Axis and Hypertrophy Flashcards

1
Q

If all the small vectors are added up in ventricular depolarization the sum is…

A

Mean QRS vector

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2
Q

‘Mean QRS Vector’ represents…

A

the general direction of ventricular depolarization

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3
Q

A normal q wave represents…

A

septal depolarization

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4
Q

Normal ventricular depolarization recorded by aVL is…

A

negative first then positive

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5
Q

Normal ventricular depolarization recorded by aVF is…

A

positive first then negative

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6
Q

A normal Mean QRS axis is typically at…

A

45 degrees

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7
Q

The frontal plane is numbered with 0 degrees being at ?? and 180 degrees being at ??.

A
  • left hand
  • right hand
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8
Q

The degrees are positive on the ?? of the frontal plane.

A

bottom half

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9
Q

The degrees are negative on the ?? of the frontal plane.

A

top half

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10
Q

What are used to determine the position of the “Axis” of the Mean QRS vector?

A

the limb leads

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11
Q

Quadrant I is angles ??-?? in the clockwise direction of the frontal plane?

A

-90 - 0 degrees

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12
Q

Quadrant II is angles ??-?? in clockwise direction of the frontal plane?

A

0 - 90 degrees

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13
Q

Quadrant III is angles ??-?? in a clockwise direction on the frontal plane?

A

90 - +/-180 degrees

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14
Q

Quadrant IV is angles ??-?? in a clockwise direction on the frontal plane?

A

+/-180 - -90 degrees

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15
Q

If the QRS is positive in Lead 1 this means the vector is pointing…

A

somewhere to the patients left half

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16
Q

If the QRS is positive in Lead aVF this means the vector is pointing…

A

somewhere downward to the patients left

17
Q

A normal QRS axis is confirmed with…

A
  1. a positive QRS in Lead 1
  2. a positive QRS in Lead aVF
18
Q

A left axis deviation is confirmed with…

A
  1. a positive QRS in Lead 1
  2. a negative QRS in Lead aVF
19
Q

A right axis deviation is confirmed with…

A
  1. a negative QRS in lead 1
  2. a positive QRS in lead aVF
20
Q

An extreme right axis deviation is confirmed with…

A
  1. a negative QRS in lead 1
  2. a negative QRS in lead aVF
21
Q

A normal QRS axis is typically in the degree range of…

A

-30 - 90 degrees

22
Q

T/F: A normal axis can be in quadrant 1 (0 - -90 degrees).

A

TRUE – but only to -30 degrees

23
Q

How do you differentiate a normal axis from a LAD?

A
  1. Lead 1 = positive QRS
  2. lead aVF = negative QRS
  3. Lead 2 = positive QRS

- if lead 2 is positive = normal axis
- if lead 2 is negative = LAD

24
Q

What are the 2 causes of LAD?

A
  1. LVH
  2. previous right ventricular myocardial infarction
25
What are the 3 causes of RAD?
1. RVH 2. previous left ventricular infarctions 3. right heart strain due to pulmonary embolism
26
T/F: The precordial reference plane is used in determining the QRS axis.
FALSE -- used in plotting the heart's electrical activity in horizontal plane
27
What are the 3 causes of LVH?
1. hypertension 2. aortic valve stenosis 3. cardiomyopathy
28
Where can a LVH be seen on an ECG?
V1 and V5 - large S/R in these leads
29
What is added to determine LVH presence?
S in V1 + R in V5
30
How many mm (boxes) determine LVH?
35 mm or 7 big boxes
31
What is a strain pattern?
an ST depression in V5 - T wave inversion characteristic of longstanding LVH
32
ECG criteria for LVH
1. Sum of S and R waves - V1 + V5 is greater than 35 mm 2. R wave or S wave only - R wave in V5 is greater than 30 mm - S wave in V1 is greater than 20 mm 3. R wave only - lead 1 is greater than 20 mm - aVL is greater than 11 mm