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Health Assessment > EKG > Flashcards

EKG Flashcards

1
Q

What is normal pathway of conduciton in heart?

A
  • SA node
    • 60-100 bpm
  • AV node
    • delays conduction for ventircular filing; intiiates impulse 40-60 bpm
  • Bundle of His
    • directs impulse to left/right bundle branches
  • Purkinje fibers
    • reaches into myocardium to stimulate ventricular depolarizaiton/contraction. initiates impulse 20-40bpm

net direction of action potential is from base to apex. heart depolarizes in to out, bottom to top

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2
Q

What are the two main vectors in EKG?

A

vector of depolarization and vectors of repolarization

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3
Q

What is the vector of depolarization?

A
  • QRS complex
  • heart depolarizes from base to apex and endocardium to epicardium
  • myocytes go from internally negative to internally positive–> produces a positive electrical current
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4
Q

What is a lead?

A
  • electrical view of heart
  • each lead represents a view of the heart from a different position
  • each lead of the EKG has two poles; a negative pole and positive pole
    • identify these poles with electrodes on skin
  • Standard limb leads are I, II, III
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5
Q

What is lead I

A
  • Lead I
    • goes from negative electrode on right upper limb to positive elctrode on left upper limb
    • corresponds to view of lateral wall of heart and areas supplied by circumflex artery
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6
Q

What is Lead II?

A
  • goes from negative elecrode on right upper limb to positive electrode on left lower limb
  • corresponds to view of inferior wall of the heart and areas supplied by the RCA
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7
Q

What is lead III?

A
  • goes from negative electrod on left upper limb to positive electrode on left lower limb
  • corresponds to view of inferior wall of heart and the reas supplied by the right coronary artery
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8
Q

What are the augmented limb leads?

A
  • Unipolar, meaning they have one positive pole and a reference point in the opposite side of the heart, but use same electrode placement as the standard limb leads
    • referred to as augmented because the voltage must be amplified by the EKG machine
      *
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9
Q

What is aVR?

A

aVR: right arm electrode is positive and the left arm and left leg electrodes are channeled together to form a common reference point that has a negative charge

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10
Q

What is aVL?

A
  • left arm electrode is positive
  • the right arm and left leg electrodes are channeled together to form a common reference point htat has a negative charge
  • corresponds to a view of the lateral wall and areas supplied by the circumflex artery
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11
Q

What is aVF?

A
  • left foot electrode is positive
  • right arm and left arm electrodes are channeled together to form a common reference point that has a negative charge
  • corresponds to a view of the inferior wall of the heart and areas supplied by the right coronary artery
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12
Q

What are the precordial leads?

A
  • Precordial leads are the last six leads of the EKG and look at events in the heart on a horinzontal plane
    • they view the anterior and lateral surfaces of the heart.
    • the positive poles are on the anterior and lateral chest and the negative poles are on the opposite side of the positive pole
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13
Q

V1?

A
  • Positive electrode placed directly over right atrium
  • corresponds to the septal wall and areas supplied by the left anterior descending (LAD) artery
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14
Q

V2?

A
  • Positive elctrode placed just anterior to AV node
  • corresponds to septal wall and areas supplied by LAD
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15
Q

v3?

A
  • Positive electrode placed over ventricular septum
  • corresponds to anterior wall of heart and areas supplied by LAD
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16
Q

v4?

A
  • Positive electrode placed over ventricular septum
  • corresponds to anterior wall of heart and areas supplied by LAD
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17
Q

V5 and V6?

A
  • Positive electrodes placed over the lateral surface of the left ventricle
  • corresponds to lateral wall of heart and areas supplied by circumflex artery
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18
Q

What is the 5-lead EKG setup?

A
  • most common system used in operating room
  • takes standard three lead system (right limb electrode, left limb electrode and left leg electrode) and adds right leg and chest electrode
    • by adding the right leg lead electrode, any of the six limb leads can be viewed (I, II, III, avR, avL, avF)
    • the chest electrode can be moved to any of the precordial V positions to obtain all six precordial views (V1-V6)
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19
Q

When does a positive deflection occur on the EKG during depolarization?

A

When vector of depolarization travels towards a positive electrode

ex- lead I

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20
Q

When do you get a negative deflection on EKG during depolarization?

A
  • When vector of depolarization travels away from a positive electrode
  • EX- avR
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21
Q

When does biphasic deflection occur on EKG?

A

When depolarization travels perpendicular to positive electrode

ex- V3

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22
Q

How does the heart depolarize?

A

base to apex and endocardium to epicardium

myocytes go from internally negative to internally positive–> produces a positive electrical current

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23
Q

What is the vector of repolarization?

A
  • T wave
  • Heart repolarizes from apex to base and epicardium to endocardium
  • myocytes go from internally positive to internally negative–> produces a negative electrical current
    • positive deflection occurs when the wave travels away from a positive electrode
  • backwards of depolarization
  • cheat if this is confusing: T wave should always match P wave!!!!
24
Q

What is each small box on EKG worth? Large box?

A

small= 0.04 sec time; vertical= 1 mm or 0.1 mV

5 boxes= 0.2 sec; vertically= 5 mm or 0.5 mV

5 “large” boxes = 1 second

25
Q

When do you expect to see change in voltage?

A

When heart contracts more forcefully or when patient has hypertrophy, voltage will be increased

if heart is contracting less forcefully (as seen is tamponade) the voltage will be decreased

26
Q

What is the p-wave?

A
  • Represents the firing of the SA node and atrial depolarization
  • normally upright in lead II
  • inverted P waves in lead II indicate that conduciton throught he atria occured in retrograde manner–> usually this means the impulse originated in the AV node
    • normal- 1 P wave before every QRS complex, duraiton 0.08-0.12 seconds
27
Q

What is the PR interval?

A
  • beginning of the P wave to beginning of QRS
  • represents the delay of electrical impulse at the AV node to allow for atrial contraction
    • normal 0.12-0.2 seconds
28
Q

What is QRS complex?

A
  • Represent ventricular depolarization
  • if duration is increased may consider WPW, LVH, BBB
    • normal <0.12 seconds with progressiv eincreased amplitude in V1-V6
29
Q

What is the Q wave?

A
  • may or mya not be present
  • consider abnormal and possible sign of an MI if amplitude is
    • 1/3 of R wave or
    • duration is >0.04 sec and depth >1mm
  • Normal <0.04 seconds
30
Q

What is ST segment?

A
  • follows QRS complex and connects to the T wave and represents ventircular repolarization
  • if ST segment is elevated or depressed by >1 mm, may indicate MI
    • normal= isoelectric
31
Q

What is the T wave?

A
  • follows QRS complex and represents ventircular repolarization
  • changes in T wave amplitude can occur with electrolyte imbalances (peaked T wave indicates hyperkalemia) or possible MI
    • normal- follows QRS and should deflect in the same direction as the QRS complex
      • smaller amplitudes in limb leads than precordial leads
32
Q

What is the J point

A
  • point where QRS segment meets the ST segment
    • used as reference for ST elevation or depression
      • normal- isoelectric
33
Q

What is QT interval?

A
  • Beginning of the QRS interval to end of the T wave, measures the amount of time it takes for ventircular depolarization and repolarization
  • shortened in faster heart rates and prolonged in slower heart rates
  • prolonged QT intervals can lead to torsade de pointes
    • <0.45 in men
    • 0.47 in women
34
Q

What is the U wave?

A
  • May follow T wave and usually has same deflection as T wave
  • If present, may b eassociated with electrolyte imbalances, paricularly hypokalemia
    • normal- not present
35
Q

What are the 5 steps for EKG evaluation?

A
  1. Determine rate
    1. 6 second rule; rule 1500; rule of 300
  2. Determine rhythm
    1. regular/irregular
    2. pwaves/QRS
    3. ectopy
    4. pauses
    5. PR interval
    6. QRS interval
    7. QT interval
    • Determine bundle branch blocks (step 2.5)
  3. Determine axis
    • (I, avf)
  4. Evaluate for hypertrophy
    • RVH- large R wave in V1, progressively smaller in V2-V4
    • LVH= height of S wave in V1 + height of R wave in V5 >35mm
  5. Infarction/ischemia
    • T wave inversion, ST segments, abnormal Q waves
36
Q

How do you determine rate?

A
  • Atrial and ventricular
  • Rule of 1500s (more accurate)
    • can only be used on regular rhythms
    • count the number of small blocks b/w the tallest point of two consecutive P waves
    • take 1500/ # of boxes= atrial rate
    • repeat to find ventricular rate
37
Q

Steps to analyze rhtyhm?

A
  • Are R-R intervals regular
  • Is the origin of rhythm sinus?
    • p waves upright before each QRS
    • QRS after each P wave
  • Ectopy? abnormal wave (u wave)
  • Pauses
  • PR interval measurement (nml 0.12-0.2)
  • QRS interval measurement *nml <0.12
  • QT interval measurement
    • nml <0.45 men
    • 0.47 women
38
Q

What is a RBBB?

A
  • Broad QRS >120 ms
  • RSR’ pattern in V1-V3
    • rabbit ears for RBBB
  • Wide, slurred s wave in lateral leads
    • I, aVL, V5-V6
39
Q

What is found in LBBB?

A
  • ST segments and T waves
  • directed opposite to the main vector of the QRS complex
  • ST elevation and upright T waves with negative QRS
  • ST depression and T wave inversion with positive QRS complex
  • all leads will show that pattern
  • also will see “top hat” on QRS
40
Q

How do you determine axis?

A
  • Normal vector of depolarization is from base to apex and endocardium to epicardium
  • when this vector is not directed in this usualy direction, it is referred to axis deviation
  • to evaluate for axis deviaiton, examine lead I and avF, speicfically the direction ofthe R wave deflection
  • axis can deivate as a consequence of ventiruclar hypertrophy, conduciton block, or a physical change in the position of the heart
  • vectors tend to point towards areas of hypertrophy and away from areas of injury (MI)
41
Q

What shows left axis deviation?

A
  • has a positive R wave deflection in lead I but negative R wave deflection in aVF
    • leaving each other= left axis deviation
42
Q

What shows right axis deviation? extreme right axis deviation?

A
  • Right axis deviaiton has a negative R wave deflection in lead I but positive R wave defleciton in aVF
    • reaching each other= right axis deviation
  • extreme right axis deviation has negative R wave deflection in both lead I and avF
    • “two thumbs down = bad, two thumbs up= normal
43
Q

What are some causes of right axis deviation?

A

Conditons that make the right side of the heart work harder or hypertrophy

  • COPD
  • Acute bronchospasm
  • cor pulmonale
  • pulmonary hypertension
  • pulmonary embolism
44
Q

What are causes of left axis deviation?

A

Conditions tha tmake the left side of the heart work harder or hypertrophy

  • chronic HTN
  • LBBB
  • Aortic stenosis
  • Aortic insufficiency
  • mitrla regurg
45
Q

How do you evaluate for RV hypertrophy?

A
  • Large R wave in V1 and gets progressively smaller in V2, V3, V4
46
Q

How do you evaluate left ventricular hypertrophy?

A
  • Large S wave in V1 and larger R wave in V5
  • Depth (in mm) of S in V1, lus height of R in V5
    • if >35 mm= LVH
47
Q

How do you identify ischemia?

A
  • T wave inversion or ST segment depression
48
Q

How do you identify injury on EKG?

A

ST segment elevation >1mm

49
Q

How you ID infarction (old MI)

A

Q waves which are >1 small box or 1/3 size of QRS

50
Q

Which leads show septal issues? Vessel associated?

A
  • V1-V2
  • anterior descending artery
51
Q

What lead limbs show anterior infarction?

A
  • V3/V4
  • anterior descending artery
52
Q

Which leads show anterior-septal? Vessel?

A
  • V1-V4
  • Anterior descending artery
53
Q

What is inferior? Vessel?

A

II, III, aVF

Right coronary artery/posterior interventricular branch

54
Q

Which leads show lateral? vessel associated?

A
  • I, avL, V5, V6
  • Circumflex artery
55
Q

Are t-wave inversions a few days after an MI a good, or bad thing?

A

Can be a good thing. Can show that the area of heart is being reperfused

Health Assessment (7 decks)

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