EKG Tutorial Lecture Notes Flashcards
Convention: conceive of electrical waves of the heart as
positive wave moving across muscle
positive wave moving to positive electrode yield what in electrocardiogram
positive peak
in most cases atria are electrically isolated from ventricles by what
fibrous tissue in the AV ring
Separate electrical activity
terminal purkinje fibers
fibers that innervate myocardial cells
R and left ventricle depolarize in what amount of time
less than 120 milliseconds
any initial negative deflection is called
Q wave
all positive deflections are called
R waves
All neg deflection that following a positive deflection
an S wave
exception: an initial negative deflection is called
a Q or QS wave
if no S wave then it is called
called a QR wave
If no Q wave then it is called
RS wave
Duration of normal QRS lasts
120 milliseconds
ST segment
plateau that signifies no waves toward or away from electrode
T wave represents
ventricular repolarization (also plateau???)
most of the time,
the wave of depolarization and repolarization is in the same direction
- opposite signed waves moving in opposite directions so wave is in same direction
- depol occurs endocardium to epicardium while repol occurs from epicardium to endocardium
repolarization can be considered
negative wave moving through heart muscle
PR interval
time it takes the impulse to go through Av node
P wave represents
atrial depolarization
atrial repolarization
such small volume of electrical activity (overwhelmed by QRS complex
EKG
plot of voltage vs Time
small squares: 1 mm by 1 mm
big squares: 5 mm x 5 mm
speed of standard EKG: 25 mmm per second
- time between 1 mm lines is 0.04 sec
- time between 5 mm line is 0.2 sec
PR interval lasts
0.16 secs (normally no more than 4 blocks)
QRS complex
0.08 secs (normally less than 0.120 sec)
where are electrodes placed
right arm
left arm
left leg
lead one
neg on right arm and positive electrode in left arm
lead two
neg on right arm and postive on left foot
lead three
neg on left arm and positive on left leg
pneumonic for lead charges
right arm is always negative
foot is always positive
left arm is either positive or negative depending on the lead
Lead AVF
positive electrode in foot
negative electrode: combination of left arm and right arm
(looks down into the foot
Lead AVR
negative electrode on left leg and left arm
pos electrode on on right arm
“looks up and to the right”
Lead AVL
neg electrode on left foot and right arm
pos. electrode on left arm
“looks up and to the left”
lead one and AVL called
lateral leads
Leads III, AVF and II are called
inferior leads
what are the chest leads
V1-V6
activity in transverse plane (compared to those in the frontal plane)
What happens to waves as you go from V1 to V6
- R wave gets taller and s wave gets less deep
Which leads are in teh right ventrcile
V1 and V2
Which leads are in teh left ventrcile
V3 and V4
give you activity in the anterior wall or septal wall
dubin procedure
rate, rhythm, axis, hypertrophy and the presence of infaction
how many milliseconds per minute
60,000 milliseconds in a minute
how to calculate beats per minute
60,000 divided by milliseconds of per one beat on the EKG
300/1, 300/2, 300/3 etc.
60,000/200
300 bpm
60,000/400
150 (etc)
How do you remember the # HR numbers (300, 150 etc)
300/1 , 300/2, 300/3, etc
More precise way to measure HR?
1500/ # of small boxes
Ex. 1500/25 =60
When they don’t line up with big boxes
What are the anterior leads
I, II, III, aVR, aVI, aVF
What are the horizontal leads
V1, V2, V3, V4, V5, V6
Rhythm strip is usually:
lead II
how do you calculate more precise HR
1500/ number of boxes = more precise HR
