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CVS > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

Bradycardia

A

HR is slow (

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2
Q

Tachycardia

A

SHR is fast (>100 bpm)

More likely to be symptomatic when arrhythmia is fast and sustained

Subdivided into supra ventricular tachycardias (SVTs) and ventricular tachycardias (VTs)

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3
Q

What is the normal cardiac pacemaker?

A

the sinus node

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4
Q

What controls the sinus node?

A

Autonomic nervous system with parasympathetic predominating, resulting in slowing of the spontaneous discharge rate

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5
Q

When is sinus bradycardia normal?

A

During sleep and in well-trained athletes

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6
Q

Causes of sinus bradycardia that are intrinsic to the heart

A

Acute ischaemia + infarction of sinus node (from MI)

Chronic degenerative changes e.g. fibrosis from atrium and sinus node (sick sinus syndrome) - elderly

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7
Q

What 2 things can sick sinus syndrome be caused by?

A

Sinus arrest

SA block

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8
Q

What would an ECG show for sick sinus syndrome?

A

Intermittent pauses between consecutive P waves (>2s, dropped P waves) and bradycardia

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9
Q

What is the normal PR interval?

A

0.12 - 0.20 seconds

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10
Q

Aetiology of heart block

A

Coronary artery disease
Cardiomyopathy
Fibrosis of the conducting tissue (esp. elderly)

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11
Q

What causes an atrioventricular block?

A

Block in the AV node or His bundle?

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12
Q

What does a block inferior to the AV node/His bundle in the conduction system cause?

A

Bundle branch blocks (right or left)

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13
Q

What is a 1st degree AV block?

A

Delayed AV conduction
Prolonged PR interval (>0.22 s) on the ECG
No change in the HR and Tx unnecessary

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14
Q

Whats a 2nd degree AV block?

A

Some atrial impulses fail to reach ventricles

Intermittent failure of AV impulse

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15
Q

What is Wencheback block phenomenon also called?

A

Type I block (in second degree AV block)

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16
Q

What happens in type I second degree AV block?

A

Progressive PR interval prolongation until a P wave fails to conduct (i.e absent QRS after the P wave)

PR wave then returns to normal + cycle repeats itself

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17
Q

What happens in type II 2nd degree AV block?

A

Dropped QRS complex isn’t proceeded by progressive PR interval prolongation. Usually QRS complex is wide

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18
Q

what type of heart block is this:

When every 2nd or 3rd P wave conducts the ventricles
e.g. 2 P waves to each QRS complex

A

2:1 or 3:1 (advanced) type of second degree AV block

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19
Q

What heart block is it when P waves and QRS complexes occur independently of teach other on the ECG

A

Third degree AV block/ complete heart block

All atrial activity fails to reach the ventricles

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20
Q

In complete atrioventricular heart block how are ventricular contractions maintained?

A

By a spontaneous escape rhythm originating below the site of the block in either the His bundle or the His-Perkinje system

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21
Q

In bundle branch block, what does the shape of the QRS complex depend on?

A

Whether the right or left bundle is blocked

It will be wide though as its always a complete block

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22
Q

RBBB - what happens and what kind of patients does it occur in?

A

The 2 ventricles dont contract simultaneously
Sequential spread of an impulse –> secondary R wave

Healthy pts, PE, RV hypertrophy, IHD and congenital

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23
Q

LBBB indicates what?

A

underlying pathology

IHD, LVH, aortic valve disease + after cardiac surgery

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24
Q

Where do supra ventricular tachycardias arise from?

A

The atrium or the atrioventricular junction

Conduction is via the His-Purkinje system

25
Q

Sinus tachycardia cause

A

Physical response during exercise + excitement

Also occurs with: fever, anaemia, HF, thyrotoxicosis, acute PE, hypovolaemia and drugs

26
Q

Tx sinus tachycardia

A

Treat underlying cause

BBs may be used to slow sinus rate

27
Q

Whats a tachycardia? and the 2 types?

A

> 100 bpm
SV ones - from the AV node
Ventricular ones - from bundle of His

28
Q

3 cellular mechanisms for cardiac arrhythmias

A
  1. abnormal conduction/re-entry
  2. abnormal automaticity: depolarisation-induced automaticity
  3. triggered activity:
    • EAD
    • DAD
      Early (EAD) and delayed (DAD) after depolarizations
29
Q

How can non-pacemaker sites result in enhanced automaticity and therefore an arrhythmia?

A 
Depolarised tissue e.g. ischamia, scar
Metabolic/electrolyte imbalance
Relatively 'depolarised' MP
Reduced threshold potential
Increased Ca2+ current
30
Q

What are AV junctional tachycardias a result of?

A

re-entry circuits in which there are 2 separate pathways for impulse conduction

31
Q

What is AVNRT?

Whats it a result of

A

Atrioventricular nodal re-entry tachycardia
Most common SVT
Due to a ring of conducting pathway in AV node. ‘Limbs’ have differing conduction times + refractory periods

Re-entry circuit. Impulse –> circus movement tachycardia

32
Q

What would the ECG of AVNRT show?

A

discrete P waves not visible

QRS complex usually normal shape as ventricles are activated in the normal way, down BoH

33
Q

Whats AVRT?

A

AV reciprocating tachycardia.
NOT NODAL
Due to presence of accessory pathway that connects the atria and the ventricles

34
Q

What is the delta wave a feature of?

A

Wolff-PArkinson-White syndrome
- a congenital abnormality

(a type of AVRT)

35
Q

ECG of Wolff-Parkinson-White syndrome

A

Path allows some of the atrial depolarisation to pass quickly to the ventricle before it gets through AV node

Early depolarisation of part of the ventricle –> shortened PR interval and a slurred start to the QRS (delta wave) QRS is narrow

36
Q

What does the magnitude of the delta wave depend on?

A

how much of myocardium is affected by the accessory pathway

37
Q

Symptoms of AV junctional tachycardias

A

rapid regular palpitations usually with abrupt onset and sudden termination

other: dizzy, dyspnoea, central chest pain + syncope

38
Q

Acute management of AV junctional tachycardia

A

Aim: to restore + maintain sinus rhythm

- emergency cardioversion

39
Q

Acute Mx for AV junctional tachycardia if haemodynamically stable?

A

Increase vagal stimulation of the sinus node by Valsalva mechanism
Adenosine

40
Q

What is adenosine and what’s its mechanism of action?

A

short-acting AV nodal-blocking drug that will terminate most junctional tachycardias

Increases AV node refractoriness, breaking the re-entry circuit –> cardioversion

41
Q

Features of atrial fibrillation?

A
  1. irregularly irregular
  2. varying rate
  3. absent p waves
42
Q

Presentation of atrial fibrillation?

A

usually incidental finding

but we worry about CLOTS (associated with 5 fold increase in stroke)

no clear p waves on ECG

43
Q

the 3 aspects to atrial fibrillation management

A

a. rate control
b. rhythm control
c. thromboprophylaxis

44
Q

How would you control the rate therapeutically for AF?

A

BB or calcium antagonists

45
Q

Rhythm control management for AF?

A

Electrical direct current (DC) cardioversion and then administration of BBs to suppress the arrhythmia

46
Q

Symptoms of ventricular ectopic premature beats

A

asymptomatic. or extra beats/ missed beats/ heavy beats

47
Q

What happens in ventricular ectopics ECG

A

beat isn’t conducted to ventricles through the normal conducting tissue

QRS complex on ECG is widened with bizarre configuration

48
Q

Tx for ventricular ectopics

A

beta blockers if symptomatic e.g. atenolol

49
Q

ECG for sustained ventricular tachycardia

A

> 30 seconds. rapid ventricular rhythm with broad abnormal QRS complexes

50
Q

What is non-sustained ventricular tachycardia?

A

VT >/= 5 consecutive beats but lasting

51
Q

How is recurrence of sustained ventricular tachycardia prevented?

A

beta-blockers or implants bel cardiac defibrilator

52
Q

What’s long QT syndrome?

A

ventricular depolarisation is greatly prolonged

53
Q

Causes of long QT syndrome?

A

congenital
electrolyte disturbances
variety of drugs

54
Q

Symptoms of long QT syndrome

A

palpitations, syncope (from polymorphic VT which normally stops spontaneously but may degenerate into VF)

55
Q

Tx of long QT syndrome

A

underlying cause + IV isoprenaline

56
Q

What natural hormone is isoprenaline similar to?

A

epinephrine/adrenaline

57
Q

What would no effective CO cause?

A

cardiac arrest!!!

58
Q

Atrial flutter rate?

A

Atrial rate is typically 300 bpm and AV node usually conducts every second flutter beat, giving ventricular rate of 150 bpm

59
Q

Atrial flutter ECG

A

‘sawtooth’ flutter waves (F waves)

CVS (14 decks)

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