Tachyarrhythmias Flashcards Preview

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Flashcards in Tachyarrhythmias Deck (67):
1

What is an arrhythmia?

An abnormality of cardiac rhythm

2

What can arrhythmias cause?

Sudden death
Syncope
Dizziness
Palpitations
Asymptomatic

3

What are the two broad categories of arrhythmias?

Describe them briefly!

Bradycardia: slow HR, less than 60 bpm

Tachycardia: fast HR, more than 100 bpm

4

What categories can tachycardias be subdivided into?

Describe them!

Supraventricular tachycardias (SVT)
- arise from the atria or atrioventricular junction

Ventricular tachycardias
- arise from the ventricles

5

What is meant by sinus rhythm?

Rhythm controlled by the sinus node!

6

What is the normal cardiac pacemaker?

The sinus node

7

What is the sinus node?
What controls it?

A collection of cells found in the upper wall of the RA
It is the main pacemaker of the cell

It is controlled by the autonomic nervous system

8

What is sinus arrhythmia?

Arrhythmia caused by changes in the sinus rhythm, specifically the sinus discharge rate

9

What is sinus tachycardia?
Is it necessarily a bad thing?

Increase in sinus rhythm causing an increase in heart rate

No, it occurs naturally in response to exercise + excitement

It also occurs in response to fever, anaemia, heart failure, acute PE, and many more

10

What causes an arrhythmia? There are two mechanisms.

Cardiac rhythm not being generated correctly by SAN

Cardiac rhythm id generated correctly by SAN but is not conducted properly through the heart

11

What is re-entry?

Don't describe

A process that occurs in the heart that is the cause of many types of arrhythmia

Involves the formation of abnormal electrical circuits in the heart

12

Describe what re-entry is, use the AV node as an example.

There are 2 pathways in the AVN, imagine a diamond shape, the pathways are on each side

- slow, with short refractory time
- fast, with long refractory time

In re-entry, the fast pathway gets transiently blocked, because a premature impulse from the SA node has meant the fast pathway is in its repolarisation phase so can't be depolarised

No impulses can travel down the pathway but the tissue is still excitable

Impulses travel down the slow pathway as normal, but when they get to the apex (where fast and slow meet) the impulses start to travel back up the fast pathway in the wrong direction

You get retrograde conduction up the fast pathway, creating a re-entry circuit

This leads to arrhythmias

13

In which node do re-entry circuits form?

AV node

14

What are ectopic beats?

Electrical disturbances that arise from tissue that is not part of the usual heart conduction system

Can be ventricular or atrial

Cause benign, non-sustained arrythmias

15

A patient complains of feeling missed heart beats, that feel a bit like a heart hiccup. What does this sound like?

Ectopic beats

16

What is the difference between a narrow and broad complex tachycardia?

Narrow: ventricles are depolarised by the Purkinje fibres still (narrow QRS complex)

Broad: ventricles are not depolarised by the Purkinje fibres (broad QRS complex)

17

Describe the electrical conduction of the heart?

Impulse generated by SAN

Travel down internodal pathways causing atrial depolarisation

Impulse reaches AVN

Down AV bundle

Down either R or L bundle branch

Into Purkinje fibres causing ventricular depolarisation

18

Name 4 supraventricular tachyarrhythmias?

Atrial fibrillation

Atrial flutter

AVNRT: atrioventricular nodal re-entry tachycardia

AVRT: atrioventricular re-entry tachycardia

19

What is atrial fibrillation?

The SA node is conducting impulses irregularly

Causing the atria to not contract properly

And, some (not all) of the chaotic SA impulses are conducted to the ventricles, causing an irregular heartbeat

20

What does an ECG of atrial fibrillation look like?

Irregularly irregular chaotic heart rhythm

No P waves visible
QRS complexes appear normal but they occur irregularly

21

Name and describe 3 types of atrial fibrillation?

Paroxysmal: spontaneous termination within 7 days

Persistent: not self-resolving, needs treatment by cardioversion

Permanent: long standing, over 1 year, not treatable by cardioversion

22

List some causes of atrial fibrillation?

Hypertension
CHD
Valve disease
Hyperthyroidism
Idiopathic

23

Clinical features of atrial fibrillation?

Asymptomatic
Palpitations
Dyspnoea
Syncope
Stroke

24

Why does atrial fibrillation cause strokes?

The blood in the atria becomes stagnant in the atria because the fibrillation means it can't be pumped out properly

Stagnant blood forms clots

25

Complications of atrial fibrillation?

Stroke or other clotting problem

Heart failure

Cardiomyopathy

26

Investigations of arrhythmias in general?

ECG
Bloods: including coagulation
CXR
ECHO

27

Management of atrial fibrillation?

HR control: beta blockers or sodium channel blocker (verapamil)

Rhythm control: electrical or chemical cardioversion

Thromboprophylaxis: warfarin, apixiban

28

What is atrial flutter?

Extremely fast atrial heart rate caused by re-entry circuits

The AV node conducts some but not all of the impulses from SAN to the ventricles

29

What is meant by 2:1 atrial flutter

Atrial flutter

Where the AV node is able to conduct every other impulse from the SAN to the ventricles

30

What is meant by 3:1 atrial flutter?

Atrial flutter

Where the AV node is only able to conduct every 1 in 3 impulse from the SAN to the ventricles

31

What would the ECG of atrial flutter look like?

Extremely fast atrial heart rate of about 300

Saw tooth pattern

Rapid, regular P waves

32

Causes of atrial flutter?

CHD
Atrial dilatation
Hypertension
Obesity

33

Presentation of atrial flutter?

Palpitations
Dyspnoea
Syncope
Heart failure
Stroke

34

Management of atrial flutter?

Cardioversion

Thromboprophylaxis

Ablation of the part of the heart causing the arrhythmia, the re-entry circuit

35

What does AVNRT stand for?

Atrioventricular nodal re-entry tachycardia

36

What is AVNRT?

An accessory conduction pathway arises in the heart, between the atrium and the AVN

Re-entry circuit is created causing arrhythmia

37

Causes of AVNRT?

Idiopathic, usually occurs in young adults, especially females

38

What would the ECG of AVNRT look like?

Rapid but normal QRS complexes

Followed immediately by P waves, caused by the retrograde excitation of the atria from the re-entry circuit

39

Presentation of AVNRT?

Palpitations
Chest pain
Syncope
Dyspnoea
Neck pulsation

40

Management of AVNRT?

Adenosine: can block the AV node so blocking the abnormal impulses from getting to ventricles

Ablation

Medication: beta blockers, calcium channel blockers

41

What does AVRT stand for?

Atrioventricular re-entry tachycardia?

42

What is AVRT?

An accessory conduction pathway arises connecting the atria to the ventricles

Re-entry circuit is formed causing arrhythmia

43

What complications can arise from AVRT? How does it occur?

Wolff-Parkinson White syndrome

When the re-entry circuit begins to travel in both directions

44

What causes Wolff-Parkinson White syndrome?

A congenital abnormality

45

Presentation of AVRT?

Palpitations
Syncope
Dizziness

46

What are the usual causes of ventricular tachycardias?

Ischaemic heart disease
Heart failure

Congenital cardiomyopathies and structural heart defects

47

List some ventricular tachycardias?

Ventricular fibrillation

Ventricular tachycardia

Torsade de pointes

Premature ventricular contractions

48

Is premature ventricular contraction a narrow or broad complex tachycardia?

Broad, because the contraction of the ventricles is not caused by the Purkinje fibres

Caused by ectopic beats arising in the ventricles

49

What is premature ventricular contraction?

Ventricular ectopic beats cause abnormal ventricular contraction

Contraction is slower than usual

These ectopic beats can occur randomly or in patterns

50

What would an ECG of premature ventricular contraction look like?

Premature broad QRS complexes

They can occur as a one off, or every other beat, or in patterns

51

Management of premature ventricular contraction?

None needed!

52

What is ventricular tachycardia (as a specific condition)?

A run of successive ventricular ectopic beats

That take the heart rate above 100bpm

Non-sustained = lasts less than 30 seconds

Sustained = lasts more than 30 seconds

53

Non-sustained vs sustained ventricular tachycardia?

Non-sustained: the ectopic beats last less than 30 seconds

Sustained: the ectopic beats last more than 30 seconds

54

What does the ECG of ventricular tachycardia (as a specific condition) look like?

Broad, odd looking QRS complexes that are all of the same shape

Like this: /\/\/\/\/\/\

Occasional P waves are seen super-imposed onto the QRS complexes

55

Presentation of ventricular tachycardia (as a specific condition)?

Syncope
Dyspnoea
Angina
Compromised CO
V-fib
Death

56

Management of Ventricular tachycardia?

Cardioversion

57

What is Torsades de Pointes?

Episodes of tachycardia interspersed with periods of bradycardia

58

Causes of Torsades de Pointes?

Long QT: congenital channelopathy

Drugs

59

Torsades de Pointes involves periods of tachycardia interspersed with periods of bradycardia

What are the risks that occur with each?

During the tachycardic sections there is a risk of going into V-fib and death

During the bradycardic sections you develop long QT which carries a risk of death as well

60

What would an ECG of Torsade de Pointes look like?

Varying amplitude of QRS

And varying width, indicating the tachy and bradycardic periods

Waxing and waning of QRS amplitude and width

61

Management of Torsade de Pointes?

Correct the underlying cause

If congenital, use beta blockers and implantable defibrillator

62

What is ventricular fibrillation?

Rapid, chaotic rhythm of ventricular contraction

Resulting in no CO, and often death if not treated quick enough

63

What would an ECG of V-fib look like?

Chaotic ventricular rhythm characterised by irregular wavelets of electrical contraction

No QRS complexes due to no ventricular contraction

64

Management of V-fib?

Urgent cardioversion

Drugs, implantable pacemaker

65

What does a delta wave look like on an ECG?
What pathology does it indicate?

A convex shape to the QR line

Indicates Wolff-Parkinson White syndrome

66

What is pulseless ventricular tachycardia?

1. HR greater than 180bpm

2. A very wide QRS complex.

3. Patient is pulseless

4. The rhythm originates in the ventricles

67

Treatment of pulseless ventricular tachycardia?

Cardioversion