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38 Cards in this Set
- Front
- Back
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Ability of specialized cells to spontaneously generate electrical impulses which may then be spread throughout surrounding tissue
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Automaticity
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Potential pacemakers within heart
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Automaticity foci
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The inherent rate for atrial foci
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60-80 beats per min
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The inherent rate for junctional foci
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40-60 beats per min
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The inherent rate for ventricular foci
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20-40 beats per min
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The pacemaker with the fastest rate is 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 previously dominant pacemaker
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Escape
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Transient escape of an automaticity focus to generate ONE BEAT is called _
This occurs when? |
ESCAPE BEAT
When there is a PAUSE in pacing activity |
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Escape if an automaticity focus (from overdrive suppression) with subsequent pacing by that automaticity focus at its inherent rate is called _
When does this occur |
Escape rhythm
Occurs when there is CESSATION of pacing activity in previously dominant pacemaker |
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What are the three possible locations of P wave in junctional beats
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- Retrograde P wave (positive in aVr) immediately preceding QRS
- Retrograde P wave immediately following QRS - Absent P wave (buried in QRS) |
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How does ventricular escape beat looks on EKG
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QRS complex is wider and follows the pause
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An increase in the tendency for automaticity foci to spontaneously generate electrical impulses
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IRRITABILITY
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Premature beat occurs when _
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Irritable automaticity focus spontaneously generates a single electrical impulse prior to the next expected beat from the dominant pacemaker
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Escape beats and premature beats differ by _
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- Timing of occurence (relative to preceding beat)
- Mechanism - escape of an automaticity focus (from overdrive suppression) due to failure of the previously dominant pacemaker, versus irritability of an automaticity focus |
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If every other beat is premature - this is called _
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Bigeminy
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If every third beat is premature this is called _
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Trigeminy
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If every fourth beat is premature this is called _
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Quadrigeminy
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Atrial premature beat that is not followead by QRS complex is called _
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Non conducted premature atrial beat
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The delay in ventricular depolarization which usually follows a premature beat is called
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Compensatory pause
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2 types of compensatory pause
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Complete
Incomplete |
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Whenever a premature beat results in atrial depolarization ( all PAC's, some PJC's and some PVC's), the SA node is reset resulting in _
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INCOMPLETE compensatory pause
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Most PAC's are followed by _
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INCOMPLETE compensatory pause
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PJC's are followed by what type of pause
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Any type of compensatory pause
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Most PVC's are followed by _
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Full or COMPLETE compensatory pause
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Sustained arrhythmia is _
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Arrhythmia that is greater than 30 seconds in duration
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Flutter rate
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Between 250 and 350
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Fibrillation rate
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Between 350 and 450
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If a T wave is right before the P wave - what does it mean?
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QT interval is markedly prolonged
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Pacemaker activity which is dependent upon preceding impulse or series of impulses (initiated by afterdepolarizations)
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Triggered activity
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Polymorphic ventricular tachycardia which is preceded by marked prolongation of QT interval
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Torsades de Pointes
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Torsade de Pointes are due to _
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Triggered activity (from early afterdepolarizations) related to "R on T" phenomenon, facilitated by marked QT prolongation
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How do you estimate length of QT interval looking at EKG
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The measured QT interval should be less than half of the R-to- R interval which includes the measured QT interval
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Bazett formula for corrected QT
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Corrected QT equals measured QT divided by square root of R to R interval
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Most common cause of SVT
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AV nodal reentry Tachycardia
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If you see saw toothed pattern on EKG - diagnosis
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Atrial flutter
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EKG
Irregular rhythm P wave shape varies Atrial rate is less than 100 Irregular ventricular rhythm |
Wandering pacemaker
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Irregular rhythm
P wave shape varies Atrial rate exceeds 100 Irregular ventricular rhythm |
Multifocal atrial tachycardia
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Delta waves on EKG
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Wolff- Parkinson- White syndrome
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