EKG Flashcards
Rules of electrocardiography
- wave of depol travels towards + pole gives a + voltage deflection
2) size of deflection : mass of tissue
SA wave
too small for a signal, not seen
P-wave
atria depolarization
PR-segment
depol wave moving through AV node
period between P-wave and Q-wave
Q-wave
left side of septum depolarizing
(wave travels from L to R away from + node)
His/Purkinje
often too small to be detected in lead I
R-wave
ventricle depole (endocardium -> epicardium) mass on L > R = positive deflection large mass = large peak
S-wave
last part of ventricle depol near the atrium
QRS complex
reflects ventricular depolarization
ST -segment
interval bet depol and repol
T-wave
repolarization of ventricle
epicardium -> endocardium
interval between P waves
sinus rhythm
heart rate
Fast = tachycardia
slow = bradycardia
measuring PR interval
amt of time it takes for the impulse to get rhough the AV node and His/Purk system (mostly AV bc it is slower)
PR longer than normal = abnormality in conduction pathway
widening of QRS complex
ventricle depolarizing more slowly than normal
ie bundle branch block
mean electrical axis
summation of all electrical activity
normally; between -30 aVl and +90 aVf
right axis deviation (towards aVr)
beyond 100
right ventricular hypertrophy, increase mass -> smaller than normal QRS in lead 1, positive deflection in aVr
left axis deviation
aVf more negative than -30
left ventricle hypertrophy
first degree AV block
PR-interval longer
every P wave followed by QRS
(conduction through AV node is slowed)
second degree AV block
PR-interval longer
some P waves NOT followed by QRS
(more severe block)
third degree AV block
dissociate of P and QRS
slower bc QRS is driven by the His/Purk system
atrial flutter
not every P wave followed by QRS
atrial rate faster than needed to get proper propagation through the AV node
atrial fibrillation
atria not driven by SA node, but by local currents = uncoordinated firing NO P-waves
ventricular tachycardia
ventricular rate > atrial rate
100-200 beats per min
ventricular flutter
> 200 beats per minute
ventricular fibrillation
electrical activity (and pumping) is completely uncoordinated) - lethal
