Week 1 ECG and Analysis Flashcards
what do we measure with an ECG
electrical signals of the heart
what is electromechanical coupling
the electrical signal on the ECG with the functional properties of the heart
what is the electrocardiogram
it captures the electrical activity produced by the hearts contraction cycle. it detects the flow of charged particles along the pathway, and detects currents.
in what directions do the heart signals travel, or in which direction does the heart depolarize?
right to left and inferior to superior and inside out.
what is the mean cardiac vector
what we get from the left ventricle, because it is bigger, and we get more of a signal
what does the QRS represent, and why is it the largest electrical event that occurs?
ventricular depolarization, its the largest because the left ventricle is the biggest
which lead has the largest QRS magnitude and why
Lead II because the positive lead is on the right arm, and the negative one is on the left leg, so its vector falls almost right in line with the mean cardiac vector.
the positive terminal is essentially the …
eye
what does the positive terminal capture
receives the signal
how do we capture signals? from negative to positive? or positive to negative?
negative to postive
what are the bipolar leads
they utilize a positive and negative electrode, and record the activity between them. Leads 1, 2, 3
what are unipolar leads
they use a single positive recording electrode and a combo of the other electrodes
what are the two types of unipolar leads
pericordial (chest, V1,2,3,4,5,6)
unipolar (augmented) aVL, aVR, aVF
where are the positive and negative for lead I? what side of the heart does it look at
(-) is on the right arm, and (+) is on the left arm. looks at the lateral heart
where are the positive and negative for lead II? what side of the heart does it look at
(-) is on the right arm, and (+) is on the left leg. Looks at the inferior surface of the heart, and the best for the ventricles.
where are the positive and negative for lead III? what side of the heart does it look at
(-) is on the left arm, and (+) is on the left leg.
what are the unipolar precordial chest leads, and what are their positions on the body
V1: 4th IC space right of the sternum V2: 4th IC space left of sternum v3: between V2 and V4 V4: midclavicular line 5th IC space V5: anterior axillary line, at V4 level V6: midaxillary line, at level of V4
what sections of the heart do the unipolar precordial leads look at
V1 and V2: septal area
V3 and V4: anterior wall
V5 and V6: lateral wall
do the unipolar leads have a positive or negative
they are the (+) and the machine is the negative
what are the three augmented leads
aVF, aVL, aVR
what does the aVF lead look at
the inferior part of the heart, since the positive is closer to the feet
what does the aVL look at
lateral wall of the heart, because this lead is placed on the left arm
what does the aVR look at
the right side of the heart, because the lead is placed on the right arm
why is aVR special (2 things)
there is an inverted T and STR waves, because the lead looks at the right side of the heart, so it is backwards. also, this is the only lead that looks at the right side of the heart
what is a 3 lead ECG
you only use the 3 electrodes, RA, LA and LL to get bipolar leads (I, II, III). you can see the lateral and the inferior parts of the heart
what is a 5 lead ECG
you use RA, RL, LA, LL and chest. so you use the 3 bipolar leads, and one chest lead (whichever you need)
where is the 5 lead ECG commonly used
in acute care
what is the saying to remember which color lead goes where for a 5 lead ECG
white on right
snow over grass
smoke over fire
everyone loves chocolate
what is a 12 lead ECG
you use all 6 chest leads and then you use all 4 limb leads. This will look at V1-6, leads I II III and then also aVR, aVL, aVF
which type of ECG is used for diagnostics
12 lead
which leads look at the septal part of the heart, and what coronary artery is that
V1 and V2, LAD
which leads look at the anterior part of the heart, and what coronary artery is that
V3 and V4, LAD left anterior descending
which leads look at the inferior part of the heart, and what coronary artery is that
II, III, aVF, PDA: posterior descending artery (from the RCA and the LCx)
which leads look at the lateral part of the heart, and what coronary artery is that
I, V5, V6, aVL, LCx (left circumflex)
how much time is represented by the thin and thick lines
the thin lines are 0.04 seconds and the thick lines are 0.2 seconds
five small boxes which are the thick lines are 0.2 sec, so 5 thick line boxes is how much time
1 second
what do the tick marks on the page represent. they happen every _____ thick boxes
3 seconds. every 15 boxes
p wave represents…
normal size
atrial depolarization
duration should be 3 small boxes and amplitude should be 2.5 small boxes
P-R interval represents?
duration should be?
the time the AP travels from the atria through the AV node to the ventricles. Duration should be 3-5 small boxes
what happens to the PR interval with exercise
it decreases, because the heart rate increases
what does the QRS represent
ventricular depolarization
what should the duration of the QRS be
between 0.06 and 0.1 seconds, or 1-5-2.5 small boxes
what should the amplitude be of the QRS
over 0.5 mV, or 5 small boxes in a standard lead
over 10 small boxes in a precordial lead
max: 25 boxes.
what else happens during the QRS, and why is it drowned out
atrial repolarization happened here, but the ventricular depolarization is so big, it drowns it out.
what does the ST segment represent
time ventricular depolarization and repolarization.
what is the T wave
ventricular repolarization
TF: the deflection of the T wave should be in the same direction as the QRS
true
what its he R-R interval? appearance? and what happens with exercise ?
the duration between heart beats, should be regular and consistent and shortens with exercise
what is the QT interval
the time it takes for ventricular depolarization and repolarization.
how long should the QT interval be in men and women
men: 10-11 small boxes
women: 11-11.5 small boxes
what is the normal time for the corrected QT interval
less than .44 seconds
what is the J point
the initiation of ventricular repolarization. where the QRS ends, and the ST begins.
what is the R wave progression.
from V1-V6, the R waves will get bigger in size, until we get to V4/5. then V6 is smaller again.
where does the transition from S>R to R>S usually occur
at leads V3, V4.
a patient is showing ST depression in leads V3,4,5,6. what could this mean
that he is having an anterolateral issue, affecting the LAD and LCx.
a patient is showing T wave inversion in leads V2,3,4,5,6. what does this mean
that there is issues with anterior, lateral heart, so that again is the LAD and the LCx.
what is the most common cause of ST segment elevation
myocardial ischemia and infarction
