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EKG Quiz 3 > Lecture 4- Axis > Flashcards

Lecture 4- Axis Flashcards

1
Q

Normal width of QRS (duration)

A

< 0.12 seconds (3 small boxes)

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2
Q

Where should you measure the QRS width?

A

Should be measured in several different leads- use the widest one

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3
Q

Causes of wide QRS?

A
  • Hyperkalemia
  • Medications (especially tricyclics)
  • Ventricular tachycardia
  • Idioventricular rhythms
  • WPW
  • Bundle branch blocks (BBB) and intraventricular conduction delay (IVCD)
  • PVCs
  • Aberrantly conducted complexes
  • Pacemaker
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4
Q

Where does a pacemaker stimulate from?

A

Right ventricle (ventricular paced)

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5
Q

These are large deflections at the end of QRS complex (much larger than benign notching) and occur in cases of severe hypothermia.

A

Osborn waves

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6
Q

Benign notching?

A
  • Small notch at end of QRS complex
  • Most common in precordial leads
  • Generally associated with benign causes of ST elevation: early repolarization, pericarditis
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7
Q

What is this difference between benign Q waves and pathologic?

A
  • Insignificant Q waves = first vector of ventricular depolarization
  • Significant Q waves = old MI in that region
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8
Q

What comes to mind when considering Q waves and respiration?

A

-Depth of the Q wave can vary slightly with respiration if axis of heart changes (obese/pregnant/ascites)

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9
Q

In what lead are Q waves common?

A

In aVR and generally not significant.

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10
Q

Criteria for pathologic Q waves?

A
  • > 1/3 total height of QRS

- 0.04 seconds wide (one small box)

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11
Q

What is the Transition Zone? Where is it located?

A

Transition from mostly negative to mostly positive complex in precordial leads. Between V3 and V4.

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12
Q

Define early and late transition?

A
  • If before V3, axis rotated counter-clockwise = early transition
  • If after V4, axis rotated clockwise = late transition
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13
Q

If your V2 net deflection is positive, what type of deflection is this?

A

Early.

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14
Q

The QT interval, generally defined?

A

Should be less than ½ the R-R interval

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15
Q

Torsade de Pointes is indicative of?

A

Prolonged QT

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16
Q

What does Axis help us diagnose?

A
  • Left or Right Ventricular Hypertrophy
  • Hemiblock
  • Pulmonary Embolus
  • Dextrocardia
  • Lead Misplacement
17
Q

Incorrect lead placement would cause what to happen when looking at the EKG?

A

-Will see negative P and QRS in Lead II and positive P and QRS in aVR (opposite from normal)
(If arm leads are not switched and this occurs = dextrocardia)

18
Q

What leads are used for determining Axis?

A

Limb leads (frontal or coronal plane)

19
Q

Two most important leads for determining Axis?

A

Lead I and aVR

20
Q

In the Hexaxial System, each spoke is separated by ____ degrees.

A

30

21
Q

Normal axis is located between ____ and ____

A

0 degrees (Lead I) and 90 degrees (aVR)

22
Q

Negative aVR and positive Lead I = ?

A

Left axis deviation

23
Q

Negative Lead I and positive aVR = ?

A

Right axis deviation

24
Q

What is the Indeterminant Axis?

A

aka “No Man’s Land”, extreme LAD, or extreme RAD. (negative in Lead I AND aVR)

25
Q

Positive Lead I and positive in aVR = ?

A

Normal Axis

26
Q

Causes of RAD?

A
  • Normal variant in adolescents and children*
  • Right ventricular hypertrophy
  • Left posterior hemiblock
  • Dextrocardia
  • Pulmonary Pathology
27
Q

Causes of LAD?

A
  • Normal variant with aging*

- Left anterior hemiblock

28
Q

What is an axis more negative than -30 degrees called?

A

Pathologic LAD

29
Q

Which lead do you look at to determine pathologic LAD?

A

Lead II (it will be net negative = pathologic)

30
Q

Hemiblocks: the left anterior fascicle innervates?

A

The anterior and lateral walls of LV

31
Q

the left posterior fascicle innervates?

A

The inferior and posterior walls of LV

32
Q

Which fascicle covers more surface area?

A

Left posterior

33
Q

Which fascicle is harder to block?

A

Left posterior (large SA, fans out)

34
Q

Which fasicular block is more common?

A

Left anterior (less SA, thin fibers)

35
Q

Bifasicular blocks: which is more concerning? RBBB with LAH or RBBB with LPH

A

with LPH: due to large area being ischemic. Could quickly deteriorate to a complete heart block with anterior MI if anterior fascicle damaged.

with LAH: ok unless new finding with ischemia

EKG Quiz 3 (2 decks)

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