Escape Beat/ Rhythm / Premature beats
Terms in this set (29)
an irritable focus spontaneously fires a single stimulus
if there is a premature beat, what needs to be identified?
what is firing
____ automaticity foci are the most sensitive to O2 sensors. When they sense low O2, they become irritable and react
what causes atrial and junctional foci irritability
*adrenaline / epi (released by adreanal glands)
*increasing sympathetic stimulation /decrease parasympathetic
*possible low O2
On and EKG, a premature atrial beat records as a P' wave. What is the give away that this exists if it hiding in the T wave?
the T wave is taller than the others of the same lead
if one t wave is taller than the others of the same lead, what might this indicate?
the P' wave from a premature atrial beat is within it
if a premature beat is present, what must occur to reset the pace?
the dominant pacemaker must be depolarized by the premature beat
if a premature beat depolarizes the dominant pacemaker, what occurs?
the rate is reset one cycle length from the premature beat
If a premature atrial beat occurs without depolarizing the dominant pacemaker, how will the rhythm continue?
the SA node (dominant pacemaker) will fire at consistent rate from last occurance... NOT from the premature beat
If a premature atrial beat fires and one bundle branch has not completely repolarized, this will cause what?
aberrant ventricular conduction
aberrant ventricular conduction occurs when a premature atrial beat fires, and one bundle branch has not completely repolarized yet (while the other one has), how will this present on an EKG?
slightly widened QRS complex for that specific premature cycle
a widened QRS complex with a premature atrial beat would indicate what?
one bundle branch has not completely repolarized
when a premature atrial beat (P') is conducted to the ventricles, the ventricles are also depolarized (earlier/later) than usual
A premature atrial beat may be unable o depolarize the AV node when
if it is not fully repolarized, and still in refractory mode
A premature atrial beat that is non-conducted (occurs during the refractory period of the AV Node) has an unusual P'wave and has what ventricular response?
none - no associated QRS-T
A non conductant PAB does not depolarize the ventricles. However, it does depolarize the SA Node. What impact does this have?
it resets the pacemaking rate
Irritable automaticity focus that fires a PAB which couples to the end of the normal cycle, and each successive normal cycle.
If an irritable atrial focus prematurely fires after two normal cycles repetitively, this is known as
a series of couplet groups in Atrial Bigeminy or Atrail Trigeminy is called what?
If you see a premature QRS complex which is slightly widened, what should you consider?
a Premature Junctional / Atrial Beat with aberrant ventricular conduction
When a Junctional automaticity focus causes retrograde atrial depolarization, the P' wave will appear how?
when an irritability focus in the AV junction initiates a premature junctional beat after each normal SA Node generated cycle, this is called
when a premature junctional beat is coupled with two consecutive normal cycles, in a repeating series of couplets, this is called what?
ventricular focus can become irritable by what?
Low K+ (hypokalemia)
Pathology - mitral valve prolapse, myocarditis
Premature ventricular contraction will display how on an EKG?
large ventricular complex
what is the most likely reason for a ventricular automaticity focus to become irritable is what?
when a PVC occurs, it does NOT depolarize the SA Node. Therefore the SA Node will fire on time. What is the pause that generally follows the PVC (wide QRS complex?)
" compensatory pause"when the SA Node fires, it is unable to depolarize the ventricles, because they have not yet repolarized from the PVC.
After a PVC, the SA Node will fire on schedule, however because the ventricles have not yet repolarized, they will not be able to depolarize the ventricles. A compensatory pause will follow. When does the SA node fire again?
normal rhythm with previous cycles
multiple PVCs indicate a very irritable focus. ____ or more PVCs/minute is considered pathological