channels Flashcards
What can result in a prolonged QT interval?
Certain drugs, electrolyte imbalance, congenital conditions such as long QT syndrome (LQTS)
Prolonged QT intervals are significant as they can lead to fatal dysrhythmias.
What is long QT syndrome (LQTS) associated with?
Delayed repolarisation of the ventricles
This delayed repolarisation can lead to fatal dysrhythmias.
What are the commonest variants of LQTS usually caused by?
A defect in the alpha subunit of the slow delay rectifier potassium channels
These defects play a critical role in the pathophysiology of LQTS.
What can AV node dysfunctions or blocks result from?
Fibrosis, sclerosis, drugs
These conditions lead to prolonged PR-interval changes but do not affect the QT interval.
How do AV node dysfunctions affect the QT interval?
They do not affect the QT interval
AV node dysfunctions primarily impact the PR interval.
What types of channels are involved in the electrical and mechanical functions of the heart?
Calcium channels
Mutations in these channels can lead to cardiac dysrhythmia syndromes.
Which cardiac dysrhythmia syndromes are associated with mutations of calcium channels?
Brugada syndrome, early repolarisation syndrome
These syndromes are not associated with LQTS.
Is SA node dysfunction associated with LQTS?
No
SA node dysfunction is identified via abnormalities with the P-waves.
What indicates dysfunction of the SA node?
Abnormalities with the P-waves
These abnormalities help in diagnosing SA node dysfunction.
What can sodium channel dysfunction be associated with?
Certain cardiac conditions including those resulting in prolonged QT syndromes
However, loss of function of sodium channels is less likely in LQTS compared to potassium channels.
In LQTS, which channels are more likely to have loss of function?
Potassium channels
Sodium channel dysfunction is less common in the context of LQTS.
