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107 Cards in this Set
- Front
- Back
What is the definition of EKG?
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Tracing or graphic representation of the heart's electrical activity.
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The hear is shaped like a ?
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inverted blunt cone
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Where and behind what is the heart located?
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The heart is located in the mediastinum and is behind the sternum.
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Where is the apex directed?
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It is directed anteriorly and slightly inferiorly at the level of the 5th intercostal space in the mid clavicular line.
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What is the path of blood flow starting at the right atrium?
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Right Atrium - right atrioventricular valve - right ventricle - pulmonary semilunar valve - pulmonary arteries - lungs - pulmonary veins - left atrium - left atrioventricular valve - left ventricle - aortic semilunar valve - aorta - gas exchange in peripheral tissues - systemic veins - superior and inferior vena cava - right atrium
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What is the primary pacemaker and what is its rate?
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SA node = 60-100 beats per minute
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Sinus bradycardia = ?
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< 60 beats per minute
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Sinus tachycardia = ?
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> 100 beats per minute
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What are the other automaticity foci?
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Atria, AV node and Ventricles/Purkinje fibers
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What are the rates for the other automaticity foci, ie. Atria, AV node and Ventricles/Purkinje fibers?
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Atria = 60-80 beats per minute
AV node = 40-60 beats per minute Ventricles/Purkinje fibers = 20-40 beats per minute |
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What is an isoelectric line?
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Straight line without + or - deflection
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What does the isoelectric line serve as?
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A reference point.
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Flow towards the lead = ?
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upward deflection
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Flow away from the lead = ?
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downward deflection
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What is a complex?
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When one wave follows another without intervals, segments or isoelectric lines between them.
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What is a segment?
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Area between 2 waves.
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What is an interval?
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Waveform + following isoelectric line.
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Moving vertical on the EKG paper represents?
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Voltage
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Moving horizontal on the EKG paper represents?
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Time
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What are the six limb leads?
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I, II, III, aVr, aVL, aVF
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What are the standard limb leads and are they unipolar or bipolar?
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The standard limb leads are bipolar and are I, II, and III
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What are the aVr, aVL and aVf leads called and are they unipolar or bipolar?
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They are known as the augmented voltage right, left and foot. They are unipolar.
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What are the V1-V6 leads called and are they unipolar or bipolar?
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They are called the precordial (chest) leads and they are unipolar.
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What is the correct placement for the V1 precordial chest lead?
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The 4th intercostal space, just to the right of the sternum.
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What is the correct placement for the V2 precordial chest lead?
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The 4th intercostal space just to the left of the sternum.
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What is the correct placement for the V3 precordial chest lead?
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Midway between V2 and V4.
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What is the correct placement for the V4 precordial chest lead?
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Mid clavicular line "nipple line", 5th intercostal space.
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What is the correct placement for the V5 precordial chest lead?
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Anterior axillary line, between V4 & V6
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What is the correct placement for the V6 precordial chest lead?
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Mid axillary line, horizontal with V4.
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What is the correct placement of the limb leads?
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On the left arm, on the right arm and left leg or on chest, at least 10 cm away from the heart.
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Which of the augmented limb leads is closest to showing the normal direction of the cardiac impulse?
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aVf
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In the precordial chest leads, in which leads is the R wave at its greatest height?
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Usually V3 and V4
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In what precordial leads is normal conduction closest to being shown?
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V2-V4
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Limb leads look at the ______ plane?
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Frontal
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Precordial chest leads look at the ______ plane?
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Horizontal (cross section)
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Atrial depolarization is represented by the?
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P wave
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Delay at the AV node is represented by?
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PR interval
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Ventricular depolarization is represented by?
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QRS complex
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Ventricular repolarization is represented by?
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T wave
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What represents no electrical activity in the EKG?
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The isoelectric line
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Where is the repolarization of the atria represented on the EKG?
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It is hidden in the QRS complex.
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This is the delay between the beginning of activity in the atria and the ventricles (atrio-ventricular conduction time)?
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PR Interval
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What is the normal duration of the PR interval?
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.12-.20 seconds
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When is the PR interval shorter?
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Increased heart rate and decreased at rest
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What is the normal duration of a QRS complex?
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0.06-0.12 seconds.
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What is the normal amplitude of a QRS complex?
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5-30 mm
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Normal QRS deflection is increased in leads?
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I, II, III, aVL, aVf and V4-V6
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Normal QRS deflection is decreased in leads?
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aVr, V1-V3
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In leads III, aVL and V2-V4 the QRS may also be?
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biphasic
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This is the 1st downard deflection from basline?
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Q wave
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What is the normal duration of the Q wave, and what is its amplitude?
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< 0.04 seconds is normal duration, and the amplitude is normally 25% of the R wave.
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Is the Q wave always present?
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Not always, and if it isn't present it doesn't mean that there is anything abnormal.
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This is the first upward deflection after the P wave?
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R wave
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This is the 1st negative deflection below baseline after the R wave?
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S wave
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What is the ST segment?
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Ventricles preparing for repolarization.
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What is the point at which the QRS complex meets the ST segment?
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J-point
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What is the normal amplitude of the T wave in the limb leads and in the precordial leads?
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Limb leads = 5mm
Precordial leads = 10mm |
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J point elevations are important in reference to what?
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When discussing myocardial infarction
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This is measured from the beginning of the QRS complex to the end of the T wave?
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QT interval
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What represents the time of ventricular depolarization and repolarization?
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QT interval
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If you have an increased heart rate what does it do to the QT interval?
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Increased heart rate decreases the QT interval
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What is the normal duration of the QT interval?
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.36 to .44 seconds
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What are some things that can cause QT prolongation?
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Psych meds, certain antibiotics, and antiemetics.
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Deflections:
Impulse travels to the __ pole or ___ ___? |
Impulse travels to the + pole or the chest wall.
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Deflections:
Impulse towards the pole leads to a __ deflection? |
+ deflection
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Deflections:
Impulse away from the pole leads to a __ deflection? |
- deflection
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Deflections:
Impulse perpendicular to the pole leads to a ____ ____? |
Biphasic wave
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With EKG regularity, what EKG events should be equal?
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P-P wave or R-R wave should be the same.
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What are the four different methods to determine heart rate?
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1. 300-150-100-75-60-50
2. 6 second interval X 10 3. 1500 method 4. Rate calculators. |
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What heart rate measuring method is especially good for bradycardia?
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6 second interval X 10 method.
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How do you perform the 1500 method?
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1500 small squares = 1 minute
Count number of small squares between 2 consecutive R waves Divide 1500 by that number Ex. 1500/30 (small boxes counted) = HR = 50 |
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What is the 5 step systematic approach to reading EKGs?
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1. Determine rate
2. Determine regularith 3. Assess P wave 4. Assess QRS wave 5. Assess PR interval |
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Overall direction and force of the current flow?
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Heart's electrical axis
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In regards to electrical axis, the angle of the arrow orientation = ?
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The direction of the current flow
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In regards to the electrical axis, the length of the arrow = ?
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voltage
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Where does a normal QRS axis point?
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To the left and downward
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What leads are used to determine the electrical axis?
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Leads I and aVf
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What is the normal range for an axis?
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-30 to +90 degrees
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What is considered left axis deviation?
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-30 to -90 degrees
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What is considered right axis deviation?
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+90 to +180 degrees
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What is considered indeterminate (extreme) axis deviation?
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-90 to +180 degrees
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In a normal axis (-30 to +90) Lead 1 =?, lead aVf = ?
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Lead 1 = Up
Lead aVf = Up |
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In left axis deviation lead 1 = ?, lead aVf = ?
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Lead 1 = Up
Lead aVf = down |
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In right axis deviation lead 1 = ?, lead aVf = ?
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Lead 1 = down
Lead aVf = Up |
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In extreme axis lead 1 = ?, lead aVf = ?
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Lead 1 = down
Lead aVf = down |
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In left axis deviation what else should be checked to make sure it is left axis deviation?
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Lead II, it should be going down, if Lead II is going up then the QRS is still normal.
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What causes a shift to the right?
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Vertical heart seen with a thin person
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What causes a shift to the left?
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Horizontal heart seen with someone obese or pregnant
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What are two other types of altered electrical axis that aren't a shift to the right or left?
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Hypertrophy and MI
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This is the case when the muscle wall becomes thicker and it mainly occurs in the ventricles?
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Hypertrophy
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What is a cause of hypertrophy?
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Pumping against increased resistance, ie. systemic hypertension or aortic stenosis.
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This is chamber enlargement, but the muscle wall dose NOT become thicker?
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Dilation.
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Where does dilation most often occur?
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Mainly in the atria
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What causes dilation?
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Volume overload ie. in mitral regurgitation.
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How do you notice an atrial enlargement?
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change in P wave.
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Where is the change in a p wave, in regards to atrial enlargement best seen, ie. what leads?
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II and V1
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In right atrial enlargement, what is the amplitude in leads II and aVf?
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>2.5mm
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In right atrial enlargement, what is meant by biphasic?
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P Pulmonale - 1st part of the p wave is taller than the terminal part in lead V1
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What are the causes for right atrial enlargement?
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COPD, mitral stenosis, mitral regurgitation or pulmonary emboli
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P wave duration is increased, a broad P wave, terminal portion of the P wave is at least 0.04 seconds and the P wave is notched in lead I, II, V4-6, the amplitued of terminal portion increases or decreases at least 1mm below isoelectric line in V1.
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Left atrial enlargement
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What are the causes of left atrial enlargement?
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nonspecific conduction irregularity or mitral stenosis.
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This is when you see the peak of the R wave happening earlier than V3-4, or they can all just stay the same?
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Right ventricular hypertrophy
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What are the causes of right ventricular hypertrophy?
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Severe pulmonary stenosis or primary pulmonary hypertension.
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What is another diagnostic tool for right ventricular hypertrophy, besides looking at V1-V4?
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Look at R wave progression, it will be poor, ie. Ld 1 - rS, V1- Rs, V6 - rS
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If the R wave runs off the chart, or into another part of the EKG what is this diagnostic for?
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Left ventricular hypertrophy
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Left Ventricular Hypertrophy
Limb Leads |
Ld 1 = >14mm
Ld aVL = >13mm Ld aVf = >21mm Ld 1 R + Ld III S = >25mm |
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Left Ventricular Hypertrophy
Pericordial Leads |
V5R or V6R + V1S or V2S = >35mm
V5R = >26mm V6R > V5R |