LAB2- EKG Flashcards
electrocardiogram
the process of recording the electrical activity of the heart using electrodes placed on the patient’s body
electrocardiogram is a graphic record of what
the DIRECTION + MAGNITUDE of the electrical activity generated by the depolarization + repolarization of the atria + ventricles
who first described the modern ECG with known landmarks PQRST waves in 1893
William Einthoven
-received Nobel Prize in 1924 for developing the modern ECG
the first 30 years, what was used to perform an ECG
string galvanometer
in 1942, who added 9 augmented leads to Einthoven’s traditional 3 lead ECG, leading to the 12 lead ECG used today
Emmanuel Goldberger
how many leads did Einthoven’s ECG have
3
how many leads did Goldberger’s ECG have
12
why is ECG also known as EKG
original spelling in German is elektrocardiogram (EKG)
purpose of ECG testing
often used (with other tests) to help diagnose + monitor conditions affecting the heart
what can ECG be used to investigate
symptoms of possible heart problems such as chest pain, palpitations, dizziness, + shortness of breath
what 4 things can ECG help detect
-arrythmias
-coronary heart disease
-heart ischemia (heart attacks)
-cardiomyopathy
P wave
atrial contraction (depolarization)
QRS complex
ventricular contraction (depolariziation)
QRS complex or P wave is larger + why
QRS complex is larger
-more muscle mass in the ventricle
T wave
ventricular relaxation + reset (repolarization)
QT interval
represents the complete depolarization + repolarization of the ventricular tissue
prolonged repolarization of ventricular tissue (QT interval) can lead to what
life-threatening arrhythmias
where does the P wave originate from
SA node
break down the QRS complex
-Q wave: initial downward deflection
-R wave: upward deflection
-S wave: downward deflection
PR interval
time from the beginning of the P wave to the beginning of the Q-wave (QRS complex)
SA node -> atria -> ventricles
PR interval is what in terms of depolarization/repolarization
the start of atrial depolarization to start of ventricular activation
PR segment
-from the end of the P wave to the beginning of the QRS segment
-represents the time delay between atrial + ventricular activation
ST segment
segment from the end of QRS complex to the beginning of the T wave
-represents time between ventricular depolarization + repolarization
what does the ST segment represent
the absolute refractory period (plateau of the AP) of the ventricular contractile cells
elevation or depression of the ST segment is based off what
PR segment
U wave
repolarization of papillary muscles or Purkinje fibers
-NOT ALWAYS SEEN
-origin is still being debated
which type of ECG is most often used in the health field
12-lead
-however, a 2-lead, 3-lead, 6-lead + many other variations can be used
ECG electrode
a conductive pad that is attached to the skin to record changes in electrical activity
pair of electrodes
any pair can measure the electrical potential difference between the 2 corresponding locations of attachment
ECG lead
consists of 2 surface electrodes that are either bipolar or unipolar
bipolar lead
opposite polarity
-1 positive + 2 negative
unipolar lead
1 positive surface electrode + a reference point
each lead gives an opportunity to do what
to look at the heart from a different electrical position
for the common 12-lead ECG, how many electrodes are positioned on the body
10
depolarization of the heart towards the positive electrode produces positive/negative deflection
positive
depolarization of the heart away from the positive electrode produces positive/negative deflection
negative
repolarization of the heart towards the positive electrode produces positive/negative deflection
negative
repolarization of the heart away from the positive electrode produces positive/negative deflection
positive
what are the 12 leads
Lead 1, 2, 3
aVR, aVL, aVF
V1, V2, V3, V4, V5, V6
limb leads
leads 1, 2, 3
lead 1
measures difference in electrical activity between L arm + R arm
ground electrode
R leg
lead 2
between L leg + R arm
lead 3
between L leg + L arm
Einthoven’s triangle
created by the 3 limb leads
-provides view of heart’s activity from the front
augmented leads
aVR, aVL, aVF
-augmented stands for average
-combines signals differently to “augment” the view from certain directions; gives additional angles to see heart’s electrical activity
aVR
views heart from R arm
aVL
views heart from L arm
aVF
views heart from L leg
chest leads
V1-6
what leads provide a horizontal view of the heart
chest leads (V1-6)
which leads provide an anterior view of the heart
limb leads (1-3)
V1 + V2
look at the septum
V3 + V4
look at the anterior part of heart
V5 + V6
look at lateral part of heart
inferior leads
2, 3, aVF
-look at lower part of heart
lateral leads
1, aVL, V5, V6
-look at side of heart
septal leads
V1 + V2
-look at heart’s septum
anterior leads
V3 + V4
-look at front part of heart
electrode placement for 12-lead ECG (modified Mason-Likar)
-this is what we use in lab
-leg electrodes are not placed on legs but rather all on chest/stomach
modified Mason-Likar 12-lead ECG placements
right arm
right infraclavicular fossae medial to the deltoid muscle roughly 2cm below border of clavicle
modified Mason-Likar 12-lead ECG placements
left arm
left intfraclavicular fossae medial to the deltoid muscle roughly 2cm below border of clavicle
modified Mason-Likar 12-lead ECG placements
left leg
in line with left anterior axillary line halfway between costal margin + iliac crest
modified Mason-Likar 12-lead ECG placements
right leg
in line with right anterior axillary line halfway between costal margin + iliac crest
modified Mason-Likar 12-lead ECG placements
V1
4th intercostal space right sternal edge
modified Mason-Likar 12-lead ECG placements
V2
4th intercostal space left sternal edge
modified Mason-Likar 12-lead ECG placements
V3
`
midway between V2 + V4
modified Mason-Likar 12-lead ECG placements
V4
5th intercostal space, mid-clavicular line
modified Mason-Likar 12-lead ECG placements
V5
anterior axillary line in straight line with V4
V6
mid-axillary line in straight line with V4 + V5
which electrodes might need to be altered in female patients due to breast tissue
V4, V5, V6
-place electrode as close as possible to anatomical location directly under breast
if you had to modify electrodes for female patient, what might occur in ECG
mild rightward shift in QRS axis
small square represents
0.04 seconds
large square (5mm) represents
0.2 seconds
sinus rhythm
a regular ECG
-P wave is upright in leads 1 + 2
-each P wave is followed by a Q
-heart rate is 60-100 bpm
tachyarrhythmia
an abnormal rhythm with a ventricular heart rate over 100 bpm
supraventricular tachycardia
arrhythmia originating from above the AV node
types of supraventricular tachycardia
-atrial fibrillation
-atrial flutter
-atrial tachycardia
types of ventricular tachycardia
-ventricular fibrillation
-ventricular tachycardia
ventricular or atrial fibrillation is more critical
ventricular fibrillation
atrial fibrillation
-absence of P waves
-irregular QRS rhythm
ventricular fibrillation
absence of normal PQRST components, replaced by chaotic uncoordinated electrical activity
bradyarrhythmia
a heart rate below 60 bpm + comprises multiple disorders
types of bradyarrhythmia
-sinus bradycardia
-first degree AV block
-second degree AV block
-third degree AV block
-SA node exit block
normal ST segment
flat + isoelectric
how is ST segment deviation (elevation or depression) measured
the height difference between the J point + the baseline (PR segment)
what amount of ST segment depression is considered pathological
5 mm or more
what naturally occurs to ST segment during exercise + is considered normal
upsloping ST segment depression
when does ST segment indicate ischemia
-downsloping or horizontal ST segment depression
-OR ST segment elevation
ECG electrode placement protocol
-locate anatomical areas that will be used
-prepare skin by removing any excessive hair
-if possible clean each site thoroughly with soap + water
-use ECG skin prep pad, paper, or abrasive tape
-explain the electrode application procedure to the patient to decrease anxiety
-when only 1 patient is present, attach the lead wire to the electrode before placement
-apply the electrode by pressing about the entire edge of the electrode center since it spreads the gel out + may create air pockets that contribute noise
should you use alcohol or soap + water before applying electrode
soap + water
-alcohol dries the skin + can diminish electrical flow
what does using skin prep pad, paper, or abrasive take do
-removes stratum corneum to allow better electrical signals
-scratches stratum ganulosum to reduce motion artifact
depolarization = contraction/relaxation
contraction
during depolarization, what does ECG do
go up
