Chapter 12/13 Flashcards

1
Q

ECG/ EKG abbreviation

A

ElectroCardioGram

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2
Q

EKG

A

A recording of the electrical currents of the heart

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3
Q

How many EKG leads

A

12 because they are more detailed and accurate. 3-5 for continuous monitoring of rhythm

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4
Q

Value of EKG

A

To detect damaged heart disease, from direct heart disease or other organ failure affecting the heart, serial ECGs are valuable in checking response to treatment, does not defects in the pumping ability of the heart

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5
Q

When to order ECG

A

Signs and symptoms of acute cardiac disorder, Pre-op screening, Hx of heart disease, Hx of Cardiac surgery, physical exam findings that would indicate the need for ECG

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6
Q

ECG leads

A

View from several different angles, electrical activity of heart at different angles. Has + and - components (12 leads- 6 limb leads, 6 chest leads, 10 wires- one on each limb, 6 on chest)

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7
Q

Chest leads (precordial leads)

A

Looking at specific areas of the heart

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8
Q

Primary electrolytes responsible for electrical difference across the RMP are

A

potassium, sodium, and calcium

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9
Q

Which has the greatest concentration inside the cardiac cell

A

potassium about 151 meq/l inside cell, 4 outside

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10
Q

Concentration of K outside the cardiac cell is

A

4 meq/l

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11
Q

Concentration of k inside the cardiac cell is

A

151 meq/l

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12
Q

Na outside the cardiac cell is

A

144 meq/l

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13
Q

Na inside the cardiac cell is

A

7 meq.l

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14
Q

Concentration of Ca is about what outside the cell

A

5 meq/l

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15
Q

Concentration of Ca inside cell

A

less than 1 meq/l

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16
Q

When the cardiac cell is in its resting or polarized state, the inside of the cell is ___Charged with what cation

A

Negatively charged with K cation

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17
Q

When the cardiac cell is in its resting or polarized state the outside of the cell is ___ charged with what cation

A

Positively charged with Na cation

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18
Q

Na+/K+ pump establishes

A
  1. an increased Na+ concentration outside the cell 2. an increased K concentration inside of the cell. both ions then diffuse along their concentration gradients. K diffuses out, Na diffuses in at the same time.
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19
Q

For every 50 to 75 K ion that diffuse out of the cell only

A

1 Na diffuses into the cell, exchange ration results in a deficiency of positive cations inside the cell

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20
Q

RMP of the mycardial cells is about

A

-90 mV

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21
Q

Cornerstone to the understanding of the electrophysiology of the heart is the five electrophysiologic phases of the action potential

A

ECG

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22
Q

ECG

A

is used to record the five phases of the action potential

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23
Q

Phase 0 name

A

Rapid Depolarization (early phase)

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24
Q

Depolarization

A

trigger for myocardial contraction

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25
Q

Rapid Depolarization (early phase) activate

A

ventricle muscle fibers initiated by the SA node

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26
Q

ventricular muscle fibers are activated between

A

60-100 times/min by an electrical impulse initiated by the SA node

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27
Q

This action changes the RMP and allows a rapid inward flow of Na into the cell through specific Na channels

A

Phase 0: Rapid Depolarization, causing the cell to become positively charged

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28
Q

The voltage inside the cell at the end of depolarization is about

A

+30 mV, producing a rapid up stroke in the action potential

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29
Q

Repolarization

A

process by which the cells of the heart return to their resting state

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30
Q

Other name for Phase 1

A

Initial Repolarization

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31
Q

Immediately after Phase 0

A

Phase 1: Initial Repolarization

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32
Q

Initial Repolarization

A

The channels for K open and permit K to flow out of the cell, an action that produces an early but incomplete repolarization

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33
Q

Illustrated as a short downward stroke in the action potential curve just before the plateau

A

Phase 1: Repolarization

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34
Q

Name for Phase 2

A

Plateau state

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35
Q

Plateau state

A

Slow inward flow of Ca which in turn significantly slows the outward flow of K

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36
Q

Prolongs the contraction of the myocardial cells

A

phase 2 : Plateau state

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37
Q

Name for Phase 3

A

Final Rapid Repolarization

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38
Q

Final Rapid Repolarization

A

Inward flow of Ca stops, the outward flow of K is again accelerated and the rate of repolarization accelerates

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39
Q

Phase 4 name

A

Resting or polarized state

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40
Q

Resting or polarized state

A

the voltage sensitive ion channels return to their pre-depolarization permeability. the excess Na inside the cell and the loss of K are returned to normal by the Na and K ion pumps. an Additional Na and Ca pump removes the excess Ca from the cell

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41
Q

The heart is composed of how many cardiac cells

A

2

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42
Q

the 2 cardiac cells are

A

Contractile muscle fibers, and specialized “pacemaker cells” called autorythmic cells

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43
Q

Myocardial contractile fiber cells make up

A

the bulk of the musculature of the myocardium and are responsible for the pumping activity of the heart.

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44
Q

Approx how much of the heart is composed of the autorhythmic cells

A

1 %, majority of which are located in the SA node

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45
Q

SA Node

A

Have the unique ability to initiate an action potential spontaneously, which in turn triggers the myocardial fibers to contract.

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46
Q

Automaticity

A

ability of the cells in the SA node (pace maker cells) to generate an action potential without being stimulated.

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47
Q

Excitability (irritability)

A

is the ability of a cell to reach its threshold potential and respond to a stimulus or irritation

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48
Q

The lower the stimulus needed to activate a cell, the more

A

excitable the cell

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49
Q

Conductivity

A

is the unique ability of the heart cells to transmit electrical current from cell to cell throughout the entire conductive system

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50
Q

Contractility

A

the ability of cardiac muscle fibers to shorten and contract in response to an electrical stimulus

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51
Q

additional properties of the myocardial contractile fibers and autorythmic cells are

A

refractory periods

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52
Q

Refractory periods entail

A
  1. the ionic composition of the cells during different phases of the action potential and 2. the ability of the cells to accept a stimulus
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53
Q

Absolute Refractory Period

A

is the time in which the cells cannot respond to a stimulus. The ionic composition of the cells isnt in place to receive a stimulus.

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54
Q

Phases 0,1,2, and about half of phase 3 represent the

A

absolute refractory period

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55
Q

Relative refractory period

A

is the time in which repolarization is almost complete and where a strong stimulus may cause depolariation of some of the cells. Some cells may respond normally, some in abnormal way, and some not at all.

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56
Q

The second half of phase 3 represents

A

the relative refractory period of the action potential

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57
Q

the Nonrefractory period

A

occurs when all the cells are in their resting or polarized state. The cells are ready to respond to a stimulus in a normal fashion

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58
Q

Phase 4 represents what period

A

Nonrefractory period

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59
Q

Duration of each refractory period may vary in response to use of

A

medications or recreational drugs, presence of disease, electrolyte imbalance, myocardial ischemia, or myocardial injury

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60
Q

components of the conductive system include

A

Sinoatrial node (sa node), atrioventricular junction (AV node), bundle of His, the right and left budle branches, and the purkinje fibers.

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61
Q

SA node

A

initiates the cardiac contraction by producing an electrical impulse that travels through the right and left atria.

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62
Q

In the right atrium, the electrical impulse that travels through the

A

anterior internodal tract, middle internodal tract, and posterior internodal tract

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63
Q

All three internodal pathways become one at the

A

AV junction

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64
Q

Bachmanns bundle

A

Conducts electrical impulses by the SA node directly to the left atrium

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65
Q

The electrical impulse generated by the SA node cause the right and left atria to

A

Contract simultaneously, in turn causing the blood in the atria to move into the ventricles

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66
Q

Where is the AV junction located

A

just behind the tricuspid in the lower portion of the right interatrial septum

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67
Q

AV junction

A

relays the electrical impulse from the atria to the ventricles via the bundle of his

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68
Q

Bundle of His location

A

enters the intraventricular septum and divides into the left and right bundle branches

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69
Q

Normal heart, total time required for an electrical impulse to travel from the SA node to the end of the Purkinje fibers is about

A

0.22 seconds (entire heart depolarize time)

70
Q

What plays an important role in the rate of impulse formation, conduction, and contraction strength

A

autonomic nervous system

71
Q

Regulation of the heart is controlled by

A

neural fibers from both the sympathetic and parasympathetic nervous systems

72
Q

Sympathetic neural fibers

A

innervate the atria and ventricles of the heart. When stimulated, the sympathetic fibers cause an INCREASE in the heart rate, AV conduction, cardiac, contractility, and excitability

73
Q

Parasympathetic neural fibers, via the vagus nerve, innervate

A

the SA node, atrial muscle fibers, and the AV junction. It has little or no influence on the ventricular musculature.

74
Q

Stimulation of the parasympathetic system causes the heart rate, AV conduction, contractility, and excitability to do what

A

DECREASE

75
Q

Which phase is the rapid upstroke in the action potential

A

Phase 0

76
Q

When does the inward flow of CA into the heart stop

A

Phase 3

77
Q

Which phase is the plateau stage of the action potential

A

Phase 2

78
Q

The SA node is also called the

A

Pacemaker

79
Q

Which of the following slows the HR and AV conduction

A

Parasympathetic nervous system

80
Q

When can a strong stimulus cause an unwanted depolarization of the heart

A

Relative refractory period

81
Q

which phase is called the resting state

A

Phase 4

82
Q

Which of the following means the ability to transmit electrical current from one cell to another

A

Conductivity

83
Q

An electrical difference across the fibers of the heart is called the

A

Resting membrane potential

84
Q

The entire sequence of electrical changes during depolarization and repolarization is called

A

Action Potential

85
Q

What are the unipolar leads

A

aVL, V6, aVR

86
Q

The imaginary line that can be drawn between the positive and negative electrodes in leads I, II, and III is called

A

Axis

87
Q

Which leads monitor the electrical activity of the heart in the frontal space

A

aVL, Lead II, aVR, Lead III, and aVF

88
Q

Which leads monitor the left ventricle

A

V5 and V6

89
Q

The small squares on the standard ECG paper represent

A

0.04 second

90
Q

The normal duration of the P wave is no longer than

A

0.11 second

91
Q

The normal duration of the PR interval is no longer than

A

0.20 second

92
Q

The normal duration of the QRS complex is less than

A

0.12 second

93
Q

The normal duration of the ST segment is

A

0.12 second or less

94
Q

The normal duration of the T Wave is

A

0.20 second

95
Q

Electrocardiogram (ECG)

A

is a graphic representation of the electrical activity of the hearts conductive system recorded over a period of time. Also used to monitor the hearts response to therapeutic interventions.

96
Q

Standard 12-ECG system consists of

A

4 limb electrodes and 6 chest electrodes.

97
Q

Collectively the electrodes (or leads) view

A

the electrical activity of the heart from 12 different positions - 6 standard limb leads and 6 precordial (chest) leads

98
Q

Each lead

A
  1. views the electrical activity of the heart from a different angle 2. has a positive and negative component 3. monitors specific portions of the heart from the point of view of the positive electrode in that lead
99
Q

Standard limb leads

A

Leads I, II, III, aVR, aVL, and aVF.

100
Q

They are called limb leads because

A

they are derived from electrodes attached to the arms and legs.

101
Q

Bipolar leads

A

Leads I, II, and III. Which means they use two electrodes to monitor the heart, one positive and one negative.

102
Q

Axis

A

Imaginary line that can be drawn between the positive and negative electrodes for leads I, II, and III

103
Q

Eithovens Triangle

A

The triangle formed around the heart by the three axes

104
Q

Unipoar Leads

A

aVR, aVL, and aVF. They monitor the electrical activity of the heart between the positive electrode and the zero electrical reference point at the center of the heart

105
Q

letter a stands for, v stands for

A

augmentation, voltage

106
Q

Collectively, the limb leads monitor the electrical activity of the heart in the

A

frontal plane

107
Q

frontal plane

A

which is the electrical activity that flows over the anterior surface of the heart; from the base to the apex of the heart, in a right to left direction

108
Q

Left Lateral Leads

A

Leads I and aVL, monitor the left lateral side of the hear

109
Q

Inferior Leads

A

Leads II, III, and aVF. view the lower surface of the heart

110
Q

which lead is usually ignored

A

aVR since it does not contribute much info

111
Q

Precordial leads monitor the heart from the

A

horizontal plane

112
Q

Horizontal plane

A

which means they record electrical activity that transverses the heart.

113
Q

Leads V1 and V2 monitor the

A

right ventricle

114
Q

V3 and V4 monitor

A

the ventricular septum

115
Q

V5 and V6 view the

A

left ventricle

116
Q

Leads V1, V2, V3 and V4 are also called the

A

anterior leads

117
Q

V5 and V6 are also called

A

Lateral Leads

118
Q

Modified chest lead (MCL)

A

is a bipolar chest lead similar to the precordial lead V1. The positive electrode is placed on the chest (in the same position as V1 and the negative electrode is placed on the left arm or left shoulder area.

119
Q

MCL may be helpful in

A

visualizing some waveforms

120
Q

ECG run at what speed

A

25 mm/ sec

121
Q

Each small square has a duration of

A

0.04 sec

122
Q

Each large square delineated by the darker lines has how many small boxes and a duration of what

A

5 small squares, and a duration of 0.20 seconds

123
Q

The paper on all ECG monitors runs at a speed of what

A

5 large squares per second, or 300 large squares per minute

124
Q

The verticle portion of each small square represents

A

amplitude (or voltage) of 0.1 mV and 1 mm in distance

125
Q

1 mv =

A

10mm (10 small verticle squares)

126
Q

ECG configurations are composed of

A

waves, complexes, segments, and intervals recorded as voltage (on vertical axis) against time (on horizontal axis)

127
Q

A single waveform begins and ends at the

A

baseline

128
Q

when the waveform continues past the baseline, it changes into another

A

waveform

129
Q

Two or more waveforms together are a

A

complex

130
Q

a flat, straight, or isoelectric line is called a

A

segment

131
Q

Interval

A

a waveform, complex, connected to a segment

132
Q

Positive Deflections

A

all ECG tracings above the baseline

133
Q

Waveforms below baseline

A

Negative Deflections

134
Q

Normal cycle of electrical activity in the heart begins with what and is recorded as what

A

begins with atrial depolarization and is recorded as the P wave

135
Q

Shape of P wave

A

Symmetrical and upright

136
Q

P wave is followed by

A

a short pause while the electrical current passes through the AV node, this is seen on the ECG tracing as a flat or isoelectric line after the P wave

137
Q

Normal duration of the P wave is

A

0.08 to 0.11 second

138
Q

The normal amplitude of the P wave

A

is 0.2 and 0.3 mV

139
Q

An increased duration or amplitude of the P wave indicates the presence of what such as

A

presence of atrial abnormalities, such as hypertension, valvular disease, or congenital heart defect

140
Q

Repolarization of the atria is usually not recorded on an ECG tracing because

A

atrial repolarization normally occurs when the ventricles are depolarizing, which is a greater electrical activity

141
Q

P prime (P’) wave

A

atria depolarize in response to a stimulus outside the SA node

142
Q

Starts at the beginning of the P wave and ends at the beginning of the QRS complex

A

PR interval

143
Q

Normal duration of the PR interval is

A

0.12 to 0.20 second

144
Q

The PR interval represents the

A

total atrial (supraventricular) electrical activity prior to the activation of the bundle of His, ventricular branches, and Purkinje fiber system

145
Q

Represents ventricular depolarization

A

QRS complex

146
Q

why is the QRS complex higher than the P wave

A

because the muscle mass of the ventricles is greater than that of the atria

147
Q

Under normal conditions, the duration of the QRS complex is

A

less than 0.12 second

148
Q

abnormal ventricular induced QRS complex waves are

A

longer than 0.12 second

149
Q

Other abnormal QRS complex include

A

premature ventricular contractions (PVCs), increased amplitude, and T waves of opposite polarity

150
Q

Represents the time between ventricular depolarization and repolarization

A

ST segment

151
Q

normally ST segment measures

A

0.12 second or less

152
Q

ST segment may be elevated or depressed due to

A

myocardial injury, ischemia, and certain cardiac medications.

153
Q

A flat, horizontal ST segment above or below the baseline is highly suggestive of

A

ischemia

154
Q

Represents Ventricular Repolarization, rest, and recovery

A

T wave

155
Q

Normally the T Wave has a what deflection of about what mV

A

Positive deflection of about 0.5 mV, although it may have a negative delfection

156
Q

The duration of the T wave normally measures

A

0.20 second or less

157
Q

At the beginning of the T wave, the ventricles are in their

A

effective refractory period

158
Q

at about the peak of the T wave, the ventricles are in their

A

relative refractory period and thus, are vulnerable to stimulation

159
Q

T waves are sensitive indicators for the presence of a number of abnormalities, including

A

acid-base imbalance, hyperventilation, hyperkalemia, ischemia, and the use of various drugs

160
Q

Follows the T wave and has the same polarity (deflection) as the T wave

A

U wave, origin not known, because of its low voltage the U wave usually is flat and not seen

161
Q

when does the U wave become prominent

A

in the presence of certain electolyte disturbance, certain medications, and heart disease

162
Q

Represents total ventricular activity

A

QT interval

163
Q

QT interval

A

Ventricular depolarization (QRS) and repolarization (ST segment and the T wave).

164
Q

Normally the QT measures about

A

0.38 second, and varies in males and females and with age

165
Q

General Rule of QT interval

A

should be about 40% of the measured RR interval

166
Q

P wave heart activity

A

Atrial depolarization

167
Q

PR interval heart activity

A

Total atrial electrical activity prior to activation of the bundle of His, ventricular branches, and Purkinje fiber system

168
Q

QRS complex heart activity

A

Ventricular depolarization

169
Q

ST segment heart activity

A

Time between ventricular depolarization and repolarization

170
Q

T wave heart activity

A

Ventricular Repolarization

171
Q

U wave heart activity

A

usually is a flat or not seen

172
Q

QT interval heart activity

A

Total ventricular activity