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CV II exam I > Rapid Interpretation of EKG's reading Dubin Book flashies > Flashcards

Rapid Interpretation of EKG's reading Dubin Book flashies Flashcards

1
Q

how does electrical current travel in the heart.
at rest what is the charge of mycocytes

what is repolarization

A

at rest myocytes are negatively charged

wave of depolarization is a wave of positive charge within the heart’s myocytes

the cell to cell conduction of depolarization through the myocardium is carried by fast-moving sodium (Na ions)

repolarization is the myocytes returning to a negative charge

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2
Q

how does the EKG collect electrical activity of the heart

A

as the positive wave of depolarization within the myocytes flows toward a positive electrode, there is a positive upward deflection recorded on EKG

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3
Q

what is the hearts dominant pacemaker

A

SA node

creates sinus rhythm

each depolarization wave of + charges (Na+ ions) proceeds outward from the SA node and stimulates both atria to contract producing a P wave

the P wave represnts the depolarization and contraction of both atria

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4
Q

what are the 2 atrioventricular valves

what node is in between them

A

tricuspid and mitral valves

AV node

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5
Q

tricuspid valve

A

b/w right atrium and right ventricle

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6
Q

mitral valve

A

b/w left atrium and left ventricle

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7
Q

what occurs when the wave of atrial depolarization enters the AV node?

A

depolarization slows, producing a brief pause

this allows time for the blood in the atria to enter the ventricles and b/c there is a delay there is a flat baseline after each P wave

slow conduction through the AV node is carried by calcium ions

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8
Q

after the AV node, what happens with depolarization conduction

A

depolarization conducts slowly through AV node and upon reaching ventricular conduction system, depolarization rapidly shoots through the His Bundle and Left and Right Bundle Branches

so depolarization rapidly distributes to the ventricles

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9
Q

what are the His bundle and bundle branches made up of?

A

purkinje fibers

these are use fast moving Na ions for the conduction of depolarization

the terminal filaments of the purikinje fibers spread just beneath the endocardium that lines both ventricular cavities and therefore ventricular depolarization begins at the lining and proceeds toward the outside surface (epicardium) of the ventricles

these fibers don’t penetrate into the myocardium

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10
Q

what does the QRS complex on the EKG represent

A

represents depolarization of the entire ventricular myocardium

so ventricular contraction

NOTE- ventricular contraction actually lasts longer than the QRS complex

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11
Q

what is the Q wve

A

the first downward wave of the QRS

it is followed by the upward R wave

often absent on EKG

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12
Q

what is the R wave

A

the first upward wave of the QRS complex

followed by the S wave

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13
Q

what is a QS wave

A

it is just a downward deflection. since there is no upward wave we cannot determine whether number 4 is a Q wave or an S wave

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14
Q

what is the ST segment

A

a segment of horizontal baseline that is FLAT and most importantly level with other areas of the baseline

can be elevated or depressed and this represents pathology

represents the initial phase of ventricular repolarization

after this a broad T wave occurs

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15
Q

what does the T wave represent

A

the final “rapid” phase of ventricular repolarization (even though the the t wave is low, broad hump)

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16
Q

what is the length on the EKG of ventricular repolarization

A

begins immediately after the QRS and persists until the end of the T wave

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17
Q

how is repolarization accomplished?

A

potassium K ions leaving the myocytes

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18
Q

when does ventricular systole begin and end?

A

begins with the QRS and persists until the end of the T wave (QT interval)

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19
Q

what is long QT interval signficant for ?

A

the QT interval is a good indicator of repolarization

since repolarization compromises most of the QT interval, patients with Long QT interval are vulnerable to dangerous (or even deadly ) rapid ventricular rhythms.

QT interval should be less than half of the R-R interval

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20
Q

what ion causes myocyte contraction

A

Ca

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21
Q

what ion causes repolarization of myocytes

A

K

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22
Q

what ion produces cell-to-cell conduction of depolarization in the heart

what is the exception to this?

A

Na

exception–> AV node depends on slow movement of Ca ions

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23
Q

how long is each large box on the EKG paper

A

5 mm

each small square is 1 mm by 1 mm

0.2 sec = 1 big box

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24
Q

when a wave of stimulation (depolarization) travels toward a positive skin electrode, what does it produce on an EKG reading?

A

produces a positive upward deflection

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25
how many seconds is each small box ...
0.4 seconds
26
how many seconds is 4 small squares
0.16 sec
27
what are the bipolar limb leads?
each limb lead consists of a pair of electrodes one is positive and one is negative so these leads are called bipolar limb leads there are 3 (I, II, III)
28
lead I
horizontal left arm is positive right arm is negative
29
lead III
left arm electrode is negative left leg is positive
30
AVF (an augmented/unipolar lead)
uses left foot electrode as positive and both arm electrodes as common ground (negative)
31
AVR (unipolar)
right arm is electrode positive the left arm is negative left foot is negative
32
AVL (unipolar)
left arm is positive left foot is negative right arm is negative
33
what are the inferior leads?
II, III, AVF positive electrode on the left foot
34
what are the lateral leads
I and AVL positive electrode on the left arm
35
what is the center/intersection point for the chest leads>
AV node
36
V2 lead
describes as straight line directly from the front to the back of the patient
37
what is the most positive chest lead>
V5 >V6 > V4> V3 >V2 >V1
38
what are leads V3 and V4 over
oriented over the interventricular septum V3 - more near right V4 - more left
39
what does sympathetic stimulation of the heart result in
increased rate of SA node pacing increased rate of conduction increased force of contraction increased irritability of foci
40
what are the effects of the parasympathetic nervous system on the heart?
decreases SA node pacing, depresses AV node, decreases rate of conduction, force of contraction and decreases irritability of atrial and junctional foci
41
what can occur with a devastating injury....
parasym response that lowers BP and slows the heart
42
what are vagal maneuvers
induced gagging carotid sinus massage used to produce a parasympathetic response for both diagnostic and therapeutic purposes can inhibit irritable focus (atrial or AV junctional) -supraventricular tachy converts to sinus rhythm or inhibit AV node (increases refractoriness) -diagnostic aid with 2:1 AV block or atrial flutter
43
what are the 5 genearl areas of routine EKG interpretation
``` rate rhythm Axis hypertrophy infarction ```
44
what is hearts pacemaker.what is the pace?
SA node 60-100 bpm located in upper-posterior wall of right atrium generates the sinus rhythm the SA node overdrive/suppresses the slower inherent pacemaking activity of all the automaticity foci below it
45
sinus bradycardia
sinus rhythm less than 60 bpm that originates in the SA node most often results from parasympathetic excess as we see in conditioned athletes at rest
46
sinus tachy
greater than 100 most common cause is exercise sympathetic stimulation
47
what are automaticity foci
focal areas of automaticity in the heart potential pacemakers that are capable of pacing in emergency situations if the SA node fails, then one of these potential pacemakers will assume pacemaking activity at is inherent rate
48
where are junctional automaticyt foci?
middle and distal regions of the AV node (AV junction) the proximal end of the AV node has no automaticity foci
49
where are ventricular automaticity foci?
in the purkinje fibers that have automaticity--> His Bundle and Bundle Branches
50
what are the inherent rates of atrial, AV junction and ventricle automaticity foci?
Atrial- 60-80 AV junction - 40-60 Ventricles 20-40
51
what is idioventricular rate
beat of 20-40 bpm it is a ventricular focus that forms if all pacemaking centers above have failed or if there is a complete block of conduction below the AV node (including AV junction) that prevents any pacing stimulus above it
52
rule for counting rate?
300, 150, 100 | 75, 60, 50
53
sinus arrhythmia
normal extremely minimal increase in heart rate during inspiration and extremely minimal decrease in heart rate during expiration increases during inspiration b/c of inspiration activated sympathetic stimulation of theSA node and decrease b/c of expiration- parasympathetic inhibition of SA node
54
what makes up the atrial conduction system?
internodal tracts including anterior, middle, and posterior and one conduction tract (Bachmann's bundle) to the left atrium
55
are there terminal filaments of the right bundle branch in the septum?
no so left-to-right depolarization of the septum occurs immediately before the rest of the ventricular myocardium depolarizes
56
what is a U wave
this is a wave that represents the final phase of purkinje fiber repolarization . it is a wave after the T wave
57
what are the 3 irregular rhythms (atrial)
wandering pacemaker multifocal atrial tachycardia atrial fibrillation
58
what is an irregular rhythm
rhythm that lacks a constant duration b/w paced cycles
59
what does parasystolic mean
when an automaticity focus has entrance block it is said to be parasystolic
60
wandering pacemaker
P wave shape varies--> represents different automaticity foci in the atria (each has a different shape) wanders from SA node to atrial foci atrial rate less than 100--> if it irregular ventricular rhythm
61
multifocal atrial tachy
irregular rhythm P wave shape varies atrial rate exceeds 100 irregular ventricular rhythm disease of patients with COPD can be sometimes associated with digitalis toxicity in patients with heart disease
62
atrial fibrillation
irregular continuous chaotic atrial spikes irregular ventricular rhythm no single impulse depolarizes the atria completely, so no p waves it is the result of many irritable atrial foci suffering from entrance block pacing rapidly these multiple foci are all parasystolic so they're all insensitive to overdrive suppression and they all pace at once
63
Escape rhythm atrial junctional ventricular
p. 112
64
sinus arrest leads to what...
p 113
65
Junctional automaticity focus can cause retrograde atrial depolarizaiton. what is this and how does it show up on EKG
Each P wave is inverted in leads with an upright QRS
66
Stokes adams syndrome
this occurs with ventricular escape rhythm which has a rate of 20-40 bpm it is idioventricular rhythm the pacing is so slow that blood flow to the brain is signficantly reduced to the point of unconsciousness monitor airway!
67
ventricular escape beat on EKG
enormous ventricular QRS complex this can happen often b/c parasympathetic innervation inhibits the SA node and also inhibits the atrial and junctional foci but NOT the ventricular foci

CV II exam I (2 decks)

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