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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
Q

how many seconds is each small box …

A

0.4 seconds

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26
Q

how many seconds is 4 small squares

A

0.16 sec

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27
Q

what are the bipolar limb leads?

A

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
Q

lead I

A

horizontal

left arm is positive
right arm is negative

29
Q

lead III

A

left arm electrode is negative

left leg is positive

30
Q

AVF (an augmented/unipolar lead)

A

uses left foot electrode as positive and both arm electrodes as common ground (negative)

31
Q

AVR (unipolar)

A

right arm is electrode positive

the left arm is negative
left foot is negative

32
Q

AVL (unipolar)

A

left arm is positive
left foot is negative
right arm is negative

33
Q

what are the inferior leads?

A

II, III, AVF

positive electrode on the left foot

34
Q

what are the lateral leads

A

I and AVL

positive electrode on the left arm

35
Q

what is the center/intersection point for the chest leads>

A

AV node

36
Q

V2 lead

A

describes as straight line directly from the front to the back of the patient

37
Q

what is the most positive chest lead>

A

V5 >V6 > V4> V3 >V2 >V1

38
Q

what are leads V3 and V4 over

A

oriented over the interventricular septum

V3 - more near right
V4 - more left

39
Q

what does sympathetic stimulation of the heart result in

A

increased rate of SA node pacing
increased rate of conduction
increased force of contraction
increased irritability of foci

40
Q

what are the effects of the parasympathetic nervous system on the heart?

A

decreases SA node pacing, depresses AV node, decreases rate of conduction, force of contraction and decreases irritability of atrial and junctional foci

41
Q

what can occur with a devastating injury….

A

parasym response that lowers BP and slows the heart

42
Q

what are vagal maneuvers

A

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
Q

what are the 5 genearl areas of routine EKG interpretation

A 
rate
rhythm
Axis
hypertrophy
infarction
44
Q

what is hearts pacemaker.what is the pace?

A

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
Q

sinus bradycardia

A

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
Q

sinus tachy

A

greater than 100

most common cause is exercise sympathetic stimulation

47
Q

what are automaticity foci

A

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
Q

where are junctional automaticyt foci?

A

middle and distal regions of the AV node (AV junction)

the proximal end of the AV node has no automaticity foci

49
Q

where are ventricular automaticity foci?

A

in the purkinje fibers that have automaticity–> His Bundle and Bundle Branches

50
Q

what are the inherent rates of atrial, AV junction and ventricle automaticity foci?

A

Atrial- 60-80
AV junction - 40-60
Ventricles 20-40

51
Q

what is idioventricular rate

A

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
Q

rule for counting rate?

A

300, 150, 100

75, 60, 50

53
Q

sinus arrhythmia

A

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
Q

what makes up the atrial conduction system?

A

internodal tracts including anterior, middle, and posterior and one conduction tract (Bachmann’s bundle) to the left atrium

55
Q

are there terminal filaments of the right bundle branch in the septum?

A

no

so left-to-right depolarization of the septum occurs immediately before the rest of the ventricular myocardium depolarizes

56
Q

what is a U wave

A

this is a wave that represents the final phase of purkinje fiber repolarization . it is a wave after the T wave

57
Q

what are the 3 irregular rhythms (atrial)

A

wandering pacemaker
multifocal atrial tachycardia
atrial fibrillation

58
Q

what is an irregular rhythm

A

rhythm that lacks a constant duration b/w paced cycles

59
Q

what does parasystolic mean

A

when an automaticity focus has entrance block it is said to be parasystolic

60
Q

wandering pacemaker

A

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
Q

multifocal atrial tachy

A

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
Q

atrial fibrillation

A

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
Q

Escape rhythm
atrial
junctional
ventricular

A

p. 112

64
Q

sinus arrest leads to what…

A

p 113

65
Q

Junctional automaticity focus can cause retrograde atrial depolarizaiton. what is this and how does it show up on EKG

A

Each P wave is inverted in leads with an upright QRS

66
Q

Stokes adams syndrome

A

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
Q

ventricular escape beat on EKG

A

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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