12. Electrocardiogram

Question 1

What is an SA block?

Answer 1

SA node impulse blocked from aorta
No P wave
AVN takes over: slower beat

Question 2

What is AV block?

Answer 2

Decreased or total block of AV conduction

Question 3

What are causes of AV block?

Answer 3

Ischaemia, plaque, inflammation, extreme vagal stimulation

Question 4

What is first degree AV block?

Answer 4

Prolonged PR interval

Question 5

2nd degree AV block

Answer 5

Further slowing of PR

Mixed beats or new rhythm

Question 6

3rd degree AV block

Answer 6

Complete block
Ventricular escape
No relation between P and QRS

Question 7

What is Stokes-Adams syndrome?

Answer 7

Intermittent complete block

Fainting and ventricular escape

Question 8

Why might the QRS complex be increased?

Answer 8

Increased muscle mass causes increased current flow which is easier to pick up

Question 9

Why might QRS be prolonged?

Answer 9

Slow conduction through the ventricle
Takes longer to depolarise
Dilated or purkinje block

Question 10

Why might ST be elevated?

Answer 10

Current is still flowing during systole

Could be due to recent MI