9. EKG

Question 1

What causes a positive (upward) deflection of the EKG?

Answer 1

(+) wave of depolarization moves over the surface of cardiac cells towards a (+) skin electrode

Question 2

What is the normal range of time elapsed for the PR interval?

Answer 2

0.12 - 0.20 secs (3-5 mm boxes)

Question 3

What is the normal range of time elapsed for the QRS wave?

Answer 3

0.05 - 0.10 sec

Question 4

How many seconds does a 1 mm box represent?

Answer 4

0.04 secs

Question 5

What are the 3 methods used to determine HR on an EKG?

Answer 5

• 1500 / (QRS1 - QRS2 in mm)
• Use 3 sec markers on strip –> (# of QRS intervals in 6 secs) x 10
• 300-150-100-75-60-50