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38 Cards in this Set

  • Front
  • Back
Ability of specialized cells to spontaneously generate electrical impulses which may then be spread throughout surrounding tissue
Potential pacemakers within heart
Automaticity foci
The inherent rate for atrial foci
60-80 beats per min
The inherent rate for junctional foci
40-60 beats per min
The inherent rate for ventricular foci
20-40 beats per min
The pacemaker with the fastest rate is dominant pacemaker - this is called
Overdrive suppression
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
Transient escape of an automaticity focus to generate ONE BEAT is called _

This occurs when?

When there is a PAUSE in pacing activity
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
What are the three possible locations of P wave in junctional beats
- Retrograde P wave (positive in aVr) immediately preceding QRS
- Retrograde P wave immediately following QRS
- Absent P wave (buried in QRS)
How does ventricular escape beat looks on EKG
QRS complex is wider and follows the pause
An increase in the tendency for automaticity foci to spontaneously generate electrical impulses
Premature beat occurs when _
Irritable automaticity focus spontaneously generates a single electrical impulse prior to the next expected beat from the dominant pacemaker
Escape beats and premature beats differ by _
- 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
If every other beat is premature - this is called _
If every third beat is premature this is called _
If every fourth beat is premature this is called _
Atrial premature beat that is not followead by QRS complex is called _
Non conducted premature atrial beat
The delay in ventricular depolarization which usually follows a premature beat is called
Compensatory pause
2 types of compensatory pause

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 _
INCOMPLETE compensatory pause
Most PAC's are followed by _
INCOMPLETE compensatory pause
PJC's are followed by what type of pause
Any type of compensatory pause
Most PVC's are followed by _
Full or COMPLETE compensatory pause
Sustained arrhythmia is _
Arrhythmia that is greater than 30 seconds in duration
Flutter rate
Between 250 and 350
Fibrillation rate
Between 350 and 450
If a T wave is right before the P wave - what does it mean?
QT interval is markedly prolonged
Pacemaker activity which is dependent upon preceding impulse or series of impulses (initiated by afterdepolarizations)
Triggered activity
Polymorphic ventricular tachycardia which is preceded by marked prolongation of QT interval
Torsades de Pointes
Torsade de Pointes are due to _
Triggered activity (from early afterdepolarizations) related to "R on T" phenomenon, facilitated by marked QT prolongation
How do you estimate length of QT interval looking at EKG
The measured QT interval should be less than half of the R-to- R interval which includes the measured QT interval
Bazett formula for corrected QT
Corrected QT equals measured QT divided by square root of R to R interval
Most common cause of SVT
AV nodal reentry Tachycardia
If you see saw toothed pattern on EKG - diagnosis
Atrial flutter

Irregular rhythm
P wave shape varies
Atrial rate is less than 100
Irregular ventricular rhythm
Wandering pacemaker
Irregular rhythm
P wave shape varies
Atrial rate exceeds 100
Irregular ventricular rhythm
Multifocal atrial tachycardia
Delta waves on EKG
Wolff- Parkinson- White syndrome