EKG 5

Question 1

Zero point for each axis in the standard limbs of Eithoven’s triangle

Answer 1

. Midway btw positive and negative electrodes

. Center of Einthoven’s Triangle

Question 2

How to resolve an overall vector

Answer 2

. Break into component vectors
. First place the tail at 0 point
. Then extend lines from head of arrow to the axis for each lead perpendicular to each axis
. The component vectors extend from zero inn a given lead (tail of arrow) to the intersection of the lead axis w/ the perpendicular for that lead (head of arrow)
. Lead I + Lead III = Lead II

Question 3

Left axis deviation

Answer 3

. Mean QRS axis is more neg. than 0 degrees

Question 4

Right axis deviation

Answer 4

. Mean QRS axis is more positive than 90 degrees

Question 5

Indeterminate axis

Answer 5

. When QRS axis is btw -90 and +/- 180 degrees
. Can’t determine if it is due to severe right axis deviation or severe left axis deviation
. Could be due to incorrect lead placement

Question 6

Common causes of left axis deviation

Answer 6

. LV hypertrophy
. Pregnancy
. Obesity
. Infarct in RV

Question 7

Common causes of right axis deviation

Answer 7

.RV hypertrophy
. Infarct in LV
. Slight right axis deviation may be normal in Kids or very tall, thin adults