Channelopathies Flashcards
What is the normal k range in body
3.6-5.2 mmol/l
How are abnormal genes linked to cardiac arrhythmias and channelopathies
They encode for ion channels so if mutated this affect heart by arrhythmias or channelopathies
What is qt
Time between beginning of dep phase 1 to phase 3 repolarisation
Which 2 channel mutations are responsible for long qt syndrome
Mutation in kcnq1 k channel for repolarisation
Mutation in scn5a Na channel for depolarisation ie doesn’t inactivate properly
What abnormal impulse formation is seen with long qt syndrome
Early after depolarisation
What type of ventricular tachycardia occurs with lqt due to early after depolarisation
Torsades de pointes (high peaks on ecg)
Why does someone collapse after untreated lqt
Because ventricular tachycardia due to ead means lack of edv ventricles can’t fill fast so small cardiac output
What is it called when heart ends up having no rhythm due to ventricular tachycardia/torsades de pointes
Ventricular fibrillation (uncontrolled firing) causes death
When does lqt attacks usually occur
During exercise when increased heart rate
Explain the steps of early after depolarisation
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
What is the extra qrs in ead called
R on T event (dep on rep event)
How is brugada different to lqt
Ventricular tachycardia occurs at rest
What ion channelopathies cause brugada
Mainly abnormality in scn5a Na channel
How is brugada detected on ecg
Coved ST elevated segment
Which gender is brugada seen in usually
Males - 75%
How is cpvt (ventricular tachycardia) similar to lqt syndrome
Occurs during exercise
Is the ecg for cpvt normal at rest
Yes
Why is cpvt a bigger issue than lqt if they both cause ventricular arrhythmias
More arrhythmic so more chance of fibrillation
Also can’t be helped by b blockers to slow hr, lqt can
Why isn’t cpvt a channelopathu
It’s a mutation in ryr which causes abnormal ca conc in cardiac muscle cells
What is delayed after depolarisation (occurs in cpvt)
Depolarisation which occurs during rmp
What causes dad
Sr leaks of calcium due to ryr mutation
Ncx stimulation
3 Na in causes inward current causing depolarisation
How can nadr be connected to cpvt
When it binds and increases pka this can cause sr release of ca
Which is the only one which can be helped by b blockers
Lqt syndrome to reduce hr during exercise(don’t work for cpvt)
Which device which is implantable stops fibrillations during lqt or cpvt and also helps brugada
Implantable cardiac defibrillator
How can nadr be blocked during cpvt to stop sr releasing more ca
Sympathetic denervation (remove nerves in SNS)
Does lqt always happen during exercise
No lqt3 is at rest
Which area of the heart is Na abnormality seen in brugada
Right ventricular epicardium
