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A&P 2024 > EKG/Cardiac pt 3 > Flashcards

EKG/Cardiac pt 3 Flashcards

Exam 4

1
Q

The main ion responsible for transmission of AP through gap junctions is _____

A

Na+
- Ca++ bigger, and therefore slower

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2
Q

AP are bidirectional because they are _____ synapses

A

electrical, not chemical

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3
Q

______ periods prevent retrograde AP

A

refractory

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4
Q

EKG set ups that look at the frontal/coronal plane

A

3 lead and augmented leads

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5
Q

Where are the +/- electrodes for lead I?

A

(-) R arm
(+) L arm

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6
Q

Where are the +/- electrodes for lead II?

A

(+) L foot
(-) R arm

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7
Q

Where are the +/- electrodes for lead III?

A

(+) L foot
(-) L arm

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8
Q

What is the name of the triangle that connects the 3 leads?

A

Einthoven’s triangle

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9
Q

Lead II is oriented at a ____ degree angle

A

60 - lines up with mean electrical axis

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10
Q

A normal mean electrical axis of the heart is _______

A

0 to +90°

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11
Q

A right deviation of the mean electrical axis of the heart is _______

A

> 90°; aka more than 59°

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12
Q

A left deviation of the mean electrical axis of the heart is _______

A

<0°; aka less than 59°

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13
Q

What are the different causes of axis deviation?

A
  1. Bundle branch block
  2. Larger lungs - COPD (straight up and down)
  3. Ventilation - decreases = left, increases = right
  4. Hypertrophy
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14
Q

If you see a mean electrical axis described as a positive number we should move in a ______ direction until we meet the described angle.

A

clockwise

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15
Q

If you see a mean electrical axis described as a negative number we should move in a ______ direction until we meet the described angle

A

counter-clockwise

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16
Q

The mean electrical axis of a P wave is expected to be headed towards the

A

left foot - same as QRS, but smaller d/t thinner atrial muscle

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17
Q

Einthoven’s Law

A

Lead I + Lead III = Lead II
Deflection magnitude

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18
Q

Where is the last part of the heart depolarized? Why?

A

Top left (left lateral) ventricle, farthest away from AV node

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19
Q

Repolarization of the atria is usually obscured by the QRS complex. If it was not, would it be positive or negative?

A

Negative - same sequence and direction as depolarization

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20
Q

What are the angles of the 3 leads?

A

I: 0°
II: 60°
III: 120°

21
Q

Which lead would show the largest deflection?

A

Lead II

22
Q

When Schmidt references an “eyeball” looking at an electrical impulse he is using this term to represent

A

The direction “looking” from the positive lead toward the corresponding negative lead.

23
Q

What are the 3 augmented leads?

A

aVR, aVL, aVF

24
Q

Which of the augmented leads is used the least? Why?

A

aVR - because deflections are almost always negative

25
Q

There are ___ angles between Standard Leads and Augmented Leads

A

30°

26
Q

The angle of aVF is ___

A

90°

27
Q

The angle of aVL is ___

A

-30°

28
Q

The angle of aVR is ___

A

210°

29
Q

If the mean electrical axis was pointed down at 90°, which lead would have 0 deflection?

A

Lead I

30
Q

The first portion of ventricular depolarization will happen where? How is this represented on an ECG?

A

On the left lateral side of the interventricular septum - Q wave, negative deflection

31
Q

Which of the 3 leads has a Q wave?

A

I and II (negative), but not III - positive deflection - no Q wave

32
Q

Which of the 3 leads doesn’t have an S wave?

A

lead I - positive deflection

33
Q

Describe the location of the precordial (chest) leads

A

V1 and V2 - septal leads, on either side of the septum/sternum, in the 4th intercostal space
V3 and V4 - anterior leads
- V3 - between the V2 and V4
V5 and V6 - lateral leads
- V4-V6 - 5th intercostal space

34
Q

In the R wave, what would you expect to see in each of the 3 leads?

A

All positive deflections

35
Q

The chest leads/precordial leads cathode is represented by the position of ______ while the negative electrode is a combination of _______

A

The corresponding V lead (V1-V6); All of the 3 standard leads (LA, RA, LL)

36
Q

If something is positive in lead II it will likely also be positive in which augmented leads?

A

aVL and aVF

37
Q

In lead V1 we would expect to see an inverted ______ and a(n) _______ QRS complex

A

P-wave; inverted

38
Q

What lead is utilized to determine if we have an anterior vs posterior tissue injury to the heart?

A

V2

39
Q

If the current of injury is positive in lead V2 then we could confidently say the injury is _______

A

on the posterior portion of the heart.

40
Q

If the current of injury is negative in lead V2 then we could confidently say that the injury is _______

A

On the anterior portion of the heart.

41
Q

Which lead is right in the “middle” of the heart?

A

V2

42
Q

We would expect the precordial leads to have a _______ magnitude when compared to the limb leads because ______

A

Larger; they are nearer the heart tissue that is being measured.

43
Q

Of the chest leads we would expect to see the most positive deflection of the the QRS complex in lead

A

V4 - in line with normal electrical axis of heart

44
Q

An inverted T wave would likely mean the ______ is repolarizing first.

A

endocardium

45
Q

Right ventricular hypertrophy would show up as a __________ deviation. And a ______ deflection in lead I

A

Right axis; negative

46
Q

A “rabbit ears” in a QRS complex is indicative of a ________

A

bundle branch block

47
Q

You have identified a bundle branch block in the QRS complex. How do we differentiate a right from left bundle branch block?

A

A left bundle branch block would have a left axis deviation. A right bundle branch block would have a right axis deviation.

48
Q

We expect there to be no electrical current in the heart after the ventricles have repolarized. This is the ______ segment

A

TP

49
Q

Electrical current during the TP segment would indicate _______

A

A current of injury

A&P 2024 (19 decks)

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