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Critical Care Procedures > 12 Lead Interpretation > Flashcards

12 Lead Interpretation Flashcards

1
Q

What are the 4 primary characteristics of cardiac cells?

A

1) Automaticity
2) Excitability
3) Conductivity
4) Contractility

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2
Q

Describe the Action Potential in Depolarization?

A

A five cycle phase in which the electrical charge changes in the intra/extracellular space through the cell membrane

Na and Ca move in (-)
K and Cl move out (+)

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3
Q

Describe Syncytium?

A

Cardiac muscle cells are grouped together and function as a unit and therefore will normally depolarize as a unit.

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4
Q

What is the Polarized state (resting potential) of the heart?

A

the resting state of the cardiac cell where the inside of the cell is electrically negative relative to the positive exterior of the cell.

Right before depolarization

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5
Q

What is the Depolarization (action potential) of the heart?

A

An electrical occurrence normally expected to result in myocardial contraction

Movement of ions back to a homeostasis point

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6
Q

What is the Repolarization (recovery state) of the heart?

A

The depolarized cell is polarized and positive changes are again on the outside and negative charges on the inside of the cell.

At homeostasis

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7
Q

When is the Absolute Refractory Period?

A

When the cardiac cell is unable to respond to any new electrical stimulus.

  • When depolarization just happened (EARLY)
  • Non - Conductive PAC’s
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8
Q

When is the Relative Refractory Period?

A

There period in which depolarization is almost complete and the cardiac cell can be stimulated to contract prematurely if the stimulus is stronger than normal

  • Almost all of the ventricle has recovered from depolarization (LATE)
  • BBB’s
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9
Q

Which leads are Bi-Polar leads?

A

I, II, III

  • Also known as limb leads
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10
Q

Which leads are Uni-Polar leads?

A

AVR, AVF, AVL, V1- V6

  • V1 - V6 also known as chest leads
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11
Q

How do you place a 15 - Lead EKG, and what does it show us?

A 
V4 = V4R - 5th ICS to the right midclavicular line
V5 = V8 - 5th ICS midscapular
V6 = V9 - 5th ICS between V8 and the spine

Shows the Posterior Part of the Heart (V8 - V9)
Shows the Right side of the heart (V4R)

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12
Q

Which Ions are found inside the cell? and which are found outside?

A

Na and Ca are extracellular

K and Cl are intracellular

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13
Q

What is the “P” Wave? and what is a normal PR interval?

A

Atrial depolarization

0.12 - 0.2 seconds

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14
Q

What is the “QRS” Wave? and what is the normal QRS interval?

A

Depolarization of the Ventricles

less than 0.12

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15
Q

Describe “R” wave Progression?

A

As you go through V1 to V6 the R wave starts low then Peaks up and then back down

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16
Q

What is the “T” wave?

A

Repolarization of the Ventricles

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17
Q

Where is the “J” Point?

A

The junction between the ARS and the ST- segment

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18
Q

Where is the “QT” segment? and what does it represent?

A
  • The beginning of the QRS to the end of the “T” wave
  • Represents the duration of activation and recovery of the ventricular muscle
  • Normal QT is 0.41 seconds
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19
Q

What is occurring during the “ST” segment and what does any change mean?

A
  • It is the time between completion of depolarization and the onset of repolarization
  • Elevation greater than 1 mm indicated infarction
  • Depression greater than 0.5 mm indicate ischemia
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20
Q

Where is the “U” wave found?

A

After the “T” wave

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21
Q

What does it mean when there is a larger than normal Q wave?

A

Old MI

- Usually occurs 20 hours after a MI

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22
Q

Which leads look at the INFERIOR surface of the left ventricle?

A

II, III, AVF

  • Predominantly supplied by the Right Coronary Artery (RCA)
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23
Q

Which leads look at the ANTERIOR surface of the left ventricle and septum?

A

V2, V3, V4

  • Mostly perfused by the Left Anterior Descending branch of the left artery (LAD)
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24
Q

Which leads look at the LATERAL surface of the left side wall of the left ventricle?

A

I, AVL & V5, V6

  • Mostly perfused by the Circumflex branch of the left artery (LCX)
25
Q

Which leads look at the SEPTAL surface of the septum between the ventricles?

A

V1, V2

  • Perfused partly by the RCA (posteriorly) and LAD (anteriorly)
26
Q

Which leads look at the POSTERIOR surface?

A

All the V leads (chest leads)
- normally show ischemic changes (reciprocal changes)

  • Perfused mainly by the Right Coronary Artery (RCA)
27
Q

What are all the reciprocal changes that can be noted during ST-elevation?

A

Inferior ST elevation - Lateral ST depression
Lateral ST elevation - Inferior ST depression
Septal ST elevation - Posterior ST depression
Posterior ST elevation - Septal ST depression

28
Q

What is the earliest sign of acute myocardial infarction in the affected area?

A

hyperacute T waves

29
Q

What is the Pathophysiology of a BBB?

A

Loss of Syncytium

Delayed Conduction

30
Q

What happens to the electrical impulse when there is a hemi-block?

A

Once it reaches the blocked portion the electrical impulse is sent through cell to cell transmission. (slower)

31
Q

What occurs in a Left Anterior Fasicular Block (LAHB or LAFB)?

A

The blocked or delay in the anterior fascicle results in delayed activation of the anterior portion of the left ventricle

  • Left Axis Deviation
32
Q

What occurs in a Left Posterior Hemiblock (LPHB)?

A

Transmission of the electrical impulse proceeds normally along the main LBB and anterior fascicle but is blocked or delayed in the posterior fascicle.

-Right Axis Deviation

33
Q

What occurs when there is a LBBB?

A

The right ventricle depolarizes and by means of cell-to-cell conduction the electrical impulse spreads from the right ventricle to the left ventricle

34
Q

What occurs when there is a RBBB?

A

The Right Ventricle depolarizes by means of cell-to-cell conduction that spreads from the interventricular septum and Left Ventricle.

35
Q

How wide does the QRS need to be in order to consider a BBB?

A

QRS needs to be wider than 0.12 seconds

36
Q

What are some diseases and symptoms that could imitate a abnormal EKG?

A
  • Pericarditis
  • Early Repolarization
  • Left Ventricular Hypertrophy
  • Ventricular - Paced Rhythms
37
Q

What does the “Q” wave represent and what is considered an abnormal Q wave?

A

The Q wave represents depolarization in the left ventricle occurring from the left to the right

  • abnormal is greater than 0.04 seconds in width and greater than 2mm in depth
38
Q

Which type of MI is referred to as the “Widowmaker”?

A

Anterior wall MI, with occlusion of the LAD

-LAD is the largest of the coronary arteries

39
Q

If a Impulse is going toward an electrode will it be positive or negative?
If a Impulse is going away from an electrode with it be positive or negative?

A

Toward - Positive

Away - Negative

40
Q

What is a Vector in terms of Axis Deviation?

A

Vector - a mark or symbol that can be used to describe any force having both magnitude and direction

41
Q

What is Axis in terms of Axis Deviation?

A

Axis- The direction of the heart’s electrical current from positive to negative

42
Q

What are Axis determinations used for?

A
  • Diagnosing Ventricular Tachycardia
  • Diagnosing Hemiblocks
  • Identifying patients whose infarction is unstable
43
Q

For a Normal Axis (0 to +90) LRQ what is the lead configuration?

A

Lead I Upright
Lead II Upright
Lead III Upright

44
Q

For Physiologic Left Axis deviation (0 to -40) URQ what is the lead configuration?

A

Lead I Upright
Lead II Upright or Downward
Lead III Downward

45
Q

For Pathological Left Axis deviation (-40 to -90) URQ what is the lead configuration?

A

Lead I Upright
Lead II Downward
Lead III Downward

46
Q

For Right Axis Deviation (+90 - +180) LLQ what is the lead configuration?

A

Lead I Downward
Lead II Upright or Downward
Lead III Upright

  • Normal for Pediatrics
47
Q

For Extreme Right Axis Deviation (-90 - +180) LUQ what is the lead configuration?

A

Lead I Downward
Lead II Downward
Lead III Downward

48
Q

What does a Peaked “P” wave usually mean?

A

Right Atrial Enlargment (RAE)

  • Greater than 2.5 mm
49
Q

What does it usually indicate when there is an increase in the duration of the “P” wave?

A

Left Atrial Enlargment (LAE)

  • Widened “P” wave greater than 3 mm
50
Q

What is SEX-PIN?

A

a mnemonic used to remember the origin of electrolytes

  • Sodium External - Potassium Internal dominant electrolyte
51
Q

What is the normal range of Potassium (K+)?

A

3.5 - 6.5 mEq/L

Less than 3.5 = hypokalemia
greater than 6.5 = hyperkalemia

less than 5.0 - Mild Hyperkalemia
6.0 -7.0 - Moderate Hyperkalemia
Greater than 7.0 - Severe Hyperkalemia (Sine Wave)

52
Q

What is the normal range of Calcium (Ca)?

A

8.5 - 12 mg/dL

Less than 8.5 mg/dL - hypocalcemia
12-15 mg/dL - hypercalcemia

53
Q

Hypokalemia and Hypomagnesemia will present with _________ T waves.

A

Flattened

54
Q

Hyperkalemia and Hypermagnesemia will present with __________ T waves?

A

Peaked

55
Q

What occurs during hypocalcemia and hypercalcemia?

A

Hypocalcemia will have prolonged QT intervals, and QRS / ST changes that mimic an MI

Hypercalcemia will have shortened QT intervals

56
Q

To be significant an ST segment must exceed ____ in a limb lead or ____ in a precordial lead.

A

1mm, 2mm

57
Q

ST segment depression is significant if it is at least one box below baseline or _____ beyond the QRS.

A

2mm

58
Q

When determining a BBB which lead should be used?

A

V1

Critical Care Procedures (5 decks)

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