4093 6 Flashcards
What are 3 of the ways we evaluate an ECG
P wave shape
P R interval
QRS complex duration and shape
Where do you find the PR interval on the strip
from the beginning of the P to the beginning of the Q
The size of the PR interval reflects the
amount of time from the start of atrial depolarization to the start of ventricular depolarization
The normal time for PR interval is:
0.12 – 0.20 seconds (3 to 5 small boxes)
or the most part, Sinus dysrhythmias either effect the
rate or rhythm. The other stuff will be normal. So sinus dysrhythmias look similar to NSR
Sinus Rhythm is the only rhythm when
each of the five steps of rhythm analysis are “normal”
1500 method
count the little boxes between the peaks and divide into 1500
If Sinus tachycardia gets really fast, which one of the measurements are you unable to do
you can’t do the PR interval because the P is overtaken by the preceding T
Sinus Dysrhythmia often occurs as a
normal variant (can be in young people, athletes)
Sinus Dysrhythmia is frequently related to ____ and
breathing and pressure on the vagas nerve
Sinus Arrest occurs when
there’s sudden absence of electrical activity starting in the SA node
Sinus Arrest: A pause of ___-seconds is considered a medical emergency
six-seconds
Sinus Exit Block looks very much the same as
Sinus Arrest with one important distinction: with Sinus Exit Block the pause is a direct multiple of the R to R interval of the underlying rhythm. So it’s more orderly
PAC’s occur when
an early electrical impulse occurs from a location in the atria other than the SA node
PAC’s occur when an early electrical impulse occurs
from a location in the atria other than the SA node
PAC: because the signal is being fired from somewhere unusual, it results in a change in the shape of the
P wave (the shape might be fine, but it could be bisphasic)
The P wave with PAC’s will always be
upright
PAC: the R to R intervals could be
irregular
Atrial Flutter occurs when there is an obstruction within the
atrial electrical conduction system
Atrial Flutter occurs when there is an obstruction within the atrial electrical conduction system. Due to this impediment a series of
rapid depolarizations occur.
Atrial Fibrillation: P waves
are absent
What measurement can you not do in Atrial Fibrillation
PR interval (because there’s no P wave)
Atrial Fibrillation: rapid electrical activity overwhelms the AV node causing impulses to
enter the ventricular conduction system at irregular points. This results in irregular R to R intervals.
Many times when a patient has “new onset” Atrial Fibrillation the patient will report with a heart rate of
160 bpm or more
Atrial Fibrillation: When we say “Not all fibrillatory waves are created equal” what does that mean
some are coarse (big) and some are fine (small)
Atrial Fibrillation: This absence of contraction of the atria can result in a loss of cardiac output anywhere from 15 - 30% due to the absence of
atrial kick
Atrial Fibrillation: its impossible to determine the ___ rate on the ECG
atrial rate (because it’s just quivering)
Atrial Fibrillation with a ventricular response in excess of 100 bpm is commonly referred to as Atrial Fibrillation with “rapid ventricular response” or
uncontrolled A-fib
When analyzing a rhythm strip, it qualifies as being regular when
the PR interval measures the same
besides Asystole and Ventricular Fibrillation, the remaining ventricular rhythms typically have 2 key features
no P wave
will display a wide, bizarre QRS complex (measuring 0.12 seconds or greater)
Unifocal – abnormal complexes are of the same shape
all of the abnormalities have only ONE shape
Multifocal
the abnormalities have more than one shape
Bigeminy
abnormal complexes occur every second complex
PVC’s occur when
an early electrical impulse occurs from a location in either ventricle
PVC: The locus of stimulation being different, results in
a change in the morphology of the cardiac complex.
Ventricular Tachycardia: P wave
absent
Ventricular Tachycardia: QRS
wide, bizzare
at the onset of ventricular tachycardia, approximately 50% of patients
become unconscious
Although patients in V Tach may be treated with a defibrillator,
not all patients in Ventricular Tachycardia require this level of treatment
Ventricular Tachycardia: Depending upon their level of consciousness and blood pressure, the patient may be treated with
medications, synchronized cardioversion
or in the worst case scenario a defibrillator and BLS/ACLS response.
V fib: QRS
absent
V fib: Fibrillatory waves may be
coarse or very fine
The longer V Fib occurs, the smaller
the waveforms are likely to be
First degree heart block is actually a
delay rather than a block
First degree heart block finding
PR Interval will be longer than normal (over 0.20 sec)
With second degree heart block, Type I, some impulses
are blocked but not all
Second Degree Heart Block Type II (both of the main traits)
the impulse is blocked in the bundle of His.
Every few beats there will be a missing beat but the PR Interval will not lengthen
Second Degree Heart Block Type II: the impulse is
blocked in the bundle of His.
Second Degree Heart Block Type II: For every few beats there will be
a missing beat but the PR Interval will not lengthen
Second Degree Heart Block Type 1: More P waves can be observed vs
QRS Complexes (which makes sense because eventually a p wave impulse doesn’t go through so you’re missing a QRS)
Second Degree Heart Block Type 1: Each successive impulse undergoes
a longer delay
Second Degree Heart Block Type 1: the next impulse is blocked after
3 or 4 beats the next impulse is blocked
Second Degree Heart Block Type 1: PR Intervals will lengthen progressively with each beat until
a QRS Complex is missing
Third Degree Heart Block
no atrial impulses are transmitted to the ventricles
Third Degree Heart Block: no atrial impulses are transmitted to the ventricles. As a result
the ventricules generate an escape impulse, which is independent of the atrial beat.
In most cases the atria will beat at 60-100 bpm while the ventricles asynchronously beat at 30-45 bpm.
Third Degree Heart Block
