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What is electrocardiography?
graphic recording from the body surface to study the action of the heart muscle
When was electrocardiography discovered?
The electrical current generated by the heart is amplified at least _____ times.
What do the patterns of the heart waves indicate?
heart's rhythm, speed of contractions, and other actions
What is proportional to the mass of the cardiac muscles involved in the electrical activity?
the size of the deflection or wave
EKG is a measurement of _____ in the heart, not _____.
- electrical activity
- mechanical activity
What is the Cardiopet?
telephone transmission to cardiologist
How does the paper tracing for an EKG work?
a small, sensitive lever oscillates in contact with moving paper
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
What are the different parts of the heart that are involved in conduction?
- sinoatrial node
- atrioventricular node
- bundle of His
- Purkinje fibers
What is the SA node?
pacemaker - group of specialized cardiac muscle cells that depolarizes most rapidly
What does the SA node set?
the heart rate
After the SA node depolarizes, what does it do?
depolarization spreads throughout the atria rapidly, cause the atrial contraction and stimulating the AV node
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
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
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
What are the different components of a normal EKG?
- P wave
- P-R interval
- QRS complex
- T wave
What does the P wave represent?
the depolarization of the atria
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
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
What does the QRS complex represent?
depolarization of the ventricles
Is the QRS complex a big wave or a small wave?
What does the T wave represent?
repolarization of the ventricles
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
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
What are some response to therapy that would indicate us to do an EKG?
- digitalis therapy
- therapy for electrolyte imbalances
What are some electrolyte imbalances that would indicate us to do an EKG?
provide a view of the electric activity of the heart between two points
How many leads do we usually use?
four or five
Where do we attach the leads?
- front legs - point of elbo
- rear legs - over patella
- chest - "ground" electrode over right side
What is the different color codes for the leads?
- RA - white
- LA - black
- RL - green
- LL - red
- chest - brown
What are the different leads?
What is the best patient position for an EKG?
right lateral recumbency
Why is right lateral recumbency the best position for an EKG?
necessary for detecting heart chamber enlargement
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)
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
Once we have the alligator clips on the patient, what do we need to put on them?
If we don't have contact gel, what else can we use? What is the disadvantage of using this?
- evaporates quickly so we have to keep reapplying it
What is the sensitivity on an EKG?
the size of the tracing on the paper
What are the different sensitivity settings on the EKG?
1, 1/2, 2
What measurement is the sensitivity in?
What is a senstivity of 1 - 1 mV mean?
- 1 cm deflection
- standard sensitivity
What is another name for sensitivity?
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
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
What are the different types of speeds?
Which speed is the default speed?
What does changing the speed on an EKG do?
makes the PQRST waves more spread out or closer together
What is the purpose of changing the position of the needel of the EKG?
to keep the baseline in the middle of the paper
Do we usually need to worry about changing the position on our manual EKG machines?
What are the different selections for the leads?
- lead l (.) aVR (-)
- lead ll (..) aVL (--)
- lead lll (...) aVF (---)
How many complexes do we need to record for each lead?
5 - 6 complexes
What do we need to record on the strip?
- patient name
- paper speed
Which lead is the most important lead?
Why is lead ll the most important lead?
the most standardized for interval and amplitude measurements
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)
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