17 The Electrocardiogram Flashcards

1
Q

EKG’s provide info about what 5 things?

A
  • Anatomical orientation of heart
  • Size of chambers
  • Rhythm/Conduction disturbances
  • Ischemic damage
  • Effects of altered electrolytes and drugs
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2
Q

In an EKG, the convention size for small mV boxes and small time boxes is what?

A
  • 0.1 mVolt

* 0.04 sec

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3
Q

What does the S-T segment of an EKG signify?

A

-Ventricular myocytes are almost all resting/depolarized (not repolarized yet)

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4
Q

What does the P-R segment of an EKG signify?

A

-Start atrial depolarization to start ventricular depolarization (due to AV node)

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5
Q

What does QRS segment of an EKG signify?

A

-Time to depolarize the whole ventricle (due to His-Purkinje)

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6
Q

What does QT segment of an EKG signify?

A

-AP duration of ventricular myocytes

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7
Q

What is a dumb way to calculate heart rate, by using an EKG? (What is the equation?)

A

-60 divided by R-R interval

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8
Q

EKG’s record intra or extracellular voltage?

A

-Extracellular

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9
Q

A repolarization vector moving away from you would look like what on an EKG?
Thus, extracellular voltage in front of a DEpolarization wave is pos. or neg?

A
  • Positive wave

- Positive

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10
Q

A depolarization vector moving toward you would look like what on an EKG?

A

-Positive wave (if you can do these 2 you can figure out the rest)

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11
Q

In a ventricle, does the endo or epicardium depolarize first?

A

-The endocardium

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12
Q

As time passes through one beat, the VENTRICLE depolarizes in what direction?

A

-Left to right across septum, then toward apex, then toward base, then toward posterior base

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13
Q

After depolarization of ventricle, which tissue repolarizes first?

A

The LAST tissue to depolarize

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14
Q

Where are leads 1, 2, 3 placed on the body to get an EKG?

A
  • Right to left arm
  • Right arm to left foot
  • Left arm to left foot
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15
Q

As time passes through one ventricular contraction, describe what happens to the OVERALL direction of vectors the heart creates?

A

-Looking at a person face on, the first vector points toward 8:00 (down and to THEIR right) and successive vectors move counterclockwise, with the last pointing toward 2:00. (See pic, this is responsible for the shape of QRS complex)

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16
Q

How can you remember what aVR, aVL, and aVF are measuring?

A

Mneumonic:

  • avR: Right arm versus sum
  • avL: Left arm versus sum
  • avF: Foot versus sum
17
Q

What direction do leads 1,2,3 point on Einthoven’s triangle?

A

-Horizontal to the right
-Down and to the right
-Down and to the left
(these correspond to the positions of the leads on the person’s body, but are “backwards” because we are looking AT the person)

18
Q

What is the # range for the normal QRS axis?

A

-30 to 90

19
Q

Where are the 6 Precordial (V) leads located?

A

1-right 4th intercostal
2-left 4th intercostal
3,4,5,6- left 5th intercostal w/ 4th at midclavicular line