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Care of Patients with Dysrhythmias 34 (ME) QUIZLET

Terms in this set (89)

cardiac dysrhythmias
are abnormal rhythms of the heart's electrical system that can affect its ability to effectively pump oxygenated blood throughout the body.
-some are life threatening others are not
-disturbances of cardiac electrical impulse formation, conduction, or both
causes of dysrhythmias
-CAD
-electrolyte imbalance (potassium)
-impaired oxygenation
-drug toxicity (legal and illegal)
-most often in older adults
automaticity
pacing function, the ability of cardiac cells to generate an electrical impulse spontaneiously and repeativiely
information
normally only primary pacemaker cells (SA node) can generate an electrical impulse. under certain conditions, such as myocardial ischemia, electrolyte imbalance, hypoxia, drug toxicity, and infarction (cell death), any cardiac cell may produce electrical impulses indepedently and create dysrhythmias.
-disturbances in automaiticty may involve either an increase or decrease in pacing function.
excitability
ability of non-pacemaker heart cells to respond to an electrical impulse that begins in pacemaker cells and to depolarize. (ability of heart cells to reacte to the chain reaction started by the SA node to depolarize and contract
depolarization
occurs when the normally negatively charged cells within the heart muscle develop a positive charge (contraction)
conductivity
ability to send an electrical stimulus from cell membrane to cell membrane. as a result, excitable cells depolarize in rapid succession from cell to cell until all cells have depolarized.
-the wave of depolarization causes the deflections of the electrocardioram waveforms that recognize as the P wave and the QRS complex. disturbances in conduction result when conduction is too rapid or too slow, when the pathways is totally blocked, or when the electrical impulse travels an abnormal pathway.
contractility
is the ability of the atrial and ventricular muscle cells to shorten their fiber legth in response to electrical stimulation, causing sufficient pressure to push blood forward through the heart.
-in other words, contractility is the mechanical activity of the heart and the result of depolarization throughout the heart.
conduction system
SA node (starts the system),
atrioventricular junctional area (gets the ventricles on board)
bundle branch system (move the depolarization system throughout the entire heart.)
sinoatrial node (SA node)
located close the the sureface of the right atruim near its junction with the superior vena cava.
-sa node is the heart's primary pacemaker
-spontaneously and rhythmically generate electrical impulses at a rate of 60-100 beats per minute and therefore has the greatest degree of automaticity.
SA node continued
richly supplied by the sympathetic and parasympathetic nervous systems, which increase and decrease the rate of discharge of the sinus node, respectively.
-results in changes in HR
P wave
impulses from the sinus node move directly through the atrial muscle and lead to atrial depolarization, which is reflected in a P wave on the ECG. atrial muscle contraction should follow.
atrioventricular junctional area (AV node)
consists of transitional cell zone, the AV node itself, and the bundle of his.
-av node lies just beneat the right atrial endocardium, between the tricuspid valve and the ostium of the coronary sinus.
-transitional cells are here slowed down or delayed in the AV node before proceeding to the ventricles.
-PR segment on the ECG
-this delay allows the atria to contract and the ventricles to fill, without this delay the parts of the heart would be working against each other.
-"atrial kick"
bundle of his
extends as a right bundle branch down the right side of the interventricular septum to the apex of the right ventricle.
- on the left side, it extends as a left bundle branch, which further divides
purkinje fibers
at the end of both the right and left bundle branch
-interweaving network located on the endocardial surface of both ventricles, from apex to base.
-partially penetrate into the myocardium.
-responsible for the rapid conduction of electrical impulses throughout the ventricles, leading to ventricular depolarixation and the subsequent ventricular muscle contraction
---------------ELECTRICAL ANATOMY ENDS-----------------
---------------------------ECG BEGINS-------------------------
electrocardiogram (ECG)
provides a graphic representation or picture of cardiac electrical activity
-electrodes consisting of coductive gel on a pad are placed on specific sites of the body and attached to cables connected to the ECG machine
lead
provides one view of the heart's electrical activity, multiple leads, can be obtained for multiple views
-positive pole and a negative pole.
-lead axis is an imaginary line joininh these two poles
-cardiac axis is the direction of the current flow
-the relationship between cardiac axis and lead axis is responsible for the deflections seen on the ECG strip
positive deflection
toward the positive pole (hill on ecg)
away from the positive pole
negative deflection (rounded slope on ecg)
biphasic complex
neither positve nor negative (hill and slope together)
lead systems
standard is 12 lead ecg
-6 placed on limb leads
-6 placed on chest
-also a 18 lead ecg with additional on right side of chest
-80 lead ecg, you wear a vast but only comes in 4 sizes
continuous ecg monitoring
- not placed on the limbs because of movement causing noise
-placed on the trunk
-clarity is effected boy skin prep and electrode quality
-clean the skin and clip hairs if needed
-placement must be dry and gel must be moist and fresh
ecg strip interpretation
1 small block is 1mm in height and width
25mm/sec standard speed of ecg
each small block is 0.04 seconds, outlined by a darker line making a large block, representing 0.20 seconds
-five large blocks = 1 second
30 large blocks = 6 seconds
P wave
deflection representing atrial depolarization
-can be positive, negative, or biphasic
PR segment
isoelectric line from end of the P wave to the beginning of the QRS complex
-this is the delay from the atrial depolarization through the AV node just before ventricular depolarization
PR interval
beginning of P wave to the end of the PR segment
-represents the time required for atrial depolarization as well as the impulse delay in the AV node and travel time to the purkinje fibers.
-is normally 0.12 to 0.20 seconds (5 small blocks)
QRS complex
represents ventricular depolarization
-shape depends on the lead selected
- Q wave is negative not present in all leads, small and represents initial ventricular septal depolarization
- if q wave is abnormally presented, its myocardial cell death
-R wave is positive deflection, small large, or absennt, depending on the lead
-the S wave is negative deflection following the R wave
QRS duration
represents the time required for depolarization of both ventricles
-measured from the beginning of the QRS complex to the J point (junction where QRS ends and ST segment begins)
-normally 0.04 to 0.12 seconds (up to 3 small blocks)
ST segment
normally isoelectric line representing early ventricular repolarization.
-it occurs from the J point to the beginning of the T wave
-length varies with HR, meds, electrolyte disturbances
T wave
follows the ST segment and represents ventricular repolarization
-usually positive, rounded, slightly asymmetric.
-could be tall and peaked, inverted (negative) or flat as a result of myocardial ischemia, potassium or calcium imbalances, meds, ans effects
TP segment
begins at the end of the T wave and ends at the beginning of the P wave.
-it ios the true isoelectric interval in the ECG
U wave
slow repolarization of the ventricular purkinje fibers
-could be a sign of hypokalemia
QT interval
total time needed for ventricular depolarization and repolarization
-intervels vary with age and gender
-can be prolonged by meds, imbalances
-can be caused by torsades de pointes to be long
artifact
interference seen on the monitor or rhythm strip which looks like a fuzzy baseline
-caused by movement, loose or defective electrodes, improper grounding
-assess the patient to differentiate artifact from lethal rhythms
determination of HR: 6 second strip method
number of QRS completed in 6 seconds and x by 10.
-quick method but not very accurate, method of choice for irregular rhythms
big block method for determination of HR
number of big blocks between the same point in any two consecutive QRS complexes and divide that by 300
-300 big blocks in 1 minute
-number of big blocks in an interval divided by 300
memory method for determination of HR
most widely used in hospitals for calculation of HR for regular rhythms
300, 150, 75, 60, 50, 43, 37, 33, 30
-always check the patient directly.
ECG rhythm analaysis using an ECG caliper
1. determine the HR
2. determine the rhythm
3. analyze the P waves
4. measure the PR interval
5. measure the QRS duration
6. examine the ST segment
7. assess the T wave
8. measure the QT interval
-using the steps can interpret cardiac rhythm and differentiate normal and abnormal rhythms
normals of a strip
atrial and ventricule rates 60-100 beats/min
rhythm: rhythms regular
p waves: present, consistent, one P before the QRS complex
pr interval: 0.12 to 0.20
QRS duration: 0.04 to 0.10 seconds and constant
-----------------END ECG STRIP INFORMATION-------------
------------BEGIN DYSRHYTHMIA INFORMATION-----------
dysrhythmia
any disorder of the heartbeat
palpitations
premature complexe are early rhythm complexes. they occur when a cell group other than the SA node become irritable and fires an impulse before the next sinus impulse is produced
-this is called an ectopic focus
-after the premature complex there is a pause before the next normal complex, creating an irregularity in thythm
-if they become frequent the patient may experience decreased CO
premature complex: bigeminy
normal complex and premature complex occur alternately in a repetitive two beat pattern, with a pause occuring after each premature complex so that complexes come in pairs.
premature complex: trigeminy
repeated three beat pattern, usually occuring as two sequential normal complexes followed by a premature complex and a pause, with the same pattern repeating in triplets
premature complex: quadrigeminy
repeated 4 beat pattern, usually occuring as three sequential normal complexes followed by a premature complex and a pause, with the same pattern repeating itself in 4 beat pattern.
bradydysrhymias
occur when the heart rate is less than 60bpm
-myocardiac o2 demand is reduced because of prolonged diastole, which is desirable
-coronary perfusion time may be adequate because of a prolonged diastole, which is desirbale
- coronary perfusion pressure may decrease if the heart rate is too slow to provide adequate co and bp, this is a serious consequence
-if the bp is adequate this is well maintained. if the bp is low, may lead to myocardiac ischemia or infarction, dysrhythmias, hypotension, and heart failure.
tachydysrhythmias
hr grater than 100 bpm
-major concern with cad because blood flow to heart usually occurs during diastole when the aortic valve is closed
-shorten diastolic time and therefore coronary perfusion time
-initially increase CO and BP, but continued rise in HR decreases the ventricular filling time because of shortened diastole, decreasing SV
-CO and BP will decrease
-increase workload of the heart increasing o2 demand
will have :
palpitations, chest discomfort,restlessness and anxiety, pale, cole skin, syncope from hypotension
can also cause HF = dyspnea, lung crackles, distended neck veins, fatigue, weakness
pulse deficit
apical pulse minus the radial pulse
-heart is not pumping adequately to acheive optimal perfusion to the body
sinus tachycardia
when the rate of the SA node dischrage is more than 100 bpm, this is called sinus tachycardia
-initially increases co and bp, however this over time decreases coronary perfusion time, diastolic filling time, and coronary perfusion pressure while increasing myocardial o2 demand.
causes: physical activity, anxiety, pain, stress, fever, anemia, hypoxemia, hyperthyroidism
-can be a compensatory response to decrease CO or BP as occurs with dehydration, hypovolemic shock, MI, infection, heart failure
-assess for dehydration or hypovolemia, including pulse rate, decreased urinary output, decrease bp, and dry skin and mucuous membranes
-remain on bed rest and relax, don't take anything that made your heart beat like that
sinus bradycardia
parasympathetic stimulation causing a decrease of rate of the sinus node dischrage
-carotid sinus massage, vomiting, suctioning, valsalva maneuvers, ocular pressure, or pain, also can be from hhypoxia, inferior wall MI, administration of a beta blocker, CCB and digitalism lyme disease, hypothyroidism
-increases coronary perfusion time, decrease coronary perfusion pressure
-myocardial demand is less
-well conditioned athletes provide adequate stroke volume with a normal low HR
-asymptomatic except for decreased pulse rate
-syncope, diziiness, confusion, hypotension, diaphoresis, SOB, chest pain
treatment: atropine 0.5mg IV, if no result permanent pacemaker placement
temporary pacing
nonsurgical that provides timed electrical stimulus to the heart.
-transcutaneous pacing = emergency measure to provide demand pacing in profound bradycardic or asystolic patient until invasive pacing can be placed
permanent pacemaker
treat something like a complete heart block
-average 10 year life span
-bulge on your subclivicular area
-follow up exams are huge
atrial dysrhythmias
premature atrial complexes
supraventricular tachycardia
atrial fibrillation
premature atrial complex contraction
atrial tissue becomes irritable and fires an impulse before the next sinus impulse is due.
-the premature P wave may not be clearly visible, can be hidden in the T wave
causes: stress, fatigue, anxiety, inflammation, infection, caffeine, nicotine, alcohol
-no interventions needed other than treat complications like heart failure
supraventricular tachycardia
involves rapid stimulation of atrial tissue at a rate of 100-280 bpm in adults
-P waves are not not visible, because they are embedded in the proceding T wave
-this can occur in healthy young people
Atrial fibrillation (AF)
most common dysrhythmia
-associated with atrial fibrosis, muscle mass,a mutation in the gene lamin AC (LMAC) has been linked
-htn, coronary artery disease, heart failure common in Afib
-Caucasians more at risk than african americans
-af that is reversible is considered holiday heart syndrome from to much alcohol
afib continued
multiple rapid impulses from many atrial foci depolarize the atria in a totally disorganized manner at a rate of 350-600 times per minute, ventricular response is usually 120-200 bpm.
-chaotic rhythm with no clear p waves, no atrial contractions, loss of atrial kick, and an irregular ventricular response
-ventricules respond by increasing their rate which reduces ventricular filling and reduces co, impairing heart perfusion
-drug therapy is often effective in treating AF (CCB, amiodarone, beta blockers)
CHAD scoring system for afib preventive anticoagulant therapy
Congestive heart failure? yes 1 no 0
hypertension? yes 1 no 0
age of 75+? yes 1 no 0
diabetes? yes 1 no 0
stroke or tia? yes 2 no 0
score of 1 = aspirin score of 2 or more = high risk
atrial fibrilation
wavy baseline with irregular ventricular rhythm
cardioversion
used 1 in emergencies for unstable ventricular or supraventricular tachydysrhythmias or 2 electively for stable tachydysrhythmias that are resistent to medical therapies
-digoxin withheld up to 48 hours
-shock depolarizes large amount of myocardium during the cardiac depolarization. intended to stop re-entry circuit and allow the sinus node to regain control of the heart
radio frequency catheter ablation
invasive procedure that may be used to destroy and irritable focus causing supraventricular or ventricular tachydysrhythmias.
-electrophysiologic studies first
ventricular dysrhythmias
premature ventricular complexes
ventricular tachycardia
ventricular fibrillation
ventricular asystole
premature ventricular complexes
increased irritability of ventricular cells and are seen as early ventricular complexes followed by a pause
- can be positive or negative on the graph (multifocal)
-are common and frequency rises with age
-MI, chf, copd, anemia, hypokalemia, hypomagnesemia can all cause this
-asymptomatic or palpitations or chest discomfort caused by increased stroke volume of the normal beat after the pause
-peripheral pulses may be diminished or absent with this because the decreased stroke volume of the premature beat may decrease peripheral perfusion
PVC interventions
usually not treated other than eliminating any contributating factors (caffeine, stress)
-k or magnesium given for replacement therapy as needed
ventricular tachycardia
repetitive firing of an irritable ventricular ectopic focus, usually at a rate of 140-180 bpm
-ischemic heart disease, mi, cardiomyopathy, hypokalemia, hypomagnesemia, valvular heart disease, hf, drug toxicity, or hypohtn
-in patients with cardiac arrest, vt is commonly the initial rhythm before deterioration into ventricular fib as the terminal rhythm
-elective cardioversion highly recommened for stable VT
ventricular fibrillation
electrical chaos in the ventricles and is life threatening
-no cardio output or pulse with this, no bp, basically dead
-priority is to use a defibrillator or high quality cpr
-----------------------CHAPTER ENDS-------------------------
-----------------PRACTICE QUESTIONS BEGIN---------------
Which description is characteristic of normal sinus rhythm?
There is a P wave for every QRS complex.
In normal sinus rhythm, a P wave precedes every QRS complex and the PP intervals vary by no more than 3 small squares. The intrinsic firing rate of the SA node is 60-100, creating a ventricular heart rate of 60-100. A U wave is not always present in normal sinus rhythm. The normal PR interval is 0.12-0.20 second.
The nurse is assisting with resuscitation efforts on a client in the ICU when the family tearfully comes to the door and requests to be in the room with their loved one. Which response by the nurse is best?
"If you feel you need to be present for your loved one, remain to the side and I will answer your questions later."
Evidence suggests family presence during resuscitation can promote closure, providing a positive experience; however, limits may need to be set. Asking the family to remain separate from their loved one at a critical time by staying in the waiting area or outside the room may promote distress and the feeling that not everything possible was done.
When caring for a client with heart disease, which action may lead to serious bradydysrhythmias?
Oropharyngeal suctioning
Anything that causes the client to perform the Valsalva maneuver (e.g., bear down, gag, or vomit) leads to vagal stimulation. Unintended vagal stimulation can result in serious bradydysrhythmias and should be avoided. Oropharyngeal suctioning causes the client to gag and possibly vomit. Insertion of a Foley catheter, hip flexion, and moderate walking on a treadmill do not induce the Valsalva maneuver.
Which test or activity is contraindicated for clients with an implantable cardioverter/defibrillator?
Magnetic resonance imaging
Clients with an ICD should avoid sources of strong electromagnetic fields, such as large electrical generators and radio and television transmitters. Magnetic resonance imaging (MRI) should not be used. Radiation therapy, microwave ovens, and CT scans are safe to use.
In electrocardiography, what is the normal time measurement of the PR interval?
0.12-0.20
The nurse is teaching a client with a new permanent pacemaker. Which statement by the client indicates a need for further discharge education?
i don't need to take my medications anymore
-you will trigger a metal detector, you can shower shortly there after, you need to take your pulse the same time everyday
How does the nurse recognize that atropine has produced a positive outcome for the client with bradycardia?
increased heart rate
An expected outcome after the administration of atropine is increased heart rate. By definition, the bradydysrhythmia has resolved when the heart rate is >60 beats/min. Dizziness and weakness indicate symptoms of decreased cerebral perfusion and intolerance to the bradydysrhythmia. Dyspnea indicates intolerance to the bradydysrhythmia. Atropine is used to treat bradycardia; a heart rate of 42 indicates that bradycardia is unresolved.
What teaching does the nurse include for a client with atrial fibrillation who has a new prescription for warfarin?
report any signs of bleeding immediately
Warfarin causes decreased ability to clot; a nosebleed could be indicative of excessive dosing. Green leafy vegetables are high in vitamin K, which may antagonize the effects of warfarin; they should be eaten in moderate amounts. Aspirin and nonsteroidal antiinflammatory agents may prolong the prothrombin time (PT) and the International Normalized Ratio (INR), causing predisposition to bleeding; these should be avoided. It is not necessary to avoid caffeine because this does not affect clotting; however, green tea may interfere with the effects of warfarin.
The nurse is caring for a client on a telemetry unit with a regular heart rhythm and rate of 60 beats/min; a P wave precedes each QRS complex, and the PR interval is 0.24 second. Additional vital signs are as follows: blood pressure 118/68, respiratory rate 16, and temperature 98.8° F. All of these medications are available on the medication record. What action does the nurse take?
Continue to monitor.
The client is displaying normal sinus rhythm. Atropine is used in emergency treatment of symptomatic bradycardia. This client has normal vital signs. Digoxin is used in the treatment of atrial fibrillation, which is, by definition, an irregular rhythm. Clonidine is used in the treatment of hypertension; a side effect is bradycardia.
Which statement accurately describes the area of the heart that initiates the cardiac cycle?
The sinoatrial (SA) node is the primary pacemaker of the heart whose activity is reflected in the P wave on the ECG.
The SA node is the heart's primary pacemaker causing atrial depolarization, reflected in the P wave on the ECG. The atrial (A) junction and atrioventricular (AV) node receive conduction from the SA node, delaying conduction before sending the impulse to the ventricles; this is reflected in the PR segment. The bundle of His extends down the interventricular septum to both ventricles. The Purkinje fibers cause rapid conduction of impulses throughout the ventricles, causing ventricular depolarization and contraction consistent with the QRS complex.
The nurse is assisting a nurse practitioner with the wellness examination of a high school athlete and notes the cardiac rhythm strip has all the characteristics of normal sinus rhythm, except it is irregular. There is a pattern to the irregularity associated with the client's breathing. How does the nurse respond to this finding?
Nothing, as this is a healthy rhythm.
This is sinus arrhythmia which is frequently observed in healthy children and adults. The rate speeds up during inhalation and slows down during exhalation; this is considered a variant of normal sinus rhythm.
The nurse is caring for a client with heart rate of 143 beats/min. For which manifestations does the nurse observe? Select all that apply.
palpitations
chest discomfort
hypotension
not flushed skin
not increased energy
-----------------PRACTICE QUESTIONS END-----------------
--------------------------ATI BEGINS----------------------------
ECG
records electrical activity over the heart
wires (leads) connect to skin and electrodes placed on the chest and limbs
dysrhythmias
sinus bradycardia and tachycardia
atrioventricular blocks
atrial fibrillation
ventricular asystole
premature atrial complexes and ventricular complexes
supraventricular tachycardia
ventricular tachycardia
ventricular fibrillation
client presentation
cardiovascular disease
MI
hypoxia
acid-base balances
electrolyte imbalance
kidney failure, liver, or lung disease
pericarditis
drug or alcohol use
hypovolemia
shock
bradycardia (rhythm less than 60 beats a min)
atropine and isoproterenol
pacemaker to help keep bpm up
atrial fibrillation
supraventricular tachycardia
ventricular tachycardia with pulse
amiodarone, adenosine, verapamil
syncronized cardioversion
ventricular tachycardia w/out pulse or ventricular fibrillation
(deadly stuff)
amiodarone, lidocaine, epinephrine
defibrillation
cardioversion
delivery of a direct counter shock to the heart synchronized to the QRS complex.
defibrillation
delivery of an unsunchronized, direct countershock to the heart
stops all electrical activity of the heart, allowing the SA node to take over and reestablish perfusing rhythm
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