Electrocardiographs Flashcards
Transducers
convert the biopotentials of the patient to electrical signals that the medical device can interpret
Resistive Transducer
any element that changes its resistance as a function of a physical variable, pressure causes displacement, causes a change in resistance, moving the arm of the potentiometer
Strain Gauge
Yields to stretching forces that causes changes in resistance, uses fine resistive wire
Thermistor
changes resistive value in a predictable manner with changes in temperature, has a negative or positive temperature coefficient, positive coeff.: as temp increase, resistance increase, Negative coeff.: as temp increase, resistance decreases
Solid State PN Junction
resistance decreases as temperature increases (negative temperature coefficient)
Doppler Effect
As sound waves hit a moving object, frequency will change, the measured frequency shift is proportional to the change in velocity
Ultrasound Transducer
sends sound waves with transmitter, receives reflected sound waves, converts them into electrical output, used for ultrasound monitoring
Inductive Transducer
physical movements of a permeable core within an inductor Effects: iron/ferrite core inside of coil, magnetic field of the core
Capacitive Transducer
causes capacitance of the transducer to vary with stimulus Uses: stationary plate or plates, moveable plate that changes position under the influence of a stimulus
Thermocouple
two dissimilar conductors or semiconductors joined together at one end (junction), when the junction is heated, a potential is generated, electrons begin to flow
Electrodes
a device that converts ionic potentials into electronic potentials
Electrocardiographs (small voltage?)
record small voltages about 1 mV that appear on the skin surface as a result of cardiac activity
Suction Cup Electrode
used for connecting portions of the body other than the extremities (head, face chest) Disadvantage: prone to movement or slippage during long recordings
Plate Electrode
connected to a patient’s extremities, held in place by a rubber strap
Column Electrode
reduces motion artifact generated by patient movement by eliminating electrode slippage, held in place by adhesive, used for long term applications
Needle Electrode
disposable, stainless steel hypodermic needles, two to six inches in length Uses: EEG monitoring, ECG monitoring, EMG monitoring, fetal ECG monitoring,
Bipolar Lead Configuration
Lead 1: measures voltage between LA and RA
Lead 2: measures voltage between RA and LL
Lead 3: measures voltage between LA and LL
Augmented Vector
measures the voltage between one limb electrode and the average of the remaining two limb electrodes (indifferent electrode)
Precordial
Chest electrodes labeled v1 through v6, measures the voltage between one chest electrode and the average of all limb electrodes
electrocardiograph
a medical device for diagnosing diseases such as cardiac arrhythmias, conduction disorders, electrolyte imbalances, hypertension, coronary artery disease, and myocardial infarctions
intended purpose of ECG
detect the electrical activity of the heart, record small voltages 1mv that appear on the skins surface
ECG artifact
the wave that arises from sources other than the heart (noise)
Asystole
a form of cardiac arrest in which the heart stops beating and there is no electrical activity in the heart (flatline)
Cardiac Arrest
electrical malfunction of the heart that causes an arrhythmia and disrupts the pumping action of the heart
Electrocardiogram
a graphic record of voltage versus time (screen or print out)of the electrical activity of the heart produced by an electrocardiograph
Electrocardiogram
a graphic record of voltage versus time (screen or print out)of the electrical activity of the heart produced by an electrocardiograph
Myocardial Infarction
Heart attack, circulation problem in the muscular tissues of the heart , blood is blocked from reaching the tissues of the heart
Normal Sinus Rhythm
all measurements of an ECG that fall within normal limits of the characteristic of an ECG when the electrical conduction system of the heart is functioning normally
P- Wave
begins with an electrical impulse from the SA node, both atria depolarize (contract) and produce electrical activity
PR Segment
measures from the onset of the P-Wave to the onset of the QRS Complex, electrical impulse from atria passes to AV node, the AV node is depolarized (contracted) .12 to .20 seconds
QRS complex
represents electrical impulse: travels from bundle of HIS, into bundle branches, into purkinje fibers, into the myocardial cells, causing ventricular contraction, depolarization of ventricles, represents systolic pressure
Q- Wave
R-Wave
S- Wave
Q Wave: the first down stroke of the QRS complex
R Wave: first upward deflection of the QRS complex
S Wave: first downward stroke after R wave
ST segment
used to identify myocardial infarctions, the interval between depolarization (S-Wave) and repolarization (T-Wave)
T Wave
represents repolarization of the ventricles back to the resting state, diastolic pressure
ECG Heart Rate using ECG
cardiologist can measure heart rate by measuring the R to R interval of successive QRS waves
Electrocardiogram provides 2 key types of info
time intervals of an ECG and amount of electrical activity passing through the heart
Electrocardiogram standard format
4 Lead configurations per line X 2.5sec of recording per lead configuration + 3 ids- holding three specific lead configurations for 10 seconds
ECG Signals detected
0.05 to 100 Hz for diagnostic purposes
