EKG Flashcards
purpose of EKG
non-invasive test that measures electrical activity of the heart
what is important in an EKG for PT
cardiac rhythm
conduction abnormalities
evidence of myocardial ischemia
drug treatment effects
who are the people credited with EKG creation
augustus walker
- electrical activity of the heart
willem einthoven
- named the PQRST waves
- standard limb leads (einthoven’s triangle)
what is important to understand about EKG leads
always moves from negative toward positive pole
explain the einthoven triangle
- location of leads
- number of leads
Right Arm (both negative)
Left Arm (neg/positive)
Left Leg (both positive)
1 = from RA To LA
2 = RA to LL
3 = LA to LL
difference between standard and modified leads
standard = LA, RA, LL
modified = no LL, where limb attaches into trunk
what is the normal amount of waveforms and electrodes in standard-12 lead ECG
12 waveforms
10 electrodes
what does a standard 12-lead ECG tell you
rhythm captured over short periods of time
what does cardiac telemetry tell
electrical activity over long periods of time
what can cardiac telemetry NOT tell us
right or left bundle block
ventricular tachycardia
supraventricular tachycardia
ischemia
explain the normal set up of cardiac telemetry
3 to 5 electrode
- bipolar and modified precordial leads
what is a holter monitor
a portable monitor that is worn for 24-48 hrs
- pt is to record symptoms and then it is compared with activity recorded by the monitor
what does the holter monitor do vs not do
does = helps assess presence of frequent daily symptoms
does not = provide real time information
what is an event/loop monitor?
- time frame?
- at occurrence of symptoms?
portable monitor for patients in presence of less frequent symptoms
- 2 to 4 weeks
- pt can activate the monitor to record at onset of symptoms
explain what a patch monitor is
- time frame?
- symptom occurrence?
- potential advantages?
kind of what it sounds like, patch with single lead adhesive, no leads, or batteries
- 30 days
- patient or auto triggered when symptoms occur
- allows for real time monitoring
what is a mobile cardiac output telemetry unit
- time frame?
- potential advantages?
3 lead sensor that can be worn up to 30 days
- auto or patient triggered
allows for real time monitoring of symptoms with daily summary reports
what is an oscillometry device?
automated BP monitor
conduction pathway of the heart
SA node
AV node
Bundle of His
Right/Left bundle branch
Purkinje fibers
how do purkinje fibers fire
begin deep in the heart, start firing at the endocardium and move outward
what is the PSNS control of the heart
Vagus nerve that controls SA / AV node
–> is the primary system of control
explain SNS control of the heart
sympathetic cardiac nerve via cardiac splanchnic nerve
what does SNS work on in the heart
ventricular muscle
AV node
SA node
if the SA and AV node fail, what happens
ventricular muscle starts to beat to keep you alive (40-60bpm)
what is the definition of a “lead”
a view of the heart
explain the count of limb electrodes, limb leads, and precordial electrodes
4 limb electrodes that produce 6 limb leads
I, II, III, aVR, aVL, aVF
6 precordial electrodes
V1 - V6
location of RA / LA / LL RL leads
right arm (forearm/wrist)
left arm (forearm/wrist)
left lower leg (proximal to ankle)
right lower leg (proximal to ankle)
location of V1
4th intercostal space, right sternal angle
location of V2
4th intercostal space, left sternal angle
location of V3
midway between V2 / V4
location of V4
5th intercostal space, midclavicular line
location of V5
anterior axillary line
- straight in line with V4
location of V6
mid-axillary line
- straight in line with V4/V5
explain the plane of aVR, aVL, aVF
frontal plane
explain the plane of V1-6
transverse plane
what leads read the lateral aspect of the heart
aVL
V1
V5
V6
what leads read the inferior aspect of the heart
V2
V3
aVF
what leads read the right side of the heart
aVR
V1
what leads read the anterior aspect of the heart
V2
V3
V4
what are the lateral leads? what artery do they look at?
V1
aVL
V5
V6
circumflex branch of left coronary artery
what are the anterior leads? what do they look at?
V3
V4
LAD - right and left ventricle
what are the septal leads? what artery do they look at?
V1
V2
LAD - intraventricular septum
what are the inferior leads? what do they look at?
V2
V3
aVF
right coronary artery
what information is gained from a 12-lead EKG
heart rate
heart rhythm
presence of ischemia or infarct
heart size
electrolyte imbalance
drug effects
P wave indicates
atrial depolarization
normal timing and amplitude of p-wave
<0.12 seconds
<3 mm
explain the curve of a p-wave
smooth hump ;)
no notching or peaking
what does QRS complex indicate
ventricular depolarization
travel down the interventricular septum to purkinje fibers
normal duration and amplitude of QRS Complex
time = <0.10 seconds
amplitude = 5mm in lead 2 / 9mm in V3&4
explain wave deflection of Q,R,S waves
Q = negative
R = positively
S = negatively
ST segment indicated
early ventricular repolarization
explain the wave deflection of the ST segments
on isoelectric line
what is the amplitude of the ST wave
not depressed more than 5 mm from isoelectric line
what do ST segment elevation/depression indicate
elevation = myocardial damage
depression = myocardial ischemia
T wave represents
ventricular repolarization
explain amplitude for T wave in
- limb leads
- precordial leads
limb = 5 mm
precordial = 10 mm
what does PR interval indicate? how is it measured?
AV conduction time
- beginning of P to beginning of QRS
normal PR interval time length
0.12-0.20 seconds
(<5 boxes)
what does QT interval indicate? how it is measured?
ventricular depolarization and repolarization
start of Q to end of T wave
what happens during QT interval in terms of electrolytes
sodium influx
potassium efflux
what is the normal time frame of QT interval? explain the regularity of it?
less than 1/2 of R-R interval
varies with heart rate
what is the timeframe associated with QRS waveform complex
0.04-0.1
what are the four components of ECG analysis
Rate
Rhythm
Conduction
Configuration
when assessing rhythm, what do you look for?
P-P intervals equal? - atrial rhythm normality
R-R intervals equal? - ventricular rhythm normality
when assessing conduction, what is asked?
is every QRS complex preceded by a P wave?
is the P-R interval normal? each time?
is the QRS width normal?
when assessing configuration, what are the questions to ask?
is the P wave normal shaped/duration
is the QRS normal shaped/duration?
how to assess HR via ECG?
if normal, can use methods taught
if not, must have 1 full minute strip
on the EKG paper, what do small and large boxes count as? what about ticks?
small = 1 mm (0.04 sec)
large = 5 mm (0.2 sec)
five large = 1 sec
– ticks are every 3 sec
how to count atrial rate
if rhythm is regular, count boxes between P waves
if irregular, count # of P waves for a full minute
how to count ventricular rate
if regular rhythm, count number of boxes between peak of QRS wave to the next
if irregular, count number of QRS complexes for a full minute
what numbers are used to count HR if the EKG represents a regular rhythm?
schroder method
300
150
100
75
60
50
explain sinus brady or tachycardia
sinus = normal rhythm
bradycardia - <60bpm
tachycardia - >100bpm
what can possibly explain brady/tachycardia if not normal?
medication
recent surgery
electrolyte imbalance
what is the time related to P-R interval conduction
0.12-0.2 seconds
3-5 boxes
what is the time related to QRS complex conduction
0.04-0.1 seconds
