Arrythmia

Question 1

What causes long QT syndrome?

Answer 1

Decreased outward Potassium current – prolongs AP duration. This can lead to reactivation of I(Ca-L).

Question 2

Which electrolyte disturbance can lead to long QT syndrome?

Answer 2

Hypokalaemia

Question 3

What causes a delayed-after-depolarisation arrhythmia?

Answer 3

cellular calcium overload

Question 4

How does MI lead to re-entrant arrhythmia?

Answer 4

infarcted tissue leads to unidirectional block. AP can come back from wrong direction. This also depends on a slow conduction rate and short AP to allow re-excitation to occur.

Question 5

How do the catecholamines increase heart contractility?

Answer 5

increased L-type Ca2+current and increases SERCA activity.

Question 6

What does SERCA do?

Answer 6

Recycles Ca2+ back into Sarcoplasmic reticulum

Question 7

What is the receptor that releases calcium from SR into cytoplasm?

Answer 7

ryanodine receptors

Question 8

How is long QT syndrome managed?

Answer 8

beta-blockers or ICD for high-risk cases