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BMS 242 CVS & Respiration > Cardiac Channelopathies > Flashcards

Cardiac Channelopathies Flashcards

1
Q

What are two syndromes associated with Cardiac channelopathies

A

long QT and short QT

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2
Q

What is affected in long and short QT syndromes

A

changes to ventricular myocyte APs

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3
Q

What interval of the cardiac cycle do LQT and SQT affect

A

QRS wave to T wave

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4
Q

Which wave changes in QT syndromes

A

T wave changes

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5
Q

What is the effect of the T wave changing in QT syndromes

A

repolarisation is accelerated or delayed

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6
Q

What is the ventricular action potential plateau phase mediated by

A

voltage gated calcium channels

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7
Q

What is the T wave in ventricular APs associated with

A

repolarisation phase

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8
Q

What is ventricular tachycardia

A

additional beat - number of contractions in ventricles is increased

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9
Q

What is ventricular fibrillation

A

fatal - completely un co-ordinated contraction of ventricular myocytes

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10
Q

What can occur in long QT

A

ectopic beat

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11
Q

What are the implications of QT syndromes

A

signals dont spread where they should

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12
Q

What is a form of tachycardia highly associated with ventricular fibrillation - death

A

torsades de pointes

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13
Q

What is torsases de pointes associated with in an ECG

A

twisting motion

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14
Q

Mutations in what channels cause Long QT

A

KCNQ1, SCN5A, KCNE1, CACNA1C

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15
Q

What is KCNQ1

A

voltage gated potassium channel

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16
Q

What mutation affects KCNQ1 in Long QT

A

loss of function

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17
Q

What is SCN5A

A

sodium channel

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18
Q

What does SCN5A mediate

A

depolarisation of ventricular action potentials

19
Q

What mutation affects SCN5A in long QT

A

gain of function

20
Q

What is KCNE1

A

protein - potassium channel regulator

21
Q

What is the function of KCNE1

A

makes sure KCNQ1 is working properly

22
Q

What mutation affects KCNE1 in long QT

A

loss of function

23
Q

What is CACNA1C

A

main L type calcium channel

24
Q

What is the function of CACNA1C

A

maintains plateau phase of APs

25
Q

What mutation affects CACNA1C in long QT syndrome

A

gain of function mutations

26
Q

Where do the majority of mutations occur in KCNQ1 in long QT

A

transmembrane spanning domains, pore region

27
Q

What other organ can be affected by mutations in Q1

A

ear

28
Q

Where are stria vascularis found

A

epithelial cells in the ear

29
Q

What is the function of stria vascularis

A

secrete potassium into the endolymph

30
Q

What is the affect of mutated Q1 E1 complex in the ear

A

deafness - Reissner’s membrane collapses due to no endolymph

31
Q

Describe the 3 key mutations in Long QT

A

gain of function in sodium and calcium channels, loss of function in potassium channels

32
Q

What is delayed in long QT

A

start of repolarisation

33
Q

How is long QT treated

A

B blockers, Atenolol

34
Q

What is atenolol

A

B1 selective antagonist

35
Q

What is the effect of atenolol

A

reduces strength of contraction and rate of firing at SA node

36
Q

What puts you at higher risk of arthymia

A

increases heart rate

37
Q

What are the symptoms of short QT

A

reduced QT interval, arrhythmias, palpitations, fainting, death

38
Q

Describe the genes mutated in short QT

A

same as long QT but mutated in opposite ways

39
Q

What is the effect of loss of function mutations in calcium channels

A

plateau in action potential is not maintained - repolarisation occurs fastr

40
Q

What is the effect of gain of function mutations in potassium channels

A

channels overactive - drive repolarisation faster and earlier

41
Q

What mutations are associated with short QT

A

loss of function in calcium channels, gain of function in potassium channels

42
Q

What do the mutations associated with short QT cause

A

accelerated timing of repolarisation

43
Q

What is the treatment for short QT

A

implant defibrillator, quinidine

BMS 242 CVS & Respiration (10 decks)

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