Download Normal Sinus Rhythm

© Hayley Coxon 2014
ECG Rhythm Recognition
What to Look for on a rhythm strip
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Is there electrical activity?
Is it regular or irregular?
What is the QRS rate?
Is the QRS narrow or wide (>0.12 s)?
Is atrial activity present:
– If P waves, are they consistent?
– If other activity, what?
• How is P wave related to QRS?
– Is there a P wave in front of every QRS complex?
– What Is the PR interval too short (<0.12 s) or too long
(>0.2 s)?
– Is the PR interval constant or does it vary?
© Hayley Coxon 2014
Muscle Tremor
P
P
P
P
• All waveforms are present, but are difficult to define due to the
wavering appearance on the isoelectric line.
• Common causes of muscle tremor are patient shivering or
anxiety.
• It may be difficult to accurately assess an ECG where muscle
tremor is present.
© Hayley Coxon 2014
Electrical Interference
• It may be difficult to make any assessment of an ECG where
there is electrical interference; none of the waveforms are clearly
defined.
• Common causes of this phenomenon are any electrical
appliances in close proximity to the ECG machine: i.e TV,
electrical beds, infusion pumps etc.
• Usually once all appliances are unplugged, a satisfactory quality
ECG can be carried out.
© Hayley Coxon 2014
x
Atrial extrasystoles (AE)
• AE’s are a common form of supraventricular extrasystole.
• Cause is atrial beat arising outside the sinus node.
• Patients are generally asymptomatic and there is no treatment
indicated.
• A trial extrasystole falling on a critical time of atrial repolarisation
may trigger atrial fibrillation (AF) in some vulnerable patients.
© Hayley Coxon 2014
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x x x
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Atrial Fibrillation (AF)
• The atrial depolarisation is disorganised resulting in a chaotic
ventricular rhythm.
• The ventricular response rate may be normal/fast/slow and
dependent on:
• AV nodal properties
• Vagal & sympathetic tone
• Drugs that affect AV node
• The commonest sustained cardiac arrhythmia
© Hayley Coxon 2014
© Hayley Coxon 2014
Atrial Fibrillation
• It’s prevalence doubles with each advancing decade of life
• Risk factors for developing AF
• Increasing age, diabetes, HTN, valve disease
• Often caused by coexisting medical conditions
• cardiac and non cardiac
• Adverse effects results from
• haemodynamic changes – 20% reduction in CO
• thromboembolic complications – prothrombotic state
• Major cause of morbidity and mortality, increasing risk of death, heart
failure and embolic phenomena including stroke
• Treatment is usually with oral drug therapy, although may be
successfully electrically cardioverted in patients with persisting AF of
recent onset.
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Atrial Flutter
• A malfunction in the pattern of atrial depolarisation. A flutter
usually gives atrial waves in the range of 280-320bpm.
• The AV node usually blocks 1/2 of these impulses and gives a
ventricular response rate of 150bpm.
• Atrial flutter is usually regular in rhythm and displays a ‘sawtoothed’ appearance (especially V1) as above.
• Very responsive to DC electrical cardioversion.
© Hayley Coxon 2014
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Supraventricular
Tachycardia (SVT)
• SVT is a general term for tachycardias that originate above the
ventricles.
• Rate may be in the range of - 150-250bpm
• Commonly starts in early adult life and is normally inconvenient but
benign.
• Adenosine to block AV response may slow the rate to determine
underlying atrial rhythm or may facilitate chemical cardioversion.
© Hayley Coxon 2014
Junctional Rhythm (Nodal)
x
High
Mid
Low
• When the electrical pathway originates further down in the conduction
system, but is still coming from or near the AV node, a ‘nodal’ (junctional)
rhythm occurs.
• If the pacemaker is high - an inverted P-wave may occur before the QRS
complext.
• If the pacemaker is within the node - the P-wave is usually absent.
• If the conducting pathway is lower down, then the P-wave may have an
inverted appearance and occur after the QRS and even resemble a S
wave.
© Hayley Coxon 2014
Supraventricular Tachycardias
• Atrial Fibrillation
• Atrial flutter
• Atrial tachycardia,
• Automatic junctional tachycardia,
• Atrioventricular re-entry tachycardia (AVRT)
• WPW
• AV nodal re-entry tachycardia
• Can be intermittent and self-terminating
© Hayley Coxon 2014
© Hayley Coxon 2014
Wolff-Parkinson-White Syndrome (WPW)
Normal
pathway
Accessory
pathway
Paroxysmal
tachycardia
Delta
wave
anterograde / retrograde
conduction
PR
• WPW is a syndrome (AVRT) with a characteristic electrocardiogram shortened PR interval (<0.12secs) and a slurred upstroke on the QRS
complex (delta wave) together with a tendency to supraventricular
arrhythmias.
• It is caused by an accessory conduction pathway which bypasses the
AV node, Bundle of Kent
• Type A and B depending on the side of the accessary pathway
First-degree Heart Block
P
P
• The measurement from the start of the P-wave to the start of the
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R-wave is prolonged to >5 sm squares (0.20secs).
The P-waves and R-waves remain constant and regular.
The heart rate is usually within normal parameters.
Patient is not compromised and no treatment indicated.
Caused by delay within the AV node.
© Hayley Coxon 2014
Second-degree Heart Block Mobitz
type I (Wenckebach)
P
P
P
R
P
P
?
• The P-R interval becomes progressively elongated with each
heart beat; eventually conduction fails completely.
• The cycle then repeats itself once again.
• May be seen in individuals with high vagal tone especial during
sleep.
• Where it occurs in complication of inferior MI, it does not usually
require a pacemaker and often may be reversed with myocardial
reperfusion.
© Hayley Coxon 2014
Second-degree Heart
Block Mobitz type II
?
• Most P-waves conducted as normal - followed by QRS.
• The P-R interval is normal and usually constant.
• Occasionally, the atrial conduction is not followed by a QRS
complex.
• Thought to be caused by an abnormality in the bundle of His.
• Considered more serious than type I block in that it can progress
to complete heart block without warning.
© Hayley Coxon 2014
2:1 Heart Block
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?
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• Every alternate P-wave is not conducted.
• Cannot be classified as either Mobitz Type I or Mobitz Type II.
• Use of a pacemaker may be considered.
© Hayley Coxon 2014
Third-degree Heart Block
(complete heart block)
x x
P
P
P
P
P
P
• The P-P and R-R intervals are each usually regular but have no
relation to each other.
• This dissociation is due to a block at the AV junction.
© Hayley Coxon 2014
Ventricular (Unifocal)
Extrasystole
x
• Occasional extrasystoles are common in healthy adults.
• 3 or more in a row may be described as VT, but shorter runs are
usually called salvoes.
• The morphology of each ectopic is unchanged if depolarisation
originates from a single focus.
© Hayley Coxon 2014
Coupled Ventricular
Extrasystole
x
• This is the term used when every alternate beat is an
extrasystole.
• Treated only in exceptional circumstances.
• Coupled extrasystole may cause bigeminy: the condition in which
alternate ectopic beats of the heart are transmitted to the pulse
and felt as a double pulse beat followed by a pause.
© Hayley Coxon 2014
Couplets
x
• A couplet is where there are 2 ventricular ectopics in a row.
• Not usually treated except in circumstances that make the patient
vulnerable to more serious arrhythmias
© Hayley Coxon 2014
R on T Extrasystole
x
• When the ventricular extrasystole falls on the T-wave. This may
trigger serious ventricular arrhythmias.
© Hayley Coxon 2014
Ventricular (Multifocal) Extrasystole
x
x
x
• Where the origin of the ectopic beat originates from differing foci
within the ventricle.
• This may signify a high degree of ventricular excitability.
• Although extrasystoles may occasionally precipitate more
malignant arrhythmias, any decision on treatment should be
made only after considering the risk of anti-arrhythmic drugs.
© Hayley Coxon 2014
Paced Beats
Pacing
wire
x
• A ventricular paced beat will display a broadened QRS complex.
• The slim, deflection immediately preceding the R-wave denotes
the pacing spike (arrowed above).
© Hayley Coxon 2014
Idioventricular Rhythm
x
• Often seen with reperfusion following acute MI, idioventricular
rhythm can be regarded as ‘slow VT’.
• The QRS is broad and bizarre, but uniform and regular.
• The rate is less than 100bpm.
• Usually no treatment is indicated.
© Hayley Coxon 2014
Torsades de Pointes
• From the French ‘twisting of points’. This describes a form of VT
where the cardiac axis twists round the isoelectric line.
• The rhythm may be intermittent and self-terminating. If it lasts
more than a few seconds the patient will become symptomatic.
• Common causes are electrical imbalance - i.e K+ and/or Mg++
depletion or prolonged Q-T interval frequently caused by drugs
such as Sotalol/Amiodarone or tricyclic antidepressants.
© Hayley Coxon 2014
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Ventricular Tachycardia
(VT)
• The origin of the heartbeat is in the ventricles, producing a QRS
complex >0.12secs.
• 3 ventricular beats in succession may be called VT (or salvoes).
• VT can range in rate from 100-300bpm and the patient may be
conscious and asymptomatic, symptomatic, or unconscious.
Treatment will depend principally on the patients’ clinical status.
© Hayley Coxon 2014
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Ventricular Fibrillation
(VF)
x
• The ventricles are ‘quivering’, leading to a complete loss of cardiac
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output.
Bizarre complexes are characteristic, but are variable amplitude (course /
fine VF).
The most common arrhythmia causing cardiac arrest, but becomes finer
as minutes pass and soon becomes indistinguishable with asystole.
Patient will require immediate defibrillation (10% reduction in success
rate as each minute passes).
Most common cause of death in early acute MI.
© Hayley Coxon 2014
Ventricular Standstill
• No ventricular response to atrial depolarisation.
• There is no cardiac output and the patient is in cardiac arrest.
• Pacing is required. It is usually effective if atrial activity is present.
© Hayley Coxon 2014
Asystole
• Implies the absence of ventricular activity.
• No QRS complexes are present.
• Patient is in a state of full cardiac arrest.
• In asystole - always check patient, check leads, check monitoring
mode (? Paddles), increase the monitoring gain to rule out fine
VF.
© Hayley Coxon 2014
© Hayley Coxon 2014