question

action potential

answer

measurement of the difference between the electrical charges on either side of the cell membrane. -it is an indication of the cell's capability and likelihood of discharging an electrical current.

question

what is action potential described in terms of?

answer

polarization, depolarization, and repolarization

question

what level do polarization, depolarization, and repolarization occur on?

answer

cellular

question

what cells have action potential and go through the depolarization cycle?

answer

conduction system cells (ex: cells that compose sa node), as well as myocardial cells.

question

what is important to note about the cells of the sa node?

answer

they have a shorter resting phase nd start to depolarize sooner and over a longer period of time than most cardiac muscle cells. this is because the sa node is the pacemaker and must intiate the electrical current.

question

baseline/isoelectric line

answer

-the resting phase of the conduction cycle/the polarized state -striaght line on the ecg tracing that represents an absence of electrical activity. -reference point for determining the beginning and end of a waveform. -the beginning of a waveform is marked in terms of a return to the baseline. -the ending of a waveform is marked in terms of a return to the baseline. these last two points are important to undersatnd because a clear understanding of the beginning/end of waveforms is necessary to be able to examine and measure a waveform.

question

p wave

answer

-represents atrial depolarization. -relatively small rounded, and symmetrical waveform on the ecg tracing.

question

interval

answer

the duration of length of time in which a waveform occurs and is measured in fractions of a second.

question

segment

answer

-the period of time that begins when a waveform returns to baseline and lasts until the next waveform begins. -when measuring an interval, the segment following the wave form may be included in the measurement.

question

qrs complex

answer

-comes after the p wave and represents ventricular depolarization. -sharp triangular waveform that is much taller than the p wave -ventricles are larger than the atria, so it takes a stronger current to depolarize them, but the current travels faster in the ventricles, so the qrs complex takes place over a shorter period of time than the p wave.

question

pr interval

answer

duration of the p wave and is measure in fractions of a second. -measured from the beginning of the p wave to the beginning of the r wave.

question

t wave

answer

-represents ventricular repolarization. -occurs after the qrs complex. -has a rounded gentle curve, is taller than the p wave, and has a longer duration than the qrs complex.

question

repolarization of what chambers is visible on an ecg tracing?

answer

-only ventricular. -atrial repolarization occurs after the p wave. it occurs at the same time as the qrs complex and is buried in that wave.

question

refractory period

answer

-occurs during repolarization. -time during repolarization when the cardiac cell would be unable to respond to another electrical impulse. -occurs right after the qrs complex and during most of the t wave. it isnt a waveform but describes the condition of the cardiac muscle during repolarization. -in the latter part of repolarization (the last part of the t wave), most of the tissue is recovered, and an impulse may be conducted at that time.

question

u wave

answer

-may be visible after the t wave. -small rounded u wave that isn't always distinct on the ecg tracing. -it is thought that it may represnet repolarization of the purkinje fibers. -not measured and not significant unless it is prominent or larger than expected because then it may indicate a disease condition or electrolyte imbalance.

question

what happens after the t wave (or u wave if present)

answer

the tracing returns to baseline, reflecting a brief resting pd for the myocardium. then the cycle begins again.

question

cardiac cycle and types of functions

answer

it represents an electrical function of the heart and there is a corresponding mechanical ation. the electrical function is an electrical impulse that initiates the contraction, which results in the heart pumping.

question

what part of the waveform represents one heartbeat?

answer

one p wave and one qrs complex

question

heartbeat and the pressure it generates

answer

one heartbeat generates a pressure which creates a pulse that is felt in distal parts of the body, such as the wrist. the constant pumping of the heart sustains the forward movement of blood to other parts of the body. the pressure created by this pumping is bp.

question

summary of the normal cardiac cycle.

answer

the atria depolarize, creating a pwave. the impulse travels to the av node, bundle of his, bundle branches, and the purkinje fibers. the ventricles depolarize, then contract. the ventricular contraction ejects blood into the aorta, causing a bp and pulse to be produced.

question

abnormal cardiac cycle

answer

disease may cause a disruption in the events of the normal cardiac cycle which adversely affects heart function, bp, and pulse.

question

what test can be used to obtain information about the disease process and heart function?

answer

ecg

question

process of an ecg tracing

answer

pt is connected to machine using sensors/electrodes. cable wires connect sensors to the electrocardiograph, which can detect electrical activity in the heart.

question

electrocardiograph

answer

a recording device that translates the electrical signals of the heart into a tracing on paper. the paper tracing can be studied and the waveforms measured

question

what do horizontal lines on ecg paper represent?

answer

time. each small square represents .04 sec. each large square represents .2, and 5 large squares represent a second

question

what do vertical lines on ecg paper represent?

answer

voltage/electrical current

question

who can read an ecg and what does it mean?

answer

trained healthcare professionals (like doctors and nurses.) this means that deviations in the ecg can be assigned a particular meaning and a diagnosis can be made.

question

what is an ecg helpful in determining/diagnosing?

answer

ischemia, mi, pericarditis (inflammation or pericardial sac, ventricular hypertrophy (ventricular enlargement)

question

what symptoms may cause a doctor to order an ecg, and what is an ecg used to determine regarding these symptons

answer

angina, tightness/chest pressure, light headedness or sob. the ecg is then used to determine if these symptoms are related to heart function

question

what are some other circumstances that may warrant ordering an ecg?

answer

as part of a routine physical exam in a clinic, doctor's office, or hospital. the ecg is then used to compare with future ecgs to see if there's any deviation or change.

question

what type of ecg interpretation are critical care nurses trained in, and what responsibilities does this give them?

answer

12 lead ecg. nurses can detect changes and critical developments that show up on the ecg. they are then responsible for coummunicating this information to the physician.

question

what is important to remember about a patients feelings before an ecg?

answer

they may be apprehensive because they are in pain or frightened about the outcome of his or her present health problems, and the patient may not be acquainted with the hospital or clinic procedures which can add to distress.

question

verification of patient

answer

to prepare a patient for an ecg, it must be verified that the doctor has ordered an ecg for them. this means you may need to look at the patient's chart or talk with the doctor or nurse. then verify you have the correct patient by checking their name band and directly asking them to state their mae.

question

preparation for ecg: explanation

answer

technician is responsible for explaining the environment, equipment and procedure to pt. explain that they will be connected to the machine in order to gather information about their heart function and it will help doctors make an accurate diagnosis and formulate the best possible tx plan. reassure that the procedure is painless and very short.

question

what happens after the ecg proceudre is explained to the pt?

answer

-take off clothes (also stockings if applicable). respect pt's privacy when pt does this. be gentle and sensitive if pt needs help removing clothes. -shave chest if necessary (make sure to ask permission.)

question

what needs to be done to the skin surface where sensors are placed?

answer

they must be free or natural oils, lotions, and sweat. clean area with alcohol or soap and water. use dry gauze or cloth towel to dry the area.

question

sensor

answer

a disc or tab made of plastic that has a metal component as well as a layer or well of gel or conducting substance, and which is placed on a pt's skin in order to pick up electrical activity from the heart where it is transmitted through cables to the ecg machine to be processed. -also called an electrode

question

what is the electrocardiograph used to obtain?

answer

the ecg

question

what is the ecg an indicator of

answer

electrical activity that stimulates the contraction of the heart. NOT bp or mechanical contraction of the heart.

question

who was the electrocardiograph first designed by and when?

answer

developed in the early 1900s by Wilhelm Einthoven, a Dutch physiologist. won the Nobel Prize in 1924.

question

What needs to be done to pick up the heart's electrical signals?

answer

sensors are placed on the patient's body in strategic locations. locations of the sensors give information about different locations of the heart. 10 different locations for the sensors in a standard ecg, which results in 12 different views of the heart.

question

lead

answer

a configuration of positive and negative sensors, or electrodes, on the body surface that picks up the electrical information form the heart. the different sensor configurations offer different "views" of the heart.

question

why is the sensor so important?

answer

it is the first link between the patient and the machine

question

what happens when the electrical signal reaches the ecg machine?

answer

it is amplified and processed. the electrical activity that is transmitted from the heart to the skin is only a few millivolts, so in order to be diagnostically useful, it must be amplified about twenty billion times.

question

what happens to the impulse after amplification?

answer

travels to the galvanometer.

question

what does the mechanical action from the galvanometer do?

answer

it directs the movement of the stylus, which forms a tracing on the graph paper.

question

what are the lines and curves on the graph paper called?

answer

waveforms

question

ecg machine power source

answer

many ecgs are designed to be used with an internal battery. -the machine is plugged into a wall socket only when not in use in order to charge the battery, which is elpful because it creates less electrical interference during the test than a machine plugged into an outside power source. - power switch may be located on the control panel or on the side or back of the machine, but machine models may differ.

question

how many channels are new ecg machines capable of recording at a time?

answer

3 or more. this means that they can get more information in less time.

question

galvanometer

answer

a device in the ecg machine which detects electrical currents from a patient and converts it into mechanical energy, which is then recorded onto graph paper.

question

what should you do before hitting the record switch on an ekg?

answer

check waveforms, make sure the speed is on 25, and check that the name and date is there.

question

calibration

answer

the process of setting a machine to a standardized scale so the results will be comparable and tests can be compared.

question

standard ecg machine calibration

answer

10 mm high by 2 mm wide

question

stylus heat control

answer

determines lightness or darkness of markings -a hotter stylus makes a thicker, darker line and a cooler stylus makes a lighter, thinner line

question

frequency control/filter

answer

-acts to filter out extra electrical activity from the environment that may interfere with the recording. -activating the filter will diminish artifacts.

question

lead selector

answer

-designates which view of the heart will be recorded. -most machines can be run manual or automatic -multichannel recorders can usually record 3 lead at a time. if additional ones are needed, adjustments can be made to include extra leads.

question

on ecg paper, horizontal lines measure _____. vertical lines measure _______

answer

time, voltage

question

1 small square =

answer

.04 sec

question

___ small squares = 1 large square

answer

5

question

1 lg box = ___ sec

answer

.2

question

_____ lg boxes = 1 sec

answer

5

question

using speed 50 on an ecg machine

answer

creates a waveform that is stretched out and elongated from what it would look like at speed 25. -may be useful in examining complex/fast rhythms or when one wave may hiding in another

question

standard calibration

answer

1 millivolt which equals 10 mm or 2 large boxes in the vertical direction

question

why is position control important in ekgs?

answer

it determines where the baseline of the ecg will be located on the graph paper.

question

what is the standard ecg called and how did it get its name?

answer

-12 lead ecg -got the name because it uses 12 leads to obtain information about the heart. this means that 12 views, or angles, of the heart are used to reflect information about different areas of the heart

question

anatomical landmarks for the heart

answer

clavicle, sternum, ribs, intercostal spaces, axilla

question

clavicle

answer

-collarbone -major reference point when examining the heart and listening to heart sounds with a stethoscope

question

midclavicular line

answer

-a line going down the chest, parallel to the arm. this line should come close to the inside of the left nipple

question

sternum

answer

-breastbone -the firm flat surface in the center of the chest

question

ribs

answer

-form a bony cage that protects the heart and lungs. -first rib is located just beneath the clavicle. -immediately below the clavicle is the first intercostal space.

question

what are the intercostals used as?

answer

landmarks to locate proper placement of the ecg sensors. -each intercostal space shares the number of the rib directly above it. -the first rib is just behind the clavicle and can not be palated

question

difficulties when locating landmakrs

answer

obesity, chest deformities, large breasts

question

axilla

answer

-the armpit (underarm area) -midaxillary line is an imaginary line down the middle of the axilla -anterior axillary line is the imaginary line that descends from the anterior axillary fold. this line forms the border of the front of the chest and the axillary region -posterior axillary line is the imaginary line that descends from the posterior axillary fold. it forms the border between the back of the torso and axillary region.

question

where are other spots that important landmarks are found

answer

arms and legs. flat, fleshy areas are preferred, so arm sensors are usually placed either on the inner aspect of each forearm or the lateral surface of the upper arm. the inner aspect of both the legs at the lower calves is the usual placement area for the legs.

question

can tabs be left on a patient?

answer

sometimes, if they are undergoing a serial ecg for a day or 2

question

which side of heart is smaller?

answer

right side

question

function of right side of the heart

answer

function of the right side is to pump blood to the lungs. this is a relatively short distance through a relatively small number of blood vessels

question

function of left side of the heart

answer

to pump blood to the rest of the body through a relatively large number of blood vessels. that is why the left side of the heart is larger than the right side.

question

what is each of the 12 heart leads designed to do?

answer

reflect electrical activity from a specific area of heart muscle

question

heart walls

answer

anterior, anteroseptal, lateral, inferior, posterior

question

anterior wall

answer

front part of the left ventricle and comprises the main portion of the left side of the heart. lies directly beneath the left side of the chest. therefore, the ecg sensors that are place over the left left chest directly reflect the anterior portion of the heart.

question

anatomical landmark for the anterior wall of the heart

answer

left chest ribs 2 through 5

question

anteroseptal wall

answer

front to septum. the area of the heart that extends from the anterior wall to the septum.

question

anatomical landmark for the anteroseptal wall

answer

along the left sternal border.

question

lateral wall

answer

located on the side of the heart that is facing the left arm or left axilla

question

inferior wall

answer

the bottom portion of the heart that lies over the diaphragm. it is this way because the heart is tilted -this wall includes inferior portions of the left and right ventricle.

question

posterior wall

answer

-region opposite anterior wall, facing the spine

question

sensors on the back

answer

they can be placed on the left side of the back to record direct electrical activity of the posterior of the left ventricle, although this is not the usual placement for a 12-lead ecg.

question

does sensor placement change from lead to lead?

answer

no, only sensor usage changes

question

biipolar leads, and what is important to note about it?

answer

bipolar leads have a positive and negative sensor. THE POSITIVE SENSOR IS THE LOOKING SENSOR. It is the "camera" an the point from which the heart is being examined or viewed.

question

ecg measurement in bipolar leads

answer

in bipolar leads, the ecg measures the difference of the electrical energy between two points, the positive and negative sensor, which is then translated into a waveform. if the current is going toward the positive sensor, then the wave will be positive and rise from the baseline. if the current is going away from the positive sensor, the wave will be negative and descend from the baseline.

question

unipolar leads

answer

-only have a positive sensor result is similar to bipolar lead (current traveling toward sensor is positive, current traveling away is negative.)

question

standard limb leads

answer

-obtained from leads that are on the arms and legs. -limb leads are Lead I, Lead II, and Lead III -they are bipolar leads -each lead utilizes 2 of 3 active sensors. -record activity on the frontal plane (side to side, up and down)

question

ground lead

answer

-right leg sensor, -used to determine a reference point, not for electrical activity.

question

what leads form einthoven's triangle

answer

leads 1-3

question

lead one sensors and views

answer

ra sensor is negative. la sensor is positive. views the lateral wall

question

lead 2 sensors/views

answer

ra negative, ll positive, inferior wall

question

lead 3

answer

la negative, ll positive, inferior wall

question

augmented leads

answer

-unipolar (only one positive sensor used to obtain electrical information and that the electrical current is measured from one point.) -configuration of the augmented leads results in an amplitude increase of 50%

question

augmented voltage abbreviations

answer

av, augmented lead on right arm is avr, and augmented lead on left leg is avl.

question

aVR

answer

-records the voltage from the midpoint between the la and ll to the positive ra pole -positive sensor ra looks at the top of the heart.

question

avl

answer

records voltage from the midpoint between ra an ll to the positive la pole. positive sensor la looks at the superior lateral wall of the heart.

question

avf

answer

records the voltage from the midpoint between ra and la to the positive ll pole. positive sensor ll looks at the inferior wall of the heart.

question

precordial/chest leads

answer

unipolar. look at the heart on a horizontal plane, from a front to back perspective. the limb leads look at the heart from a side to side and up and down perspective

question

what wall does v1-v3 look at

answer

interventricular septum and anterior wall

question

what wall does v4 look at

answer

anterior wall and septal wall

question

what walls do v5 and v6 look at?

answer

apical and low lateral walls.

question

optional chest leads

answer

v4r (v4 from right side of the chest. used if a ventricular infarction is suspected. sensor location would be mirrored as if it were on the left side of the chest.) -also a v7 (posterior axillary line), v8 (between v7 and v9), and v9 (midpoint of the left back) can be ordered if a posterior infarction is suspected

question

artifacts and sensors

answer

if theres not gel under the sensors or pregelled sensors have dried out, then conduction from the skins surface to the electrode and cable will be impaired and an artifact will be visible on the recording.

question

wandering baseline

answer

usually the result of a loose limb lead connection. may also be the result of an inadequate amount of gel on the sensor. caused by patient movement such as deep breathing.

question

what on the patients body can cause interference with the transmittal of the electrical signal?

answer

lotions or creams on the patient's body

question

what to do if a machine operates on a battery

answer

always run the test using battery power. keep the machine plugged in when not in use to ensure that the battery is adquately charged

question

cables and other power cords and appliances as related to the ekg machine

answer

keep them flat, straight, and along body lines. keep other appliances and power cords away from the patient.

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