Quiz 3 - EKG Quiz Flashcards
What do each of these means:
- P Wave:
- PR Interval:
- PR Segment:
- QRS Complex:
- ST Segment:
- ST Interval:
- T Wave:
- TP Interval:
- U Wave:
- P Wave: Atrial depolarization (or contraction)
- PR Interval: From start of P wave to R (or right before QRS. So it includes atrial depolarization and AV node delay).
- PR Segment: JUST the portion of the AV node delay / atrial kick. (S = S … Segment = Small)
- QRS Complex: Ventricle contraction or depolarization (and atrial relaxation or repolarization … can’t see because its behind QRS complex)
- ST Segment: Final part of ventricles contracting to when ventricles start repolarizing / relaxing. From end of S to start of T. (S = S … Segment = Small). Where you’d see elevation (=infarction), or depression (=ischemia).
- ST Interval: From S to end of T, so includes end of ventricular contraction and ventricular repolarization.
- T Wave: Ventricle repolarization
- TP Interval: Space of time between a cardiac cycle when the ventricles are relaxing and filling.
- U Wave: Repolarization of pukinjie fibers (probably won’t see this ever).
Depolarization means:
Repolarization means:
Clever way to remember:
Contracting. After a cell has established a resting potential, that cell has the capacity to undergo depolarization. … As the sodium ions rush back into the cell, they add POSITIVE charge to the cell interior, and change the membrane potential from negative to positive.
Relaxing. Refers to the change in membrane potential that returns it to a NEGATIVE value just after the depolarization phase of an action potential has changed the membrane potential to a positive value.
Re = RElax De = detonate / contract
Where does P wave originate from (gets its conduction from)?
SA Node
What is the AV Node delay:
Why is it important:
What is another name for this:
Where would this show up on an EKG?
The action potential is initiated at the SA node and spreads as a wave through the atrial muscle. When the impulse reaches the AV node there is a slight delay before the AV node fires (which will start conductivity / depolarization for the ventricles). This gives the atria time to squeeze extra blood into the ventricles before they fire.
This delay in the cardiac cycle is extremely important: It ensures that the atria have ejected their blood into the ventricles first before the ventricles contract. IT increases EDV.
Atrial kick: the priming force contributed by atrial contraction immediately before ventricular systole that acts to increase the efficiency of ventricular ejection due to acutely increased preload.
After the P Wave, there is a flat line before the QRS complex called the PR segment, and this would be the AV node delay / “atrial kick.”
What segment indicates atrial relaxation / repolarization:
You can NOT see it, because it is behind the QRS complex.
The first heart sound (lub) is associated with what complex / segement on an EKG reading? Why?
QRS complex. Because as the ventricles contract, it causes the AV valves to close. This closure is the 1st heart sound (lub).
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For NORMAL TIMING of intervals, what is the normal time between:
- PR Interval:
- QRS Complex:
- QT Interval:
- PR Interval: 0.12-0.20 seconds
- QRS Complex: 1-3 boxes (0.04-0.12secs)
- QT Interval: < 0.40 seconds
EKG Paper Measuring:
1) How much time between each hashmark?
2) How much time between 2 hashmarks (or 3 total if you count the one at the front)?
3) When you interpret EKG’s you want to look at how long of a strip?
4) What is a BIG Box on an EKG strip (how many little boxes are in it and what time it represents)? VERTICALLY AND HORIZONTALLY
5) What is a LITTLE Box and what TIME it represents?
6) What SIZE does a LITTLE box represent?
7) How can you tell the Heart Rate looking at an EKG strip?
8) On an EKG strip, in one second, generally, that represents how many little and big boxes?
9) How many big and little boxes on an EKG strip represent 1mV
1) 3 seconds
2) 6 seconds
3) 6 seconds
4)
Horizontally
- Big Box: 5 little boxes across, each at 0.04 sec’s, so 0.20 seconds total across horizontally. Each little box is 1mm so big box is 5mm total across horizontally.
Vertically
- Bix Box: 5 little boxes up, each one is 1mm, so 5 mm up for big box. And one little box is 0.1 mV so for 5 boxes it is 0.5 mV up.
5) Little Box: 0.04 seconds (Horizontally)
6) Little Box: 1mm x 1mm
7) Count how many R waves (QRS complexes) there are between 6 seconds and times it by 10 (so if you get 6 in 6 seconds, HR = 60 bpm)
8) It is 25mm/sec, so 5 big boxes and 25 little boxes in a second on an EKG strip.
9) This is vertically … Each little box is 0.1mV, so 5 for a big box is 0.5mV. That means you’d need 2 big boxes and thus 10 little boxes to get 1mV (or 10mm).
How do you tell if you have a regular vs. irregular rhythm?
Get out your CALIPERS and measure between R and R waves (QRS complex to QRS complex). If it is the same distance between each R - R in the 6 seconds, then it is regular. If not, irregular.
1) How do you tell the difference between A-fib and A-flutter? What do you ask / look for to know?
2) Do you have a P Wave in A-fib or A-flutter?
3) A-fib is the pretty or the ugly sister?
4) Which one is typically a REGULAR beat?
1) Does it have a P Wave? NO - there is NO P wave in A-fib and a nice fluttery repeated P wave looking flows in A-flutter. But of there are 2 nice looking flutters, that equals sinus tachycardia. If there are 3 nice fluttery p waves, that is when it is A-flutter. A fib is IRRegular rhythm, A flutter is REGular rhythm.
2) A flutter
3) A-fib is the UGLY sister. The waves between R-R are all over the place and ugly. But the A-flutter is the pretty sister (flutters her eyes) because the waves are nice and smooth and look much better.
4) A flutter is usually regular, A fib is NOT a regular beat.
ECG stands for =
What is an ECG - what does it do?
Is ECG and EKG synonymous? Why?
What is an Echocardiogram:
Electrocardiogram
The ECG records the electrical signal of the heart as the muscle cells depolarize (contract) and repolarize.
YES, they are the same. They replaced the K with C because ECG sounded like EEG which is a neural screen.
Echocardiogram: The echo test or heart ultrasound,
is a test that takes “moving pictures” of the heart with sound waves to look at heart health.
What generates the initial electrical impulse and begins the cascade of events that results in a heart beat.
Normally, the SA Node.
Cardiac cells resting have what charge?
What is the charge during depolarization?
What is the charge during repolarization?
Cells that are resting have a NEGATIVE charge with respect to their exterior.
Depolarization consists of POSITIVE ions rushing into the cell.
Repolarization is when positive ions rush out of the cell causing the cell to go back to a NEGATIVE charge.
Is there a difference between the EKG graph and a single cell depolarization graph?
Explain the 4 phases of a single cardiac cell graph:
Which Phase is Depolarization?
Which phase is repolarization?
YES. EKG shows the PQRST complexes … the entire cardiac cycle. Where a single cardiac cell is just the graph of one cardiac cell (looks like a sail boat).
Phase 4: Cell is resting potential of a -90mV (Na+ and Ca+ channels closed, K+ channels open).
Phase 0: Action potential hits cell and Na+ channels open and Na+ floods IN to cell. (line goes from resting straight up).
Phase 1: At the peak, K+ channels open again and K+ flows OUT (causing line to slightly dip)
Phase 2: Influx of Ca+ IN to cell, and K+ out (so it balances … causing line to plateau).
Phase 3: K+ goes OUT causing charge to go back to negative (resting potential).
Phase 4: Flat line before another depolarization where Na+ and Ca+ channels are closed and K+ are open. REPEATS
Depolarization: Phase 0-2
Repolarization: Phase 3
T or F: Electrical activity / action potential / stimulation = repolarization?
T or F: With depolarization, the membrane is more permeable to sodium ions, allowing them to flow inward and creating a positive charge on the inside.
T or F: A cell at rest has a positive charge, while outside the cell is a negative charge?
How and why do the cells rush in / out of cells?
False. It is DEpolarization. Electrical stimulation to the cardiac muscle cell membrane causes depolarization.
True
False. A cell at rest has a negative -90mV charge, and outside the cell is Na+ and Ca+ ions that create a positive charge on the outside / transmembrane. AND - during depolarization, it switches.
It is all about diffusion from high concentration to low concentration based on the action potentials opening the gates to allow flowage of these ions. And action potentials change the gated channels allowing ions in/out.
With EKG’s:
1) What is an electrode:
2) What does an electrode measure?
3) What type do hospitals use?
4) What will we use in class?
5) How many leads are in a 12-lead EKG
6) RA =
7) LA =
8) RL =
9) LL =
10) V1-V6 =
11) Do all 12 leads say the same thing?
1) Electrode: Pad that sticks onto patient to detect electrical activity of heart.
2) Electrical activity of the heart from varying places / angles of electrodes all over the body.
3) 12-lead EKG
4) 5-lead EKG
5) 10 leads
6) Right arm (electrode)
7) Left arm (electrode)
8) Right leg (electrode)
9) Left leg (electrode)
10) Various places along chest underneath heart where you place electrodes
11) All 12 leads / electrodes are the same heart and beat, they just shows different angles / leads of the electrical activity.
Just know that EKG’s today are pretty similar to what was created originally / historically. Heart is placed in the middle of a triangle (two arms and Left leg) about the body to pick up electric signals from the randomly placed electrodes.
Willem Einthoven developed the EKG system.
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What is the Einthoven triangle?
What are Leads I, II, III
If ever in doubt, look at which lead?
What are:
- aVR =
- aVL =
- aVF =
V1-V6 leads that are close to the heart are called:
Briefly explain where each of the V1-V6 leads are placed, and why - or what they measure?
From RA -> LA -> down to LL -> back up to RA. This is the triangle. Heart right in the middle.
Lead I: RA to LA
Lead II: LA to LL
Lead III: LL to RA
Lead II
- aVR - right arm
- aVL - left arm
- aVF - left leg
PRECORDIAL LEADS
Leads V1 and V2: are placed over the right side of the heart (measuring RV)
Leads V3 and V4: are located over the interventricular septum
Leads V5 and V6: demonstrate changes on the left side of the heart (measuring LV).
Accronym to remember for the 5-leads set up and what electrode goes where:
W = white (right) G = green (grass) B = black (smoke) R = red (fire) V1 = brown (crack)
White = right
Clouds (white) over Grass (green)
Smoke (Black) over Fire (Red)
Brown (V1) in the crack
Which one, from the two below, look at the entire heart, and which one looks at just one cardiac cell?
Ventricular Action Potential (Graph)
EKG (Graph)
Ventricular Action Potential (Graph) = looks at one mycardial cell
EKG (Graph) = looks at entire heart
What is the primary pace maker of the heart?
If the primary pace maker gets knocked out, then what is the back up pace maker?
If the back up gets knocked out, then what is the back up to the back up?
SA Node
Then AV node takes over
Bundle of His and Purkinjie fibers take over
Pace from the SA Node is:
SA Node would be 100 bpm if it weren’t for what:
Pace of AV Node is:
Pace of Purkinjie fibers (or ventricular cells) is:
SA Node: 60-100 bpm
Vagus nerve slowing it down
AV Node / JUNCTION: 40-60 bpm
Bundle and Purkinjie fibers: 20-40 bpm
The heart behaves as a syncytium. What does that mean?
How many syncytia of the heart are there?
A network of cardiac muscle cells connected by gap junctions that allows coordinate contraction of the atria. So, once a wave is initiated, it continues to propagate uniformly into the remaining myocardium that is still at rest (“all or nothing” concept).
There are two syncytia of the heart: the ventricular syncytium and the atrial syncytium separated by fibrous tissue.