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240 > cardiac + arrhythmias > Flashcards

cardiac + arrhythmias Flashcards

1
Q

4 properties of cardiac cells

A

automaticity
excitability
conductivity
contractility

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2
Q

automaticity

A

ability of cardiac pacemaker cells to spontaneously generate an electrical impulse

SA node, AV junction, Purkinje fibers

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3
Q

excitability

A

ability of cardiac cells to respond to an electrical impulse

depolarization occurs when cells become electrically excited

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4
Q

conductivity

A

ability of cardiac cells to transmit an electrical impulse to neighboring cardiac cells

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5
Q

contractility

A

ability of cardiac cells to shorten in response to electrical stimulation (mechanical event)

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6
Q

cardiac action potential

A

change in electrical charge inside the cardiac cell when it is stimulated

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7
Q

polarization

A

electrical state of cardiac cell membrane when cell is at rest
no electrical activity occuring
ECG is flat, isoelectric line

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8
Q

depolarization

A

electrical event that results in a contraction of cardiac muscle

P wave = atrial depolarization
QRS complex = ventricular depolarization

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9
Q

repolarization

A

restoration of polarized state of cell membrane

ST segment and T wave = ventricular repolarization

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10
Q

absolute refractory period

A

brief period during depolarization when the cells will not respond to further stimulation, no matter how strong the stimulus

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11
Q

relative refractory period

A

vulnerable period during which some cardiac cells have repolarized but may respond to a stronger-than-normal stimulus

can cause v-fib
“R on T phenomenon”

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12
Q

cardiac conduction system

A

SA node
AV node
Bundle of His
Purkinje fibers

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13
Q

SA node

A

pacemaker of the heart located in right atrium
generates impulses at 60-100 bpm
P wave = atrial depolarization

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14
Q

AV node

A

electrical pathway between atria and ventricles located in lower right atrium behind tricuspid valve
generates impulses at 40-60 bpm
isoelectric line after P wave

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15
Q

Bundle of His

A

where ventricular conduction system originates
penetrates AV valves then bifurcates into L/R branches to Purkinje fibers
QRS complex on ECG
generates impulses at 20-40 bpm

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16
Q

Purkinje fibers

A

can act as pacemaker if there are no impulses from SA or AV nodes

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17
Q

ECG leads

A

6 limb leads provide view of frontal plane of heart

6 chest leads provide view of horizontal plane of heart

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18
Q

speed of ECG monitors

A

25 mm/sec

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19
Q

vertical line of ECG

A

represents voltage/amplitude of waveforms

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20
Q

waveform

A

either a deflection upward or downward from baseline of ECG recording

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21
Q

segment

A

line between waveforms that usually falls on ECG baseline

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22
Q

interval

A

a waveform and an adjoining segment

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23
Q

complex

A

made up of multiple deflections, such as QRS

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24
Q

P wave

A

start of cardiac cycle

SA node fires and results in atrial depolarization

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25
Q

PR segment

A

after P wave, short segment that usually falls on isoelectric line

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26
Q

PR interval

A

P wave + PR segment following P wave
reflects atrial depolarization and impulse delay through AV junction (PR segment)
beginning of P to beginning of QRS complex
0.12-0.2 seconds

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27
Q

QRS complex

A

Q wave - first negative deflection after P wave
R wave - first positive deflection of the complex
S wave - downward deflection following R wave

depolarization of both ventricles
measured from where Q leaves baseline to where last wave levels out at baseline
<0.12 seconds

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28
Q

ST segment

A

isoelectric line between QRS and T wave
early repolarization of ventricles
considered elevated or depressed if it deviates above or below the isoelectric line by more than 1 mm

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29
Q

T wave

A

follows ST segment
represents ventricular repolarization
usually rounded

30
Q

QT interval

A

QRS complex + ST segment + T wave
total time required for ventricular repolarization
0.38-0.42 seconds

31
Q

7 steps to interpreting cardiac rhythm

A
  1. determine heart rhythm
  2. determine HR
  3. examine P waves
  4. examine P to QRS ratio
  5. measure PR interval
  6. examine QRS complex
  7. interpret the rhythm
32
Q

heart rate

A

normal 60-100 bpm
atrial and ventricular rates should be the same
6-second method
large-box method

33
Q

normal sinus rhythm (NSR)

A

originates at SA node
P to P and R to R intervals are regular
P waves are uniform and upright with ONE P wave preceding each QRS complex

34
Q

sinus arrhythmia

A

AKA respiratory sinus arrhythmia
originates at SA node but is irregular with repetitive variation in cycle length
PR interval and QRS duration are normal and consistent
(not a true arrhythmia)

35
Q

sinus bradycardia

A 
originates in SA node but <60 bpm
regular P to P and R to R intervals
P waves are uniform and upright with one P wave per QRS complex
PR interval is between 0.12-0.2 seconds
QRS complex is <0.12 seconds
36
Q

sinus tachycardia

A 
originates in SA node at >100 bpm
regular P to P and R to R intervals
P waves are uniform and upright with one P wave per QRS complex
PR interval is between 0.12-0.2 seconds
QRS complex is <0.12 seconds
37
Q

atrial dysrhythmias

A

originate in atria but outside of the SA node

P wave configuration will be upright, but shaped differently than P waves originating in SA node

38
Q

premature atrial complexes (PACs)

A

early beats that most often originate from an irritable focus in the atria
single early beats with an underlying rhythm rather than an abnormal rhythm itself
P wave may be hidden in preceding T wave

39
Q

causes of atrial dysrhythmias

A 
emotional stress/anxiety
fatigue
nicotine, medications, alcohol, caffeine
infection
electrolyte imbalances
CHF, myocardial ischemia
40
Q

supraventricular tachycardia (SVT)

A

rapid dysrhythmia that originates above the ventricles in either the atria or the AV junction
>120 bpm (usually 150-250 bpm)

41
Q

atrial flutter

A

regular atrial rhythm; ventricular rhythm may or may not be regular depending on AV conduction
initiated by irritable focus in atria
causes rapid depolarization (250-350 bpm)
usually no P wave, instead “flutter” waves with saw-toothed appearance

42
Q

atrial fibrillation

A

occurs from rapid firing of multiple irritable foci in atria
no effective atrial contraction bc no uniform wave of depolarization
decreased cardiac output
atrial rate 350-600 bpm
no P wave, instead fib waves with wavy baseline

43
Q

atrial kick

A

blood pushed out of the atria into the ventricles after they depolarize and contract together

lost in A-fib

44
Q

atrial dysrhythmia collaborative care

A

rate control with chronic anticoagulation (usually Coumadin)
beta blockers and calcium channel blockers for rate control
digoxin if no response to BBs or CCBs
cardioversion
TEE

45
Q

ventricular dysrhythmias

A

originate in ventricles
ventricles may take over as the pacemaker for the heart if:
SA node fails to discharge an impulse
impulse is blocked and does not reach the ventricles
SA node and AV node are pacing slower than impulse generation of ventricles
an irritable site in one of the ventricles produces a rapid rhythm

46
Q

premature ventricular complexes (PVCs)

A

an early beat with an underlying rhythm initiated by an irritable focus in one of the ventricles
no PR interval
no P wave
may be unifocal or multifocal

47
Q

unifocal PVCs

A

look the same and originate from the same irritable focus in the ventricles

48
Q

multifocal PVCs

A

look different and may originate from different irritable foci in the ventricles

49
Q

ventricular escape rhythm

AKA idioventricular rhythm

A

occurs in ventricles with no association in atria
may exist when both SA and AV nodes fail to pace the heart or when their impulses are blocked
P waves usually absent

50
Q

ventricular tachycardia

AKA VT, VTach

A 
run of 3+ PVCs in succession
ventricular rate 110-250 bpm
regular rhythm
P waves absent or hidden in QRS
wide QRS
51
Q

ventricular fibrillation

A

severe electrical chaos in ventricles
multiple irritable foci firing in erratic, disorganized manner
no ventricular contraction
no cardiac output/systemic perfusion
fatal within minutes without intervention

52
Q

Torsades de pointes

A

type of ventricular tachycardia that can become ventricular fibrillation

53
Q

ventricular asystole

A

AKA cardiac standstill
no ventricular activity
no cardiac output
flatline ECG

54
Q

pulseless electrical activity (PEA)

A

organized electrical activity is present
pulseless due to absent mechanical activity or inability of heart to fill/contract
poor prognosis unless reversible cause is rapidly ascertained and treated

55
Q

defibrillation

A

unsynchronized shocks that use higher energy level than cardioversion
used for shockable pulseless arrests including VF, VT
must call “all clear” before delivering shock

56
Q

cardioversion

A

synchronized with pt’s QRS complex
must use “synchronize” button on defibrillator
shock occurs on R wave

57
Q

cardioversion indications

A

unstable SVT
atrial fibrillation
atrial flutter
ventricular tachycardia (with a pulse)

58
Q

pacemaker

A

device designed to assist in stimulating the heart when the natural pacemaker is too slow or its impulses are blocked from reaching the ventricles

59
Q

external temporary pacemaker

A

used in emergency situations for pts with unstable bradycardia
most defibrillators can perform this function
AKA transcutaneous pacing

60
Q

internal temporary pacemaker

A

AKA transvenous or epicardial pacing
insertion of pacing wire into either right atrium or right ventricle via central venous catheter
epicardial pacing wires may be placed during an open chest cardiac procedure

61
Q

permanent pacemaker

A

used to resolve dysrhythmias that are not temporary

involves placing one or more wires into the heart chambers

62
Q

demand (synchronous) pacing

A

synchronized with pt’s HR

63
Q

fixed-rate (asynchronous)

A

fires continually at a preset rate regardless of pt’s intrinsic HR

64
Q

failure to pace

A

pacemaker fails to deliver an electrical stimulus
absence of pacer spikes on ECG
pt may become bradycardic and hypotensive

65
Q

failure to sense

A

pacer fails to recognize pt’s natural electrical activity

seen on ECG as pacer spikes too close behind QRS complex

66
Q

oversensing

A

pacer senses extraneous electrical stimuli or artifact for actual atrial or ventricular depolarization
fails to fire

67
Q

implantable cardioverter-defibrillator

A

similar in size and placement to pacemaker
constantly monitors HR and rhythm
programmable to deliver pacing, cardioversion, and/or defibrillation

68
Q

implantable cardioverter-defibrillator indications

A

pts at risk of sudden cardiac death 2/2 VF

pts who have experienced one or more episodes of VT or VF unrelated to an MI

69
Q

radiofrequency catheter ablation

A

treats tachydysrhythmias (SVT, atrial flutter, A-fib)
performed in EP lab under conscious sedation
high frequency electrical current creates small necrotic lesions in the heart by means of thermal injury

70
Q

MAZE procedure

A

series of incisions arranged in maze-like pattern in atria
used for pts in chronic A-fib who are scheduled for an open heart procedure for other cardiac problems
largely replaced by RFCA

71
Q

cardiac/EP mapping

A

multiple flexible wires are threaded into the heart
catheters have miniature electrodes that act as antennae and receive signals from all around the heart chamber
computer process into 3D image of chamber

240 (7 decks)

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