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136 Cards in this Set

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What is an EKG?
An EKG is a graphical representation of the heart's electrical activity.
What is an electrode?
A sensing device that picks up the electrical activity of the heart.
What is a lead?
A view of the heart provided by the electrodes.
What are the 3 types of EKG leads?
1. Bipolar limb leads
2. Augmented limb leads (unpolar limb leads)
3. Precordial leads
A single lead can provide considerable information including...
Rate.
Regularity.
Rhythm interpretation.
What is a normal P wave?
Upright, slightly rounded, smooth.
Why is a P wave upright? (positive deflection)
It represents a wave of depolarization moving toward a positive electrode (in lead II).
What is a normal PRI?
0.12-0.20 seconds (3-5 small boxes).
What is th duration of a normal QRS complex?
<0.12 seconds (<3 boxes).
What is a normal T wave?
Rounded and upright, usually taller and wider than the P wave.
Absolute refractory period?
No stimulus can excite the cardiac muscle cells.
Relative refractory period?
Som, but not all, of the cells are repolarized. If stimulated, only some will depolarize.
rhythm strip analysis 5 step process
1. rhythm (regularity)
2. rate
3. P waves
4. PR intervals
5. QRS complexes
rhythm
1. Are the RR intervals regular?
2. Are the PP intervals regular?
Two methods for determining rate...
1. Boxes method
2. Six second method
What is a rate called that is too slow?
Bradycardia.
What is a rate called that is too fast?
Tachycardia.
A bradycardia is a rate less than __ bpm.
60.
A tachycardia is a rate greater than ___ bpm.
100.
P waves questions
Are there ANY P waves present?
Are the P waves upright?
Do the P waves all look alike?
Is there a P wave in front of every QRS?
Is there a QRS behind every P wave?
If the PRI is too short (<0.12 seconds), what does that mean?
1. Pacemaker site is below the SA node- in the atria or in the AV junction.
2. Bypass tract between the atria and the ventricles.
If the PRI is prolonged (>0.20 seconds), what does that mean?
A block in the AV node.
If the QRS is too wide (>0.12 seconds), what does that mean?
It could be a number of things. For example:
-ventricular rhythm
-PVC
-drug effects
-bundle branch block
-hyperkalemia
common etiology of sinus block and sinus arrest
-insult to the SA node
-increased parasympathetic tone
-hypoxemia
sinus block
The SA node discharges an impule that is blocked before it exits the node; the rhythm resumes in step with the beats preceding the pause.
sinus arrest
The SA node fails to discharge an impulse at all; the rhythm resumes out of synch with the beats preceding the pause.
By defintion, a sinus rhythm must originate n the _______. Therefore, the P waves must be _____ P waves.
SA node, sinus
How do we recognize sinus P waves?
-upright in lead II
-they all look alike
-PRI >0.12 seconds
Atrial rhythms...
Originate in the atria.
wandering atrial pacemaker
Pacemaker site shifts between SA node, other atrial sites, and AV junction; P waves keep changing.
wandering atrial pacemaker rhythm
regular- slightly irregularly irregular
wandering atrial pacemaker rate
60-100 (may be slower)
wandering atrial pacemaker P waves
vary (should be 3 different morphologies)
wandering atrial pacemaker PRI
may vary
wandering atrial pacemaker QRS
<0.12 seconds
wandering atrial pacemaker etiology
May be associated with lung disease; may be normal in the young.
multifocal atrial tachycardia
Similar to WAP but rate is >100 bpm.
multifocal atrial tachycardia rhythm
regular- slightly irregularly irregular
multifocal atrial tachycardia rate
>100
multifocal atrial tachycardia P waves
vary (should be 3 different morphologies)
multifocal atrial tachycardia PRI
may vary
multifocal atrial tachycardia QRS
<0.12 seconds
multifocal atrial tachycardia etiology
Uncommon, not well understood; associated with heart or lung disease; associated with theophylline use (no longer commonly prescribed).
premature atrial contraction
Results from premature discharge of an ectopic atrial focus; characterized by premature abnormal P wave accompanied by normal QRS followed by a pause.
premature atrial contraction rhythm
Underlying is usually regular made irregular because of premature beat
premature atrial contraction rate
underlying rate with PAC
premature atrial contraction P waves
P wave of PAC may be abnormal or even buried in preceding T wave.
premature atrial contraction PRI
May be normal of <0.12 seconds.
premature atrial contraction QRS
Usually <0.12 seconds
premature atrial contraction etiology
Caffeine, tobacco, or alcohol; sympathomimetic drugs; ischemic heart disease; hypoxia; digitalis toxicity; idiopathic.
paroxysmal atrial tachycardia
Results from rapid discharge of ectopic focus in atria; may be indistinguishable from paroxysmal junctional tachycardia and therefore referred to as paroxysmal supraventricular tachycardia (PSVT).
paroxysmal atrial tachycardia rhythm
Regular.
paroxysmal atrial tachycardia rate
150-250.
paroxysmal atrial tachycardia P waves
Seldom seen because buried in the T waves if seen, all alike.
paroxysmal atrial tachycardia PRI
May be normal or <0.12 seconds; not always measurable.
paroxysmal atrial tachycardia QRS
Usually <0.12 seconds (unless there's aberrant conduction).
paroxysmal atrial tachycardia etiology
Caffeine, nicotine, or alcohol; stress, overexertion; sympathomimetic drugs; underlying heart disease.
atrial fibrillation
1. A fib is cause by many irritable atrial foci firing at rapid rate resulting in rapid chaotic atrial rhythm...
2. The atrial impulses bombard the AV node but only some pass through creating a random ventricular pattern- irregularly irregular.
atrial fibrillation rhythm
Irregularly irregular.
atrial fibrillation atrial rate
Very fast, chaotic.
atrial fibrillation ventricular rate
Varies.
atrial fibrillation P waves
Fibrillatory waves.
atrial fibrillation PRI
Not measurable.
atrial fibrillation QRS
<0.12 seconds (unless aberrant conduction)
atrial fibrillation etiology
Underlying heart disease, coronary artery disease, hypertension, alcohol.
What are the problem associated with A fib?
1. Blood pools in the atria causing clots leading to possible stroke.
2. A fib with rapid ventricular return (uncontrolled rate).
3. Because of the chaotic alectrical activity, the atria don't contract leading to reduced cardiac output.
If the atria don't contract, how does blood get into the ventricles?
Gravity!
atrial flutter
Rapid discharge of an ectopic focus in the atria causing atrial rate of 250-500; only some impulses are conducted through to the ventricles causing slower ventricular rate.
atrial flutter rhythm
Regular or irregular.
atrial flutter atrial rate
250-450.
atrial flutter ventricular rate
Varies.
atrial flutter P waves
Sawtooth flutter waves.
atrial flutter PRI
Not measurable.
atrial flutter QRS
<0.12 seconds
atrial flutter etiology
Underlying heart disease, may result from MI, chronic heart failure.
pacemaker cells
Specialized cells of the elecrical conduction system responsible for the generation of electrical impulses.
myocardial cells
Working or mechanical cells.
actin and mysosin
contractile protein filaments
electrolyte
A substance whose molecules dissociate into charges particles (ions) when placed n water, producing positively and negatively charged ions.
membrane channels (pores)
Openings through which ions pass back and forth between the extracellular and intracellular spaces.
concentration gradient
Particles in a solution move, or diffuse, from areas of higher concentration to areas of lower concentration.
electrical gradient
Like charges repel; opposite charges attract.
sodium-potassium pump
A mechanism that actively transports ions across the cell membrane against its electrochemical gradient.
right bundle branch
Conducts the electrical impulse to the right ventricle.
left bundle branch
Divides into two divisions: the anterior fascicle and the posterior fascicle.
anterior fascicle
Carries the electrical impulse to the anterior wall of the left ventricle.
posterior fascicle
Carries the electrical impulse to the posterior wall of the left ventricle.
Purkinje fibers
Conduction fibers.
His-Purkinje system
Refers to the bundle of His, bundle branches, and the Purkinje fibers.
P wave
Depicts atrial depolarization, or the spread of the impulse from the SA node throughout the atria.
PR interval
Represents the time from the onset of atrial depolarization to the onset of ventricular depolarization.
PR segment
The short isoelectric line between the end of the P wave to the beginning of the QRS complex.
QRS complex
Depicts ventricular depolarization, or the spread of the impulse throughout the ventricles.
ST segment
Represents the end of ventricular depolarization and the beginning of ventricular repolarization.
T wave
Represents the latter phase of ventricular repolarization.
U wave
Thought to represent further repolarization of the ventricles.
QT interval
Represents both ventricular depolarization and repolarization.
R-R interval
From one R wave to the next R wave.
biphasic deflection
A deflection having both a positive and negative component.
absolute refractory period
During this period the cells absolutely can't respond to a stimulus.
relative refractory period (vulnerable period of repolarization)
During this perios the cardiac cells have repolarized sufficiently to respond to strong stimulus.
supernormal period
During this period the cardiac cells will respond to a weaker than normal stimulus.
p pulmonale
The abnormal P wave in right atrial enlargement (RAE).
p mitrate
The abnormal P waves seen in left atrial enlargement (LAE).
Wolff-Parkinson-White (WPW) syndrome
The electrical impulse is conducted from the atria to the ventricles through an accessory pathway that bypasses the AV node, depolarizing the ventricles earlier than usual.
J point
The point where the QRS comlex ends.
QS complex
Entire complex is negative.
R prime
Second R wave.
S prime
Second S wave.
notch
A wave that changes direction but doesn't cross the baseline.
rapid rate calculation
Count the number of R waves in a 6-second strip and multiply by 10 (6 seconds x 10 = 60 seconds, or the heart rate per minute).
precise rate calculation
Count the number of small squares between two consecutive R waves and refer to the conversion table printed on the last page of the book.
arrhythmia (dysrhythmia)
Refers to all rhythms other than the normal rhythm of the heart (normal sinus rhythm).
sympathetic nerves
Stimulation produces an increase in heart rate, an increase in conduction through the atriovenricular (AV) node, and an increase in the strength of myocardial contraction.
parasympathetic nerves
Stimulation (from the vagus nerve) produces a slowing of the heart rate, a decrease in conduction through the AV node, and a slight decrease in the strength of myocardial contraction.
tachy-brady syndrome
Sick sinus syndrome.
sinus pause
A broad term to describe rhythms in which there is a sudden failure of the SA node to initiate or conduct an impulse.
ectopic
Commonly applied to rhythms that originate from any site other than the SA node.
ectopic pacemaker
A pacemaker other than the sinus node.
altered automaticity
The automaticity of the sinus node does not exceed that of all other parts of the conduction system.
triggered activity (after-depolarization)
An abnormal condition in which myocardial cells may depolarize more than once after stimulation by a single electrical impulse.
reentry
An impulse travels through an area of myocardium, depolarizes it, and then reenters that same area to depolarize it again.
abberantly conducted PACs
PACs associated with a wide QRS complex.
bigeminal PACs
Appearing every other beat.
trigeminal PACs
Appearing every third beat.
quadrigeminal PACs
Appearing every fourth beat.
couplets
Pairs of PACs.
atrial escape beats
Ectopic atrial beats that occur late instead of early.
T-P wave
The T wave and P wave appear as one deflection.
flutter waves (F waves)
Sawtooth delfections.
fibrillatory waves (f waves)
Irregular, wavy deflections.
coarse fibrillatory waves
Large waves.
fine fibrillatory waves
Small waves.
fib-flutter
Flutter waves mixed with fibrillatory waves.
controlled atrial fibrillation
Ventricular rate is less than 100 beats/minute.
uncontrolled atrial fibrillation (atrial fibrillation with a rapid ventricular response)
Ventricular rate greater than 100 beats/minute.