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Cardiovascular system > Anti-arrythmics > Flashcards

Anti-arrythmics Flashcards

1
Q

What is meant by inotropy?

A

Modification of the force of contraction

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2
Q

What is meant by lusitropy?

A

Modification of the rate of relaxation (Length of Diastole)

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3
Q

What is meant by Chronotropy?

A

Modification of heart rate

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4
Q

What is Torsades de pointes?

A

A highly irregular form of arrhythmia

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5
Q

What is an arrhythmia?

A

A condition where there are disturbances to the electrophysiology of the heart

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6
Q

What are the 2 causes of arrhythmias?

A

Abnormal impulse formation
Abnormal impulse conduction

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7
Q

What are the 2 types of abnormal impulse formation?

A

Triggered rhythm
Automatic rhythm

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8
Q

What are the 2 types of Triggered rhythm?

A

Ectopic foci - APs arise from sites other than the SA node
Enhanced normal automaticity - More AP from SA node

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9
Q

What are the 2 types of Automatic rhythm?

A

Delayed After-Depolarisations
Early After-Depolarisations (Phase 2&3)

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10
Q

What are the 2 types of abnormal impulse conduction?

A

Conduction Block
Re-Entry

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11
Q

What are the 3 main types of Conduction block?

A

1st degree
2nd degree
3rd degree

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12
Q

What is meant by a 1st degree conduction block?

A

AV delay >0.2 ms without disrupting the hearts function

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13
Q

What is meant by a 2nd degree conduction block?

A

Intermittent failure of the heart to conduct between SA and AV nodes

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14
Q

What is meant by a 3rd degree conduction block?

A

Complete loss of communication between the atria and ventricles

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15
Q

What are the 2 types of Re-entrant arrhythmia?

A

Circus movement
Reflection

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16
Q

What is meant by circus movement?

A

Circular motion of electrical impulses in the heart leading to fluttering

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17
Q

What is meant by reflection?

A

Movement of electrical impulses forwards from the atria to the ventricles, and then back down the same pathway

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18
Q

What are the 6 classes of Vaughn-Williams anti-arrhythmic drugs?

A

Class 1a
Class 1b
Class 1c
Class 2
Class 3
Class 4

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19
Q

What is meant by a class 1 anti-arrhythmic drug?

A

Sodium channel blocker:
a = Moderate strength
b = Weak
c = Strong

20
Q

What is meant by a class 2 anti-arrhythmic drug?

A

ß-adrenoceptor blockers

21
Q

What is meant by a class 3 anti-arrhythmic drug?

A

Potassium channel blocker

22
Q

What is meant by a class 4 anti-arrhythmic drug?

A

Calcium channel blocker

23
Q

How do class 1 (Sodium channel blockers) anti-arrhythmics work?

A

Na+ channel blockers slow the depolarisation of the myocytes, preventing contraction which occurs by opening of Na+ channels

24
Q

What are the main uses of Class 1 (Na+ channel blockers) anti-arrhythmics?

A

They can be used in life-threatening ventricular arrhythmias, ischaemic tissue and inherited long QT syndrome

25
Q

What are some examples of Class 1 (Na+ channel blockers) anti-arrhythmics?

A

Lidocaine
Mexilitine

26
Q

How does lidocaine work?

A

Lidocaine is a type 1b anti-arrhythmic and a local anaesthetic
It only blocks inactive or open channels, so blocks damaged, depolarised tissue
It blocks during depolarisation and then rapidly dissociates

27
Q

How do Class 2 (ß-adrenoceptor blockers) anti-arrhythmics work?

A

ß1 adrenoceptors are bound to GßY and Gαs
Gαs ad GTP activates adenylyl cyclase
This converts AMP to cAMP
cAMP increases protein kinase A levels
Protein Kinase A leads to a shorter funny current
ß-adrenocpetors stop this and so increase the length of the funny current

28
Q

What are the 2 types of ß-blockers?

A

Cardio selective
Non-selective

29
Q

What are some examples of Cardio selective ß-blockers?

A

Atenolol
Bisoprolol
Carvedilol
Metoprolol

30
Q

What are some examples of non-selective ß-blockers?

A

Propranolol
Soltalol

31
Q

Why should asthmatics not be given non-selective ß-blockers?

A

They also act on ß2-adrenoceptors and thus can cause bronchospasm

32
Q

What are the main uses of Class 2 (ß-adrenoceptor blockers) anti-arrhythmics?

A

They can be used to manage non-sustained ventricular arrhythmias, atrial tachycardia, angina and hypertension

33
Q

What are the risks of Type 3 (K+ channel blockers) anti-arrhythmics?

A

They are extremely difficult to manage and can lead to Torsades de pointes, meaning they are only used in those who have tried other treatments

34
Q

How do Class 3 (K+ channel blockers) anti-arrhythmics work?

A

They decrease the probability of K+ influx leading to depolarisation.
This increases the length of the plateau in myocytes and thus, increases the length of the refractory period

35
Q

What is an example of a Class 3 (K+ channel blocker) anti-arrhythmic?

A

Amiodarone (Also has Class 1,2 and 4 actions)

36
Q

How can some Class 3 anti-arrhythmic become pro-arrhythmic?

A

Lengthening the refractory period should prevent another action potential occurring too soon, however, some can prolong the QT interval and thus become pro-arrhythmic

37
Q

What are some main uses of amiodarone?

A

It prolongs the action potential, mainly by blocking K+ channels, this can suppress tachyarrhythmias due to re-entry and can be used in atrial fibrillation

38
Q

How do Class 4 (Ca2+ channel blockers) anti-arrhythmic drugs work?

A

They block Ca2+ influx in the pacemaker cells of the SA node
This causes a delay in the depolarisation phase and extends the refractory period

39
Q

What are some examples of class 4 (Ca2+ channel blockers) anti-arrhythmic drugs

A

Verapamil
Diltiazem

40
Q

What are the main uses of Class 4 anti-arrhythmics?

A

They decrease aberrant pacemakers, conduction velocity and depolarisation
This blocks re-entrant rhythms such as supra ventricular tachycardia

41
Q

Where do Atrial and supra-ventricular arrhythmias occur?

A

In the Sino-Atrial or Atria-Ventricular Node

42
Q

Where do Ventricular arrhythmias occur?

A

In the common Bundle of His, bundle branches or Purkinje fibres

43
Q

What is atrial fibrillation?

A

A supra-ventricular tachyarrhythmia with uncoordinated atrial electrical activation and thus ineffective atrial contraction

44
Q

What is meant by a paroxysm?

A

A sudden attack or occurrence of symptoms

45
Q

How does Ivabradine work?

A

It blocks HCN Na+ channels and thus elongates the funny current

46
Q

How does Adenosine work?

A

It is a natural nucleoside that binds to adenosine A1 receptors
It alters opening of some K+ and Ca2+ channels
This slows AV nodal conduction
It also hyperpolarises the cell

Cardiovascular system (45 decks)

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