ECG Cardio Stuff

Question 1

2nd degree AV block: whats going on and what does it look like?

Answer 1

Something is slowing down the path between the SA node and the AV node. This is usually due to high vagal tone (opioids or GI disease)

• variable PR intervals
• missing QRS waves

Question 2

3rd degree AV block: whats happening and what does it look like?

Answer 2

There is no correlation between the atria and the ventricles. The atria are beating at 120bpms and the ventricles are beating at 60 bpm. It is an escape rhythm.

• extra P waves
• Missing QRS waves

Question 3

What is a supraventricular rhythm

Answer 3

The signal starts from “above the ventricles” ie the SA node. This is normal:

• normal P waves
• QRS is skinny indicating depolarization happened fast
• HR is generally faster

Question 4

Junctional rhythm

Answer 4

When the signal starts from the AV node:

• absent P waves
• slower HR

Question 5

Ventricular rhythm

Answer 5

The signal is starting from below the AV node (ie the ventricles)

• no P waves
• wide and bizarre QRS
• HR is slow

Question 6

LBBB: whats going on and what does it look like?

Answer 6

The impulse starts in the AV node and the ventricles take longer to depolarize because there is a block.

• wide QRS
• QRS is mostly positive

Question 7

RBBB: whats happening and what does it look like?

Answer 7

The impulse starts at the AV node and it takes longer for the ventricles to depolarize because something is blocking it.

• wide QRS
• QRS will be mostly negative

Question 8

Ventricular tachycardia: whats going on and what does it look like?

Answer 8

The SA node and AV node are not working. So the ventricles take over but they arent doing well, so the Perkinje cells start to take over.

• > 3 consecutive VPCs.
• it’s a REGULAR rhythm! (This is how you differentiate it from a-fib or supraventricular tachycardia)
• increasing R-R intervals

Watch out for the R-on-T phenomenon - can set off ventricular fibrillation!

Question 9

Paper speed: 50mm/s

Describe x axis for one tiny box and one big box

Answer 9

• most common
  X axis:
  small - 20ms
  large - 100ms

Question 10

Paper speed: 25mm/s

What is 1 tiny box and one large box on the x axis

Answer 10

Slower - best for rhythm analysis
Tiny box = 40ms
Larger box = 200ms

Question 11

Irregular rhythms:

What is regularly irregular vs irregularly irregular?

Answer 11

Regularly irregular: if the irregular rhythm has a rhythm of its own

Irregularly irregular: no discernable rhythm

Question 12

5mm/mV = half sensitivity

WHat is the length (y-axis) of one large box?

Answer 12

1mV = 5mm (this is used when complexes are so large that they start running into each other on the ECG)

Question 13

Atrial fibrillation: whats going on and what does it look like?

Answer 13

The SA node is firing way faster than the AV node.

• irregularly irregular rhythm
• more P waves than QRS complexes