EKG 1-4 Flashcards
a wave of repolarization traveling towards a positive EKG causes a
downward deflection
a wave of repolarization traveling away from a positive EKG electrode causes
upward deflection
In EKG an interval includes what
at least one of the waves that it is named after
PR interval
beginiing of P wave to beginning of QRS
QT interval
beginning of QRS to end of T wave
ST interval
end of QRS to end of the T wave
P wave represents
atrial depolarization
T wave represents
ventricular repolarization
QRS represents
ventricular depolarization
where is early diastole
end of T wave beginning of P wave
U wave represents
repolarization of the purkinje fibers
each 5 boxes represent
.2 seconds
how many big blocks per second
5
how many big blocks per minute
300
heart rate is equal to 300 divided by
number of big blocks between consecutive beats on standard EKG tracing with regular rhythms
for slow heart rates or irregular rhythms the _____-marks may be used to determine heart rate
3 second marks
how do you determine the heart rate for slow heart rates or irregular rhythms
count number of cardiac cycles over 2 consectuvei 3 second intervals and multiply by 10
lateral leads are
I and AVL
inferior leads are
II, III, and AVF
normal frontal plane axis is
0-90 degrees
O is lead
I
positive 30 degrees is
R (-)
positive 60 is
lead II
positive 90 is LEAD
F
positive 120 is
lead III
what are the 3 steps for locating QRS in the frontal plane
locate the most isoeletric lead, locate the lead 90 degrees from the most isoeletric lead and the QRS axis is along this lead in the direction corresponding to the polarity of the QRS complex in THAT lead
if lead 1 qrs is positive and AVF is negative them
extreme RAD
if lead 1 is positive and AVF is positive them
normal
if lead 1 is positive and AVF QRS is negative them
LAD
V1 is mostly
negative
V6 is mostly
positive
rules for determining the QRS axis in the horizontal plane
if R to S ration changes from negative to positive
after V4- leftward
at or before V2- rightward
between V2 and V4 then normal
if starts negative and stays negative -leftward
if starts positive and stays positive–rightward
if starts positive and becomes negative by V6 then leffward
what is automaticity
ability of specialized cells to spontaneously generate electrical impulses which may then spread throughout surrounding tissue
rate for atrial foci
60-80
rate of junctional foci
40-60
rate of ventricular foci
20-40
overdrive suppresion
the pacemaker with the fastest rate is the dominant pacemaker
what is escape
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 the previous dominant pacemaker
escape beat
transient escape of automaticity focus to generate one beat; occurs when there is a pause in pacing activity in the previously dominant pacemaker
escape rhythm
escape of automaticity focus with subsequent pacing by the automaticity focus at its inherent rate which occurs when there is a cessation of pacing activity in the previously dominant pacemaker
what is the criteria for sinus rhythm
each QRS complex is preceded by a P wave and the P waves MUST BE positive in lead II and negative in lead AVR
normal sinus rhythm is a heart rate of
60-100
sinus bradycardia
less than 60 beats/minute
sinus tachycardia
sinus rhythm with a heart rate greater than 100 beats/minute
what are the criteria for sinus arrhthmia
sinus rhythm criteria and there is a GREATER than .16 (r small boxes) between the shortest and the longest PP intervals within the same EKG tracing
what is the most common cause of sinus arrhthmia
respiration
inverted P wave in lead two
atrial automaticity focus
the key to determining the origin of a completely inverted P wave in lead II is the
length of the PR invertival assuming there is NO AV node dysfunction
if automaticity is midwave between AV node and bundle of his then
P wave is nonexistent
if P wave is close to the bundle of his them
P wave after QRS
