ECG Flashcards
interval vs segment
intervals INclude a wave/complex
segments don’t
size: QRS
< 120 ms (1/2 box?)
size: p wave
< 120 ms wide
< .25 mV heigh
size: t wave
< 200 ms wide
< 0.5 mV tall
non-pathologic Q waves
< 1 small block wide
< 1/3 height of R
size: PR interval
< 200 ms
J point
start of ST segment
QTc
rate corrected QT interval
QTc = QT/sqrtRR
size: QTc
males < 440 ms
females < 460 ms
size: ECG paper sections
25 mm/s –> 25 small boxes/s –> 5 big boxes/s
1 big box = 0.2 s
1 small box = 0.04 s
height: 1 mm = 0.1 mV = 1 small block
calculate rate
big boxes btwn QRS –> 300, 150, 100, 75, 60, 50 (300/#)
or
10 x # in 6 seconds
signs of normal axis
I and aVF are both (+)
I (+), aVF (-) but II is (+)
– if II (-) –> LAD
phase 0
Na influx, rapid depolarization
phase 1
K outflow, early repolarization
phase 2
Ca influx, Na influx, plateau phase
phase 3
K outflow, repolarization
phase 4
resting phase
when is the effective refractory period (absolute)
0, 1, 2, early 3
when is relative refractory period
late 3, 4
what does a wife QRS show
usually a ventricular rhythm
ex: BBBs, WPW, HK, ventricular rhythms
1st degree AV block EKG
long PR interval (> 0.20 s, 1 big block)
1st degree AV block location
above AV node
2nd degree AV block (type I) EKG
Wenckeback
PR gets longer and longer until the QRS is dropped
2nd degree AV block (type I) location
in AV node
2nd degree AV block (type II) EKG
more P waves than QRS
2:1 - 5:1, etc
2nd degree AV block (type II) location
below bundle of His
3rd degree AV block EKG
complete heart block
Ps and QRSs aren’t coordinated at all
regular P-P intervals and regular R-R intervals, but not together
PACs: problem?
no problem if ASx
atrial flutter EKG
ventricular rate regular, narrow QRS
atrial rate regular but FAST (250-300)
sawtooth Ps
atrial fibrillation EKG
irregularly irregular
ventricular rate regular, narrow QRS
atrial rate regular but FAST (250-300)
may not see Ps, if can see = coarse
causes of A flutter
HTN, valves, AMI, chronic angina, PE, chronic pulm dz
causes of A fib
PIRATES PE, Pericarditis Ischemia Rheumatic/Valve heart dz Atrial enlargement Thyroid dz EtOH, electrolytes Sick sinus synddrome
junctional rhythm: pacemaker?
AV node
junctional rhythm: P waves
if present 1:1 P:QRS
can be before but inverted, during or after
junctional rhythms: QRS
narrow, regular (40 - 60)
AV nodal reentry –>
SVT
regular, narrow, fast QRS
rate of ventricular rhythms
20 - 40
WPW EKG
short PR wide QRS delta waves (upsloping PR)
