12 lead

Question 1

Lead I is

Answer 1

bipolar with the positive electrode at the left arm and the negative electrode at the right arm.

Question 2

Lead II is

Answer 2

positive in the left leg and negative in the right arm.

Question 3

Lead III is

Answer 3

positive in left leg and negative in left arm.

Question 4

The unipolar augmented leads share:

Answer 4

the frontal plane of the heart with the bipolar leads

Question 5

aVR is

Answer 5

positive in the right arm,

Question 6

aVL is

Answer 6

positive in the left arm

Question 7

aVF is

Answer 7

positive in the left leg

Question 8

chest leads are

Answer 8

unipolar and reflect changes in the horizontal plane

Question 9

Leads V1 and V2 are

Answer 9

close the the RV

Question 10

where is increased voltage from RV hypertrophy seen?

Answer 10

V1 and V2

Question 11

where are septal infarcts seen

Answer 11

V1/V2

Question 12

which leads are close to anterolateral portion of LV

Answer 12

V5/V6

Question 13

where is increased voltage from LV hypertrophy seen?

Answer 13

V5/V6

Question 14

where are changes in anterolateral infarct seen?

Answer 14

V5/V6

Question 15

Normal depolarization of the ventricles goes from

Answer 15

right to left and downward from the right arm towards the left leg.

Question 16

Lead aVR which has its _____ electrode to the upper right (right arm) is _____

Answer 16

positive

negative since all forces are away from it leftward and downward.

Question 17

The normal axis ranges from

Answer 17

straight downward +90 degrees to leftward slightly above the horizontal +30 degrees.

As seen in the normal 12 lead tracing

Question 18

Left axis deviation (LAD)

Answer 18

-30 to -90 degrees

Question 19

Right axis deviation (RAD)

Answer 19

+90 to +180 degrees

Question 20

Lead I is perpendicular to

Answer 20

+90

Question 21

LEad 2 is perpendicular to

Answer 21

-30

Question 22

How do you determine the QRS axis?

Answer 22

1. Normal axis is
   positive in both leads I and II
2. Left axis is positive in lead I and negative in lead II
3. Right axis is negative in lead I and positive in lead II
4. Indeterminate axis is negative in both leads I and II