Chapter 11 Heart Rhythms
ECG leads
o Sees action of the myocardial cells
o 3-lead ECG
Basic one to look at the heart
Quickly see what’s happening
The MINIMUM amount of leads you need
Can get a couple different views of the heart
Seen a lot in the ER; white, black & red
o 5-lead ECG
Most hospitals have this for continuous monitoring; the screen
Pts in ICU for a few days
o 12-lead ECG
Portable, paper print out ECG
Think of machine seen in the clinical ER
NEEVR leave someone on a 12-lead the whole time
This is the best for clinical data; you can see what is going on from an electrical
standpoint from many different points of view
o Preparation
5-lead
1 brown; middle of chest (4th intercostal space mid sternum)
Black (arm) over Red (leg); left side
White (arm) over Green (leg); right side
***AVOID bony areas, hair, dirty flesh, irritation to breaks in the skin
Will have gel; conductive substance that allows signal to travel through, reach
the lead and travel back through the wire
Intervention: shave area, clean area, check for abrasions, etc.
o Troubleshoot
Sometimes, if you have leads that are a little farther away from the heart, there
might be an alteration in the electrical stimulus d/t movement of the muscle
Muscular movement affects this a lot (ex: shivering, moving, etc)
Artifact: something in the way of fully reaching the heart signals
Ex: lot of hair, someone who coughs a lot, touching pt before shock from
CPR machine
Intervention: change patches every 24 hours bc patches will dry out
Anatomy of electrical heart pattern
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o SA node intrinsic rate: 60-100 bpm
SA (60 bpm) node is the pacemaker of the heart, which excites the right atrium
to contract
o If SA node fails, AV node takes over, which is 40-60 bpm
AV (20-40 bpm) node is there to be a “backup plan”; middle between R atrium
and L ventricle; extra “kick” of the heart
THE PULSE STARTS BIG AND THEN GOES SMALL ONCE IT GETS TO THE
VENTRICLES: SLOWS IT DOWN ENOUGH BEFORE ENTERING THE VENTRICLES TO
THE BODY
POINT OF THE AV NODE = ALLOW THE VENTICLES TO FILL PROPERLY
o Ventricular intrinsic rate 20-40; cannot last long!!
o Goes to L and R bundle branches, breaking out into the purkinje fibers, which send out
the final impulses, or final contractions of the L and R ventricle
ECG Analysis
o In between each tic mark is 3 seconds; 6 seconds total
o **if HR is 7 beats in 6 seconds, what is it per minute?
A: 70 bpm (7 bpm * 60 seconds or 1 min)
o ***bigger squares = 0.20 seconds per square, so how many to make 1 second?
A: 5 big squares
o ***how many in 3 seconds?
A: 15 big squares
o Smaller squares are 0.04 seconds per square, so how many would equal a big square?
A: 5 small squares
o Read ECG from left to right
,o Waveforms
P wave
P wave: atrial depolarization; the start of atrial concretion (atrial
kick)
WE ONLY FOCUS ON LEAD II bc it is the standard
QRS
QRS complex: ventricular depolarization (ventricle contraction)
Normal: 0.06-0.12
T wave
T wave: ventricular repolarization (ventricle relaxation)
ST segment
ST segment: measure of end of time of QRS to ventricular
repolarization
PR interval
, PR interval: the time it takes for the atria to start contracting to the
ventricles to start contracting
Normal: less than 0.20
Ischemia and Infarction
o ECG changes indicating ischemia and infarction
ST segment; elevated? Depressed?
Is it on the isometric line where it should be
Elevated ST segment; sign of myocardial injury, preinfarction, or pericarditis
Depressed ST segment; sign of myocardial ischemia
T wave
o Absolute Refractory
From the start of the Q to the middle of the T wave
absolute is time in which ventricle cannot be ready to go again, if we try to,
nothing will happen
o Relative Refractory
Could kill a person if shocked by a defibrillator
Ex: “shock not advised”
This could send them into Vfib and kill them
Do NOT touch pt or your heart will be sent into an abnormal rhythm
relative is might get something going, but nothing good will occur….we can
cause a ventricular arrhythmia and cause death
ECG assessment questions to ask
o What’s the HR? (normal 60-100 bpm)
**if youre looking at a 6 second strip, and the HR is 60-100 bpm, how many
QRS’s do you want to have?
ECG leads
o Sees action of the myocardial cells
o 3-lead ECG
Basic one to look at the heart
Quickly see what’s happening
The MINIMUM amount of leads you need
Can get a couple different views of the heart
Seen a lot in the ER; white, black & red
o 5-lead ECG
Most hospitals have this for continuous monitoring; the screen
Pts in ICU for a few days
o 12-lead ECG
Portable, paper print out ECG
Think of machine seen in the clinical ER
NEEVR leave someone on a 12-lead the whole time
This is the best for clinical data; you can see what is going on from an electrical
standpoint from many different points of view
o Preparation
5-lead
1 brown; middle of chest (4th intercostal space mid sternum)
Black (arm) over Red (leg); left side
White (arm) over Green (leg); right side
***AVOID bony areas, hair, dirty flesh, irritation to breaks in the skin
Will have gel; conductive substance that allows signal to travel through, reach
the lead and travel back through the wire
Intervention: shave area, clean area, check for abrasions, etc.
o Troubleshoot
Sometimes, if you have leads that are a little farther away from the heart, there
might be an alteration in the electrical stimulus d/t movement of the muscle
Muscular movement affects this a lot (ex: shivering, moving, etc)
Artifact: something in the way of fully reaching the heart signals
Ex: lot of hair, someone who coughs a lot, touching pt before shock from
CPR machine
Intervention: change patches every 24 hours bc patches will dry out
Anatomy of electrical heart pattern
\\
,
o SA node intrinsic rate: 60-100 bpm
SA (60 bpm) node is the pacemaker of the heart, which excites the right atrium
to contract
o If SA node fails, AV node takes over, which is 40-60 bpm
AV (20-40 bpm) node is there to be a “backup plan”; middle between R atrium
and L ventricle; extra “kick” of the heart
THE PULSE STARTS BIG AND THEN GOES SMALL ONCE IT GETS TO THE
VENTRICLES: SLOWS IT DOWN ENOUGH BEFORE ENTERING THE VENTRICLES TO
THE BODY
POINT OF THE AV NODE = ALLOW THE VENTICLES TO FILL PROPERLY
o Ventricular intrinsic rate 20-40; cannot last long!!
o Goes to L and R bundle branches, breaking out into the purkinje fibers, which send out
the final impulses, or final contractions of the L and R ventricle
ECG Analysis
o In between each tic mark is 3 seconds; 6 seconds total
o **if HR is 7 beats in 6 seconds, what is it per minute?
A: 70 bpm (7 bpm * 60 seconds or 1 min)
o ***bigger squares = 0.20 seconds per square, so how many to make 1 second?
A: 5 big squares
o ***how many in 3 seconds?
A: 15 big squares
o Smaller squares are 0.04 seconds per square, so how many would equal a big square?
A: 5 small squares
o Read ECG from left to right
,o Waveforms
P wave
P wave: atrial depolarization; the start of atrial concretion (atrial
kick)
WE ONLY FOCUS ON LEAD II bc it is the standard
QRS
QRS complex: ventricular depolarization (ventricle contraction)
Normal: 0.06-0.12
T wave
T wave: ventricular repolarization (ventricle relaxation)
ST segment
ST segment: measure of end of time of QRS to ventricular
repolarization
PR interval
, PR interval: the time it takes for the atria to start contracting to the
ventricles to start contracting
Normal: less than 0.20
Ischemia and Infarction
o ECG changes indicating ischemia and infarction
ST segment; elevated? Depressed?
Is it on the isometric line where it should be
Elevated ST segment; sign of myocardial injury, preinfarction, or pericarditis
Depressed ST segment; sign of myocardial ischemia
T wave
o Absolute Refractory
From the start of the Q to the middle of the T wave
absolute is time in which ventricle cannot be ready to go again, if we try to,
nothing will happen
o Relative Refractory
Could kill a person if shocked by a defibrillator
Ex: “shock not advised”
This could send them into Vfib and kill them
Do NOT touch pt or your heart will be sent into an abnormal rhythm
relative is might get something going, but nothing good will occur….we can
cause a ventricular arrhythmia and cause death
ECG assessment questions to ask
o What’s the HR? (normal 60-100 bpm)
**if youre looking at a 6 second strip, and the HR is 60-100 bpm, how many
QRS’s do you want to have?
