L10 - Cardiac Channelopathies Flashcards Preview

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Flashcards in L10 - Cardiac Channelopathies Deck (98)
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1

How many sudden cardiac deaths per year in the UK

70000

2

What % of sudden cardiac deaths are caused by ischaemic heart disease

60%

3

What % of sudden cardiac deaths have no identifiable cause

40%

4

Long and Short QT syndromes are examples of __________ syndromes

Inherited

5

What is the main effect of long/short QT

Change to the action potentials of ventricular myocytes

6

P wave represents

Atrial depolarisation

7

QRS complex represents

Ventricular depolarisation

8

T wave represents

Ventricular repolarisation

9

Why is atrial repolasrisation not shown on an ECG

Because it is masked by the depolarisation of the ventricles

10

In long QT

Repolarisation is delayed
QT interval increases

11

In short QT

Repolarisation is accelerated
QT interval decreases

12

What is phase 0 of the ventricular AP

Depolarisation

13

What currents mediate depolarisation of the ventricles

Influx Ina

14

What is phase 1 of the ventricular AP

Partial repolarisation

15

What currents mediate the partial repolarisation of the ventricles

Ito influx

16

What is phase 2 of the ventricular AP

Plateau

17

What currents mediate the plateau phase

Influx Ina Ica
Efflux Iks Ikr Ikur

18

What is phase 3 of the ventricular AP

Repolarisation

19

What currents mediate repolarisation

Efflux: Iks Ikr Ikur IkATP IkACh

20

What is phase 4 of the ventricular AP

Resting

21

What currents mediate the resting state of the ventricular AP

Influx Ina Ica
Efflux Ik1 Ik2p

22

Normal QT interval is

0.36

23

Threshold for short QT is

0.34

24

Threshold for long QT is

0.45

25

Two main classes of implications of long and short QT, what can they lead to

Triggered activity
Re-entrant excitation
Lead to ventricular tachycardia and then to ventricular fibrilation

26

Describe triggered activity

Cells reach the threshold when they shouldn't and fire action potentials
Leads to an additional beat - ectopic

27

Describe re-entrant excitation

Few layers of cells affected that include the extra beat
This can spread to other cells
Spatial and temporal distortion
AP propagation
When actual signal arrives cells are in refractory so can't respond

28

What is spatial distortion

Electrical signals that can spread from one affected group of cells to another

29

What is temporal distortion

Where one cluster of cells fires an action potential - these then fire again at another point in time

30

Main symptom of Long QT

Syncope