Bradyarrhythmias Flashcards Preview

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Flashcards in Bradyarrhythmias Deck (34):
1

What is heart block?

An obstruction in the electrical conduction system of the heart

Results in problems transmitting impulses to some regions of the heart

Bradyarrythmias occur

2

Why does heart block cause slower heart rate?

Because there are problems in the conduction of impulses from one bit of the heart to others

The impulse takes longer to conduct, or doesn't even get there

3

List some types of heart block?

R + L bundle branch block

First degree
Second degree
Third degree heart block

4

Where do the bundle branches transmit impulses from and to?

From the AV bundle (which has come from the AV node)

Down through the septum

To the apex of the heart where they split into Purkinje fibres

5

What is bundle branch block?

When electrical impulses from the AV node can't be transmitted through the bundle branch due to a blockage

The impulse has to travel from the healthy bundle branch on one side across to the other via the muscle fibres

This is slower and more irregular

Ventricular depolarisation occurs at different times on each side

Reduced CO

6

Causes of bundle branch block?

MI
Heart pathologies
Cardiac surgery

7

Describe right BBB?

A blockage in the right BBB

Impulse goes from left BB across the heart to the right side

The ventricles don't depolarise at the same time

8

What would the ECG of right BBB look like?

C1 lead shows a characteristic M shape

The 'M' is large and lopsided

9

What type of bundle branch block does RV hypertrophy cause?

Right BBB

10

What type of bundle branch block does LV hypertrophy cause?

Left BBB

11

Describe left BBB?

A blockage in the left BBB

Impulse goes from right BB across the heart to the left side

The ventricles don't depolarise at the same time

12

What would the ECG of left BBB look like?

The peak of the C6 lead has a characteristic M shape

A tiny W or M!

13

What is the worst heart block to have?

First, second or third degree?

Third degree

14

Describe the electrical conduction problems briefly in:
- First degree
- Second degree
- Third degree?

First: delayed conduction from atria to ventricles

Secondary: intermittent blocking of conduction from atria to ventricles, not all impulses get through

Third degree: complete blocking of conduction from atria to ventricles

15

What is Wenckebach another name for?

Mobitz 1 heart block

16

What is 'complete heart block' another name for?

Third degree heart block

17

What is first degree heart block?

Delayed conduction from the atria to the ventricles

18

What does first degree heart block look like on an ECG?

Prolonged PR interval more than 0.2 seconds

No other changes, normal heart rate

19

Causes of first degree heart block?

Athletes
Myocarditis
Hypokalaemia
Drugs

20

Presentation of first degree heart block?

Asymptomatic
Often incidental finding

21

Management of first degree heart block?

None needed, monitor it

22

What are the two types of second degree heart block?

Mobitz 1
Mobitz 2

23

What is second degree heart block?

Some impulses are blocked from traveling from the atria to the ventricles, but not all of them

24

What does second degree heart block look like on ECG?

Cycles which result in a P wave being blocked from generating a QRS complex

So you get occasional P waves which are not followed by a QRS wave

Then the cycle resets, it repeats itself

Mobitz 1: prolongation of PR intervals until the dropped QRS occurs

Mobitz 2: no prolongation of PR interval

25

Causes of second degree heart block?

Athletes
Post MI
Lyme disease
Drugs

26

Symptoms of second degree heart block?
Mobitz 1 vs 2

Mobitz 1:
- light headedness
- dizziness
- syncope

Mobitz 2:
- chest pain
- dyspnoea
- tiring on exertion

27

Complications of second degree heart block?

Can progress to complete (third degree) heart block

Which can result in cardiac arrest and death

28

Treatment second degree heart block?

Implantable pacemaker

29

What is third degree heart block?

Complete heart block

The impulse generated in the SAN does not get to the ventricles

So an accessory pacemaker kicks in called an escape rhythm

This is a pacemaker found in the ventricles that activates independently of the SAN

So the ventricles still contract, just not in rhythm with the atria

30

What would third degree heart block look like on an ECG?

P waves are normal and regular

But the QRS waves are not being controlled by the SAN so they occur independently to the P waves

31

What is meant by 'escape rhythm'?

An accessory pace maker found in the ventricles that activates independently of the SAN

It prevents the heart stopping completely in complete heart block

32

What are the causes of third degree heart block?

CHD
Radiotherapy
Infection
Hypertension
Drugs

33

Symptoms of third degree heart block?

Light headedness
Dizziness
Fatigue
Syncope
Bradycardia

34

Management of third degree heart block?

Implantable pacemaker