Axis and Hypertrophy Flashcards
If all the small vectors are added up in ventricular depolarization the sum is…
Mean QRS vector
‘Mean QRS Vector’ represents…
the general direction of ventricular depolarization
A normal q wave represents…
septal depolarization
Normal ventricular depolarization recorded by aVL is…
negative first then positive
Normal ventricular depolarization recorded by aVF is…
positive first then negative
A normal Mean QRS axis is typically at…
45 degrees
The frontal plane is numbered with 0 degrees being at ?? and 180 degrees being at ??.
- left hand
- right hand
The degrees are positive on the ?? of the frontal plane.
bottom half
The degrees are negative on the ?? of the frontal plane.
top half
What are used to determine the position of the “Axis” of the Mean QRS vector?
the limb leads
Quadrant I is angles ??-?? in the clockwise direction of the frontal plane?
-90 - 0 degrees
Quadrant II is angles ??-?? in clockwise direction of the frontal plane?
0 - 90 degrees
Quadrant III is angles ??-?? in a clockwise direction on the frontal plane?
90 - +/-180 degrees
Quadrant IV is angles ??-?? in a clockwise direction on the frontal plane?
+/-180 - -90 degrees
If the QRS is positive in Lead 1 this means the vector is pointing…
somewhere to the patients left half
If the QRS is positive in Lead aVF this means the vector is pointing…
somewhere downward to the patients left
A normal QRS axis is confirmed with…
- a positive QRS in Lead 1
- a positive QRS in Lead aVF
A left axis deviation is confirmed with…
- a positive QRS in Lead 1
- a negative QRS in Lead aVF
A right axis deviation is confirmed with…
- a negative QRS in lead 1
- a positive QRS in lead aVF
An extreme right axis deviation is confirmed with…
- a negative QRS in lead 1
- a negative QRS in lead aVF
A normal QRS axis is typically in the degree range of…
-30 - 90 degrees
T/F: A normal axis can be in quadrant 1 (0 - -90 degrees).
TRUE – but only to -30 degrees
How do you differentiate a normal axis from a LAD?
- Lead 1 = positive QRS
- lead aVF = negative QRS
- Lead 2 = positive QRS
- if lead 2 is positive = normal axis
- if lead 2 is negative = LAD
What are the 2 causes of LAD?
- LVH
- previous right ventricular myocardial infarction