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671A - Anesthesia I > Week 2 - Basic EKG > Flashcards

Week 2 - Basic EKG Flashcards

1
Q

The resting cardiac cell myocyte has a membrane potential of __________ mV

A

-90

inside is negative relative to outside

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2
Q

When the cardiac cell is depolarized, what occurs?

A

Influx of positive ions come into the cardiac cell (Ca++ for nodal and Na+ for cardiac myocytes) - making the inside positive compared to the negative outside
Once this action peaks, K+ is released from the cells driving the cell back to its resting state (-90 mV cardiac myocytes, -60 mV nodal cells)

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3
Q

What is the normal order for the cardiac conduction system

A

SA node –> AV node –> Bundle of His (left and right bundles) –> Purkinje fibers

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4
Q

The _____ ________ is electrically dominant

A

Left Ventricle

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5
Q

What are the normal interval lengths?
PR ______
QRS _______
QTc _______

A

PR: 0.12-0.20 seconds (120-200 msec) or 3-5 small boxes
QRS: 0.08-0.12 seconds (80-120 msec) or 2-3 small boxes
QTc: 0.35-0.44 seconds ish (350-440 msec)

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6
Q

Voltages can be represented as?

A

Vectors (direction and magnitude)

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7
Q

Is a normal T wave symmetrical or asymmetrical?

A

Asymmetrical
Slurred upstroke

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8
Q

What are the bipolar leads

A

Lead I, Lead II, Lead III
(limb leads)
Measures electrical differences between 2 electrodes. 1 positive, 1 negative

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9
Q

Where are the augmented leads placed?

A

aVR - Right arm, above wrist
aVL - Left arm, above wrist
aVF - Left foot, above ankle

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10
Q

How much time is represented by one little square on the ECG strip? One big square?

A

Little square - .04 seconds/40msec
Big square - .2 seconds/200msec

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11
Q

What are the waves of an ECG? What do they represent?

A

P wave - Atrial depolarization
QRS complex - Ventricular depolarization
T wave (and U wave) - Ventricular repolarization

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12
Q

A signal of 1 mV amplitude produces a ________ mm deflection

A

10
* 10 little boxes or 2 big boxes

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13
Q

Where is correct placement of the precordial leads?

A

V1 - 4th intercostal space, right of sternum
V2 - 4th intercostal space, left of sternum
V3 - midway between V2 & V4
V4 - 5th intercostal space, midclavicular line
V5 - anterior axillary line, same level as V4
V6 - midaxillary line, same level as V4, V5

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14
Q

What axis deviation would you suspect in a mainly negative deflection in lead I and a mainly positive deflection in an aVF lead sample

A

Right axis deviation

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15
Q

What axis deviation would you suspect in a mainly positive I lead and a mainly negative II lead sample

A

Left axis deviation

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16
Q

How would you describe the axis deviation if defletions were positive in lead I and II?

A

Normal axis deviation

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17
Q

The initial QRS vector is directed in which way?

A

To the right, anteriorly and slightly superiorly or inferiorly.

depolarization through interventricular septum
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18
Q

The main QRS vector is directed which way?

A

To the left, posteriorly and inferiorly. Represents R wave

ventricular depolarization through bundle branches
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19
Q

The terminal QRS vector is directed which way?

A

Backwards and upwards, may go to the left or right. Represents S wave

depolarization of purkinje fibers

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20
Q

What are the precordial leads? Are they unipolar or bipolar?

A

V1-V6 (chest leads), unipolar

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21
Q

What parts of the heart can we visualize from the precordial/chest leads?

A

Anterior, septal, and lateral walls

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22
Q

What is the relationship of R and S waves in the precordial leads? Moving from right to left

A

rS —> Rs
R waves increase in size as S waves decrease in size

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23
Q

What is the transition zone?

A

Equal R and S waveform voltages. Usually occurs around V3-V4. Normal variant to have an early V2 or late V5 transition zone

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24
Q

In what lead is the R wave amplitude the greatest?

A

Usually lead V5, sometimes lead V4. V6 has a smaller R wave due to interference of the left lung

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25
Q

How long would a broadened P wave be (prolonged atrial activation time)?

A

> 0.11 seconds

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26
Q

What might be the cause of a prolonged p-wave (>0.11 seconds)?

A
  • Inter atrial conduction delay
  • Sick sinus syndrome
  • Dual chamber pacemaker
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27
Q

P wave abnormalities in Right Atrial Enlargement

A

Normal conduction speed, increased p wave amplitude >2.5 mm
Lead II is best for p waveform

Associated with pulmonary valve stenosis, pulmonary hypertension, and cor pulmonale

RAE = right atrial enlargement LAE = left atrial enlargement
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28
Q

Wandering atrial pacemaker characteristics

A
  • Three different looking p waves (less than 100 bpm)
  • Natural pacemaker cells move from SA node to distant cells within the SA node
  • Caused by varying vagal tone (increased tone causes a decreased conduction speed within the SA node)
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29
Q

What could an accelerated idioventricular rhythm indicate?

A

Usually indicates reperfusion of the heart (short lived) after a cardiac event

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30
Q

How would you describe a 1st degree AV block?

A

PR intervals longer than .2 seconds
QRS complex for each p wave
* Slowing of conduction within the AV node

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31
Q

Which block consists of progressively longer PR intervals followed by a dropped QRS.

A

Second degree AV block Type 1 (Mobitz I or Wenckebach)
* “Longer, longer, longer drop, then you have a wenckebach”

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32
Q

Second degree Mobitz II AV block characteristics

A
  • PR interval remains constant, can be normal or prolonged
  • Intermittent QRS dropped
  • Always INFRANODAL
  • Usually an emergent scenario
  • Usually wide QRS!
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33
Q

Every other P wave being conducted is an example of __________

A

2:1 AV block.
Unless there has been an MI, generally if it has a wide QRS complex it is occurring in the His/Purkinje system. This means a 2nd degree type 2 block! BAD, get pacing pads

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34
Q

Which AV block consists of P waves and QRS complexes occuring, but independent of each other?

A

3rd degree AV block (complete)
NEEDS A PACEMAKER

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35
Q

The frontal plane consists of leads:

A

I, II, III, aVR, aVL, aVF
(limb leads and augmented limb leads)

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36
Q

The horizontal plane consists of leads:

A

V1-V6
(precordial leads)

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37
Q

When a wave of depolarization spreads toward a lead’s positive pole, it causes a _________ deflection

A

positive (upward)

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38
Q

When a wave of depolarization spreads toward a lead’s negative pole, it causes a _________ deflection

A

negative (downward)

39
Q

A biphasic deflection occurs when a wave of depolarization is moving _________

A

at a right angle to the lead

40
Q

What two things determine the QRS Axis?

A
  • Anatomical position of the heart
  • Direction the stimulus spreads through the heart
41
Q

What is a possible pathological cause of right axis deviation

A
  • Right ventricular hypertrophy
  • Lateral wall MI
  • COPD
42
Q

What is a possible pathological cause of left axis deviation?

A
  • Left ventricular hypertrophy
43
Q

True or false:

Palpitations are always an abnormal/pathological finding

A

False
* may occur with increased sympathetic stimulation (e.g. excitement, anxiety, exercise)

44
Q

Treatment of sinus tachycardia associated with a pathologic cause must always be directed at ____________

A

the underlying cause (sepsis, fever, internal bleeding, etc.)

45
Q

What is an escape beat or rhythm?

A

If a primary or “higher level” pacemaker (e.g. SA node) fails to fire or conduct, another pacemaker (e.g. AV node) may generate a “rescue” beat or rhythm, generally at a slower rate

46
Q

What are the rates for the secondary pacemakers?

A
  • Atrial cells: 60-80 bpm
  • AV nodal/junctional: 40-60 bpm
  • His/Purkinje: 20-40 bpm
  • Ventricular myocytes: <20 bpm
47
Q

In junctional escape rhythm, the atria are activiated in a retrograde fashion, producing ___________ p waves in leads II, III, aVF

A

negative

48
Q

Idioventricular escape rhythms usually have ________ complex QRS and indicate a potentially life threatening situation

A

wide
* infranodal causes asynchronous depolarization of ventricles

49
Q

In urgent situations, intravenous __________ can be adminstered to increase the rate of atrial or AV nodal pacemakers

A

atropine

50
Q

__________ will may be effective for bradycardia resulting from infranodal escape rhythms - instead __________ agents should be adminstered

A

sympathomimetic (dopamine, isuprel)

51
Q

The most common cause of short term sinus arrhythmia is _________

A

respiration
* inspiration increases sympathetic tone (increased RR)
* Expiration increases vagal tone (decreased RR)

52
Q

What is the progression of treatment for acute PSVT?

A
  • Vagal maneuvers
  • IV adenosine
  • Beta/Calcium channel blockers
  • Cardioversion (rarely needed)
53
Q

How does the ECG for A-flutter and A-fib differ?

A
  • Flutter: regular interval, nearly identical saw-tooth waves (suggestive of single, stable reentrant pathway)
  • Fib: “wavelets”, varying continuosly in amplitude and polarity (suggestive of multiple, unstable ectopic foci)
54
Q

1:1 AV conduction of a-flutter is a medical emergency treated with _________

A

immediate synchronized cardioversion

55
Q

Acute treatment of a-fib or a-flutter focuses on ________. This can be achieved with the use of __________

A
  • rate control or rhythm control
  • AV nodal blocking agents (beta blockers, calcium channel blockers
56
Q

What is AVNRT?

A

Atrioventricular nodal reentry tachycardia. Most common reentry SVT (60%). More common in females

57
Q

What are the characteristics of AVNRT?

A

A circuit is formed via 2 separate pathways. This generally creates a slower and faster pathway. The slower pathway (normal conduction) arrives to the ventricles later. The faster pathway activates the atria and ventricles simultaneously. Normal QRS waveform. Because circuit is within the AV node, the QRS looks “normal”

58
Q

AVNRT and AVRT are _________ on AV nodal conduction.

A

dependent

59
Q

What is AVRT?

A

Atrioventricular reentry tachycardia
Second most common reentry tachycardia. Most common in males

60
Q

How does AVRT work?

A

Conduction circuit involving the atria and ventricles. This causes the faster conduction pathway to hit the ventricles before the normal pathway does. The result is wide QRS complexes manifested by delta waves.
Short PR, delta waves, and wide QRS

61
Q

Multifocal atrial tachycardia characteristics

A

Rate greater than 100
3 different looking p waves
Generally occurs in COPD patients

62
Q

Sustained VT is defined as lasting longer than _______ _________

A

30 seconds

63
Q

______ or more PVC’s is considered _________ ___________

A

3, ventricular tachycardia

64
Q

What causes the wide QRS morphology in PVC’s

A

Impulse begins in one of the ventricles and they are simultaneously stimulated

65
Q

PVC’s arising from the base of the heart have an inferior/rightward axis and are considered ___________, occuring in a structurally ____________ heart

A
  • benign
  • normal
66
Q

During PVC’s, ST-T waves directed in the opposite direction of the QRS is a __________ finding, and ____________ myocardial ischemia

A
  • common
  • is not indicative
67
Q

Polymorphic VT in the absence of QT prolongation most often indicates _________

A

ACUTE MYOCARDIAL ISCHEMIA

68
Q

Accelerated idioventricular rhythm (AIVR) is particularly common in __________ and may be a sign of __________

A
  • acute MI
  • reperfusion
69
Q

Determine which rhythm is pictured:

A

1st Degree AV block

70
Q

Determine which rhythm is pictured:

A

2nd Degree AV block Type I - Wenkebach

71
Q

Determine which rhythm is pictured:

A

2nd Degree AV block Type II

72
Q

Determine which rhythm is pictured:

A

3rd Degree AV Block

73
Q

Wolfe-Parkinson-White is characterized by ___________ of the ventricles

A

Pre-excitation

74
Q

Describe the WPW triad. Why does this occur?

A
  • Short PR interval, Wide QRS, delta wave
  • Ventricles are stimulated early via an accesory conduction path
75
Q

What ECG findings are consistent with hyperkalemia?

A
  • peaked T waves in precordial leads, sometimes taller than R waves
  • widened QRS
  • small or indiscernible p waves
  • 1st degree AV block
76
Q

What ECG findings are consistent with hypokalemia?

A
  • U wave prominence
  • Increased P wave amplitude

ECG changes aren’t as dramatic and may be rare

77
Q

QT prolongation may be a manifestation of what electrolyte abnormality? What is a possible complication?

A
  • hypomagnesemia
  • Torsades
78
Q

Hypocalcemia may present with a _______ ST segment, while hypercalcemia may present with a _________ ST segment

A
  • long
  • short
79
Q

True or false
Mechanical component of the heart is shown on an ECG

A

False

80
Q

Which heart valves interact with deoxygenated blood?

A

Tricuspid and pulmonic valve

81
Q

4 main ions responsible for electrical conduction within the heart?

A

Ca ++, Na +, K +, Cl-

82
Q

Which heart pump is responsible for maintaining the resting potential of the heart?

A

Na+/K+ pump. 3 Na+ taken OUT of the cell, 2 K+ brought INTO the cell!
(-90 mV resting potential)

83
Q

Changes in membrane potentials causing depolarization and repolarization cause ______________

A

Contraction and relaxation of the cardiac myocyte

84
Q

Increased muscle thickness causes _________ conduction times

A

Increased

85
Q

What ion is responsible for depolarization of SA nodal cells?

A

Calcium
(think about the effect of CALCIUM channel blockers on HR - they slow the SA node and subsequently the HR)
Funny channels allow Na+ to enter the cell first, than Ca+ is primarily responsible for depolarization via L type (Main) and T type channels

86
Q

Which leads are best to visualize the p waves

A

II and V1

87
Q

The P waves should always be positive (upward deflections) in normal conduction in which leads

A

II, III, aVF

88
Q

Which arrhythmia has a shift of the natural pacemaker site from the head of the SA node to distant sites within the SA node

A

Wandering Pacemaker

3 different looking p waves
Rate less than 100

89
Q

What is occuring during the plateau phase of myocyte action potentials?

A

There is an equal outflow of potassium (+) from the cell and inflow of calcium into the cell (+). The balance in charges causes a relatively flat morphology.

90
Q

PVC’s are followed by a _________ ____________

A

Compensatory Pause

91
Q

The following is a diagram of the action potential of which type of cardiac cell?

A

SA/AV Nodal

92
Q

The following is a diagram of the action potential of which type of cardiac cell?

A

Cardaic Myocyte
* morphology for atrial vs ventricular is slightly different, but follow this general pattern

93
Q

What does a negative delta wave in lead I suggest in WPW?

A

right sided accessory pathway

94
Q

When would you likely see Osborn waves?

A

Hypercalcemia, hypothermia
Opposite of a normal T wave, quick upstroke slurred downstroke. Can look like an MI

671A - Anesthesia I (22 decks)

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