ECG 2 Flashcards
12 leads and 2 axes:
* The 12 lead ECG gives — different views of the heart
– this is why the waveforms look — to each other
* The limb leads and augmented leads view the heart in the — plane
– limb leads are leads —
– augmented leads are leads —
* The chest leads (C1-6) view the heart in the — plane
12
different
vertical
lead I , II , III
AvR, AvL, AvF
horizontal
the bipolar limb leads:
lead I :
lead II:
lead iii :
the augmented leads:
lead AvF:
lead AvL:
lead AvR:
- Lead I
– records right arm to left arm - Lead II
– records right arm to left leg - Lead III
– records left arm to left leg - Lead AvF
– records lead I to left leg - Lead AvL
– records lead II to left arm - Lead AvR
– records lead III to right arm
the precordial or chest leads:
* The chest leads had — anatomical positions
* The record in the — plane from the heart – to the –
the 12 lead ECG:
* Each lead gives a different view of the heart
* The anterior surface is seen in leads
– —-
* The lateral surface in seen in leads
– —
* The inferior surface in seen in leads
– —
* The right side of the heart is seen in leads
– —
fixed
horizontal
out
electrodes
V1, V2, V3 & V4
I, AvL V5 & V6
II, III & AvF
AvR & V1
- The ECG provides information about—, — and the — of events in the cardiac cycle
– arrhythmias, conduction blocks - It can also give information about the —- such as ishcmeia , damage and hypertrophy
- The shape of the ECG waveform will change in certain conditions and different leads highlight different sections of the myocardium
– increased voltages (height) suggest increase —
– wider waves or intervals imply — conduction
rate , rhythm , timing
heart muscle
increased muscle mass
slowed
rhythm:
* Check the rhythm strip at the – of the trace
* Rate should be between — bpm
– the — interval
* Is the pattern regular?
* Does every P wave produce a QRS?
* The heart rhythm should be — and —
– not too fast: — > — bpm
– not too slow: — < – bpm (not as clear cut)
* If it is not regular then, by definition, it is irregular
– an —
* Irregular rhythms can be described as being either — or
—
– think here about the decimal expansion of fractions
– regular & repeating (e.g. 1/3 = 0.3333333333333333333*)
– irrational & irregular (e.g. Pi = 3.14159265358979323846…)
bottom
60-100
R-R
regular and consistent
tachycardia >100
bradycardia <60
arrhythmia
regularly or irregularly irregular
arrhythmia ( disambiguation ) :
* The term arrhythmia should not to be taken literally
– it literally means without rhythm (as in amoral, atheist etc)
* It collectively describes a — in the — sequence of — impulses
* These can be altered — (tachy- or bradycardia)
– regular — but fast or slow
* These can be rhythmical
– — patterns
* These can be conduction problems
– — and — are ok but — too slow or fast
change
normal
electrical
rate
heart bear
irregular pattern
rate and rhythm
conduction
sinus rhythm:
* Comes from the —
– is reflected in the —
* Normal sinus rhythm regular and — beats/min
* Spreads through the —
* Conducts more — through AV node
* Conducts — through Bundles of His and Purkinje fibres
SA node
p wave
60-100
atrium
slowly
rapidly
altered sinus rhythm:
* Sinus tachycardia: – rate but — rhythm
– mainly – as in — or — to —
– also increased high — or cardiac —
* Sinus bradycardia: – rate but — rhythm
– seen in – , — rate but — stroke volume
– — vagal (PNS) activity (e.g. carotid sinus syndrome)
* Sinus arrhythmia: a — rhythm from the — node
– cross talk between — signals
– heart rate increases on —
increased
normal
sympathetic
expertise
2ndary
low blood pressure
temp or cardiac toxicity
decreased
normal
atheltes
low
large
increased
regularly irregular
sa node
cardiorespiratory signals
inspiration.
mechanisms of arrhythmia:
* Arrhythmias may arise due to a number of reasons
* These include:
1. Changes in —
2. — activity (after — )
3. Conduction — and appearance of – circuits
automaticity
triggered
depolarisation
delay
re entery
automaticity:
* The SA node is not alone in its automaticity
– but it is the —
* Sino-atrial (SA) node
– depolarisation rate —/min
– depends on the — nervous system
* Atrio-ventricular (AV) node
– depolarisation rate — /min
* Purkinje fibers
– depolarisation rate ~–/min
fastest
60-100
autonomic
40-50
35
afterdepolarisation:
* Afterdepolarisations are abnormal — outwith the normal activity
* They are either early- ( —) or delayed afterdepolarisations (—)
* EADs occur when stimulation occurs during the— (Phase –) or— phase (Phase –)
* DADs occur during — (–) and trigger—, but— the time normally expected
– due to elevated — levels
stimuli
EAD
DAD
platue ( phase 2)
repolarisation phase ( phase 3 )
phase 4 ( resting )
depolarisation
before
ca+2
re-entery circuits:
* Not all parts of the heart will —
– blood vessels, damaged fibrotic tissue etc
* When depolarisation hits these areas it cannot go through, but must
go around
– think of a road diversion or a crowd avoiding an obstacle
* Providing the routes are the — length there is no problem…but if one is—, then problems may arise
– — plaques or – heart— path length
– ischaemia — conduction, due to high — and —
– this goes back to the —
depolarise
same
longer
fibrous and dilated heart
increases
slows
high k+ and depolarisation
refractory period
fibrillation:
* Rather than the coordinated spread of depolaristion through the heart this is — and —
* Atrial fibrillation
– no coordinated — of the atria, so no —
– — transmission to ventricles, —- tachycardia
* Ventricular fibrillation
– individual myocytes depolarising so no — waveform
– no coordinated — , no —
uncoordinated ad sporadic
depolarisation
no p wave
irregular
irregularly irregular
discernible
contraction , cardiac output
check slide 21 so important
ectopic beats ( atria) :
* These are — contractions due to abnormal — from ectopic (abnormal) —
– areas of — (altered —)
– excessive — of muscle fibres
– — actions
* Premature atrial contractions are –
– show up as extra – and — pulse on the ectopic beat
* Premature AV node contraction is similar
– also has — pulse but no — here since depolarisation travels to atria AND
ventricles
– P wave is – in the resulting QRS
premature
impulses
foci
ishcmeia
membrane potential
stretch
drug action
fairly common
extra p wave
weak pulse
no p wave
lost
ectopic beats ( ventricles ) :
* Also called —
* Present as a — and — and —
– conduction through muscle is — than conducting system
– the slow conduction means fibres that depolarised first also — first
* Minor PVCs caused by — (nicotine/coffee) but others are major and may lead to fibrillation
* Anomalous pathways between atria and ventricles in pre-excitation of
ventricle PVCs
– e.g. — Syndrome
premature ventricular contractions (PVCs)
winded and QRS and inverted T wave
slower
repolarise
drugs
Wolff-Parkinson-White Syndrome
summary:
* The ECG reflects the — and so the — should reflect this
– everything in the correct order, not too fast or too slow
* The rhythm should be regular
– if irregular, is it repeating (—)
– or is it just random (—- )
* A change in the refractory period can disrupt the — of depolarisation and create — circuits
– the muscle is affected by — , — etc all can disrupt the electrophysiology
cardiac cycle
waveforms
regular irregular
irregular irregular
synchronisation
re enetery
stretch , oxygen
