Term
3 standard leads (I, II, III) 3 augmented leads (aVR, aVL, aVF) 6 precordial leads (V1V6) 

Definition
list the leads of an ECG (12) 


Term
arrhtmias, ischemia, damage 

Definition


Term
depolarization, repolarization (currents generated in the heart generate slight potential differences across the body surfaces ~1mV) 

Definition
what does an ECG measure? 


Term

Definition
what do ECG measurements depend on? 


Term
P: atrial depolarization QRS: ventricular depolarization T: ventricular repolarization 

Definition
define the following: P wave, QRS complex, T wave 


Term
the QRS supposedly hides it, even with an AV block 

Definition
why can't you see atrial repolarization on an ECG? 


Term
the peak of one ventricular deoplarization to the next, this is used to determine heart rate 

Definition
what is the RR inverval defined as? 


Term
the time between atrial contraction and the beginning of ventricular contraction normally is o.120.20 s 

Definition
what is the PR interval? what is its normal value? 


Term

Definition
how long does it take before every part of the heart is depolarized? 


Term
the time of ventricular contraction (how long it takes to de & repolarize)
normally = 0.35 s 

Definition
what is the QT inertval? what is its normal value? 


Term
look at the RR interval. Count the big boxes between the two peaks and divide 300 by this number.
This works because 5 * 60 = 300, and every 5 big boxes = 1 second so divide 300 by the # of boxes and you can estimate HR like it's nobody's business. 

Definition
how can you tell a person heart rate from the ECG? 


Term
it means that the conduction is going through the muscle rather than the purkinje fibers
this is shown be a widened QRS complex 

Definition
what is an ectopic foci? how is this seen on an ECG? 


Term
ischemia & cardiac myocyte damage (chronically depolarized cells) 

Definition
what does an ST change indicate? 


Term
180() right arm 0(+) left arm
points to positive 

Definition
what is the angle of the standard bipolar limb lead I? (indicate pos and negative) 


Term
120 () right arm 60 (+) left leg 

Definition
what is the angle of the standard bipolar limb lead II? (indicate pos and negative) 


Term
60 () left arm 120 (+) left leg 

Definition
what is the angle of the standard bipolar limb lead III? (indicate pos and negative) 


Term
toward the positive electrode 

Definition
which direction does the vector point for the ECG leads? 


Term

Definition
where do the vectors point for the augemented leads? (list the augmented leads and their angles (+)) 


Term
lead 2, the heart depolarizes at approximately the same angle 

Definition
on which lead will you see the strongest(best) QRS complex? why? 


Term
they measure the augemented vector resulting from the potential that points toward either the right arm, left arm, or feet (the positive terminal points to the limb described in the name of the lead)
there are 2 negative electrodes on 2 limbs and a positive on one. This is like an average of the standard limb leads, and looks like them except aVR is inverted 

Definition
what do the augmented lead measure? 


Term
the electrical potential of any limb equals the sum of potentials of other two limb leads 

Definition


Term
it is a triangle drawn around the heart that indicates fluids in the body have equal resistance, so the potential is carried equally 

Definition
what is Einthoven's triangle? 


Term
the negative potential of the body (sum of all potentials) located at the center of the heart 

Definition
whatdoes the negative end of the precordial(chest) leads represent? 


Term
anterior/posterior location (can tell you where a heart attack occurs) 

Definition
what do the chest leads(V1V6) tell you? 


Term
2 large boxes on the y axis 

Definition
on a typical ECG, what is 1 mV? 


Term
the voltage of the potential (mV) 

Definition
on an ECG, what is the length of the vector proportional to? 


Term

Definition
if a vector is horizontal and points to the patients left, what angle is it at? 


Term

Definition
a vector that points downwards is what angle? 


Term

Definition
what does 5 large boxes on the x axis of an ECG represent? 


Term
instantaneous mean vector 

Definition
what is "A" in vector analysis ? 


Term
projected vector on the lead 

Definition
what is "B" in vector analysis? 


Term
the largest QRS, because the direction of polarization is most aligned with it 

Definition
the lead with the largest depolarization will be indicated by what? why? 


Term

Definition
are the standard lead vectors negative or positive in the Q wave normally? 


Term

Definition
are the standard lead vectors negative or positive in the R wave normally? 


Term
I is positive, but II and III are negative
the action potential is headed toward the positive cathode of lead I (the left ventricle) so it is positive 

Definition
are the standard lead vectors negative or positive in the S wave normally? why? 


Term
the last to depolarize are the first to repolarize 

Definition
in a normal heart: the ____ area to depolarize is the ____ area to repolarize 


Term
changes in heart position, hypertophy, bundle branch blocks 

Definition
what 3 things can shift the axis of depolarization? 


Term
deep expiration, lying down, obesity (abdominal fat pushes up) 

Definition
what causes a change of position of the heart which results in a left shift? 


Term
deep inspiration, standing up, being Abe Lincoln(tall and thin with a long thorax) 

Definition
what causes a change of position of the heart which results in a right shift? 


Term
left shift (and right hypertrophy causes right shift) 

Definition
what kind of shift does left ventricular hypertrophy cause? 


Term
left shift (right BBB causes right shift) 

Definition
what kind of shift does a left bundle branch block cause? 


Term
the depolarization will be prolonged where the block is, so it is more positive (thats where the vector will shift to) 

Definition
why does a bundle branch block cause a shift in the direction of the block? 


Term
use 2 leads, draw the vector at the proper angle for the lead, with a magnitude equal to the voltage (units) of the QRS
draw perpendicular lines from the ends of the vectors and then draw a line from the center (the original vector's intersection) to the place where th perpendicular lines meet.
this new line is the axis of depolarization 

Definition
how do you calculate the axis of depolarization? 


Term
the direction the heart is depolarizing, you can use this to determine if the angle is being shifted by something 

Definition
what does the axis of depolarization tell you? 


Term

Definition
what is the current of injury most often caused by? 


Term
opposite of the injury, the injury is negatively charge and the vector always points towards the positive 

Definition
which direction does the current of injury vector point? why? 


Term
the place where the potential = 0, right after QRS (the whole ventricle is depolarized so there is no potential) 

Definition


Term
standard and augmented leads 

Definition
which leads determine the left and right position of an injury? 


Term
the difference between the voltage of the ECG immediately before the onset of the P wave, and the J point (0 reference point) 

Definition
where is the injury potential in each lead? 


Term
120 degrees aka right ventricle 

Definition
if the mean axis of injury is 30 degrees, where is the current of injury? 


Term

Definition
what leads are used to determine anterior/posterior position of an injury? 


Term

Definition
what does it mean if V2 is negative? 


Term

Definition
what does it mean if V2 is positive? 


Term
mild ischemia (& shortening/lengthening of the QRS complex 

Definition
what can lead to an inverted t wave? 


Term
one of the branches of the bundle of his is blocked (left or right) so one of the ventricles depolarizes before the other 

Definition
what happens in a bundle branch block? 

