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EKGs > EKG Basics Part 1 > Flashcards

EKG Basics Part 1 Flashcards

1
Q

How long does a standard EKG last?

A

10s. Speed: (25mm/s)

Each view will be 2.5s

Running lead will be 10s.

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2
Q

What is the standard gain on an EKG?

A

10mV

Higher gain = higher magnification

Ex: a 30mV chest gain would make much larger chest leads.

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3
Q

What are primary errors associated with EKGs?

A
  • Interpretation Error
  • Performance Error
  • Artifact
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4
Q

What does the P wave correspond to in terms of electrical activity?

A
  • The first half is the RA.
  • The second half is the LA.

Bachmann’s bundle depolarizes the LA.

Impulse begins at the SA node.

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5
Q

How long does a large box on an EKG strip correspond to? Small Box?

A
  • Large: 0.2s
  • Small: 0.04s
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6
Q

What does the P wave, QRS complex, and T wave correspond to in terms of electrical pathway?

A
  • P Wave: Atrial depolarization
  • QRS: Ventricular depolarization + (covered atrial repolarization)
  • T Wave: Ventricular depolarization
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7
Q

What is the difference between a Q and an R and a S on EKG?

A
  • Q is always the first NEGATIVE deflection.
  • R is always POSITIVE.
  • S is the negative deflection after R always (if it is present)
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8
Q

What is the difference between a segment and an interval?

A
  • Segment is between a wave and complex.
  • Intervals include a wave and a segment.
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9
Q

Where is the electrical signal in the heart during a PR segment?

A

AV Node

Traveling from the SA node.

It is paused because the ventricles are currently filling.

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10
Q

What interval includes both ventricular depolarization and repolarization?

A

QT interval

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11
Q

What are the 3 types of cells that make up the electrical system of the heart?

A
  • Pacemaker cells
  • Conduction fibers
  • Cardiac myocytes
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12
Q

For depolarization, what direction generates a positive deflection? Negative?

A
  • Towards an electrode: positive
  • Away from an electrode: negative

The primary indicator of deflection

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13
Q

For repolarization, what direction generates a positive deflection? Negative?

A
  • Towards an electrode: negative
  • Away from an electrode: positive
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14
Q

What are the limb leads and the precordial leads?

A
  • Limb (frontal plane): I, II, III, aVF, aVR, aVL
  • Precordial/Chest (horizontal plane) : V1, V2, V3, V4, V5, V6
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15
Q

What intercostal space are V1 and V2 usually placed?

A

4th intercostal space

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16
Q

Einthoven’s triangle for I, II, III

A
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17
Q

Einthoven’s triangle for aVL, aVR, aVF

A
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18
Q

What are the inferior limb leads? Lateral? Right-sided?

A
  • Inferior: II, III, aVF
  • Lateral: I, aVL
  • Right-sided: aVR

Based on the direction they point to.

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19
Q

What are the anterior chest leads? Lateral? Right-sided? Septal?

A
  • Anterior: V2, V3, V4
  • Lateral: V5, V6
  • Right-sided: V1
  • Septal: V2, V3

V2 and V3 are just lateral to the interventricular septum.

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20
Q

What is unique about septal depolarization?

A

It goes from left to right, which is opposite of ventricular.

21
Q

What leads can typically show a small Q wave due to septal depolarization?

A

I, aVL, V5, V6 (Lateral leads)

Sometimes can appear in II, III, aVF, V3, and V4

22
Q

What is R wave progression?

A

The R wave should get larger beginning from V1 to V6.

Slowly getting bigger as it gets towards V6.

R wave is representative of ventricular depolarization.
Usually peaks around V4 or V5.

23
Q

What two leads are used to determine EKG axis and why?

A

We only require frontal plane leads.

Specifically, we use lead I and aVF.

aVF and I should both be positive in their QRS deflection, which corresponds to the bottom left quadrant of the heart, which is normal.

24
Q

What lead abnormality would suggest right axis deviation?

A
  • aVF normal with positive deflection.
  • Lead I with negative deflection.
25
Q

What lead abnormality would suggest left axis deviation?

A
  • aVF with negative deflection.
  • Lead I with positive deflection.
26
Q

What lead abnormalities would suggest extreme right axis deviation?

A
  • aVF with negative deflection.
  • Lead I with negative deflection.
27
Q

What does the AP of a cardiac pacemaker cell look like?

A

No true resting potential.

28
Q

What is the term given to the ability of every cell in the heart to behave like a pacemaker cell?

A

Automaticity.

It is suppressed by the SA node cells, but can appear problematic when there is SA node dysfunction.

29
Q

How many large boxes is 1mV equivalent to on a normal EKG?

A

2 large boxes.

30
Q

What are the 3 divisions of the left bundle branch?

A
  • Septal fascicle: IV septum in a left-to-right direction.
  • Anterior fascicle: anterior LV
  • Posterior fascicle: posterior LV
31
Q

6 QRS complexes

32
Q

What does the PR segment correspond to?

A

Conduction pause at the AV node

33
Q

What limb leads generate the frontal plane of a 12-lead?

A
  • Lead I: 0 deg
  • Lead II: 60 deg
  • Lead III: 120 deg
  • Lead aVL: -30 deg
  • Lead aVR: -150 deg
  • Lead aVF: +90 deg
34
Q

What are the inferior leads?

A
  • Leads II
  • Lead III
  • Lead aVF
35
Q

What are the left lateral leads?

A
  • Lead I
  • Lead aVL
  • V5
  • V6
36
Q

What are the right sided leads?

A
  • Lead aVR
  • V1
37
Q

What are the anterior leads?

38
Q

Which frontal lead should present with a negative P-wave?

A

aVR, because the depolarization is moving AWAY from the electrode.

39
Q

What frontal lead should present with a biphasic wave?

A

Lead III, which begins positive then becomes negative.

40
Q

What is a normal PR interval duration?

A

0.12s-0.2s

41
Q

Describe R wave progression.

A

As we going from V1 to V5, the R wave amplitude is expected to increase.

R refers to the first positive deflection after the PR segment.

42
Q

How long is a typical QRS complex?

A

.08s to .12s

AKA 2-3 small boxes

43
Q

In a lead that has a tall R wave, what kind of T wave should I expect?

A

Positive T wave.

Ex: V1 has a very small R wave, and its T wave is negative.
V6 has a tall R wave, and its T wave is positive.

Generally, a T wave is 1/3-2/3 the amplitude of its preceding R wave.

44
Q

On average, how much of an R-R interval does a Q-T interval take up?

A

40%, as the T wave is generally wider than the QRS.

45
Q

What leads do we look at to determine normal axis?

A
  • I (Positive QRS)
  • aVF (Positive QRS)

0-90 deg

This generates the bottom left quadrant of the heart (towards the apex)

46
Q

How would right axis deviation present on I and aVF?

A
  • Lead I should have a NEGATIVE QRS.
  • Lead aVF should have a POSITIVE QRS.

AKA, going away from Lead I causes it to be negative.
aVF is still positive because it is pointing right but down.

47
Q

How would left axis deviation present on I and aVF?

A
  • Lead I should have a POSITIVE QRS.
  • Lead aVF should have a NEGATIVE QRS.

AKA, going towards the left = positive in I.
Going up towards the head = negative in aVF.

48
Q

How would extreme right axis deviation present on I and aVF?

A
  • Lead I should have a NEGATIVE QRS.
  • Lead aVF should have a NEGATIVE QRS.

Going towards the right = negative in I.
Going up towards the head = negative in aVF.

49
Q

What do you look for to define axis angle more precisely and why?

A
  • You look for a biphasic QRS (positive and negative deflection approximately equal on both sides)
  • The axis must be perpendicular to whatever lead has the biphasic wave.
  • The biphasic wave tells you that there are only two axis orientations possible (90 deg perpendicular to the lead)
  • Based on whether you have normal axis, left, or right, you can determine which one makes the most sense.
  • This requires 3 leads: I and aVF to determine normal axis, and the lead with a biphasic QRS to determine the axis degree specifically.

Example: Lead III shows a biphasic QRS. A normal III has an orientation of 120 deg. Perpendicular to that is either 30 or -150 deg.
If the axis is normal (aka I and aVF are positive), then it must be 30 deg.

EKGs (6 decks)

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