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EKG Midterm > 2 Basics: Waves, Complexes, Intervals, and HR > Flashcards

2 Basics: Waves, Complexes, Intervals, and HR Flashcards

1
Q

The vertical axis of the ECG paper represents ______ and the horizontal axis represents ______

A

Voltage

Time

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2
Q

One large box on the ECG paper represent…

A
  1. 2 seconds of time

0. 5 mV

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3
Q

One small box on the ECG paper represents …

A
  1. 04 seconds

0. 1 mV

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4
Q

What is the isoelectric line?

A

Flat line that occurs when no electrical activity is occurring or impulses are too weak to be detected

Used as a baseline to identify changing electrical movement

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5
Q

The P wave is produced by…

A

Initiation of impulse in SA node
Depolarization of RA and LA
Impulse passing through AV junction

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6
Q

Normal P waves are…

A

Upright and round

  1. 06-0.10 s (60-100 ms)
  2. 5-2.5 mm high
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7
Q

The PR interval begins at _________ and ends at _________

A

The start of the P wave

The beginning of the QRS complex

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8
Q

Normal PR interval

A

0.12 - 0.20 s (120-200 ms)

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9
Q

The beginning of the P wave to the beginning of the QRS complex

A

PR interval

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10
Q

What is the PR segment?

A

Flat (isoelectric) line between the end of the P wave and the start of the QRS complex

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11
Q

What are the components of the QRS complex?

A

Q wave - first negative deflection following PR segment

R wave - any positive deflection following Q wave or PR segment

S wave - any negative deflection that extends below the baseline following the R wave

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12
Q

Normal QRS duration is…

A

0.06 to 0.12 s (60-120 ms)

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13
Q

Flat line that follows QRS complex

A

ST segment

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14
Q

Larger, slightly asymmetrical waveform that follows ST segment

A

T wave

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15
Q

Point were the QRS complex meets the ST segment

A

J-point

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16
Q

What is the QT interval?

A

Beginning of the QRS complex to the end of the T wave

Represents time of ventricular depolarization and repolarization

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17
Q

Normal duration of QT interval

A

0.36 - 0.44 s (360-440 ms)

Varies depending on the HR - as HR slows, the QT increases

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18
Q

What does a normal ECG rhythm look like (Limb Lead II)?

A

Upright, round P waves occurring at regular intervals at ~60-100 bpm

PR interval of normal duration (0.12-0.20 s) followed by a QRS complex of normal upright contour and duration (0.06-0.12s)

Flat ST segment followed by an upright, slightly asymmetrical T wave

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19
Q

What is the calibration mark and why is it there?

A

Helps ensure ECG machine is properly calibrated

Serves as reference point on ECG tracing

Standard signal is 1.0 mV in amplitude (2 large boxes)

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20
Q

Markings on ECG tracing that are not a product of heart’s electrical activity

A

Artifact

Many causes (ie patient movement)

Can mimic life-threatening dysrhythmias

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21
Q

These leads record difference in electrical potential between a positive and negative electrode using a third electrode called a ground

A

Bipolar leads (limb leads I, II, III)

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22
Q

What are the poles for Lead I?

A

Right arm is negative

Left arm is positive

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23
Q

What are the poles for Lead II?

A

Right area is negative

Left leg is positive

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24
Q

What are the poles for Lead III?

A

Left arm is negative

Left leg is positive

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25
Q

Which leads are bipolar?

A

Leads I, II, III

All the rest are unipolar

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26
Q

______ use one positive electrode and a reference point calculated by the ECG machine (center of the heart)

A

Unipolar leads

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27
Q

Which leads are unipolar?

A

Augmented Limb Leads
• aVr - augmented vector Right
• aVl - augmented vector Left
• aVf - augmented vector foot

Precordial leads (“chest” or “V” leads)
• V1-6
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28
Q

What are the three augmented limb leads?

A

aVr, aVL, aVf

All unipolar

Enhanced by ECG machine b/c waveforms produced by these leads are normally small

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29
Q

Augmented limb leads use the same electrodes as limb leads but …

A

One is positive, the other two have no charge and serve as a common ground

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30
Q

Which direction is positive for aVr?

A

Right arm - views base of the heart (atria and great vessels)

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31
Q

Which direction is positive for aVL?

A

Left arm - views lateral wall of left ventricle

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32
Q

Which direction is positive for aVf?

A

Left leg - view inferior wall of left ventricle

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33
Q

The precordial leads are all…

A

Positive electrodes

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34
Q

Lead placement:

V1

A

4th ICS on the right side of the sternum

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35
Q

Lead placement:

V2

A

4th ICS on the left side of the sternum

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36
Q

Lead placement:

V3

A

Halfway between V2 and V4 🙄

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37
Q

Lead placement:

V4

A

5th ICS in MCL (Septum)

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38
Q

Lead placement:

V5

A

Anterior auxiliary line, same horizontal plane as V4

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39
Q

Lead placement:

V6

A

Midaxillary line, same horizontal plane as V4

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40
Q

Leads _________ should be on the same horizontal plane

A

V4-V6

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41
Q

What views are provided by the precordial leads?

A

Anterior and lateral views of the heart in a horizontal plane

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42
Q

When are Modified Chest Leads (MCL) used?

A

For patient monitoring in ED, telemetry, and ICU

MCL1 and MCL6 provide continuous cardiac monitoring

43
Q

When using Modified Chest Leads, where do you place the positive electrode?

A

In the same position as precordial leads V1 or V6

44
Q

Different combinations of leads will tell you about…

A

Different surfaces of the heart

45
Q

Which are considered the Anterior Leads?

A

V1-4

46
Q

Which are considered the Lateral Leads?

A

Lead I, aVL, and V5-6

47
Q

Which are considered the Inferior Leads

A

II, III, aVf

48
Q

Why do we use so many god damn leads?

A

Help to distinguish focal problems from more widespread problems (Ischemia/infarct vs drug/electrolyte effects)

49
Q

What are the five steps in analyzing an ECG?

A

Determine regularity

Calculate rate

Evaluate P waves

Evaluate QRS complexes

Evaluate PR intervals

50
Q

Characteristics of Normal Sinus Rhythm

A

Rhythm: Regular

Rate: 60-100 bpm

P waves: Upright and rounded (in most leads), one preceding each QRS complex

QRS complexes: Narrow, 0.06 - 0.12 seconds

PR interval: 0.12 - 0.20 seconds

T waves: Upright and slightly asymmetrical

51
Q

How do you describe a regular rhythm?

A

The distance of the R-R intervals and P-P intervals is the same

52
Q

How do you describe an irregular rhythm?

A

The distance of the R-R intervals and P-P intervals differs

Irregular rhythms are considered ABNORMAL

53
Q

What are the three methods of determining rhythm regularity?

A

Caliper Method

Pen and Paper Method

Counting the Small Squares Method

54
Q

What are the different types of rhythm irregularity?

A

Occasional or very

Slightly

Sudden acceleration in HR (or slowing)

Patterned

Totally

Variable Conduction Ratio

55
Q

What type of rhythm is this:

Pacemaker changes location from site to site

A

Slightly irregular

Referred to as “wandering atrial pacemaker”

56
Q

Sudden HR acceleration is also referred to as…

A

Paroxysmal tachycardia

A normal rate that suddenly accelerates to a rapid rate producing an irregularity in the rhythm

57
Q

Irregularity repeating itself in a cyclic fashion is referred to as…

A

Patterned irregularity

Examples:
Sinus Dysrhythmia (ie - respiration)
2nd-degree AV heart block
Type I

58
Q

Totally Irregular (or Irregularly Irregular) rhythms are typically seen in ….

A

Atrial fibrillation

Ectopic sites in the atria fire at a rate of more than 350 bpm

Only some of the atrial impulses are conducted through the AV node

59
Q

What are the different methods for calculating HR?

A

6-second interval x 10 method

Large-Box Estimate (count-down method)

1500 method

Rate Calculator

60
Q

How does the 6-second interval x 10 method work?

A

Count the number of QRS complexes found in a 6-second portion of the ECG and multiply by 10

Quick and easy (no tools) but not as accurate as other methods

61
Q

How does the Large-Box countdown method work?

A

Find an R wave located on or near a bold line

Count down along each bold line until the next consecutive R wave (300, 150, 100, 75, 60, 50, 43)

The bold line it falls on or is closest to represents the HR

62
Q

What is the downside of the countdown method?

A

Less accurate with irregular rhythms

63
Q

What’s the best way to interpolate the rate when use the countdown method and the R-R interval falls between the large boxes?

A

If rate is between 100-75, there are 25 numbers between them, so each small box can represent 5 bpm (25/5) - so 95, 90, 85, 80

64
Q

Most accurate method for calculating HR

A

1500 method - count the number of small squares between two consecutive R waves and divide 1500 by that number

Requires no special tools but math is required (boo)

CANNOT be used with irregular rhythms

65
Q

What is a normal HR in adults?

A

60-100 bpm

66
Q

Heart rate < 60

A

Bradycardia

67
Q

Heart rate > 100

A

Tachycardia

68
Q

First deflection from baseline at the beginning of cardiac cycle

A

Sinus P wave

69
Q

How does a normal p wave appear on lead II?

A

Upright and rounded

Precedes each QRS complex

Duration 0.06 - 0.10 seconds

Amplitude 0.5 - 2.5 mm

70
Q

Tall, rounded or peaked, P waves may be seen with …

A

Increased right atrial pressure and right atrial dilation

Amplitude > 2.5 mm suggests RAE

Aka P pulmonale

71
Q

Wide (enlarged), notched or biphasic P waves may be seen in …

A

Increased left atrial pressure and left atrial dilation

Width > 10.s (2.5 small boxes) suggests LAE

Aka P mitrale

72
Q

What is P pulmonale?

A

Right Atrial Enlargement (RAE)

P wave > 2.5 mm TALL

73
Q

What is P mitrale?

A

Left Atrial Enlargement (LAE)

P wave > 0.10s (2.5 small boxes)

74
Q

What can cause different looking P waves?

A

Impulses arising from the atria but NOT the SA node

Seen with:
• Premature atrial complexes (PACs)
• Wandering atrial pacemaker
• Atrial tachycardia

75
Q

P wave of early beat that differs in appearance from underlying rhythm

A

Premature atrial complex (PAC)

76
Q

What happens to the P wave during atrial tachycardia?

A

With the rapid rate, the P wave is likely buried in the T wave of the preceding beat

When this occurs, the T waves are often peaked, notched, or larger than normal

77
Q

What are “F” waves?

A

Flutter waves - produced when an ectopic site in the atria fires rapidly at a rate of 250-350 bpm

Often described as a “saw-toothed” pattern - more P waves than QRS complexes

78
Q

What are ”f” waves?

A

Fibrillatory waves - Produced when the atria fire rapidly from many sites at a rate >350pm

Absence of discernible P waves, instead there is a chaotic looking baseline preceding the QRS complexes

79
Q

What produces inverted P waves?

A

Retrograde depolarization of the atria

Associated with dysrhythmias that originate from the AV junction

80
Q

Inverted P waves occur when…

A

Depolarization arises from the:
• Lower right atrium near the AV node
• Left atrium
• AV junction

May immediately precede, occur during, or follow the QRS complex

81
Q

What does more P waves than QRS complexes indicate?

A

The impulse was initiated in the SA node or atria but was blocked and did not reach the ventricles

82
Q

What are the different components of the QRS complex?

A

Q wave - first negative deflection following he PR segment

R wave - any positive deflection following Q wave or PR segment

S wave - any negative deflection that extends below the baseline following the R wave

83
Q

Normal QRS duration is ….

A

0.06 to 0.12s

84
Q

When looking at the QRS complex, there is only one _______ but there can be more than ________

A

Q wave

R or S wave

In that case, the second R or S wave is called R’ or S’

If the R or S wave is small, use the lower case “r” or “s”

85
Q

How to measure the QRS complex

A

Starting point is where the first wave of complex starts to move away from baseline

Ending point is where the last wave of the complex begins to level out (flatten) at, above, or below the baseline

86
Q

Measurement of the QRS complex should include _______ but it shouldn’t __________

A

Entire S wave

Overlap into the ST segment or the T wave

87
Q

QRS complexes should appear normal (upright and narrow) if…

A

Rhythm is initiated from a site above the ventricles (SA node, atria, AV junction)

Conduction has progressed normally from the bundle of His, through the right and left bundle branches, and through the purkinje fibers

Normal depolarization of the ventricles has occurred

88
Q

Normal QRS can be seen in dysrhythmias that…

A

Arise from above the ventricles, unless there is a conduction delay through the ventricles or other type of abnormality

89
Q

When do you see abnormal QRS complexes?

A

When there is abnormal depolarization of the ventricles

Pacemaker site in these abnormal QRS complexes can be…
• SA node
• Ectopic pacemaker in the atria, AV junction, bundle branches, purkinje network, or ventricular myocardium

90
Q

What are some examples of causes for abnormal QRS complexes?

A 
Ventricular hypertrophy
Intraventricular conduction disturbance
Aberrant ventricular conduction
Ventricular pre-excitation
Ventricular ectopic or escape pacemaker
Ventricular pacing by cardiac pacemaker
91
Q

TALL QRS complexes are usually caused by…

A

Hypertrophy of one or both ventricles

An abnormal pacemaker

Aberrantly conducted beat

92
Q

Low-voltage QRS complexes are more commonly seen in…

A

Obese patients
Pericardial effusion
Hypothyroidism

93
Q

Wide-Bizarre QRS complexes are often the result of…

A

Intraventricular conduction defect - right or left bundle branch block

They are of supraventricular origin

94
Q

Aberrant conduction occurs when …

A

Electrical impulses reach the bundle branch while it is still refractory after conducting a previous electrical impulse

The impulse travels down the unaffected bundle branch first, followed by the other —> wider than normal QRS complex

95
Q

_______ denotes depolarization of the heart from the SA node through the atria, AV node, and His-Purkinje system

A

PR interval

Measured from the beginning of the P wave to the beginning of the Q wave (or R wave if Q is absent)

96
Q

PR intervals are considered abnormal if they are…

A

Shorter than 0.12 s
Longer than 0.20 s
Absent
Vary in duration

97
Q

Shorter PR intervals (< 0.12 s) occur when…

A

The impulse originates in the atria close to the AV junction or in the AV junction

An impulse arises from a supraventricular site but travels through abnormal accessory pathways to the ventricles

98
Q

Shorter PR intervals lead to …

A

Premature ventricular depolarization (PRE-EXCITATION)

99
Q

Longer PR intervals occur when…

A

There is a delay in impulse conduction through the AV node

Ex: 1st-degree AV heart block

100
Q

In __________, the pacemaker site moves from beat to beat causing the P waves to appear different and the PR intervals to vary

A

Wandering atrial pacemaker

101
Q

2nd degree AV heart block Type I has PR intervals that are…

A

Progressively longer until a QRS complex is dropped, then the cycle repeats

102
Q

Absent PR intervals occur in…

A

Atrial flutter and fibrillation and in ventricular dysrhythmias

103
Q

In 3rd degree AV heart blocks, what happens to the PR interval

A

It is not measurable

All of the impulses are blocked as they travel through the AV node

Essentially, the atria and ventricles are beating independently of each other

EKG Midterm (4 decks)

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