Arrhythmias

Question 1

What HR is considered bradycardia?

Answer 1

<60 bpm (<50 bpm when asleep)

Question 1

What are arrhythmias?

Answer 1

Arrhythmias are common disturbances of cardiac rhythm which are:
*Often benign, but may reflect underlying heart disease
*Often intermittent, causing diagnostic difficulty
*Occasionally severe, causing cardiac compromise

Question 2

What HR is considered tachycardia?

Answer 2

> 100 bpm

Question 3

What are the two broad groups of tachycardia?

Answer 3

1) supraventricular tachycardia
2) ventricular tachycardia

Question 4

What structure acts as the pacemaker of the heart?

Answer 4

SAN

Question 5

What branch of the nervous system acts to slow the activity of the SAN?

Answer 5

parasympathetic nervous system

Question 6

Give an example of a hormone that can accelerate automacy of cardiac depolarisation:

Answer 6

adrenaline from sympathetic stimulation can produce sinus tachycardia

Question 7

What constitutes ‘supraventricular’ rhythms?

Answer 7

1. Sinus rhythm
2. Atrial rhythm
3. Junctional rhythm

Question 8

Describe how abnormal oscillations can come about in cardiac tissue:

Answer 8

myocardial damage can result on oscillations at the end of the action potential called ‘after depolarisation’

Question 9

Give 4 factors that may exaggerate abnormal oscillations of the heart:

Answer 9

1) catecholamines
2) electrolyte disturbances
3) hypoxia
4) acidosis

Question 10

What is cardiac re-entry?

Answer 10

when a ring of cardiac tissue surrounds an unexcitable core (e.g. region of scarred myocardium) resulting in electric signals not completing the normal circuit, but rather an alternative circuit looping back upon itself

Question 11

Give 2 intrinsic causes of bradycardia:

Answer 11

1) acute ischaemia and infarction of the SAN
2) chronic degenerative changes such as fibrosis of the atrium and SAN

Question 12

Give 5 extrinsic causes of tachycardia:

Answer 12

1) hypothermia
2) hypothyroidism
3) raised intracranial pressure
4) beta blockers
5) antiarrhythmic drugs like digoxin

Question 13

What is sick sinus syndrome?

Answer 13

Physiologically inappropriate sinus bradycardia, sinus pause, sinus arrest, or episodes of alternating sinus tachycardia and sinus bradycardia

Question 14

What usually causes sick sinus syndrome?

Answer 14

idiopathic fibrosis

Question 15

What are the two broad management approaches for sinus bradycardia?

Answer 15

1) remove any extrinsic factors (e.g. hypothermia, beta blockers)
2) pacemaker

Question 16

What is heart block?

Answer 16

a conduction abnormality in either the AV node of conducting tissue of the heart

Question 17

Where is the block found in atrioventricular block?

Answer 17

AV node or bundle of His

Question 18

Where is the block found in bundle branch block?

Answer 18

lower conducting system (e.g. Purkinje fibres)

Question 19

What is first degree atrioventricular bloack?

Answer 19

prolonging of the PR interval to more than 0.2 seconds followed by conduction of the ventricles for each P wave

Question 20

What is second-degree atrioventricular block?

Answer 20

Where P waves conduct and others do not

Question 21

What are the three types of second-degree atrioventricular block?

Answer 21

1) Mobitz I block
2) Mobitz II block
3) 2:1 or 3:1 (advanced) block)

Question 22

Is AF narrow complex or broad complex?

Answer 22

Narrow

Question 23

What are class I antiarrhythmic drugs?

Answer 23

membrane depressant drugs that reduce the entry of Na+ into the cell which slows conduction or reduces spontaneous activity

Question 24

How do Class Ia antiarrhythmic drugs work?

Answer 24

they lengthen the action potential

Question 25

Give an example of a Class I antiarrhythmic drug:

Answer 25

disopyramide

Question 26

Give two examples of Class Ib antiarrhythmic drugs:

Answer 26

1) lidocaine
2) mexiletine

Question 27

How do Class Ib antiarrhythmic drugs work?

Answer 27

they shorten the action potential

Question 28

Give an example of a Ic antiarrythmic durg:

Answer 28

flecainide

Question 29

What are class II antiarrhythmic drugs?

Answer 29

drugs and affect and prevent the effects of catecholamines of the action potential (beta-adrenoceptors)

Question 30

Give an example of a class II antiarrhtymic drug:

Answer 30

bisprolol (beta blockers)

Question 31

What are class III antiarrytmic drugs?

Answer 31

drugs that prolong the action potential by blocking the K+ current

Question 32

Give two examples of class III antiarrythmic drugs?

Answer 32

1) amiodarone
2) sotalol

Question 33

What are class IV antiarrythmic drugs?

Answer 33

non dihydropyridine calcium-channel blockers that act to slow conduction of nodal tissue

Question 34

Give two examples of class IV antiarrythmic drugs:

Answer 34

1) diltiazem
2) verapamil