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NURS 305 > Dysrhythmias > Flashcards

Dysrhythmias Flashcards

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1
Q

Depolarization

A

movement of ions across a cell membrane, causing the inside of the cell to become more positive

an electrical event expected to result in contraction

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2
Q

Repolarization

A

movement of ions across a cell membrane in which the inside of the cell is restored to its negative charge

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3
Q

Ectopic

A

impulse(s) originating from a source other than the SA node

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4
Q

Permeability

A

ability of a membrane channel to allow passage of electrolytes once it is open

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5
Q

Absolute Refractory Period

A

corresponds with the onset of the QRS complex to approximately the peak of the T wave

cardiac cells CANNOT be stimulated to conduct an electrical impulse, no matter how strong the stimulus

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6
Q

Relative Refractory Period

A

corresponds with the downslope of the T wave

cardiac cells CAN be stimulated to depolarize if the stimulus is strong enough

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7
Q

Location of SA node

A

top of right atrium

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8
Q

Location of AV node

A

bottom of right atrium

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9
Q

AV node separates into….

A

right and left bundles branches

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10
Q

The majority of blood flow from atria to ventricles is:
a) passive
b) active

A

a) passive

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11
Q

The right ventricle is normally a
a) low pressure system
b) high pressure system

A

a) low pressure system

pumping blood to lungs which is a short distance

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12
Q

The left ventricle is a
a) low pressure system
b) high pressure system

A

b) high pressure system

pumping blood to the entire body
requires force to overcome higher resistance in systemic arteries, particularly the aorta

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13
Q

Automaticity

A

unique ability of the heart

heart can contract by itself, independently of any signals or stimulation from the body

safeguard if SA node isn’t working properly

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14
Q

3 main areas of the heart’s conduction system

A

1) SA node

2) AV node

3) conduction fibers within the ventricle
specifically:
-bundle of His
-bundle branches
-Purkinje fibers

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15
Q

T or F: The SA node sets its own depolarization

A

FALSE

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16
Q

Intrinsic pacemaker rate of the SA node (bpm)

A

60 - 100

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17
Q

Intrinsic pacemaker rate of the AV node (bpm)

A

40 - 60

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18
Q

Intrinsic pacemaker rate of the Purkinje fibres (bpm)

A

15 - 40

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19
Q

Cardiac Monitoring

A

continuous real-time observation of heart’s electrical activity

non-invasive, quick & effective diagnostic tool

typically through a bedside monitor

used for ongoing assessment

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20
Q

Which lead is typically used for cardiac monitoring?

A

lead 2

upright, positive, easiest to read***

inferior view

can also use lead 3 or 5

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21
Q

Why cardiac monitoring is used (6)

A

1) To monitor a patient’s HR

2) To evaluate the effects of disease or injury on heart function

3) To evaluate pacemaker function

4) To evaluate the response to medications (e.g., antiarrhythmics).

5) To obtain a baseline recording before, during, and after a medical procedure

6) To evaluate for signs of myocardial ischemia, injury, and infarction.

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22
Q

ECG

A

measures heart’s electrical activity from different views

do when you suspect that something is wrong

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23
Q

How many leads does a conventional ECG have?
a) 12
b) 16

A

a) 12

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24
Q

Reasons to use cardiac monitoring (6)

A

1) To monitor a patient’s HR

2) To evaluate the effects of disease or injury on heart function

3) To evaluate pacemaker function

4) To evaluate the response to medications (e.g., antiarrhythmics)

5) To obtain a baseline recording before, during, and after a medical procedure

6) To evaluate for signs of myocardial ischemia, injury, and infarction

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25
5-Lead ECG placement
RA - white - 2nd intercostal space LA - black - 2nd intercostal space V - brown - right of the sternum RL - green LL - red
26
Preload
end-diastolic volume force exerted by the blood on the walls of the ventricles at the end of diastole helps to determine how effective contraction with be - e.g. filling a balloon with a lot of air and letting it go stretch
27
Afterload
pressure or resistance against which the ventricles must pump to eject blood what they’re pushing AGAINST squeeze
28
Contraction
ability of cardiac cells to shorten, causing cardiac muscle contraction in response to an electrical stimulus
29
Venous return
amount of blood flowing into the RIGHT ATRIUM each minute from the systemic circulation
30
Stroke volume
amount of blood ejected from a ventricle with each heartbeat
31
Ejection Fraction
% of blood pumped out of a heart chamber with each contraction
32
A normal ejection fraction is between __ - __ %
50 - 80%
33
Cardiac Output
amount of blood pumped into the aorta each minute by the heart SV x HR
34
Diastole
rest period with filling phase of the cardiac cycle in which the atria and ventricles relax between contractions and blood enters these chambers
35
When the term diastole is used without reference to a specific chamber of the heart, the term implies ___________ diastole
ventricular
36
Systole
contraction of the heart during which blood is propelled into the pulmonary artery and aorta
37
When the term systole is used without reference to a specific chamber of the heart, the term implies _________ systole
ventricular
38
Blood Pressure
force exerted by the circulating blood volume on the walls of the arteries
39
Heart Failure
condition in which the heart is unable to pump enough blood to meet the metabolic needs of the body may result from any condition that impairs: -preload -afterload -cardiac contractility, or -HR
40
Shock
inadequate tissue perfusion that results from the failure of the cardiovascular system to deliver sufficient oxygen and nutrients to sustain vital organ function
41
Cardiac Cycle
refers to 1 complete mechanical cycle of the heartbeat
42
The cardiac cycle begins with _________ and ends with __________
ventricular contraction ventricular relaxation
43
Steps of the cardiac cycle (5)
1) atrial systole 2) isovolumetric contraction 3) ventricular contraction 4) isovolumetric relaxation 5) ventricular diastole
44
Atrial Systole
atrial kick at end with contraction rest of blood pushed from atria into ventricles
45
Isovolumetric Contraction
closed system AV valves shut - S1 - lub ALL valves shut ventricles tensing so pressure beyond aortic and pulmonary
46
Ventricular Contraction
depolarization is making muscles contract pumping blood pressure is greatest in ventricles semilunar valve open
47
Isovolumetric Relaxation
closed system semilunar valves shut - S2 - dub ventricular pressure decreases ALL valves shut
48
Ventricular Diastole
blood flows from atria into ventricles as atria fill and pressure becomes greater, AV valves open passive filling of ventricles
49
T or F: Depolarization is the same as contraction
FALSE we hope that depolarization results in contraction, but they are not the same
50
Depolarization is a: a) electrical event b) mechanical event
a) electrical event
51
Contraction is a: a) electrical event b) mechanical event
b) mechanical event
52
Resting State - Extracellular Electrolyte Concentrations for K+, Na+, Ca2+
K+: 4 Na+: 145 Ca2+: 2
53
Resting State - Intracellular Electrolyte Concentrations for K+, Na+, Ca2+
K+: 135 Na+: 10 Ca2+: 0.1
54
Phases of an action potential (5)
Phase 0: Upstroke Phase 1: Overshoot Phase 2: Plateau Phase 3: Repolarization Phase 4: Resting membrane potential
55
Phase 0: Upstroke
Ionic Movement: -Na+ into cell -K+ leaves the cell -Ca2+ moves slowly into cell Mechanism: -Fast Na+ channels open
56
Phase 1: Overshoot
Ionic Movement: -Na+ into cell slows -Cl- into cell -K+ leaves the cell Mechanism: -Fast Na+ channels close partially
57
Phase 2: Plateau
Ionic Movement: -Na+ and Ca2+ into cell -K+ out Mechanism: -Multiple channels (Ca2+, Na+, K+) open to maintain membrane voltage
58
Phase 3: Repolarization
Ionic Movement: -K+ out of cell Mechanism: -Ca2+ and Na+ channels close -K+ channel remains open
59
Phase 4: Resting membrane potential
Ionic Movement: -Na+ out -K+ in Mechanism: -Na+–K+ pump
60
Rhythm Strip
graphic tracing of electrical impulses movement of charged ions across membranes of myocardial cells creates certain wave forms on the tracings
61
Wave forms represent ____________ and _____________ of myocardial cells
depolarization repolarization
62
Box width in seconds
0.04 ***good to know for midterm
63
P wave length (seconds)
0.06 to 0.12 seconds
64
PR interval length (seconds)
0.12 to 0.20 seconds
65
QRS complex length (seconds)
0.06 to 0.12 seconds
66
ST segment length (seconds)
deviation from baseline
67
QT interval length (seconds)
0.34 to 0.43 seconds
68
EKG Analysis Steps (7)
1) Determine heart rhythm 2) Measure HR 3) P-wave evaluation 4) PR-interval evaluation 5) P-QRS ratio 6) QRS complex evaluation 7) Interpret the rhythm
69
1) Determining the rhythm
regular or irregular take paper, measure top of R to R has to be off by 1 small box to be irregular
70
2) Measure HR
of QRS complexes in 1 minute 6 second method R-R intervals in 6 seconds, and multiply by 10
71
High HR leads to: a) higher ventricular volume b) lower ventricular volume
b) lower ventricular volume less time for passive filling, lower volume in ventricles, less output
72
3) P-wave evaluation
upright and uniform
73
What does the P wave represent?
atrial depolarization time it takes an impulse to travel from the atria to the AV node, bundle of His, and Purkinje fibres
74
4) PR-interval evaluation
0.12 to 0.20 seconds
75
5) P-QRS ratio
Is there a P for every QRS? P without QRS: means that it didn’t go through SA node to AV node QRS without P: started in AV node or ventricles, ventricles depolarized but atria did not, safety mechanism
76
What does the P-QRS ratio represent?
ventricular depolarization
77
6) QRS complex evaluation
0.06 to 0.12 seconds 1.5 to 3 boxes
78
T or F: Everyone has a Q wave
FALSE
79
What does a physiologic Q wave look like?
small, narrow, shallow
80
What does a pathologic Q wave look like?
wide and deep usually means they've had heart attack in the past
81
7) Interpret the rhythm
lots of different rhythms :)
82
Normal Sinus Rhythm
normal everything
83
Sinus Tachycardia
regular rhythm HR over 100 bpm
84
Sinus Bradycardia
regular rhythm HR under 50-60 bpm
85
Atrial dysrhythmias definition
reflect abnormal electrical impulse formation and conduction in the atria rhythms starting elsewhere in the heart, other than the SA node
86
T or F: Most atrial dysrhythmias are life-threatening
FALSE most are not because most of filling into ventricles is passive, only losing about 30% of volume
87
Type of atrial dysrhythmias (3)
1) Premature Atrial Contraction 2) Atrial Fibrillation 3) Atrial Flutter
88
Premature Atrial Contraction
Heart rhythm - regular except for premature beats (impulse of origin of the underlying rhythm remains in the SA node) P waves - regular except 1 or 2 beats are abnormal Regular P wave – uniform, upright, smooth, rounded Premature beat – upright, flattened, or notched QRS MAY be absent following premature P wave
89
Treatment for Premature Atrial Contraction
usually none, assess patient status and determine if it's significantly impacting CO
90
Atrial Fibrillation
1) Heart rhythm - atrial and ventricular rhythms are irregular 2) HR - atrial rate 350 to 700 bpm, ventricular rate varies, usually slower -Controlled Atrial Fibrillation - less than 100 -Uncontrolled Atrial Fibrillation - greater than 100 3) P waves – no consistently identifiable P wave 4) P to QRS ratio - more fibrillatory waves than QRS, can’t measure 5) PR interval - not measurable
91
Treatment for Atrial Fibrillation and Atrial Flutter (4)
1) Conversion 2) Rate control (less than 100) 3) Anticoagulation 4) Ablation
92
Atrial Flutter
1) Heart rhythm - atrial regular, ventricular may be regular or irregular 2) HR - atrial rate 250 to 300 bpm (less than fib), ventricular rate varies, usually slower 3) P waves - flutter waves, “saw tooth” looking, can have multiple waves 4) P to QRS ratio - more flutter waves than QRS 5) PR interval - not measurable
93
Patients with this dysrhythmia are better candidates for ablation therapy a) atrial fibrillation b) atrial flutter
b) atrial flutter limited to 1 spot
94
Medications for Atrial Fibrillation and Flutter (5)
1) Calcium channel blockers (Diltiazem) 2) β-adrenergic blockers (metoprolol) -slowing HR 3) Digoxin -slowing HR 4) Anti-dysrhythmic agents (amiodarone) -back into sinus rhythm 5) Anticoagulants
95
Patients on Digoxin would likely have this chronic condition as well
heart failure
96
Situations when the ventricles would become the pacemaker (4)
1) SA node fails to discharge 2) impulse from the SA node is generated but blocked as it exits the SA node 3) rate of discharge of the SA node is SLOWER than that of the ventricles 4) irritable site in either ventricle produces an early beat or rapid rhythm
97
Ventricular Dysrhythmias (3)
1) Premature Ventricular Contraction (PVC) 2) Ventricular Tachycardia 3) Ventricular Fibrillation
98
Premature Ventricular Contraction (PVC)
1) Heart Rhythm – regular EXCEPT for premature beat if impulse of origin of the underlying rhythm remains in the SA node 3) P waves - regular or premature 4) P to QRS ratio - PVC will not have a P wave 5) PR interval - NONE 6) QRS complex - longer than 0.12 seconds, wide and bizarre
99
Premature Ventricular Contraction Treatment (3)
none if CO not impacted, frequent PVC’s can decrease CO as they interrupt diastolic filling 1) Oxygen therapy for hypoxia 2) Electrolyte replacement 3) Drugs: β-adrenergic blockers, procainamide, amiodarone, lidocaine
100
Types of Premature Ventricular Contraction (4)
1) Ventricular Bigeminy bi=2, every other beat is a PVC 2) Multifocal PVCs 3) Coupled PVCs 2 together 4) Short run of VT 3 or more beats
101
Ventricular Tachycardia
2) HR - 110 to 250 bpm 3) P waves - usually absent 4) P to QRS ratio - PVC will not have a P wave 5) PR interval – none 6) QRS complex - greater than 0.12 seconds, are all similar, often wide and bizarre
102
First thing you should do if you see ventricular tachycardia
TAKE PULSE*** (pulse vs pulseless) CO is compromised, losing a great deal of passive filling
103
Treatment for pulseless ventricular tachycardia
CPR and defibrillation
104
Treatment for ventricular tachycardia with pulse
Stabilize patient, treat underlying cause O2 antiarrhythmic drugs to suppress the rhythm (e.g. procainamide, amiodarone, sotalol) cardioversion
105
Cause of ventricular tachycardia
severe underlying myocardial disease
106
Ventricular Fibrillation
chaotic ventricular rhythm that rapidly results in death
107
Treatment for Ventricular Fibrillation
CPR defibrillation ACLS protocols

NURS 305 (5 decks)

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