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Year 1-Cardiovascular System > Arrhythmia Therapies > Flashcards

Arrhythmia Therapies Flashcards

1
Q

What is an arrhyhmia?

A

A deviation from the normal heart rhythm

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2
Q

What is sinus arrhythmia?

A

Irregular heart rhythm. Normal in most cases

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3
Q

What are the two main groups of tachyarrhythmias?

A

Supraventricular arrhythmia
Ventricular arrhythmia

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4
Q

What is the difference between ventricular defibrillation and ventricular tachycardia?

A

VT- rapid, regular tachycardia
VF- rapid, irregular tachycardia

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5
Q

RECAP- what is the conc. of the inside of a cell compared to the outside?

A

Negative

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6
Q

Discuss what happens to charge when an action potential occurs.

A

Starts off negative, is positive during depolarisation and goes negative upon repolarisation

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7
Q

In terms of the Vaughan-William’s classification, what channels do class one antiarrhythmics act on?

A

Sodium channels

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8
Q

In terms of the Vaughan-William’s classification, what channels do class two antiarrhythmics act on?

A

Beta adrenergic receptors.

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9
Q

In terms of the Vaughan-William’s classification, what channels do class three antiarrhythmics act on?

A

Potassium channels

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10
Q

In terms of the Vaughan-William’s classification, what channels do class four antiarrhythmics act on?

A

Calcium channels

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11
Q

In terms of the Vaughan-William’s classification, what channels do class five antiarrhythmics act on?

A

Any other than classes 1-4

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12
Q

What do sodium channel blocker drugs do (class 1)?

A

Membrane-stabilizing agents so-
-Decrease the amplitude (size of Action potential)
-Reduce velocity of conduction/Excitability

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13
Q

Class one sodium channel blocker drugs are divided into which three subdivions?

A

A, B, C

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14
Q

Give an example of a Class 1A sodium channel blocker.

A

Quinidine

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15
Q

Give an example of a Class 1B sodium channel blocker.

A

Lidocaine

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16
Q

Give an example of a Class 1C sodium channel blocker.

This is the most clinically used one so good to remember it :)

A

Flecainide

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17
Q

Describe the effect flecainide has on the action potential.

A

Slows down depolarisation and shortens the plateau phase

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18
Q

Give three examples of common beta-blockers (class 2).

A

Atenolol, bisoprolol, propranolol

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19
Q

What do beta blockers do?

A

Acts via β1 receptors to block sympathetic stimulation of the heart

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20
Q

Describe the effect of beta blockers on the action potential.

A

Prolongs phase 4 depolarization
Shortens plateau phase

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21
Q

What is the first line choice of medication for atrial fibrillation?

A

Beta blockers, usually bisoprolol

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22
Q

Give some examples of potassium blockers (class 3).

A

Amiodarone, bretylium, sotalol

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23
Q

Describe the effect of potassium channel blockers on the action potential.

A

Increases the duration of the action potential by prolonging repolarisation in phase three and the effective refectory period.

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24
Q

Which potassium channel blocker is most commonly used?

A

Amiodarone

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25
Q

Give two examples of calcium channel blockers.

A

Verapamil, diltiazem

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26
Q

Describe the effect of calcium channel blockers on the action potential.

A

Depress phase 4 depolarization in SA and AV nodes, slowing the heart rate
Shorten phase 2 Plateau phase (reduce contractility)

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27
Q

What are two important drugs in Class 5?

A

Digoxin, adenosine

28
Q

What does digoxin do?

A

Inhibits the sodium-potassium ATPase pump

29
Q

Describe the effect of digoxin on the action potential.

A

Reduces the refractory period in myocardium

30
Q

When might you use digoxin?

A

In patients with particularly troublesome to control atrial defibrillation
or atrial flutter

Second line treatment so might be prescribed alongside something else

31
Q

On an ECG, what would be a sign of digoxin toxicity?

A

‘Reverse tick’ appearance of ST segment in lateral leads

32
Q

What is one of the issues when trying to treat digoxin toxicity?

A

It has a long half life

33
Q

When is digoxin toxicity more severe?

A

When potassium levels are low

34
Q

What does adenosine do?

A

Blocks conduction of the AV node

35
Q

What is adenosine used for?

A

Used to convert paroxysmal supraventricular tachycardia to sinus rhythm

36
Q

What is the half life like for adenosine?

A

Very short

37
Q

What can antiarrhythmic drugs end up causing?

A

Arrhythmia

38
Q

What is the most common type of arrhythmia?

A

Atrial fibrillation

39
Q

What score can identify a patient’s risk of a stroke?

A

CHADS-VASC score

40
Q

What is important to note about the CHADS-VASC score?

A

If you are over 75, you get two points, <75=1 point

41
Q

Who is more at risk of having a stroke due to atrial fibrillation- men or women?

A

Women

42
Q

What is the CHADS-VASC score?

A

A scoring method used to see how likely someone is to have a stroke due to atrial fibrillation.

43
Q

A CHADS-VASC score or 2 or greater suggests what?

A

Moderate/high risk of stroke

44
Q

A CHADS-VASC score of one suggest?

A

Low/moderate risk of stroke

45
Q

What are some of the risks of using the drugs warfarin and clopidogrel?

A

Can cause bleeding, like anticoagulants

46
Q

What are the three main groups of anticoagulants?

A

Vitamin K antagonist
Direct Thrombin Inhibitor
Direct Xa (10a) inhibitors

47
Q

Give an example of a vitamin K anticoagulant.

A

Warfarin

48
Q

Give an example of a direct thrombin inhibitor.

A

Dabigatran

49
Q

List some direct xa (10a)inhibitors.

A

Rivaroxaban,
Apixaban,
Edoxaban

50
Q

What do direct thrombin inhibitors, like dabigatran, do?

A

Prevents activation of fibrinogen into fibrin.

51
Q

What do direct xa inhibitors do?

A

They inhibit factor 10a production, preventing prothrombin being converted into thrombin.

52
Q

How does warfarin work?

A

Inhibits Vitamin K epoxide reductase
Reduced levels of vitamin K

53
Q

What happens when there are reduced levels of vitamin K?

A

Cannot produce clotting factors

54
Q

How can you monitor warfarin therapy?

A

By measuring the INR (international normal ratio)

55
Q

How is INR calculated?

A

Standard PROTHROMBIN time

56
Q

What are the main adverse effects of warfarin?

A

-Can cause bleeding
-Can interact with many other drugs
-Has to be avoided in some phases in pregnancy

57
Q

Which score calculates a patient’s risk of bleeding while on warfarin?

A

HAS-BLED score

58
Q

How does aspirin and Sulfonamides increase the activity of warfarin?

A

Decreased binding to albumin, leading to an increase in INR

59
Q

How can antibiotics increase the activity of warfarin?

A

Antibiotics interfere with the absorption of vitamin K so reduced clotting factors

60
Q

Which drugs can interact with warfarin and increase risks of bleeding?

A

Anticoagulants like aspirin
Heparin antimetabolites

61
Q

How can aspirin interact with warfarin to increase bleeding risks?

A

They affect platelet function

62
Q

How can vitamin K decrease warfarin activity?

A

Promotes clotting factor synthesis

63
Q

List some of the inhibitors of cytochrome P450

A

I am not expected you to remember these all, lecturer just said it was a good idea to have a basic idea of inhibitors/ inducers :)

Omeprazole
Disulfiram
Erythromycin
Valproate
Isoniazid
Ciprofloxacin and Cimetidine
Ethanol (acutely)
Sulphonamides

64
Q

List some of the inducers of cytochrome p450

A

I am not expected you to remember these all, lecturer just said it was a good idea to have a basic idea of inhibitors/ inducers :)

Alcohol (chronic use)
Barbiturates
Carbamazepine
Phenytoin
Rifampicin
Sulphonylureas

65
Q

How can cytochrome p450 have an effect on the activity of warfarin?

A

Warfarin is metabolised by cytochrome p450 enzymes

Year 1-Cardiovascular System (41 decks)

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