Channelopathies

Question 1

What is the normal k range in body

Answer 1

3.6-5.2 mmol/l

Question 2

How are abnormal genes linked to cardiac arrhythmias and channelopathies

Answer 2

They encode for ion channels so if mutated this affect heart by arrhythmias or channelopathies

Question 3

What is qt

Answer 3

Time between beginning of dep phase 1 to phase 3 repolarisation

Question 4

Which 2 channel mutations are responsible for long qt syndrome

Answer 4

Mutation in kcnq1 k channel for repolarisation

Mutation in scn5a Na channel for depolarisation ie doesn’t inactivate properly

Question 5

What abnormal impulse formation is seen with long qt syndrome

Answer 5

Early after depolarisation

Question 6

What type of ventricular tachycardia occurs with lqt due to early after depolarisation

Answer 6

Torsades de pointes (high peaks on ecg)

Question 7

Why does someone collapse after untreated lqt

Answer 7

Because ventricular tachycardia due to ead means lack of edv ventricles can’t fill fast so small cardiac output

Question 8

What is it called when heart ends up having no rhythm due to ventricular tachycardia/torsades de pointes

Answer 8

Ventricular fibrillation (uncontrolled firing) causes death

Question 9

When does lqt attacks usually occur

Answer 9

During exercise when increased heart rate

Question 10

Explain the steps of early after depolarisation

Answer 10

Slow repolarisation phase 1 and 3 due to k channel abnormalities causes increased ap time and chance of depolarisation again

K can’t leave the cell fast enough so there is inward current potential via Na channels like scn5a (which can also be mutated)

These lead to further depolarisation and vt eventually vf

Question 11

What is the extra qrs in ead called

Answer 11

R on T event (dep on rep event)

Question 12

How is brugada different to lqt

Answer 12

Ventricular tachycardia occurs at rest

Question 13

What ion channelopathies cause brugada

Answer 13

Mainly abnormality in scn5a Na channel

Question 14

How is brugada detected on ecg

Answer 14

Coved ST elevated segment

Question 15

Which gender is brugada seen in usually

Answer 15

Males - 75%

Question 16

How is cpvt (ventricular tachycardia) similar to lqt syndrome

Answer 16

Occurs during exercise

Question 17

Is the ecg for cpvt normal at rest

Answer 17

Yes

Question 18

Why is cpvt a bigger issue than lqt if they both cause ventricular arrhythmias

Answer 18

More arrhythmic so more chance of fibrillation

Also can’t be helped by b blockers to slow hr, lqt can

Question 19

Why isn’t cpvt a channelopathu

Answer 19

It’s a mutation in ryr which causes abnormal ca conc in cardiac muscle cells

Question 20

What is delayed after depolarisation (occurs in cpvt)

Answer 20

Depolarisation which occurs during rmp

Question 21

What causes dad

Answer 21

Sr leaks of calcium due to ryr mutation

Ncx stimulation

3 Na in causes inward current causing depolarisation

Question 22

How can nadr be connected to cpvt

Answer 22

When it binds and increases pka this can cause sr release of ca

Question 23

Which is the only one which can be helped by b blockers

Answer 23

Lqt syndrome to reduce hr during exercise(don’t work for cpvt)

Question 24

Which device which is implantable stops fibrillations during lqt or cpvt and also helps brugada

Answer 24

Implantable cardiac defibrillator

Question 25

How can nadr be blocked during cpvt to stop sr releasing more ca

Answer 25

Sympathetic denervation (remove nerves in SNS)

Question 26

Does lqt always happen during exercise

Answer 26

No lqt3 is at rest

Question 27

Which area of the heart is Na abnormality seen in brugada

Answer 27

Right ventricular epicardium