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Diagnostic M.'s Sara Peer mentor > Electrophysiologic Tests > Flashcards

Electrophysiologic Tests Flashcards

1
Q

What are electrophysiologic tests?

A

They use electrical activity and electrical devices to evaluate disease/injury to a specific area of the body

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2
Q

What are the two types of electrical impulses?

A

Generated spontaneously = EKG

Stimulated = EMG

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3
Q

What is a cardiac stress test?

A

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

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4
Q

What are the indications for a cardiac stress test?

A

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)

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5
Q

What is the goal of the cardiac stress test stressor?

A

To increase the heart rate to just below maximal levels or to the “target heart rate”

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6
Q

What is the target heart rate?

A

80 to 90% of the maximal heart rate

220 - patients age

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7
Q

When is a cardiac stress test stopped?

A

If patient reaches the target heart rate or develops any symptoms or EKG changes

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8
Q

What is the criteria for discontinuation of an exercise stress test?

A

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

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9
Q

What is the procedure for a cardiac stress test?

A

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

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10
Q

What is the post procedure for Cardiac stress testing?

A

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

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11
Q

What is an Electrocardiography test?

A

Records electrical impulses that stimulate heart to contract

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12
Q

What are the indications for an EKG?

A 
Evaluates:
Arrhythmias
Conduction defects
Myocardial injury/damage
Hypertrophy

Diagnoses:
Electrolyte imbalances
Drug level abnormalities
Pulmonary diseases

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13
Q

What are the two different planes for EKG?

A

Six limb leads

Six chest leads

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14
Q

What is the pre-procedure for EKG?

A

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

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15
Q

What is an electroencephalography test?

A

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

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16
Q

What are the indications for EEG?

A

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

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17
Q

What is the pre-procedure for an EEG?

A

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

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18
Q

What can alter the results of an EEG?

A

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

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19
Q

What is the procedure for an EEG?

A

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

20
Q

What is an Electromyography (EMG)?

A

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

21
Q

What are the indications for an EMG?

A

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

22
Q

What are the contraindications for EMG?

A

Patients receiving aggressive anticoagulant therapy as electrodes may induce intramuscular bleeding

Skin infection, as electrodes may penetrate infected skin and spread infection to muscle

23
Q

What are interfering factors of EMG?

A

Edema
Hemorrhage
Thick SQ fat

Patients with excessive pain the precludes the patient’s ability to relax

24
Q

What is the pre-procedure for EMG?

A

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

25
Q

What is the procedure for an EMG?

A

1) Patients position and position of electrode depend on muscle being studied
2) Tiny needle that acts as a reference electrode inserted into muscle being examined
3) A reference electrode is placed nearby on the skin surface
4) The patient is instructed to keep muscle at rest
5) The oscilloscope display is viewed for any evidence of spontaneous electrical activity
6) Then patient is asked to contract muscle slowly and progressively
7) Electrical waves produced examined for their number, form, and amplitude
8) A nerve innervation a particular muscle group is then simulated and resulting muscle contraction is evaluated

26
Q

What disease are marked by reduced muscle electrical activity with spontaneous contraction?

A

Gillian-Barre Syndrome

Myasthenia Travis

Peripheral nerve injury, entrapment, or compression

Acetylcholine blockers like snake venom

Diabetic neuropathy

Anterior poliomyelitis

Muscle denervation

Amyotrophic lateral sclerosis

27
Q

What primary muscle diseases are denoted by decreased electrical activity and amplitude?

A

Muscular dystrophy
Myopathy
Traumatic injury

Even with nerve stimulation, little or no activity is seen

28
Q

What is a nerve conduction test?

A

Evaluates integrity of nerves and allows for detection and location of peripheral nerve injury or disease

Electrical impulse is initiated at one site of nerve and the time it takes impulse to travel to a second site of the same nerve is recorded then docnudtion velocity of the impulse in that nerve can be determined

Usually done in conjunction with an EMG

Can indicate diseases affecting either the motor or sensory nerves

Takes about 15 minutes and is performed by a psychiatrist, neurologist, or trained tech

May be uncomfortable because a mild shock is required for nerve impulse stimulation

29
Q

Where are electrical impulses placed in a nerve conduction study?

A

For evaluating motor nerves = proximal

For evaluating sensory nerves = distal

30
Q

What does a nerve conduction test evaluate?

A

Neuromuscular junction
Nerve axon loss
Variations in nerve recovery time

31
Q

What are the indications for a nerve conduction study?

A

Performed to identify peripheral nerve injury in patients with:

Localized or diffuse weakness
Muscle atrophy
Dysesthesia/paresthesia
Neurogenic pain
So as to differentiate primary peripheral nerve disease from muscular injury
Documents severity of injury
Used to monitor the nerve injury and response to treatment

32
Q

What is the procedure for a nerve conduction test?

A

1) Test can be performed in the nerve conduction lab, office setting, or a the patients bedside
2) Patients position depends on the area of suspected peripheral nerve injury or disease
3) A recording electrode is placed on the skin overlying a muscle innervated solely by the relevant nerve
4) a reference electrode is placed nearby
5) The nerve is stimulated by a shock emitting device at an adjacent location
6) FOr the evaluation of a motor nerve, the time between nerve impulse and muscular contraction is measured in ms on an EMG machine
7) The nerve is stimulated similarly at a location proximal to the area of suspected injury or disease
8) the time required for the impulse to travel from the site of initiation to muscle contraction is recorded in ms

33
Q

What is Distal latency?

A

The time between nerve impulse and muscular contraction

34
Q

What is total latency?

A

Time required for the impulse to travel from the site of initiation to muscle contraction

35
Q

What is the distance between site of stimulation and recoding electrode measured in?

A

Centimeters

36
Q

What is conduction velocity converted to?

A

Meters/second

37
Q

What is the normal conduction velocity for the lower extremeties?

A

40-50m/sec

38
Q

What cause slowing of conduction velocity?

A

Trauma or contusion of a nerve

Neuropathies

39
Q

A conduction velocity that is greater than normal does not indicate what?

A

Pathologic conditions

40
Q

When is no nerve conduction noted?

A

IN complete nerve transactions

41
Q

What is a Holter monitor?

A

Continuous recording of electrical activity of the heart

Can be performed for up to 72 hours

EKG is recorded continuously on magnetic tape during unrestricted activity, rest, and sleep

It is equipped with a clock that permits accurate time monitoring on the EKG tape

Patient carried diary and records daily activities, as well as any cardiac symptoms that may develop during the period of monitoring

42
Q

What are the indication for a Holter monitor ?

A

Patients who experience:

Syncope
Palpitations
Atypical Chest pains
UNexplained dyspnea

43
Q

What occurs after the Holter monitor is worn for the 72 hour period?

A

1) Record tape is played back at a high speed
2) EKG tracing is usually interpreted by computer, which can detect any significant abnormal waveform patterns that occurred during the test
3) Computer printouts are generated

44
Q

What are the two types of computer printouts that can be generated from a Holter monitor?

A

1) Event recording

2) Full disclosure recording

45
Q

What is an event recording printout?

A

Representative tracings during noted events are printed out

Tracings demonstrate maximum and minimum heart rates

46
Q

What is a full disclosure recording?

A

All the beats are printed out and are scanned by a tech who looks for aberrant waveforms

47
Q

What are the clinically significant test results seen on a Holter monitor?

A

Cardiac arrhythmias:
Tachycardia
Bradycardia
Premature beats

Ischemic changes:
Unusual pain symptoms during a particular exercise
A monitor can be applied and that particular exercise performed
If pain occurs and associated EKG ischemic changes are noted on the monitor, the diagnosis of angina can be made even though the pain is atypical

Diagnostic M.'s Sara Peer mentor (27 decks)

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