interval prolongation

  • AntiArrhythmics (amiodarone, sotalol, flecainide)
  • AntiBiotics (quinolones, macrolides, aminoglycosides)
  • AntipsyChotics (haloperidol, quetiapine, risperidone)
  • AntiDepressants (SSRIs, tricyclic antidepressants)

*Diuretics

  • AntiEmetics (ondansetron)
  • AntiFungals (azoles)
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5
Q

What is Amiodarone used for?

A

To treat arrhythmias

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6
Q

What is the adult dose for Amiodarone?

A

200mg THREE times a day for 1 week,
then 200mg TWICE a day for 1 week,
then 200mg daily (Maintenance dose)

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7
Q

What are the side effects of Amiodarone?

A

Acronym PHOTOgenicBITCH:

  • Phototoxicity - slate grey skin
  • Photosensitivity and Peripheral Neuropathy
  • Bradycardia
  • Interstitial lung disease
  • Thyroid Issues (Hyper/Hypo)
  • Corneal Microdeposits (occular)
  • Hepatoxicity - discontinue if signs of liver disease
  • Optic neuropathy (can cause blindless) - stop is vision is impaired
  • Pulmonary toxicity - Suspect pneumonitis if progressive shortness of breath or dry cough develops.
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8
Q

What is corneal microdeposits?

A

Dazzled by headlights at night.

This can be reversed when patient stops taking amiodarone.

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9
Q

Why does Amiodarone cause hypo and hyper thyroidism?

A

Because it contains iodine, which causes disorder of thyroid function.
Therefore amiodarone should be avoided in patients with thyroid disorders.

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10
Q

What are signs of hepatoxicity?

A

Nausea, vomiting, jaundice, abdominal pain, malaise, 3 raised liver enzymes

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11
Q

What is Peripheral Neuropathy?

A

Tingling and numbness in hands and feet

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12
Q

What are the patient carer advice for Amiodarone?

A
  • Shield skin from sunlight during and for several months after treatment
  • Use a wide spectrum sunscreen - at least SPF 30
  • Seek medical attention if:
    • Shortness of breath
    • Light headaches
    • Unusual tiredness
    • Fainting
    • Palpitations
    • Chest pain
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13
Q

What are the contraindications of Amiodarone?

A
  • Iodine sensitivity
  • Thyroid dysfunction
  • Very asthmatic
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14
Q

What are the monitoring requirements for Amiodarone?

A
  • Thyroid function test (before treatment and every 6 months)
  • Liver function test (before treatment and every 6 months, monitor liver transaminases closely)
  • Serum potassium concentration - causes hypokalaemia
  • Chest X-Ray
  • Annual Eye Tests
  • Blood pressure
  • ECG (with IV use)
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15
Q

What are the interactions of Amiodarone?

A

Amiodarone has a long half life, so interactions can occur several weeks/ months after stopping the medication

  • Warfarin, digoxin, ciclosporin, phenytoin - increases plasma concentration
  • Lithium, - increases risk of arrhythmias
  • Statin - increases risk of myopathy
  • QT Prolongation drugs (abcdde) - a special caution with antidepressants, antipsychotics, lithium, macrolides and quinolones
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16
Q

What does Digoxin do?

A

It increases the force of myocardial contraction and decreases heart rate by reducing conductivity in atrio-ventricular node.

It helps control atrial fibrillation, atrial flutter and heart failure for patients in sinus rhythm

17
Q

How is the maintenance dose of digoxin determined?

A

The maintenance dose is determined by the ventricular rate at rest, which should not fall below 60bpm persistently.

Response may take several hours (even with IV), and is therefore not suitable for rapid heart rate control

18
Q

What route cannot be taken for Digoxin?

A

Intramuscular route is NOT recommended

19
Q

How many times a day is Digoxin usually taken for?

A

Usually once daily because Digoxin has a long half-life.

Very high doses may be divided to twice daily to prevent nausea

20
Q

What’s the maintenance dose for digoxin in Atrial Fibrillation or flutter?

A

125 to 250mcg once daily - loading dose required

21
Q

What’s the maintenance dose for digoxin in Worsening / severe heart failure (in sinus rhythm)?

A

62.5 to 125mcg once daily - no loading dose required

Reduce dose in elderly patient however

22
Q

What’s the Therapeutic and Toxic range for Digoxin?

A

Therapeutic range: 1 to 2 mcg/L

Toxic range: 1.5 to 3 mcg/L

23
Q

What should be done if toxicity occurs?

A

Withdraw digoxin and reverse with digoxin-specific antibody fragments

24
Q

What is the dose of digoxin based on?

A

Renal function

25
Q

What drugs are normally given with digoxin?

A

K+ sparing diuretics like Spironolactone or k+ supplements to prevent hypokalaemia.

Because low potassium increases digoxin toxicity.

26
Q

What levels should be monitored when taking digoxin?

A

-Magnesium

Low magnesium (hypomagnesemia) can also lead to digoxin toxicity.

  • Calcium
    High calcium levels (hypercalcaemia) can also increase digoxin toxicity

Low oxygen also leads to digoxin toxicity

27
Q

What should be done if toxicity occurs with digoxin?

A

Withdraw digoxin

If life threatening overdose, reverse with ‘digoxin specific antibody fragments’ (digibind).
This is normally used when life threatening associated with ventricular arrhythmias.

28
Q

What are the side effects of digoxin?

A
  • Arrhythmias
  • Cardiac conduction disorder
  • Diarrhoea
  • Dizziness
  • Nausea
  • Vomiting
  • Skin reaction
  • Vision disorders (yellow vision)
29
Q

What do you monitor with digoxin?

A

Plasma-digoxin concentration - blood taken at least 6 hours after a dose

Serum electrolyte

Renal function - reduce dose in renal impairment

Potassium, calcium and oxygen levels

30
Q

What are the important digoxin interactions?

A

CRASED

C- Calcium channel blockers (verapamil)
R- Rifampicin
A- Amiodarone
ST - John wort
E- Erythromycin
D- Diuretics

Drugs which reduce renal excretion - NSAIDs, ACE/ARBs

Drugs which decrease dioxin concentration - st john worts, rifampicin

Drugs which increase digoxin concentration - macrolides, amiodarone, rate limiting CCB

Drugs which decrease potassium - diuretic, steroids, theophylline

31
Q

What do antifibrinolytic drugs and haemostatics do?

A

Stop bleeding

32
Q

Example of anti-fibrinolytic?

A

Tranexamic acid

33
Q

What’s the dose of tranexamic acid for management of menorrhagia?

A
  • 1g 3 times a day for up to 4 days
  • Initiate when menstruation starts
  • Max 4g per day
33
Q

What are the indications for tranexamic acid?

A
  • Management of menorrhagia
  • Hereditary angioedema
  • Epistaxis
  • General fibrinolysis
  • Thrombolytic

Cardiovascular System (9 decks)

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