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68 Cards in this Set
- Front
- Back
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A wave of depolarization traveling towards a positive EKG electrode causes a _ deflection on paper
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UPWARD
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A wave of depolarization traveling away from positive electrode causes a _ deflection on paper
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DOWNWARD
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A wave of repolarization traveling towards a positive EKG electrode causes _ deflection on paper
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DOWNWARD
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A wave of repolarization traveling away from a positive EKG electrode causes a _ deflection on paper
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UPWARD
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What is the difference between segment and interval?
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In electrocardiography, an interval includes at least one of the waves that it is named after, whereas a segment does not. In other words, a segment is simply a section of baseline which is between the waves that it is named after
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Which segment on EKG represents plateau phase of repolarizaton
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ST
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In normal heart rate what is longer systole or diastole
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Diastole
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Where is ventricular systole on EKG
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Begins at QRS complex and ends at the end of T wave
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Where on EKG is early ventricular diastole
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Between the end of T wave to beginning of P wave
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Where on EG is late ventricular diastole
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From beginning of P wave to the beginning of QRS complex
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Is atrial repolarization seen on EKG
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No
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What is the physiological event behind U wave
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Repolarization of Purkinje fibers, Purkinje fibers depolarize very fast but repolarize very slowly which causes U wave
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The vertical axis of the tracing represents ?
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Voltage
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The horizontal axis of the tracing represents?
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Time
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At standard calibration, 1 mm = voltage?
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0.1 mV
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Standard paper speed of EKG
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25 mm/sec
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1 mm = how many seconds?
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0.04 sec = 40 msec
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horizontal distance between consecutive bold lines on an EKG represents how many seconds
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0.2 sec = 1/5 sec = 1/300 min
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the heart rate (the number of beats per minute) equals ?
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300 divided by the number of “big blocks” between consecutive beats on a standard EKG tracing
ONLY FOR REGULAR RHYTHMS |
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For exceptionally slow heart rates or irregular rhythms, how do you determine heart rate
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the 3 second interval marks may be used to determine heart rate.
Simply count the number of cardiac cycles (R-to-R intervals) over 2 consecutive 3 second intervals, and then multiply this number by 10 in order to determine the heart rate in beats per minute |
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Name 6 limb leads
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I, II, III, avf, avl, avr
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6 limb leads allow determination of axis in _ plane
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FRONTAL
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6 precordial chest leads (V1-V6) allow determination of axis in _ plane
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HORIZONTAL
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Bipolar limb lead means?
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Each has 1 positive and 1 negative electrode
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Augmented unipolar limb lead means?
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Each has 1 positive electrode and 1 compound reference electrode (sum of the other 2)
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Right arm - Left arm - which lead? Which electrode positive?
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Lead I
Left arm |
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Right arm - left leg - which lead?
Which electrode positive |
Lead II
Left leg |
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Left arm - left leg - which lead?
WHich electrode positive? |
Lead III
Left leg |
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Which leads are lateral
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I and avL
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Which leads are inferior
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II, III, avf
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Where is normal QRS vector located on axis
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Between 0 and 90, down and to the left
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-30 --> + 150 axis - which lead
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AVL
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0--> + 180 axis - which lead
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I
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+ 30--> -150 axis - which lead
Is it positive or negative |
Avr
negative |
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+ 60 --> - 120 axis --> which lead
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LEAD ii
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+ 90 --> - 90 AXIS --> WHICH LEAD
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avF
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+ 120--> -60 which lead
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Lead III
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Negative lead I
Negative aVf Deviation? |
Extreme right axis deviation
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Positive in I
Negative in avF Deviation |
Left axis deviation
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Positive lead I
Positive lead avF Deviation |
Normal
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Negative lead I
Positive lead avF Deviation? |
Right axis deviation
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What is the difference between devitation and rotation for axis in EKG
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Deviation = frontal plane
Rotation = horizontal plane |
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If the change from negative to positive in precordial leads happens after V 4 (V5, V6, or never) - what type of rotation
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Leftward axis rotation
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If the change from neg to pos in precordial leads happens at V1 or V2 - what type of rotation
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Rightward axis rotation
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If the change from - to + in precordial chest leads happens after V 2 and at or before V4 - what type of rotation?
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NO rotation, normal
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If axis in precordial leads starts positive and stays positive - what type of rotation
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Rightward axis
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If axis in precordial leads start positive and ends positive - what type of rotation
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Leftward axis
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If axis in precordial leads starts positive and becomes negative by V6 = what type of rotation
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Leftward axis
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-QRS axis between –45 and –90 degrees
-QRS duration < 120 msec (unless associated with RBBB) -Small Q waves in I and aVL -rS patterns in II, III, and aVF |
Left anterior fascicular block
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QRS axis +120 degrees or greater
QRS duration < 120 msec (unless associated with RBBB) Small Q waves in II, III, and aVF RS patterns in I and aVL Exclusion of other causes of RAD Lateral wall MI RVH |
Left positerior fascicular block
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Ability of specialized cells to spontaneously generate electrical impulses which may then spread throughout surrounding tissue
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Automaticity
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Potential pacemakers within the heart are also called
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Automaticity foci
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Rate for atrial automaticity foci
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60-80
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Rate for junctional (AV nodal) foci
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40-60
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Rate for ventricular foci
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20-40
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The pacemaker with the fastest rate is the dominant pacemaker - this is called _
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Overdrive suppression
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A protective mechanism whereby an automaticity focus with the next highest inherent rate begins pacing in the event of a pause or cessation of pacing activity of the previously dominant pacemaker
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Escape
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Transient escape of an automaticity focus (from overdrive suppression) to generate one beat.
This occurs when there is a pause in pacing activity in the previously dominant pacemaker. |
Escape beat
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Escape of an automaticity focus (from overdrive suppression) with subsequent pacing by that automaticity focus, at its inherent rate.
This occurs when there is a cessation (or arrest) of pacing activity in the previously dominant pacemaker |
Escape rhythm
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Escape beat occurs when _ while escape rhythm occurs when _
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Escape beat = pause in present pacemaer
Escape rhythm = cessation of present pacemaker |
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Give EKG criteria for sinus rhythm
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Each QRS complex is preceded by a P wave.
The P waves must be positive in lead II, and negative in lead aVR |
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EKG criteria for normal sinus rhythm
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Sinus rhythm with a heart rate between 60 and 100 beats per minute
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EKG criteria for sinus bradycardia
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Sinus rhythm with a heart rate less than 60 beats per minute
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EKG criteria for sinus tachycardia
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Sinus rhythm with a heart rate greater than 100 beats per minute
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EKG criteria for sinus arrhythmia
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Same criteria as sinus rhythm and there is greater than 0.16 sec. difference between the shortest and the longest PP intervals within the same EKG tracing
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Heart rate increases with inspiration or expiration
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Inspiration
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Most common cause of sinus arrhythmia
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Most common cause is respiration
Heart rate increases with inspiration and decreases with expiration (due to changes in vagal tone during respiration) |
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The key to determining the origin of a completely inverted P wave in lead II is the
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Length of PR interval (provided there is no AV nodal dysfunction)
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