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
alterations in ST waves
ventricular repol very sensitive to myocardial perfusion, pertubation of perfusion can lead to alterations in ST waves
Myocardial Infarction - recent w/in days after
ST depression
mild to moderate deprivation of flow
subendocardial layers of myocardium effected
ST elevation
severe transmural deprivation of flow
subepicardial and subendocardial layers
fast conduction
contracting regions, His/Purkinje
slow conduction
pacemaking, and slow conduction (AV node)
