Chapter 12 Cardiopulmonary Procedures Flashcards
P wave
Contraction of the Atria
Q wave
Contraction of the ventricles
T wave
aka ventricular repolarization, relaxation
QRS complex
the depolarization of the ventricles
P-R segment
the time between the end of atrial depolarization and the beginning of ventricular depolarization
S-T segment
from the end of ventricular depolarization to the beginning of repolarization of ventricles
Baseline
after T wave or U wave, period when entire heart returns to resting or polarized state
segment
time between two waves
-p-r segment, s-t segment
interval
length of a wave or length of wave with a segment
Q-T interval
time interval from the beginning of ventricular depolarization to the end of repolarization of the ventricles
P-R interval
time interval from the beginning of atrial depolarization to the beginning of ventricular depolarization
Normal standardization mark
10 mm high and 2 mm wide
electrocardiograph paper
thermosensitive paper divided into two sets of squares: small squares and large squares
-physician uses graph to measure waves, intervals and segments
electrocardiograph must be ________________ for every recording
standardized,
it is a quality control measure
if standardization mark is more or less than 10 mm high:
the machine must be adjusted, consult operating manual for adjustment information
Lead
a tracing of the electrical activity of the heart between two electrodes
- each lead provides an electrical photograph of heart’s activity from a different angle
- results in 12 photographs
Electrode (electrolyte)
a substance that facilitates the transmission of the heart’s electrical impulses
amplifier
device located in machine that amplifies the electrical impulses.
-electrical impulses given off by the heart are very small 0.0001 to 0.003 volt, therefore it must be amplified
galvanometer
changes amplified voltages into mechanical motion
The 10 lead wires:
- 4 limb lead wires (right and left arm, right and left leg)
- 6 chest lead wires
The right leg lead is used for ____________.
grounding of the machine,
not used for recording, serves as an electrical reference point
Electrodes _________ amplify the electrical impulses.
DO NOT
*note: the electrocardiograph amplifies
Lead I
records electrical current between right arm and left arm
Lead II
record electrical current between right arm and left leg
-shows hearts rhythm more clearly than other leads
Lead III
records electrical current between left arm and left leg
bipolar lead
aka stander lead, uses two limb electrodes to record electrical activity of heart
Rhythm strip
- longer recording (12 inches) of lead II
- often requested by physician
- confirms if there is dysrhythmia
aVR
augmented voltage-right arm; records electrical current travelling between right arm and a central point between left arm and leg
aVL
augmented voltage-left arm; records electrical current travelling between the left arm electrode and a central point between right arm and left leg
aVF
augmented voltage-left leg or foot; records electrical current travelling between left leg electrode and a central point between right arm and left arm
3 augmented leads
aVR, aVL, aVF
V1, V2, V3, V4, V5, V6
record heart’s voltage from front to back of heart
-from a central point “inside the heart, to a point on the chest wall
Leads must be properly located to:
ensure an accurate and reliable recording
Normally ECG is recorded with paper moving at a speed of ________.
25 mm/second
Recommended position for ECG V1 chest electrode
fourth intercostal space at right margin of sternum
Recommended position for ECG V2 chest electrode
fourth intercostal space at left margin of sternum
Recommended position for ECG V3 chest electrode
midway between positions 2 and 4
Recommended position for ECG V4 chest electrode
fifth intercostal space at junction of left midclavicular line
-at nipple
Recommended position for ECG V5 chest electrode
at horizontal level of position 4 at left anterior axillary line
Recommended position for ECG V6 chest electrode
at horizontal level of position 4 at left midaxillary line
preparation for an ECG
- ask patient not to exercise before procedure,
- to wear loose clothing or clothing that is easily removed
- no oil, body lotion or powder
maintenance of electrocardiograph
use a soft cloth slightly dampened with a mild detergent to remove dust and dirt
- clean patient cable, lead wires and power cord periodically with a moistened cloth and disinfectant
- inspect cables for cracks and fraying-check metal tip of each lead wire for gel or residue
- clean alligator clips
three-channel recording capability
records electrical activity of three leads simultaneously and sensitively
single-channel recording capability
records only one lead at a time
What patient information is recorded on the top of the ECG chart?
patient’s name, DOB, Gender, date and time of procedure
Teletransmission
- transmits recording electronically over phone line to ECG data interpretation site
- interpreted by cardiologist
- electronically transmitted to sending office on the same day
interpretive elctrocardiograph
built-in computer program, analyzes recording as it’s being run, provides immediate information on heart’s activity
-patient’s data must be entered before running (name, sex, height, weight, medications, +reason for interpretation)
artifact
additional electrical activity picked up by electrocardiograph
-interferes with normal appearance of ECG cycles
EMR
electronic medical record allows electrocardiograph to be linked with office computer; digital image of ECG sent to computer
- software analyzes ECG
- can copy and print out ECG, then report reviewed and interpreted by physician and stored electronically in patient’s EMR
Artifacts affect ECG by:
- making it difficult to manually measure ECG cycles,
- may cause, a false-positive on ECGs
-can be identified and corrected by MLA
Most common artifacts:
muscle, wandering baseline, 60-cycle interference (alternating current artifact), interrupted baseline artifact
if unable to correct artifacts, this may indicate a _______________.
broken machine
Electrocardiography
non invasive recording of the electrical activity of myocardium
electrocardiograph
instrument used to record the electrical activity of the heart
electrocardiogram
graphic representation of the electrical activity of the heart
What does the ECG exhibit
the ECG exhibits the amount of electrical activities produced by the heart at the time required for the impulse to travel through the heart
What is the difference between Holter and ECG?
ECG measures the patient’s electrical activity for a brief amount of time (like 10 seconds), Holter is attached to the patient for a long time (18 hrs, 24 hrs or a week) to observe the patient’s electrical heart activity through daily activities
Purpose of ECG:
evaluate the following symptoms: chest pain, shortness of breath, dizziness, heart palpitations, detect dysrhythmia, or detect cardiac ischemia.
- diagnose myocardial infarction
- determine presence of enlargement of the heart
- detect myocarditis or pericarditis
- assess effect on the heart of digitalis or other cardiac drugs
- determine presence of electrolyte disturbances
- detect congenital heart defects
- assess cardiac risk during surgery
- part of a complete examination
cardiac ischemia
presence of impaired blood flow to heart muscle
coronary artery
the vessel that feeds the heart muscle oxygen, if there is a block in the coronary artery it causes ischemia
myocardial infarction (MI)
death of myocardial muscle cells (tissue)
What are some downfalls of ECG?
- cannot detect all cardiovascular disorders
- ECG is taken in patient’s resting state
- only records 10 seconds of heart’s activity
- patient with angina pectoris doesn’t always show symptoms in a resting state
To obtain a complete assessment of cardiac functioning, ECG must be used in combination with:
-patient history, patient’s health, physical exam, other tests
MLA responsibilities for running ECG:
-patient preparation, operation of electrocardiograph, ID and eliminate artifacts, care and maintenance of electrocardiograph
Is it the MLA’S duty to translate results of ECG?
no
ECG machine formats:
single-channel format, three channel format
structure of the heart’s layers/lining from inside to outside?
- endocardium
- myocardium
- epicardium
- visceral pericardium
- parietal pericardium
structure of the heart’s layers/lining from outside to inside?
- parietal pericardium
- visceral pericardium
- epicardium
- myocardium
- endocardium
What is the job of the pericardial sac?
to protect the heart muscle
note: it is a layer of tissue that covers the heart
heart consists of 4 chambers:
upper chambers: left and right atria, lower chambers: left and right ventricles
where does the heart receive it’s nourishment?
the coronary arteries
Sinoatrial node
aka pacemaker of the heart, a knot of modified myocardial cells, located in upper portion of right atrium, regulates the heartbeat
What is the order of impulses?
- SA Node
- AV node
- Bundle of His
- Bundle branches
- Purkinje network
What happens after the Purkinje Network?
Contraction of the ventricles
What does the AV node do?
it delays the impulse, to allow the atria to contract completely and fill with blood
What stimulates the QRS wave?
the purkinje fibres
How is the electrocardiograph paper divided?
into two sets of squares
- small square 1mm x 1mm
- large square 5mm x 5mm
note: each large square is made up of 25 small squares
How do we know the ECG machine is standardized?
At the beginning of the test the machine automatically shows a standardized mark about 10mm in height and 2mm in width
How does a cardiac ischemia appear on the ECG?
-depressed ST segment and inverted T wave
How does a myocardial infraction appear on the ECG?
-larger than normal Q wave and elevates S-T segment
Electrode
made of a substance that is a good conductor of electricity
-conducts impulse into machine by lead wires
bipolar leads are aka
stander leads
Normally ECG is recorded with paper moving at a speed of:
25 mm/second
Minimal patient preparation for an ECG
- facilitate placement of electrodes
- ensure good adhesion of the electrodes to skin
- instruct patient to wear comfortable clothing and not to wear lotion or oil
Artifacts
additional electrical activity picked up by electrocardiograph
Most common artifacts:
-muscle, wandering baseline, 60 cycle interference, interrupted baseline
Muscle artifact
- characterized by a fuzzy, irregular baseline
- due to involuntary and voluntary muscle movement
note: if patient has a condition characterized by involuntary muscle movement, position the patient in a way that reduces movement
ie. a patient with parkinsons would be positioned with hands under buttocks with palms facing downward
Wandering Baseline artifact
caused by loose electrodes, dried-out electrolyte on electrode, body creams, oils on skin, excessive movement of chest wall during respiration
-basically anything that causes the electrode not to properly adhere
60-cycle interference artifact
also known as AC artifact, appears as small straight spiked lines that are consistent, causes baseline to be thick and unreadable
-due to electrical interference, dangling lead wires, other electrical equipment in room, wiring in walls, improper grounding of the ECG
Interrupted baseline artifact
caused by a frayed or broken patient cable, ill-attached lead wire to alligator clip
Holter monitor electrocardiography
portable ambulatory monitoring system that continuously records electrical activity for 24 hrs or more
- detects cardiac abnormalities
- designed so that patient is able to maintain daily activities
purpose of holter monitor
used to diagnose cardiac rate, rhythm and conduction abnormalities
-frequently used to assess the rate and rhythm of the heart during daily activities for patients with unexplained chest pain
in regards to holter monitor, MLA is responsible for:
preparing the patient, applying and removing the monitor, instructing patient in guidelines to follow during the monitoring period
What can cause interference artifacts while using the holter monitor
magnets, metal detectors, areas with high-voltage electrical wires
cardiac dysrhythmia
abnormal electrical activity in the heart causing an irregular heartbeat
categories of cardiac dysrhythmia
extra beats, abnormal rhythm, abnormal heart rate
premature atrial contraction
an abnormal p wave shape but with normal QRS complex and T wave
-common in healthy individuals, but can also be associated with serious atrial dysrhythmias
Paroxysmal Supraventricular Tachycardia (PSVT)
abrupt episode of tachycardia, with a heart rate of 150-250, sudden onset and termination
-ECG cycles are very close together
What does a patient experience with PSVT?
sudden pounding or fluttering of chest, weakness and breathlessness, acute aprehension
Atrial Flutter
one of most common rhythm disorders
-rapid regular fluttering of atrium, heart rate of 250-250 bpm, more than one P wave precedes QRS complex
How does an atrial flutter appear in the ECG?
p wave appears as saw toothed spikes, QRS is normal and t wave usually lost in p waves
How does atrial fibrilation appear inECG?
p waves have no definite pattern or shape
How does premature ventricular contraction appear in ECG?
beat comes early in a cycle, not preceded by a p wave
-wide and distorted QRS complex
