2: RATE Flashcards
4 big boxes is equivalent to
75 bpm
two components of the rhythm
sinus/ non sinus
regular/irregular
Sinus Criteria
Must originate from the SA node
P wave before each QRS
normal P waves should be upright leads I, II, and inverted in lead aVR
Rhythm must always have P wave, QRS complex, & T wave
what is sinus arrhythmia
irregular rhythm coming from the SA node influenced by respiration
usually seen as the lengthening of the RR interval on expiration?
what is the PR interval exactly?
represents the time taken from the Sa node into the atria and into the beginning of the AV junction where the message gets slightly delayed
PR interval duration
0.12-0.20 seconds;
or 3-5 small boxes
Wolf-Parkinson-White
Wolf-Parkinson-White (Bundle of Kent í Delta Wave Present + Short PRI)
í Pre-Excitation Syndromes are seen as what PR interval
SHORT (<0.12 sec)
less than 3 boxes
PR Interval - LONG (>0.20 sec) is indicative of a
Consider AV Block
Why care about Wolf-Parkinson-White (WPW)?
Can cause ventricular fibrillation & sudden death. Be suspicious of a healthy, young patient w/ syncopal episode.
~ PR interval progressively lengthens until QRS complex is DROPPED.
2nd degree AV block
“ Mobitz type I
” QRS Duration
Normal: 0.08-0.12 seconds; 2-3 small boxes
” QT Interval í max
<440 in males (11 boxes)
<460 in females (9 boxes)
0.45 seconds (11-12 boxes);
prolonged QT =
prolonged QT = @ risk for sudden death due to fatal arrhythmia from electrolyte imbalances
(hypokalemia, hypomagnesemia, hypocalcemia)
ventricular depolarization and repolarization is represented by what interval
QT interval
