12 lead Flashcards
Lead I is
bipolar with the positive electrode at the left arm and the negative electrode at the right arm.
Lead II is
positive in the left leg and negative in the right arm.
Lead III is
positive in left leg and negative in left arm.
The unipolar augmented leads share:
the frontal plane of the heart with the bipolar leads
aVR is
positive in the right arm,
aVL is
positive in the left arm
aVF is
positive in the left leg
chest leads are
unipolar and reflect changes in the horizontal plane
Leads V1 and V2 are
close the the RV
where is increased voltage from RV hypertrophy seen?
V1 and V2
where are septal infarcts seen
V1/V2
which leads are close to anterolateral portion of LV
V5/V6
where is increased voltage from LV hypertrophy seen?
V5/V6
where are changes in anterolateral infarct seen?
V5/V6
Normal depolarization of the ventricles goes from
right to left and downward from the right arm towards the left leg.
Lead aVR which has its _____ electrode to the upper right (right arm) is _____
positive
negative since all forces are away from it leftward and downward.
The normal axis ranges from
straight downward +90 degrees to leftward slightly above the horizontal +30 degrees.
As seen in the normal 12 lead tracing
Left axis deviation (LAD)
-30 to -90 degrees
Right axis deviation (RAD)
+90 to +180 degrees
Lead I is perpendicular to
+90
LEad 2 is perpendicular to
-30
How do you determine the QRS axis?
- Normal axis is
positive in both leads I and II - Left axis is positive in lead I and negative in lead II
- Right axis is negative in lead I and positive in lead II
- Indeterminate axis is negative in both leads I and II