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12. EKG introduction Flashcards

1
Q

Know this this

A

know image

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2
Q

ECG waveforms

A

know this

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3
Q

ECG with heart tracings:

helps with readings

A

Just for reference

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4
Q

Cardiac conduction: to get your bearings

A

just FYI

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5
Q

Action potentials for Cardiac Myocytes

A

image from slide 3

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6
Q

Direction of electrical current flow by convention is from:

A

negatively to positively charged areas

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7
Q

At rest, cell surface is _____ charged

With depolarization, outside of cell becomes ____

A

Positive

Negatively

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8
Q

Direction of current outside cell moves toward the positive electrode of voltmeter during depolarization thus we see ______ defleciton

A

positive deflection

(refer to A and B)

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9
Q
A
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10
Q

When charge on outside surface of cell is homegenous there is no potential difference between positive and negative electrodes: we see volmeter at

A

zero

Refer to B

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11
Q

During repolarization of single cell, the end of cell initially depolarized is the _____ to repolarize thus current moves _____ to _____, away from positve electrode volemeter and registers negative deflection

A

First to depolarize

Negative to Positive

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12
Q

What is it that ECG is recording?

A

When depolarization spreads through the heart, each cell generates a force that can be measure in the skin

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13
Q

In an intact heart, sequence of repolarization is ______ to depolarization, as action potential duration is SHORTER near outer epicardium (last to depolarize)

A

OPPOSITE

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14
Q

Unlike single cell model, in double cell model, electircal deflection of depolarization and repolarization are usually oriented in

A

same direction

thus see + QRS and + T wave

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15
Q

What are my frontal referece limb leads?

A

Lead I, II, III

aVR, aVL, aVF

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16
Q

What are my 6 transverse/precordial leads?

A

V1- V6

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17
Q

Direction and magnitude of deflection on each lead depends on:

A

how cumulative electircal forces are aligned with the axes or leads

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18
Q

What are my unipolar leads?

A

no single negative pole/negative pole is composite reference of other avereaged leads:

aVR, aVF, aVL and V1-V6 are all unipolar

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19
Q

What do the aVR, aVL and aVF look like?

A

know these bitches

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20
Q

What do standard/bipolar limb leads look like?

A

Have single electrode as positive pole and a single electrode as negative reference

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21
Q

Einthovens Triangle

A

See image

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22
Q

Where is aVL on circle of Axes

A

-30 degress (upper right quad)

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23
Q

Where is lead I on circle of axes?

A

0 degrees, pointing right

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24
Q

Where is lead II on cirlce of axes?

A

+60 degrees (in lower right quad)

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25
Whre is aVF in circle of axes?
+90 degrees (pointing directly down)
26
Where is Lead III on circle of axes?
+120 degress (in bottom left quad)
27
where is lead aVR on circle of axes?
-150 degrees (in upper left quad)
28
Electrical force directed toward + pole of a lead generates a ____ deflection Force directed away from + pole results in _____ defelction
positive negative
29
How is magnitude of deflection determined?
By how parellel electrical force is to the lead axis: more parellel = GREATER magnitude of deflection in that lead When forcei is perpendicular to a lead; get a flat line on recording
30
Sequence of events in cardiac depolarization
1. Depolarize atria (starts at SA node) 2. Depolarize setpum from L--\> R 3. Depolarize anteroseptal region of myocardium; towards apex 4. Depolar bulk of ventricle myocardium... from ENDO to EPI 5. Depolarize posterior part of base of Left ventricle 6. Ventricles are now polarized
31
Inital septal depolarization is directed anteriorly:
left to right; toward V1 and away from V6
32
As lateral wall LV depolarized, electrical forces of thick LV outweigh RV and depolarization is directed:
leftward and posteriorly towards V6
33
Intially, as septal is depolarized we see a small _____ in V1 and small ____ in V6 As lateral wall depolarizes, we see a subsequent large ____ in V1 and large ____ in V6
small r in V1 small q in V2 large S in V1 large R in V6
34
Verticle axis measures _____ in standard 1mm = \_\_\_ Horizonal measures\_\_\_\_ in 1mm = \_\_\_\_
voltage; 1mm= -.1mV time; 1mm= 0.04 seconds \*\*IG use every 5th line = .2 seconds
35
What is normal hearth rhythm determined by
termed sinus rythm with intact AV conduction initiated by depolarization of sinus node and conduction to ventricles
36
Normal EKG: Every P followed by: Upright P present in leads: PR interval between:
followed by QRS upright P in I, II, III PR interval btwn 120 and 200 ms
37
LImits for bradycardia and sinus tachycardia
bradycardia is \<60 tachycardia is \>100
38
Trick to approximate HR on grid paper
Count off large (5mm) boxes between 2 consecutive QRS using sequence: 300, 150, 100, 75,60,50
39
How to calculate irregular rhythm
count # of QRS durign 6 secs and multiply by 10
40
Way to find HR
[25mm/sec x 60sec/min] / mm between beats
41
Calculate PR interval: what is normal
onset of P to onset of QRS 0.12 to 0.2 seconds
42
Define QRS interval and normal time
beginning to end of QRS
43
QT interval and normal value
onset of QRS until end of T wave (QT corrected: measured QT/square of RR interval) QTc
44
What is the mean QRS axis?
ave of instantatneous electrical forces generated during ventricular depolarization in FRONTAL plane Normal: -30 to +90 degrees Left axis deviation: negative to -30 Right axis deviation: Positive to +90
45
46
How to do Rough, rapid estimation of axis
Evaluate QRS in leads I and II if net QRS positive in both leads; upward deflection\>negative defection; aixs is normal range between -30 and +90
47
Calculating axis: geometric method
Use Lead I and II
48
Inspection method of calculating axis
Find axis perpendicular to isoelectric lead (will be a flat line on the read) Then find the largest QRS to see if it's + or -
49
What do we expect to see in a P wave for Right atrial activation/enlargement? left atrial activation/enlargement?
Right: II: increaed RA V1: increased RA and Left: II: double hill V1:large decrease of LA
50
What does a normal P wave look like IN lead II and V1
51
This is P wave... whats going on?
Left atrial activation/enlargement
52
This is a P wave, whats going on?
Right atrial enlargement
53
What happens in LVH?
increase amplitude of electircal forces directed to left and posteriorly. Repolarization abnormalities--\> result in ST segment depression and T wave inverion in leads with promiment R wave
54
What changes to QRS do we see in LVH?
ST segement depression T Wave inversion causing promient R wave
55
What do we see in a RVH?
shift QRS vector to the right leading to a R, RS or qR complex in lead V1 possible T wave inversions in right precarodial leads
56
Key ECK measurements for LVH
S in V1 plus R V5 OR V6 \>35mm OR R in aVL \>11mm, or R in I \>15mm
57
Key ECG measures for RVH
R\>S in V1 and right axis deviation
58
Whats going on with this dude?
Note tall R wave in V1 right axis deviation T wave inversion V1-V3 \*\*\*RVH\*\*\*\*
59
When do we see an S1 Q3 pattern in EKG
With acute or chornic right ventricle overload sydromes or severe right ventcile pressure overload
60
Interuption of Left Anterior fasicular division or LAD results in:
intial inferior (1) followed by domiant superior (2) direction of activation.
61
Interruption of Left posterior Fascicle or division LPD results in:
intial superior (1) followed by dominant inferior (2) direction of activation.
62
If you see wide QRS: think LBBB or RBBB and check V1 and V6
Review image
63
Image on left is V1 on right is V6 Dx?
Right Branch Bundle Block
64
Image on left is V1 Image on right is V6 Dx?
Left Branch Bundle Block
65
Criteria for RBBB?
QRS complex over .12 sec RsR' (Mshaped) QRS comples in V1 Widended or 'slurred' S wave in leads I and V6
66
Criteria for LBBB
QRS greater then .12 sec widened or 'slurred' R wave in leads I and V6 Prominent QS or rS in leave V1
67
Dx?
RBBB; see QRS more then .12 (means L or R BBB) RsR' (M shaped) QRS in V1 Widened S wave in V6 and I
68
Dx?
LBBB QRS over .12 (can be Rt or LEft) widened R wave on I and V6 Prominent QS or rS in lead V1
69
With predominant subendocardial ischemia; the ST vector is director toward:
inner layer of afftected ventricle and ventricular cavity Leads overlying it should record ST depression
70
With ischemia involving outer ventricular (transmural or epicardial) injury, we see:
ST vector is directed OUTWARD and overlying leads record ST segment elevation Recipricol ST segment depression can appear in conralateral leads
71
Acute ischemia can alter ventricular AP by inducing lower RMP and decreaed amplitude of phase 0... what can we see reflected in ECG
deviation of ST segment (effects create a voltage gradient between ischemic and normal cells at dif phases in cardiac cycle)
72
In MI we see ______ in leads I, aVL, and V2-V6
ST segment elevation
73
Subendocardial Ischemia will cause \_\_\_\_
ST depression
74
In and ST elevated MI, unless reperfusion of occluded artery is achieved we have irreversible necrosis and will eventually develop:
Pathologic Q wave in overlying infarcted tissue (nectrotic tissue can't generate electric force)
75
Why do we get Pathologic Q wave?
Lead over necrotic tissue (from MI) detects currents from health tissue on opposite regions of ventricle directed away from infarct thus a downward deflecting Q wave
76
See a small Q wave defelcting down that is 20 ms long and at 20% QRS height.. is there any pathology associated with this?
No: small initial Q waves can be normal as long as they are \>40ms and low magintude of \>25% QRS --are not localized to single lead but can see them in anatomical grouping
77
What changes do we see in ST segments in Anterior lateral infarcts?
ST seg ELEVATION in I, aVL and precordial leads along with ST depression in II, III and aVF
78
What changes do we see with acute inferior (or poseterior) infarcts?
Recipricol ST segment depression in leads V1-V3
79
What would a normal varient with early repolarization look like on ECG?
ST elevation most markeldy in V4 and recipricol ST depression and PR depression are absent (while these are present in ischemia dn pericarditis... escpecially in lead aVR)

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