ECGs Flashcards
what does height and width indicate
height: voltage
width: time
what is height and width of 1 small box
H: 0.1mV
W: 40ms
what is height and width of large box
H 0.5mV
W: 200ms
what does pulse at beginning mean
1mV
how long is a full strip
10s
2 ways to figure out HR
- count all and x6
2. 300/# of squares between beats
what does pos vs neg wave mean
direction of wave
what is key to measure of whether pos or neg
area under the curve
which leads measure coronal vs. transvers
coronal: limb leads
transverse: precordial
where are leads 1,2,3
1 - left arm 0deg
2 - left leg +60
3 - right arm +120
where are aVL, aVF, aVR
aVL: -30
aVF: +90
aVR: -150
which 2 pairs are perpendicular
- 1 and aVF
2. 2 and aVL
where do precordial leads go
V1 and V2: either side of sternum
V4: midclavicular
V6: mid axillary
what do V1 and V2 measure
septum
what do V3 and V4 measure
L vent
what measures lateral wall
1, aVL, V5, V6
what measures inferior wall
2, 3, aVF
where is normal vent. polarization from
1 and 2
where is normal QRS axis
-30 to +90
where is left axis deviation (LAD)
-90- -30
where is RAD
+180 - +90
what do P R T wave represent
P - atrium
R - ventricles
T - reporlarization
what is normal P wave amplitude and duration
amp: <0.25mv (2.5 small boxes)
dur: 40-120 (1-3 small boxes)
what is PR interval and what does it represent
start of P to start of R
- time through atria and AV node
normal PR interval
120-200 (3-5 small squares)
what is PR segment
end of P to beginning of R
- AV node delay
what is normal amplitude of PR segment
flat
what is QRS interval and what does it represent
beginning of Q to end of S
- his, purkinje, ventricles
what is normal QRS interval
<120ms (3 small squares)
what is ST segment
end of S to beginning of T
- completion of ventricular polarization
what is J point
junction of QRS and ST
what is normal T wave amp
1/3 to 1/2 of corresponding wave
what is QT interval
beginning of Q to end of T
what is normal QT interval
1/2 of RR - 300-440 ms
7 things that must be inspected in ECG
- Rate
- Rhythm and PR interval
- Axis
- The QRS
- ST segment
- QT interval and QTc
- T wave abnormalities
RATE: what is normal rate
60-100brm
RHYTHM: 3 things to assess in rhythm
- are P and R connected
- reg or irreg
- P before each QRS
where is normal sinus rhythm pos in leads
pos towards feet and L
AXIS: what 2 leads to check for normal axis
1 and aVF should both be pos
THE QRS: 2 things to check in QRS
- width
2. voltage
what is too wide QRS and what does it mean
> 120ms - bundle block
what is QRS interval for R and L bundle block
R: 110-130
L: 120-140
what will we see in RBBB
big pos. jump on V1 and V2 because of RV hypertrophy
what will we see in LBBB
big neg S wave in V1 and V2
what does big or small QRS tell us
too big - hypertrphy
too small - dead tissue or far from lead
what will we see in RV hypertrophy (3)
- R wave in V1 > 7mV
- R axis deviation > 110
- R<S in V5,V6
what will see in limb leads of LV hypertrophy (2)
- R wave in aVL > 11mm
2. R wave lead 1 + S wave lead 3 > 25mm
what will see in precordial leads in LV hypertrophy (2)
- R wave V5 or V6 > 26,,
2. R wave V5 or V6 + S wave V1 > 35mm
ST SEGMENT: what to look for
elevated or depressed
QT INTERVAL: what to look for
length of interval (8-11 normal)
T WAVE: what to look for (2)
- size
2. inversion
what do probes with T wave indiacate
pre death
