1 Flashcards
segment is a
line connected by two points
what is a normal PR interval
0.12-0.20 seconds; 3-5 small boxes
normal QRS
Normal: 0.08-0.12 seconds; 2-3 small boxes
” QT Interval normal
max: 0.45 seconds (11-12 boxes);
prolonged QT
over 12 boxes?
prolonged QT = @ risk for sudden death (hypokalemia, hypomagnesemia, hypocalcemia)
SA nodes bpm
60-100
Atrial muscle BPM
60-80
AV node BPM
40-60
placement of precordial leads
V1 4th intercostal space to right of atrium
V2 same as V1 but to the left
V3 directly between 2 and 4
V4 5th intercostal midclavicular
v5 to the left of V4 left anterior axillary line
V6 to the left of V5 midaxillary line
which precordial leads give us a view of the septum
V1 and V2
Which precordial leads give us a view of the anterior heart
V3 and V4
which anterior leads give us a view of the lateral heart
V5 and V6
What are the labels of the limb leads
I, II, II
aVR, aVF, aVL
where should a normal heart sit
between 0 and 90 degrees
what does isoelectric line refer to
if the mean depolarization path is directed at right angels (perpendicular) to any lead there will be a biphasic deflection and the isoelectric line can be drawn through this
1st area of ventricular muscle to be activated is is the inter-ventricular septum which is seen as what on a EKG
Q wave
negative
impulse travel at what speed through the AV node
slowly
impulse typically travels at what speed through the bundle of his
very quickly
where does impulse travel once thru the AV node
bundle of his–> BB>–> ventricualr muscle
what does the R wave represent
left and right ventricular muscle activation (endocardial first followed by epicardial)
big positive
s waves
a few small areas of ventricles are activated at a late stage and this is represented by the s wave
typically seen as negative
atrial depolarization is represented by the
p wave
intervals are
wave(s) and segments
order of signals starting with pacemaker cells in the SA
sa atrial syncytium juntional fibers atrioventricular node BB PF ventricular synctium
which atrium contracts first
the right
usually SA node stimulus appears as a
P wave
AV node signal is delayed by
.12 seconds
this is important because AV node blocks will prolong this signal
AV junction is made up of
AV node
bundle of his
R and L bb
SA node typically beats around
60-100
atria beats typically
40-60
ventricles bpm
20-40
atrial junction is typically seen with what bpm
60-80
1st degree normal AV block might be seen in what pt population
athletes
things that can change the conductions in a EKG
hair wheelchair bra pacemaker, bone, muscle movement, dried out electrodes, heavy breathing and sweating
V1 and V2 will tell you the
septum
V3 and V4 will tell you
the anterior
V5 and V6 will tell you
lateral
V1 is lovated where
4th intercostal space to right of sternum
V2 is located
4th intercostal space to left of sternum
V3 placement
directly between V2 and V4
v4 placement
5th intercostal space at midclavicular line
v5
level with V4 at left anterior axillary line
v6 location
level with v5 at left midaxillary line
positive electrode will appear on a ekg
as a positive wave (mountain top)
isoelectric line what is it?
is the straight line drawn across a depolarization path that is at a right angle ( or perpenducular ) to any lead
1st area of ventricular muscle to be activated is the interventricular septum which activates L–> R and is represented as the
Q wave
L& R ventricular muscle walls get activated after w/ the endocardial surface BEING activate before epicardial surface creating the
R wave
a few small areas of ventricles are activated in the late stage known as the
S wave
ventricular muscle repolarizes and is represented as a
T wave
QRS complex represents
ventricular depolarization/ventricular contraction
atrial depolarization is represented by
p wave
U waves are usually detected in the presence of
Electrolyte imbalance
usually this U wave is merged with the T wave
i small box is what amount of time
.04 seconds
5 small boxes represent what amt of time
.2 seconds
1 big box is
1 mv (10 small boxes)
i small box is
.1 mv
TELEMETRY
putting pt on EKG monitor and observing continuously
Long-term ekg
two thumbs up method
looking at AVF and I to determine deviation
if I and AVF are positive
heart is in normal placement
if I is positive and AVF is negative
left axis deviation
negative I and negative avf
indeterminate axis
negative I and positive avf
right axis deviation
depolarization is synonymous with
contraction
QRS complex is representative of
ventricular depolarization
ventricular repolorization is seen as the
T wav
U wave
after potential of ventricular muscle and re-polarization of purkinje fibers
why would se typically see a U wave
electrolyte imbalance.
- Identify the differences between analog imaging and digital imaging and some of the advantages of digital over analog.
Digital imaging can be sent and viewed anywhere. It can also be manipulated without having to re-expose the patient
Define PACS. Identify and recognize correct view box placement of films.
PACS = Picture Archiving and Communication Systems
Viewbox films are placed with the pts R on your L
Old → new
films are placed L → R
b. Two things make an image more radiopaque:
Identify and recognize radiolucent and radiopaque.
i. Density
ii. Thickness
radiopaque is more white
radio lucent is less
a. Pt must remain still
b. Magnification issues.
Objects are magnified when:
i. Beam is close to the pt
ii. Pt is far from cassette surface
c. Distortion issues.
ii. Example is “lordotic CXR” where pt is in bed, angled
1. This makes the base of the heart look larger
2. You can tell it’s lordotic if the clavicles are high
d. *Never judge cardiomegaly from a CXR unless it’s a perfect PA!!
- Identify those factors which must be considered by an x-ray technician before obtaining a plain film, including positioning of the patient, the cassette and the beam.
i. Beam is close to the pt
ii. Pt is far from cassette surface
magnifications issues occur when
Objects aren’t perpendicular when
objects are distorted in xray when
where pt is in bed, angled
- This makes the base of the heart look larger
- You can tell it’s lordotic if the clavicles are high
“lordotic CXR
a. Frontal (from the front, coronal), same as PA
b. PA (from behind, coronal)
c. Oblique (anything other than the cardinal planes
d. Cephalo-caudal (birds eye view) → AKA “axial”
- Identify and recognize frontal projection, lateral view, posteroanterior, anteroposterior and oblique views.
CT and MRI both use the_______ to describe the views
CT and MRI both use the three cardinal planes to describe the views
a. Contrast is bright white (e.g. barium)
b. Don’t use it if the thing you’re looking for is also high attenuation!
c. PO and IV contrast both are eliminated by the kidneys. (They will appear as high attenuation either way!)
- Recognize a CT scan with and without oral and/or IV contrast
d. Contraindications ofr CT contrast
CI for contrast w/ d. Contraindications:
i. Allergy
ii. Renal insuff. (creatinine >1.5) → CT, Contrast, Creatinine!
iii. Current metformin (d/c 24 before and resume 48h after)
iii. Current metformin (d/c 24 before and resume 48h after)
10. Recognize 3-D CT image reconstruction. Identify how this technique is useful in contrast to non-enhanced CT images.
a. Can give you a 3D orientation
b. Can subtract out stuff you don’t want to see (e.g. isolate renal vessels)
- Identify those patients for whom MRI is not an option and identify why.
a. Unstable patients (can’t run a code until the machine powers down)
b. Pacemakers
c. Other ferrous metal implantations (titanium & stainless steel ok)
when would you not want to use a xray (what are they not good at evaluating)
detail, precise location, solid organs, brain, or vasculature
what imagining would you want to run for a pt coming in with a new seizure or changed mental status
CT
when would you want a CT of the chest vs CXR
CT:lung tumor, effusion, infxn, PE, etc)
CXR: resp sx, chest pain, upper GI, trauma, procedures, fever)
two tests for the detection of a metallic fb
XRAY and CT
what imaging would you need for ligament or tendon injuries
MRI
Exceptional detail
Contrast not renal toxic
unless GFR <30
Safe in pregnancy
what imaging would you do for a pt with a CVA
CT 1st followed by MRI
MRI is more subtle
how do you describe an ULS
black
whiter
darker
casts shadow
Anechoic (black) Hyperechoic (whiter) Hypoechoic (darker) Echogenic (casts acoustic shadow, Ca+2)
Biliary tract stuff (stones, etc) would be evaluated best with what imagining
MRI
V/Q scan (PEmbolus) is an example of what type of imaging
nuclear studies
HIDA scan (gallbladder) is an example of what type of imaging
nuclear scan
Vessels (DVTs) are evaluated best with what type of imagery
ULS
low attenuation refers to
Low attenuation = less dense
Shades of grey to black
CT
