ECG Intro/ECG Vs. Telemetry Flashcards
Normal path for electrical conduction system of the heart:
SA node ==> AV node ==> Bundle of His ==> Purkinje fibers
Location of SA node
S RA
Location of AV node
Base of RA
Location of Bundle of His
IV septum
Location of Purkinje fibers
B V’s
What term refers to the heart’s ability to beat by itself without a nerve impulse?
Automaticity
What term refers to the heart’s ability to sustain a steady beat?
Rhythmicity
What term refers to the ability of the heart’s myocytes to conduct electrical activity?
Conductivity
How does repolarization of the cells occur?
K+ builds up outside of the cell as Na+ moves into the cell via fast channels when the cell membrane increases permeability to ions c the electrical impulse ==> the outside of the cell becomes more positive
How does depolarization of the cells occur?
Na+ moves into the cell via fast channels as the cell membrane increases its permeability to ions c the electrical impulse ==> the outside of the cell becomes more negative
During what phase of the electrical cycle does the contraction process occur?
Depolarization
How is depolarization possible if K+ is moving out of the cells while Na+ is moving into the cells?
K+ moves out more slowly than Na+ moves in because Na+ moves into the cell via the fast channels, so there is a period of time when the outside of the cells is less negative relative to the inside because more Na+ is inside the cells than K+ is outside the cells
What affects heart contractility and therefore heart rhythm?
Anything that affects electrolytes (Na+/K+)
Meds and health conditions
1 small box =
0.04sec
5 small boxes or 1 large box =
0.20sec
5 large boxes =
1sec
Hash marks are present every…
3sec ==> there should be 2 on a 6-sec telemetry strip
How many large boxes are in 6 seconds?
30 ==> 30 large boxes are in a 6-sec telemetry strip
A hash mark should be present every how many large boxes?
15
5 vertical small boxes =
0.5mV
How many small boxes are in 1 minute?
1500
Which imaging method yields only 1 view of the heart?
Telemetry
Which imaging method yields a 360 view of the heart?
12-lead ECG
A 12-lead ECG can give information about…
HR Heart rhythm Hypertrophy (and the axis) Infarction/ischemia Views of the heart every 30 degrees
T/F: a 12-lead ECG can be used to dx conditions
T
How can a 12-lead ECG give information about hypertrophy?
The impulse will take longer to move through thicker muscle tissue
How can a 12-lead ECG give information about infarction/ischemia?
Bad conduction or contraction will be shown through abnormal electrical movement
Can a telemetry monitor be used to monitor a heart condition after is is dx’d?
Yes
A telemetry strip yields information about…
HR
Heart rhythm
Views the heart from one direction
What are the 6 limb leads in a standard 12-lead ECG?
I, II, III, aVR, aVL, aVF
The limb leads evaluate the heart in what plane?
Frontal
Electrical information travels in what direction through the ECG leads?
Impulses flow from negative –> positive ions
What does aV stand for?
Augmented voltage
I direction:
R arm –> L arm (across chest)
II direction:
R arm –> L foot (top –> bottom)
III direction:
L arm –> middle (top –> bottom)
Direction aVR:
–> R
Direction aVL:
–> L
Direction aVF:
Foot –> middle
The chest leads are known as:
Precordial
What are the 6 precordial leads in a standard 12-lead ECG:
V1, V2, V3, V4, V5, V6
The precordial leads evaluate the heart from which plane?
Transverse plane
What are the R leads (that evaluate the R side of the heart)?
AVR, V1, V2
What are the A leads (that evaluate the A portion of the heart)?
V3 (septum), V4
What are the lateral leads (that evaluate the L side of the heart - and the LV)?
AVL, I, V5, V6
Which leads evaluate the LV?
AVL, I, V5, V6
What are the I leads (that evaluate the I portion of the heart)?
II, III, aVF
What is at the top of Einthoven’s triangle?
I
What is at the bottom (apex) of Einthoven’s triangle?
LL (and positive ions)
What is at the top right of Einthoven’s triangle?
RA (and negative ions)
What is at the top left of Einthoven’s triangle?
LA (and positive ions on the top and negative ions on the bottom)
What is at the diagonal right on Einthoven’s triangle?
II
What is at the diagonal left of Einthoven’s triangle?
III
What is at the center of Einthoven’s triangle?
The heart
What is at the top right diagonal on the inside of Einthoven’s triangle?
AVR (and positive ions)
What is at the top left diagonal on the inside of Einthoven’s triangle?
AVL (and positive ions)
What is at the bottom on the inside of Einthoven’s triangle?
AVF (and positive ions)
The circle of axes gives view of the heart every how many degrees?
30
In the circle of axes, aVR is located where?
~150 degrees (in between 150 and 120) (top R corresponding to position in Einthoven’s triangle)
In the circle of axes, aVL is located where?
~-30 degrees (in between -60 and -30 degrees) (top L corresponding to location on Einthoven’s triangle)
In the circle of axes, I is located where?
0 degrees (L middle, corresponding to direction ions flow across chest)
In the circle of axes, II is located where?
60 deg (bottom L, corresponding to direction ions flow from R arm –> L foot)
In the circle of axes, aVF is located where?
90 deg (bottom center, corresponding to location on inside of Einthoven’s triangle)
In the circle of axes, III is located where?
120 deg (bottom R, corresponding to direction ions flow from L arm to the middle)
In the circle of axes, what is “normal?”
~30 deg - ~105 deg
A lateral ECG view can give information about which artery?
Lateral circumflex a. Or descending branch of LAD a.
An inferior ECG view can give information about which artery?
RCA or lateral circumflex a.
An anterior or septal ECG view can give information about which artery?
LAD a.
A lateral ECG view can give information about which artery?
L circumflex a. Or diagonal branch of LAD a.
Why is the LAD artery important to view?
If the Pt. Had an MI, there will be plaque in that artery, which can require a cardiac cath to further view/dx
The deflection of an ECG complex is POSITIVE (upright) if…
The depolarization wave moves TOWARDS a POSITIVE electrode
The deflection of an ECG complex is NEGATIVE (upside down) if…
The depolarization wave moves AWAY FROM a POSITIVE electrode
The deflection of an ECG complex is ISOELECTRIC (flat) if…
The depolarization wave moves PERPENDICULAR to a POSITIVE electrode
Inversion can be a sign of…
MI
The waves seen on complexes represent depolarization or repolarization?
DEpolarization
