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Systems: Cardiovascualar AB > Arrythmias: Therapy > Flashcards

Arrythmias: Therapy Flashcards

1
Q

What is an arrhythmia?

A

Any deviation from the normal rhythm of the heart

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2
Q

What are the 4 major classes of arrhythmias?

A
  • Sinus arrhythmia
  • Supraventricular arrhythmia
  • Ventricular arrhythmia
  • Heart block
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3
Q

What is responsible for the resting membrane potential?

A
  • Inside the cardiac cell there is a net negative charge relative to the outside of the cell
  • Due to uneven distribution of ions across the membrane
  • Sodium potassium ATPase pump maintains this
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4
Q

What causes cardiac cells to become excited?

A

A change in distribution of ions

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5
Q

What results in the propagation of the electrical impulse?

A

Movement of ions across the cardiac cell’s membrane

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6
Q

What does the electrical impulse lead to?

A

Contraction of the myocardial muscle

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7
Q

What is the Vaughan-Williams classification of drugs to treat arrhythmias?

A
  • Class Ia
  • Class Ib
  • Class Ic
  • Class II
  • Class III
  • Class IV
  • Other
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8
Q

What is the electrophysiological property of class IA drugs?

A

Fast sodium-channel blockade

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9
Q

What is the electrophysiological property of class IB drugs?

A

Intermediate sodium-channel blockade

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10
Q

What is the electrophysiological property of class IC drugs?

A

Slow sodium-channel blockade

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11
Q

What is the electrophysiological property of class II drugs?

A

B-Adrenergic receptor antagonism

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12
Q

What is the electrophysiological property of class III drugs?

A

Prolong refractoriness

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13
Q

What is the electrophysiological property of class IV drugs?

A

Calcium channel blockade

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14
Q

Give 3 examples of class IA drugs.

A
  • Quinidine
  • Procainamide
  • Dispyramide
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15
Q

Give 4 examples of class IB drugs.

A
  • Lidocaine
  • Mexiletine
  • Tocainide
  • Phenytoin
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16
Q

Give 2 examples of class IC drugs.

A
  • Flecainide

- Propafenone

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17
Q

Give 2 examples of class II drugs.

A
  • Atenolol

- Bisoprolol

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18
Q

Give 3 examples of class III drugs.

A
  • Amiodarone
  • Bretylium
  • Sotalol
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19
Q

Give 2 examples of class IV drugs.

A
  • Diltiazem

- Verapamil

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20
Q

What do class I drugs do?

A

Stabilise membrane

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21
Q

What do class IA drugs do?

A
  • Block sodium channels
  • Delay repolarisation
  • Increase action potential duration
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22
Q

What are class IA drugs used to treat?

A
  • Atrial fibrillation
  • Premature atrial contractions
  • Premature ventricular contractions
  • VT
  • Wolff-Parkinson-White syndrome
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23
Q

What do class IB drugs do?

A
  • Block sodium channels
  • Accelerate repolarisation
  • Decrease the action potential duration
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24
Q

What are class IB drugs used to treat?

A

Ventricular dysrthmias only

  • Premature ventricular contractions
  • VT
  • VF
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25
Q

What do class IC drugs do?

A
  • Block sodium channels (more pronounced effect)

- Little effect on action potential duration or repolarisation

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26
Q

What are class IC drugs used to treat?

A
  • Sever ventricular dysrthmias

- Can be used for atrial fibrillation/flutter

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27
Q

What are class II drugs otherwise known as?

A

B-blockers

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28
Q

What do class II drugs do?

A
  • Reduce or block sympathetic nervous system stimulation, thus reducing transmission of impulses in the heart’s conduction system
  • Depress phase 4 depolarisation
  • General myocardial depressants for both supraventricular and ventricular dysrhythmias
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29
Q

What is now the first line for atrial fibrillation?

A

Bisoprolol

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30
Q

What do class III drugs do?

A
  • Increase action potential duration

- Prolong repolarisation in phase 3

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31
Q

What are class III drugs used to treat?

A
  • Dysrythmias that are difficult to treat
  • Life-threatening VT or VF, atrial fibrillation/flutter resistant to other drugs
  • Sustained VT
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32
Q

What do class IV drugs do?

A

-Depress phase 4 depolarisation

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33
Q

What are class IV drugs used to treat?

A
  • Paroxysmal supraventricular tachycardia

- Rate control for atrial fibrillation and flutter

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34
Q

Why do other antidysrhythmics not place in a class?

A

They have properties of several classes

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35
Q

What is digoxin?

A

Cardiac glycoside

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36
Q

What does digoxin do?

A
  • Inhibits the sodium potassium ATPase pump
  • Positive inotrope: improves the strength of cardiac contraction
  • Allows more calcium to be available
37
Q

What is digoxin used to treat?

A
  • Heart failure

- Atrial dysrhythmias

38
Q

What must be monitored with digoxin?

A

-Potassium levels and drug levels for toxicity

39
Q

Who is digoxin commonly used in?

A

The elderly

40
Q

What is important to note with digoxin and the elderly?

A
  • Many have renal impairment

- Digoxin is not effectively removed by dialysis

41
Q

What is the half life of digoxin?

A

36-48 hours

42
Q

What are the signs and symptoms of digoxin toxicity?

A
  • Reverse tick appearance of ST segment in lateral leads
  • Nausea and vomiting
  • Xanthopsia
  • Bradycardia
  • Tachycardia
  • VT and VF
43
Q

How is digoxin toxicity treated?

A
  • Stop digoxin (long half life)

- If levels are very high and risk of significant arrhythmia then give Digiband

44
Q

What is Digiband?

A
  • Digoxin immune antibody
  • Binds with digoxin, forming complex molecules
  • Excreted in urine
45
Q

When is digoxin toxicity more serious?

A

If potassium levels are low

46
Q

What is amiodarone used for?

A
  • VT

- Occasionally SVT

47
Q

What does amiodarone interact with?

A

-Many other drugs but mainly digoxin

48
Q

What are the side effects of amiodarone?

A
  • Hypo/hyperthyroidism
  • Pulmonary fibrosis
  • Grey pigmentation
  • Corneal deposits
  • LFT abnormalities
49
Q

What is adenosine used for?

A

To convert paroxysmal SVT to sinus rhythm

50
Q

What does adenosine do?

A

Slows conduction through the AV node

51
Q

What type of half life does adenosine have?

A

Short half life

52
Q

How is adenosine administered?

A

Fast IV push

53
Q

What can happen after adenosine is administered?

A

May cause asystole for a few seconds

54
Q

What can all antiarrhythmics cause?

A

Arrythmias

55
Q

What are the indications for anticoagulation?

A
  • Atrial fibrillation
  • Risk of stroke
  • Peripheral emboli
  • Valvular heart disease
  • VTE
  • DVT/PE
  • Following surgery
  • Immobilisation
56
Q

Give examples of anti-coagulation drugs.

A
  • Warfarin
  • Dabigatran
  • Rivaroxaban
  • Apixaban
  • Edoxaban
57
Q

What is arterial thrombosis caused by?

A

Adherence of platelets to arterial walls

58
Q

Describe an arterial thrombus.

A
  • White in colour

- Full of platelets/cells

59
Q

What are arterial thrombi associated with?

A
  • MI
  • Stroke
  • Ischaemia
60
Q

What is venous thrombosis caused by?

A

Stagnant blood flow

61
Q

Describe a venous thrombus.

A
  • Red in colour

- Full of fibrin particles

62
Q

What are venous thrombi associated with?

A
  • Congestive heart failure
  • Cancer
  • Surgery
63
Q

Where does warfarin come from?

A

Sweet clover

64
Q

What is warfarin used as?

A

Rat poison

65
Q

What is warfarin structurally related to?

A

Vitamin K

66
Q

What does warfarin do?

A

Inhibits production of active clotting factors

67
Q

How is a warfarin overdose treated?

A

Vitamin K

68
Q

Why do some drugs increase warfarin activity?

A
  • Decrease synthesis of clotting factors
  • Inhibit degradation
  • Decrease binding to albumin
69
Q

What drugs decrease binding to albumin?

A
  • Aspirin

- Sulfonamides

70
Q

Why do some drugs promote bleeding?

A
  • Inhibition of clotting factors

- Inhibition of platelets

71
Q

What drugs inhibit platelets?

A

Aspirin

72
Q

What drugs inhibit clotting factors?

A
  • Heparin

- Antimetabolites

73
Q

Why do some drugs decrease warfarin activity?

A
  • Induction of metabolising enzymes (cytochrome P450)
  • Promote clotting factor synthesis
  • reduced absorption
74
Q

What drugs induce cytochrome P450?

A
  • Barbiturates

- Phenytoin

75
Q

What drugs promote clotting factor synthesis?

A

Vitamin K

76
Q

What drugs reduce absorption?

A

Cholestyramine

77
Q

What drugs inhibit degradation?

A
  • Cimetidine

- Disulfiram

78
Q

What drugs decrease the synthesis of clotting factors?

A

-Oral antibiotics

79
Q

What does the direct effect of warfarin depend on?

A
  • Concentration of warfarin in the liver

- Rate of accumulation of warfarin

80
Q

Why does heparin have to be given first for DVT?

A

Warfarin has a long half life which means it has a slow onset of action

81
Q

Describe the use of INR.

A
  • International normalised ratio
  • Actual thromplastin time divided by standard thromboplastin time
  • Normal INR is1
  • Therapeutic INR is normally 2.5-4
82
Q

What are the adverse effects of warfarin?

A
  • Bleeding
  • Teratogenic (chondrodysplasia)
  • Retroplacental bleeding and foetal intracerebral bleeding
83
Q

How is warfarin therapy monitored?

A
  • Regular INR
  • Watch if therapy is altered
  • Patient education
  • Alcohol intake
84
Q

What type of drugs can warfarin interact with?

A
  • Macrolide antibiotics
  • Antifungals
  • Anti-epileptic drugs
85
Q

How is bleeding risk assessed on warfarin?

A

-CHADS2 score

86
Q

What is the CHADS2 score?

A
  • Congestive heart failure
  • Hypertension
  • Age>75
  • Diabetes mellitus
  • Stroke/TIA
87
Q

What are the characteristics of the ideal anticoagulant?

A
  • Oral
  • No need for monitoring
  • No interaction with food or drugs
  • Given once or twice a day/ fixed dose irrespective of body weight/age
  • As effective as warfarin
  • Safer than warfarin
88
Q

Give 2 examples of direct thrombin inhibitors.

A
  • Dabigatran

- Apixaban

89
Q

What is rivaroxaban?

A

Factor Xa inhibitor

Systems: Cardiovascualar AB (42 decks)

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