Complex Care
5-18-10
EKG, Arrythmias, & Treatment
Review pathway of blood through the heart:
We can look electrically at the heart (ECG) and see what’s happening mechanically
Polarized heart cell: one that is ready to fire (a knight with his sword and shield and he’s ready)
Depolarization: one that strikes, fires (the knight lashes out with his sword)
Repolarization: everything resets (the knight has to go get his sword and get ready again). This is the MOST
vulnerable state, or most at risk for damage.
ECGs can be used for diagnosis but are not used alone; they are always combined with other things. We draw
labs, assess CP, and check BP. It’s a diagnostic tool but NEVER used alone.
Gelatinous substance on backside of electrode serves two purposes (1): has electrolytes in it (electricity flows
better because it’s a negative energy source), (2) it has an abrasive in it that breaks the oil that is on the skin so
that it comes in better contact c the skin. Make sure pt isn’t allergic to the gel. Electrodes are changed about
once a day or every other day (avoid getting an allergy, irritating skin, or skin breakdown).
SA node is the pacemaker of the heart (it lives in the right atrium) it is what normally initiates electrical activity
in the heart, fires at a rate of 60-100. The electrical activity then goes to the AV node (or the junction, or the AV
junction), then Bundle of HIS, then down R L bundle branches (which are down the L & R ventricles), the
Purkinjie fibers, then cell to cell to cell to cell. Because cardiac cells are able to depolarize from cell-to-cell-to-
cell.
My side of the room is the atria; Cole is the SA node (because he is bossy). He fires and depolarizes the atria; it
gets to Dena, who is the AV node which also makes her the bridge that goes from the atria to the ventricles.
Dena says “STOP!” she stops all electrical activity, gathers it within herself and says “GO!” and it goes down the
ventricles, through the L & R bundle branches, purkinje fibers and cell-to-cell to cell. (Slide 5, page 1).
SNS increases irritability. When the cells get pissed off they start firing electrical currents which makes extra
beats on the EKG. The SNS increases the irritability in the cells, which increases the incidence of ectopic beats.
“My patient’s having lots of ectopy” = they’re having lots of beats they shouldn’t be having.
Parasympathetic affects the atria only. If a pt is having lots of ectopy it makes sense that we would give them
something to block they’re sympathetic system (Beta blocker) b/c it will decrease irritability of cells.
When you put Lead II (slide 4, p 2) on a patient you have a negative electrode up top and a positive electrode on
bottom. If you have an impulse that fires: the electrodes that are put on pt’s chest are like eyeballs and they’re
looking at the electricity. If the electricity is coming towards me, then I make a positive deflection, which means I
have a spike that goes up. If the electricity moves away from me then I have a negative deflection, which is a
spike that goes down (slide 2, pg 2).
You have to have a minimum of three leads in order to get a pic on an EKG.
Horizontal lines (left to right) are used to measure voltage. The more electricity emitted by the heart, the higher
the spike will be on the EKG. It will cross more horizontal lines. If they have a weak heart we may see little bitty
complexes, if they have a strong heart we will see big complexes. The vertical lines are time, the further you go
Page 1 of 12
, on vertical lines across the paper, the more time has passed. There are little baby blocks that are 0.04 seconds
each, big blocks are 0.2 seconds. There’s five baby blocks in one big block.
The baseline of the EKG is the isoelectric line. It’s there when nothing’s happening in the heart between
complexes when it’s just that flat line. The isoelectric line is the polarized or resting state. Kind of like the hum of
the heart, the potential energy.
P wave is depolarization of the atria; it’s gently rounded and normally positive. It’s poking up because it is
moving down the heart towards the positive electrode.
Measure the P-R interval (PRI) from the beginning of the P wave to the beginning of the QRS. Cole says, “Fire!”
we depolarize to get it to Dena. Dena says “STOP! OK, GO!” this makes the ventricle part of it. The PRI is just
looking at how long it takes from the time he fires to the time she releases the current into the ventricles (time it
takes from the time the SA node fires to the time the AV node releases to the ventricles). It’s telling how long it
takes for the atria to do their part of the cycle. This time includes Dena’s (AV node’s) delay. So if she starts acting
up and taking too long, the PRI is the part of the EKG that will be messed up, it’ll be too long if she takes too
long. Normal PRI is 0.12-0.20 seconds (which is 3-5 baby blocks).
The QRS is the depolarization of the ventricles; it is much larger than the P because the ventricles are the money
maker of the heart. We like for the atria to work, it’s better for us if they do, but if they go out we can survive
with just the ventricles. We cannot survive w/o ventricles. The atria cannot pull the weight. It’s like the atria is
the coach and the ventricles are the football players.
It’s measured from the 1st deflection from the isoelectric line to the beginning of the ST segment. Normal is 0.05
to 0.10 seconds, its tiny, they’re itty bitty skinny. When the QRS starts getting wide, it means it’s taking the
ventricles too long to depolarize (fire), it should be a very fast action.
The ST segment is the flat part that’s between the QRS and the T (hence the name ST segment). It should go
back to the isoelectric line so we can compare that flat part to the part between the complexes to make sure
that they’re level. If it’s not then it’s either elevated or depressed. There are several things that can cause this
such as MI, conduction disturbance, electrolyte imb, hypertrophy, or Digoxin. Dig. is the most common drug that
causes changes in the ST segment, either for it to elevate or depress.
The T wave is when the ventricles are getting repolarized, so they’re getting back armed for the next beat. This is
the MOST vulnerable period of the ventricles. If electricity happens on the T wave, bad things happen to the
heart.
The QT interval is QRST, the whole ventricular cycle. It tells us how long it took the ventricles to depolarize and
repolarize (fire and get ready again). How long this cycle is depends on age, sex, heart rate. If HR increases, you
have less time to do this. The QT interval should shorten as the HR increases, due to lack of time between beats.
Normal is less than half of the previous R to R interval. So if you look at how long it is between R to R, at least ½
of the time between R to R, the ventricles should be resting, so they’ve got less than half that time to do a full
QRST.
If the QRS is tall, thin, and beautiful then we know it’s going down the interstate (Slide 4, p 3).
Sinus arrhythmia: started in the sinus node (SA node’s fault). Also may be a sinus rhythm, which means it’s
perfectly normal. If it has the word “sinus” in it, then the beat was initiated by the SA node.
Atrial: some other cell in the atria besides the SA node started it (because all cardiac cells are able to transmit
electricity, and all are able to initiate electricity, they’re just not usually supposed to. Sometimes they just get
irritated, or Cole (SA node) isn’t doing his job and someone else has to come in and pick up the slack.)
A junctional rhythm: Dena (AV node) started it.
A ventricular rhythm: someone on the ventricles side of the room started it (ventricles started it).
Page 2 of 12
5-18-10
EKG, Arrythmias, & Treatment
Review pathway of blood through the heart:
We can look electrically at the heart (ECG) and see what’s happening mechanically
Polarized heart cell: one that is ready to fire (a knight with his sword and shield and he’s ready)
Depolarization: one that strikes, fires (the knight lashes out with his sword)
Repolarization: everything resets (the knight has to go get his sword and get ready again). This is the MOST
vulnerable state, or most at risk for damage.
ECGs can be used for diagnosis but are not used alone; they are always combined with other things. We draw
labs, assess CP, and check BP. It’s a diagnostic tool but NEVER used alone.
Gelatinous substance on backside of electrode serves two purposes (1): has electrolytes in it (electricity flows
better because it’s a negative energy source), (2) it has an abrasive in it that breaks the oil that is on the skin so
that it comes in better contact c the skin. Make sure pt isn’t allergic to the gel. Electrodes are changed about
once a day or every other day (avoid getting an allergy, irritating skin, or skin breakdown).
SA node is the pacemaker of the heart (it lives in the right atrium) it is what normally initiates electrical activity
in the heart, fires at a rate of 60-100. The electrical activity then goes to the AV node (or the junction, or the AV
junction), then Bundle of HIS, then down R L bundle branches (which are down the L & R ventricles), the
Purkinjie fibers, then cell to cell to cell to cell. Because cardiac cells are able to depolarize from cell-to-cell-to-
cell.
My side of the room is the atria; Cole is the SA node (because he is bossy). He fires and depolarizes the atria; it
gets to Dena, who is the AV node which also makes her the bridge that goes from the atria to the ventricles.
Dena says “STOP!” she stops all electrical activity, gathers it within herself and says “GO!” and it goes down the
ventricles, through the L & R bundle branches, purkinje fibers and cell-to-cell to cell. (Slide 5, page 1).
SNS increases irritability. When the cells get pissed off they start firing electrical currents which makes extra
beats on the EKG. The SNS increases the irritability in the cells, which increases the incidence of ectopic beats.
“My patient’s having lots of ectopy” = they’re having lots of beats they shouldn’t be having.
Parasympathetic affects the atria only. If a pt is having lots of ectopy it makes sense that we would give them
something to block they’re sympathetic system (Beta blocker) b/c it will decrease irritability of cells.
When you put Lead II (slide 4, p 2) on a patient you have a negative electrode up top and a positive electrode on
bottom. If you have an impulse that fires: the electrodes that are put on pt’s chest are like eyeballs and they’re
looking at the electricity. If the electricity is coming towards me, then I make a positive deflection, which means I
have a spike that goes up. If the electricity moves away from me then I have a negative deflection, which is a
spike that goes down (slide 2, pg 2).
You have to have a minimum of three leads in order to get a pic on an EKG.
Horizontal lines (left to right) are used to measure voltage. The more electricity emitted by the heart, the higher
the spike will be on the EKG. It will cross more horizontal lines. If they have a weak heart we may see little bitty
complexes, if they have a strong heart we will see big complexes. The vertical lines are time, the further you go
Page 1 of 12
, on vertical lines across the paper, the more time has passed. There are little baby blocks that are 0.04 seconds
each, big blocks are 0.2 seconds. There’s five baby blocks in one big block.
The baseline of the EKG is the isoelectric line. It’s there when nothing’s happening in the heart between
complexes when it’s just that flat line. The isoelectric line is the polarized or resting state. Kind of like the hum of
the heart, the potential energy.
P wave is depolarization of the atria; it’s gently rounded and normally positive. It’s poking up because it is
moving down the heart towards the positive electrode.
Measure the P-R interval (PRI) from the beginning of the P wave to the beginning of the QRS. Cole says, “Fire!”
we depolarize to get it to Dena. Dena says “STOP! OK, GO!” this makes the ventricle part of it. The PRI is just
looking at how long it takes from the time he fires to the time she releases the current into the ventricles (time it
takes from the time the SA node fires to the time the AV node releases to the ventricles). It’s telling how long it
takes for the atria to do their part of the cycle. This time includes Dena’s (AV node’s) delay. So if she starts acting
up and taking too long, the PRI is the part of the EKG that will be messed up, it’ll be too long if she takes too
long. Normal PRI is 0.12-0.20 seconds (which is 3-5 baby blocks).
The QRS is the depolarization of the ventricles; it is much larger than the P because the ventricles are the money
maker of the heart. We like for the atria to work, it’s better for us if they do, but if they go out we can survive
with just the ventricles. We cannot survive w/o ventricles. The atria cannot pull the weight. It’s like the atria is
the coach and the ventricles are the football players.
It’s measured from the 1st deflection from the isoelectric line to the beginning of the ST segment. Normal is 0.05
to 0.10 seconds, its tiny, they’re itty bitty skinny. When the QRS starts getting wide, it means it’s taking the
ventricles too long to depolarize (fire), it should be a very fast action.
The ST segment is the flat part that’s between the QRS and the T (hence the name ST segment). It should go
back to the isoelectric line so we can compare that flat part to the part between the complexes to make sure
that they’re level. If it’s not then it’s either elevated or depressed. There are several things that can cause this
such as MI, conduction disturbance, electrolyte imb, hypertrophy, or Digoxin. Dig. is the most common drug that
causes changes in the ST segment, either for it to elevate or depress.
The T wave is when the ventricles are getting repolarized, so they’re getting back armed for the next beat. This is
the MOST vulnerable period of the ventricles. If electricity happens on the T wave, bad things happen to the
heart.
The QT interval is QRST, the whole ventricular cycle. It tells us how long it took the ventricles to depolarize and
repolarize (fire and get ready again). How long this cycle is depends on age, sex, heart rate. If HR increases, you
have less time to do this. The QT interval should shorten as the HR increases, due to lack of time between beats.
Normal is less than half of the previous R to R interval. So if you look at how long it is between R to R, at least ½
of the time between R to R, the ventricles should be resting, so they’ve got less than half that time to do a full
QRST.
If the QRS is tall, thin, and beautiful then we know it’s going down the interstate (Slide 4, p 3).
Sinus arrhythmia: started in the sinus node (SA node’s fault). Also may be a sinus rhythm, which means it’s
perfectly normal. If it has the word “sinus” in it, then the beat was initiated by the SA node.
Atrial: some other cell in the atria besides the SA node started it (because all cardiac cells are able to transmit
electricity, and all are able to initiate electricity, they’re just not usually supposed to. Sometimes they just get
irritated, or Cole (SA node) isn’t doing his job and someone else has to come in and pick up the slack.)
A junctional rhythm: Dena (AV node) started it.
A ventricular rhythm: someone on the ventricles side of the room started it (ventricles started it).
Page 2 of 12
