Electrophysiologic Tests Flashcards
(47 cards)
What are electrophysiologic tests?
They use electrical activity and electrical devices to evaluate disease/injury to a specific area of the body
What are the two types of electrical impulses?
Generated spontaneously = EKG
Stimulated = EMG
What is a cardiac stress test?
Noninvasive study that provides info about a patient’s cardiac function
Heart is stressed by exercise, medicine, or pacing then heart is evaluated during the stress
Changes indicating ischemia point to coronary occlusive disease
What are the indications for a cardiac stress test?
Chest pain in patient with suspected coronary disease
Limits of safe exercise during a cardiac rehab program
Labeled or exercise-related hypertension
INtermittent claudication in patients with suspected vascular occlusive disease
Effectiveness of treatment in patients who take antianginal or anti arrhythmic medications
Effectiveness of cardiac intervention (such as bypass grafting or angioplasty)
What is the goal of the cardiac stress test stressor?
To increase the heart rate to just below maximal levels or to the “target heart rate”
What is the target heart rate?
80 to 90% of the maximal heart rate
220 - patients age
When is a cardiac stress test stopped?
If patient reaches the target heart rate or develops any symptoms or EKG changes
What is the criteria for discontinuation of an exercise stress test?
Abnormal EKG changes such as Ectopy, Flipped T waves, or ST changes
Attainment of maximal performance
Chest pain
Cyanosis
Excessive heart rate change
Excessive hypertension/hypotension
Leg claudication
Severe SOB
Syncope
What is the procedure for a cardiac stress test?
1) NPO and avoid smoking for 4 hours prior
2) Obtain protest EKG
3) Record patient’s vital signs for baseline values
4) Apply and secure appropriate EKG electrodes
5) After patient begins to exercise, adjust treadmill to apply increasing levels of stress at specific intervals
6) EKG tracing and vital signs are monitored continuously
7) Terminate test if patient becomes symptomatic
8) Testing usually takes approx. 45 min
What is the post procedure for Cardiac stress testing?
Place patient in supine position to rest after test
Monitor EKG tracing and record vital signs at post-stress intervals until recordings and values return to protest levels
Remove electrodes and paste
What is an Electrocardiography test?
Records electrical impulses that stimulate heart to contract
What are the indications for an EKG?
Evaluates: Arrhythmias Conduction defects Myocardial injury/damage Hypertrophy
Diagnoses:
Electrolyte imbalances
Drug level abnormalities
Pulmonary diseases
What are the two different planes for EKG?
Six limb leads
Six chest leads
What is the pre-procedure for EKG?
Leads are positioned as follows:
V1 in fourth intercostal space at the right sternal border
V2 in 4 ICS at the left sternal border
V3 midway between V2 and V4
V4 in 5 ICS at the midclavicular line
V5 at the left anterior auxiliary line at the level of V4 horizontally
V6 at the left midaxillary line at the level of V4 horizontally
What is an electroencephalography test?
Electrodiagnostic test performed to identify and evaluate patients with seizures, tumors, and infarction
Confirmatory test for determination of brain death
Provides graphic recording of electrical activity of the brain
Electrodes are placed on scalp overlying multiple areas of brain to detect/record electrical impulses within it
What are the indications for EEG?
Important in evaluating epileptic states which is characterized by rapid, spiking waves seen on the graph
Patients with cerebral lesions will have abnormally slow EEG waves, depending on size and location of lesion
Used to evaluate trauma, drug intoxication, and cerebral death in comatose patients
What is the pre-procedure for an EEG?
If sleep EEG will be attempted at time of testing, sleep should be shortened night before test:
Adults = no more than 4-5 hours Children = no more than 5-7 hours
Instruct patient to wash hair night before test
No oils, sprays, or lotion should be used
Some meds may need to be d/c before study but anticonvulsants should be taken unless C/I by the physician
What can alter the results of an EEG?
1) Fasting may cause hypoglycemia which could modify EEG pattern
2) Drinks containing caffeine interfere with test results
3) Body and eye movements during test can cause changes in brain wave patterns
4) Lights (especially bright or flashing) can alter test results
5) Sedatives may affect results
What is the procedure for an EEG?
1) EEG usually performed in specially constructed room shielded from outside disturbances
2) Patient placed in supine position on bed or reclining on a chair
3) 16 or more electrodes applied to scalp in a specific pattern over both sides of the head = prefrontal, frontal, temporal, parietal, and occipital areas
4) One electrode may be applied to each earlobe for grounding
5) After electrodes applied, patient is instructed to lie still with eyes closed
6) Technician continuously observes patient during recording or any movements that could alter results
7) Approx. Every 5 minutes recording is interrupted to permit the patient to move if desired
What is an Electromyography (EMG)?
Monitors electrical activity of skeletal muscle similar to EKG
Electrical activity displayed on oscilloscope as electrical waveform
Audio electrical amplifier can be added to system so that both appearance and sound of electrical potentials can be analyzed and compared simultaneously.
Performed by a psychiatrist, musculoskeletal physician, or neurologist in 30-60 min.
Small needle size helps reduce discomfort
Usually done in conjunction with nerve conduction studies
Can detect spontaneous muscle movement such as fibrillation and fasciculation
When evident, these waveforms indicate injury/disease of nerve or muscle being evaluated
Decrease in number of muscle fibers able to contract typically observes with peripheral nerve damage
What are the indications for an EMG?
Used in evaluating patients with diffuse or localized muscle weakness/atrophy
Used to detect:
Primary muscular disorders
Muscular abnormalities caused by other system such as nerve dysfunction, sarcoidosis, and paraneoplastic syndrome
What are the contraindications for EMG?
Patients receiving aggressive anticoagulant therapy as electrodes may induce intramuscular bleeding
Skin infection, as electrodes may penetrate infected skin and spread infection to muscle
What are interfering factors of EMG?
Edema
Hemorrhage
Thick SQ fat
Patients with excessive pain the precludes the patient’s ability to relax
What is the pre-procedure for EMG?
If serum enzyme tests ordered, specimen should be drawn 5-10 days afterward because penetration of muscle by electrodes may cause misleading elevations
Premedication/sedation usually avoided
