ECG interpretation Flashcards
How many little boxes does one big box contains?
5 little boxes
Each little box represents ____ seconds
0.04s
Multiply 0.04 by ___ small boxes to make up __ large box
5 small boxes to make up 1 large box
How many seconds does each large box make up?
0.20 seconds
What does P wave mean?
atrial depolarization
What does a good P wave look like?
smooth, round and upright
What to look for with the P wave…..
- if there are no P waves
- if a P wave is present, but not followed by a QRS complex
- can give clues to pacemaker site
- P waves that vary in size and configuration
- Upright or inverse
What is the PR interval? How is it measured?
- amount of time it tasks atria to DEPOLARIZE and for impulse to travel through the AV node
- measured from the start of the P wave to the point at which the QRS complex begins
How long is the PR interval supposed to be?
<0.20s (one bigger box, 5 little ones)
What does the QRS complex supposed to look like?
Narrow, with sharply pointed waves and has a duration of less than 0.12s (3 small boxes or less)
What does the QRS complex represent?
Ventricular depolarization
What does a wide QRS mean?
a BLOCK somewhere
Do T waves really matter in reading a lead II ECG?
NOPE
What is the 1st step in reading an ECG rhythm?
Measure the heart rate
- 6 sec strip
- 300 rule
What is the 2nd step in reading an ECG rhythm?
Identify the P waves.
- upright? contoured? retrogade? inverted?
- do they all look the same?
What is the 3rd step in reading an ECG rhythm?
Measure the PI interval.
- should be less than 0.20s (one bigger box, 5 little ones)
What is the 4th step in reading an ECG rhythm?
Determine the relationship of the P waves with QRS.
- should be 1:1 ratio
What is the 5th step in reading an ECG rhythm?
Determine if the QRS complex is wide or narrow.
- wide means there is a block
- narrow=normal, <0.12s, 3 little boxes
What is the 6th step in reading an ECG rhythm?
Determine rhythm regularity.
- are the QRS’s equally distance from each other?
- is it regularly irregular? irregularly irregular?
What is the number sequence for the 300 rule?
300, 150, 100, 75, 60, 50, 43, 38, 33, 30
What are the 3 different categories of dysrhythmias?
- disorder of impulse formation
- SA node failure, other pacemakers and ectopic focuses - Disorders of impulse conduction
- Delayed or blocked in the heart - Artifact
- 60 cycle inference, poor contact, damaged cable
Rate: 60-100 bpm
P waves: present/ upright
PRI: <0.20s
QRS: <0.12s
Ratio: 1:1
Rhythm: regular
Normal Sinus Rhythm
Rate: 60-100 bpm, but sometimes below rates of 60bpm, the rate slightly increases and decreases with expiration and inspiration
P waves: present/ upright
PRI: <0.20s
QRS: <0.12s
Ratio: 1:1
Rhythm: regular irregular, it coincides w breathing patterns
Heart rate varies slightly with respiratory pattern
Sinus Arrhythmia
Rate: <60bpm
P waves: present/ upright
PRI: <0.20s
QRS: <0.12s
Ratio: 1:1
Rhythm: regular
Sinus Bradycardia
Rate: >100bpm
P waves: present/ upright
PRI: <0.20s
QRS: <0.12s
Ratio: 1:1
Rhythm: regular
Sinus Tachycardia
Rate: 140-250bpm
P waves: buried under the preceding T wave
PRI: N/A
QRS: narrow <0.12s
Ratio: N/A
Rhythm: regular
Supra ventricular Tachycardia
Rate: rate change is sudden and unexpected (120-230bpm)
P waves: may be seen during slower phase
PRI: N/A during fast rate
QRS: narrow
Ratio:1:1(during slower rhythm)
Rhythm: each section has regular rhythm
Paroxysmal Supraventricular Tachycardia (PSVT)
What is RE ENTRY syndrome?
when conduction is abnormally slow in some area (ex. heart damage) the myocardial cells are unable to activate the fast sodium channel
part of impulse will arrive late and potentially be treated as a new impulse
series of beats, sudden onset
What is pre excitation syndrome?
occurs because there exists muscle fibre that penetrates the AV ring that normally isolates the 2
What are types of pre excitation syndromes?
WPW- (kent bundle): pathway through the AV ring that bypasses the Av node
MANHEIM FIBERS: from the AV node, bundle of His or branches
LGL- bypass the AV node and goes directly to the bundle of His
Rate: generally slow-normal
P waves: present and upright, the FOLLOWING beat will have a different morphology from the other P waves
PRI: interval normal
QRS: narrow
Ratio: 1:1
Rhythm: regular, expect where disrupted by the pause
sinus arrest
Rate: slow-normal
P waves: present except when dropped (after dropped, returns to normal)
PRI: normal
QRS: narrow
Ratio: 1:1
Rhythm: regular except where disrupted by dropped beats
Sinus exit block / SA block
- Ectopic beat from somewhere in the atria
- Contraction ahead of the regular P wave
- similar OR diff morphology
- PRI can be normal or long
- SA node is firing normally and the atrium decided to shoot a single off
Premature Atrial Complex (PAC)
When the P wave must be upright during a PAC, if it is inverted/ retrograde, what is it called?
- coming from the AV node
Premature Junctional Complex (PJC)
Rate: 40-60bpm
P waves: absent, inverted or retrograde (after T)
PRI: is normal or short or N/A
QRS: usually narrow
Ratio: 1:1
Rhythm: regular
Junctional
Rate: >100bpm
P waves: retrograde
PRI: short
QRS: narrow
Ratio: 1:1
Rhythm: regular
Junctional tachycardia
- waves with NO organization or regularity
- indication of random electrical activity
- can be atrial or ventricular
- wavy line
Fibrillation
Rate: will vary
P waves: not discernible
PRI: N/A
QRS: usually narrow
Ratio: N/A
Rhythm: irregularly irregular= the HALLMARK…
A-Fib (Atrial fibrillation)
What should we give to pt’s who are in A FIB?
blood thinners
Rate: 200-350bpm
P waves: saw tooth appearances
PRI: n/a
QRS: usually narrow
Ratio: 2:1, 3:1, 4:1
Rhythm: usually regular
Atrial Flutter
Ventricular Rhythms: What are the different types of AV blocks?
1st degree (long PRI)
2nd degree: type I & II
3rd degree
Rate: depends on the underlying rhythm
P waves: normal
PRI: >0.20s
QRS: narrow
Ratio: 1:1
Rhythm: regualr
1st degree AV block
Rate: generally slow-normal
P waves: present, stand alone
PRI: becomes increasingly longer until a beat is dropped (hint: the PRI before dropped beat will be longer the one after) LONG before—> SHORT after
QRS: narrow
Ratio: 1:1
Rhythm: regularly irregular
2nd degree- type I
Rate: generally slow
P waves: present, stand alone
PRI: when there are P waves associated with QRS the PRI will be CONSTANT
QRS: narrow
Ratio: FIXED ratio
Rhythm: usually regular
2nd degree, type II
Rate: slow 45 or below, atrial rate is normal
P waves: present, stand alone
PRI: N/A
QRS: wide
Ratio: N/A
Rhythm: regular
- No connection between the atrium and ventricles
- Pt will obviously be SICK
3rd degree (complete block)
Rate: 20-40bpm
P waves: absent
PRI: N/A
QRS: >0.12 and BIZARRE looking
Ratio: N/A
Rhythm: regular
Idioventricular
Rate: >40 less than 100bpm
P waves: absent
PRI: N/A
QRS: wide >0.12 and BIZARRE
Ratio: N/A
Rhythm: regular
Accelerated Idioventricular- AIVR
Rate: 120-250bpm
P waves: N/A
PRI: N/A
QRS: always wide >0.12s (usually >0.14s)
Ratio: N/A
Rhythm: usually regular unless polymorphic
Ventricular Tachycardia
What is monomorphic V Tach?
All QRS complexes have the same morphology
What is polymorphic V Tach?
When the QRS complexes vary in size/shape!
What is torsades de pointes?
axis of the QRS complex changes from positive to negative in a haphazard fashion
“twisting of points”
can convert to NSR or V FIB
- caused by premature firing of the ventricular cell
- ventricular pacer fires before the SA node
- underlying pacing rhythm schedule is not altered, so the beat after the PVC on arrive on time
- ectopic complexes
- occurs EARLY than expected
Premature Ventricular Complex
What does multifocal mean?
arising from 2 or more ectopic foci
- results in multiple QRS morphologies
What does unifocal mean?
arising from a single ectopic foci
- results in each PVC looking identical
Two consecutive PVCs?
couplet
Every other beat is a PVC?
Bigeminy
Every third beat is a PVC?
Trigeminy
Every fourth beat is a PVC?
Quadrigeminy
- Rhythm most commonly seen in cardiac arrests
- Responds well to defibrillation
- CPR compressions help make heart more susceptible to defibrillation
- can be coarse or fine
Ventricular Fibrillation (V FiB)
V fib pts are clinically _______ !!
DEAD
2 types of V FIB:
coarse and fine
- Flatline
- Entire heart is no longer contracting
- Generally confirmation of death
ASYSTOLE
- clinically dead or VSA (no pulse)
- presence of some form of electrical activity and a rhythm but the pt is apenic and pulseless
- CPR is indicated
- can be any heart rhythm
Pulseless Electrical Activity (PEA)
What are the 6 H’s of causes of PEA:
Hyperkalemia
Hypoxia
Hydrogen Ion Access
Hypoglycemia
Hypothermia
Hypovolemic
What are the 6 T’s of causes of PEA:
Tamponade
Toxins
Thrombosis (MI)
Thrombosis (PE)
Trauma
Tension pneumothorax
What is artifact?
- somatic tremors from skeletal muscle contraction
- alternating current
- disrupt the baseline as well as the clarity of the tracing
