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What is electrocardiography?
graphic recording from the body surface to study the action of the heart muscle
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When was electrocardiography discovered?
in 1887
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The electrical current generated by the heart is amplified at least _____ times.
3000
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What do the patterns of the heart waves indicate?
heart's rhythm, speed of contractions, and other actions
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What is proportional to the mass of the cardiac muscles involved in the electrical activity?
the size of the deflection or wave
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EKG is a measurement of _____ in the heart, not _____.
- electrical activity
- mechanical activity
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What is the Cardiopet?
telephone transmission to cardiologist
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How does the paper tracing for an EKG work?
a small, sensitive lever oscillates in contact with moving paper
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How does the normal conduction system of the heart work?
conducts the electrical impulses that coordinate heart contractions in a rapid and organized manner for maximum pumping efficiency
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What are the different parts of the heart that are involved in conduction?
- sinoatrial node
- atrioventricular node
- bundle of His
- Purkinje fibers
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What is the SA node?
pacemaker - group of specialized cardiac muscle cells that depolarizes most rapidly
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What does the SA node set?
the heart rate
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After the SA node depolarizes, what does it do?
depolarization spreads throughout the atria rapidly, cause the atrial contraction and stimulating the AV node
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What is the function of the AV node?
delays the wave of depolarization for a fraction of a second to give the ventricles a chance to fill with blood
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What is the function of the Bundle of His?
conducts the wave of depolarization down the interventricular septum to the apex of the heart and to the Purkinje fibers
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What is the function of the Purkinje fibers?
directs the wave of depolarization back up toward the base of the heart squeezing blood into the aorta and pulmonary artery
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What are the different components of a normal EKG?
- P wave
- P-R interval
- QRS complex
- T wave
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What does the P wave represent?
the depolarization of the atria
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Is the P wave a big wave or small wave? Why?
small deflection since the atria are small and thin walled compared to the ventricles
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What is the P-R interval and what does it represent?
- flat line between the P wave and the QRS complex
- represents the delay at the AV node
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What does the QRS complex represent?
depolarization of the ventricles
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Is the QRS complex a big wave or a small wave?
big wave
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What does the T wave represent?
repolarization of the ventricles
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What are some reasons why we would do an EKG?
- heart problems
- monitoring during anesthesia
- monitoring during critical cases
- response to therapy
- geriatric work-up
- electrolyte imbalances
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What are some heart problems that would indicate us to do an EKG?
- murmurs, arrhythmias
- fainting spells, ascites
- enlargement, myocarditis
- fluid in or around lungs
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What are some response to therapy that would indicate us to do an EKG?
- digitalis therapy
- therapy for electrolyte imbalances
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What are some electrolyte imbalances that would indicate us to do an EKG?
hyperkalemia
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Define leads
provide a view of the electric activity of the heart between two points
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How many leads do we usually use?
four or five
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Where do we attach the leads?
- front legs - point of elbo
- rear legs - over patella
- chest - "ground" electrode over right side
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What is the different color codes for the leads?
- RA - white
- LA - black
- RL - green
- LL - red
- chest - brown
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What are the different leads?
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What is the best patient position for an EKG?
right lateral recumbency
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Why is right lateral recumbency the best position for an EKG?
necessary for detecting heart chamber enlargement
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How do we place a patient in right lateral recumbency?
- legs perpendiculary to body
- legs parallel to each other (do not allow legs to touch each other)
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When would we not use right lateral recumbency for an EKG?
- patient in respiratory distress
- patient who is overstressed in that position
- during surgery when another position is necessary for the surgery
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Once we have the alligator clips on the patient, what do we need to put on them?
contact gel
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If we don't have contact gel, what else can we use? What is the disadvantage of using this?
- alcohol
- evaporates quickly so we have to keep reapplying it
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What is the sensitivity on an EKG?
the size of the tracing on the paper
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What are the different sensitivity settings on the EKG?
1, 1/2, 2
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What measurement is the sensitivity in?
cm
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What is a senstivity of 1 - 1 mV mean?
- 1 cm deflection
- standard sensitivity
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What is another name for sensitivity?
gain
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When would we use a 1/2 - 1 mV deflection, instead of 1 - 1 mV?
if the complexes are too big and it will not fit on the paper
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When would we use a 2 - 1 mV deflection, instead of 1 - 1 mV?
- if complexes are too small
- if the complexes are hard to distinguish
- commonly used in cats
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What are the different types of speeds?
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Which speed is the default speed?
25 mm/sec
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What does changing the speed on an EKG do?
makes the PQRST waves more spread out or closer together
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What is the purpose of changing the position of the needel of the EKG?
to keep the baseline in the middle of the paper
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Do we usually need to worry about changing the position on our manual EKG machines?
no
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What are the different selections for the leads?
- lead l (.) aVR (-)
- lead ll (..) aVL (--)
- lead lll (...) aVF (---)
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How many complexes do we need to record for each lead?
5 - 6 complexes
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What do we need to record on the strip?
- patient name
- date
- paper speed
- sensitivity
- leads
- movement
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Which lead is the most important lead?
lead ll
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Why is lead ll the most important lead?
the most standardized for interval and amplitude measurements
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How much paper do we need to print for our EKG and what speeds?
- 12 - 18 inches
- 25 AND 50 mm/sec (50 mm/sec so we can do our measurements)
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How do we put the EKG in the patient's permanent record?
- cut and mount EKG paper strip on standard holder for permament patient file
- computerized storage for paperless practices
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