[ECGmadeasy][arrhythmias] Flashcards
extra beat supraventricular arryhthmias bradyarryhthmias ventricular arryhthmias
yes
yes
smoking alcohol caffiene
Mg2+ Ca2+ K+
thyroid disease
phaechromocytoma thyroid disease
hypoxia hypercapnia
pneumonia
metabolic acidosis
palpitations chest pain syncope/pre-syncope
hypotension pulmonary oedema
depolarisation begins at the sinus node
the place in the heart where depolarisation occurs
P waves present? P+QRS wave relationship (should be 1 QRS per P) width of QRS
less than 120 ms
most frequent depolarisation (SA node usually has the highest frequency of discharge)
Lead in which the P wave is most easily seen.
AVN atria (anywhere) Ventricles (anywhere)
junctional nodal
sinus atrial junctional *the depolarization waves spreads normally through His*
Normal as the depolarisation wave is spreading normally through the bundle of His. i.e. it is the same if the initiation is at the AVN/atrial/SA node
Depolarisation spread through the purkinje fibres (slower/abnormal)
Repolarisation is also abnormal.
supraventricular arrhythmia *with a few exceptions
ventricular arrhythmia
Wolff-Parkinson-White (WPW) Supraventricular + LBBB Supraventricular + RBBB
activation of the atria/ventricles is totally disorganised.
early single beats
the SAN has the highest intrinsic frequency of depolarisation
70bpm
50bpm
30bpm
slow and protective rhythms which initiate depolarisation if SAN fails. ‘escape from their normal inhibition’
Explain why.
Atrial escape.
Initial sinus beat. Then failure to depolarise.
There is atrial ‘escape’ of SAN inhibition.
Abnormal P wave seen (depolarisation starts elewhere in atrium).
Normal QRS complex - normal His.
Returns to sinus.
Why?
Junctional escape.
No P wave in junctional as atria do not contract or hidden by QRS.
QRS normal width.
This cannot be ventrucular as there is normal QRS width.
Cannot be atrial escape as no abnormal P wave.
Complete heart block
Accelerated idioventricular rhythm (AIVR)
Why?
Ventricular escape
3 sinus beats. SAN failure.
No atrial or nodal escape. Single wide and abnormal QRS. Abnormal T wave.
Sinus rhythm restored.
Why?
Complete heart block.
Normal P waves.
Abnormal QRS (due to ventricular escape).
No relationship between P an QRS.
Why?
AIVR
3 sinus beats.
SAN failure.
Ventricular escape - continuous regular rhythm with wide QRS and abnormal T waves.
the accompanying heartbeat to any earlier than usual depolarisation. (‘ectopic’ = abnormal location)
[arrhythmias]: what is the difference between an ‘extrasystole’ and an escape beat?
escape = late
Extrasystole = early
Junctional/nodal extrasystole.
No P wave.
Atrial extrasystole. Abnormally shaped P wave.
Abnormal QRS complex early in the T wave of the preceding beat. (?ventricular fibrillation?)
Ventricular extrasystole.
5 sinus beats.
early abnormal beat close to abnormal T wave.
ventricular extrasystole.
‘R on T’ phenomenon.
i.e. ventricular extrasystoles have occured at the peak of the preceding sinus beats.
Atrial extrasystole
supect ventricular problem - supraventricular tend to produce the same shaped QRS complexes.
ventricular beat
supraventricular beat.
it resets the P wave cycle (i.e. it does not come at the expected time)
No effect - the P wave comes at the expected time.
c. 200/min
(above this you get AV block - which differs from 2nd degree as the AVN is functionin properly)
Atrial tachycardia.
150/min. P wave superimposed on T waves. QRS are the same as the first 3 sinus beats.
atrial rate > 250/min
no flat baseline between P waves. (‘sawtooth’ appearance’)
atrial contracting at 250/min with 2:1 block = ventricular contraction at a rate of 125/min
Atrial flutter.
P waves at a rate of 250/min (sawtooth)
4:1 block
ventricular activation at 75/min
Atrial flutter (250/min) with 2:1 block = ventricular rate of 125/min.
(T waves cannot be identified)
Junctional
QRS are essentially normally shaped. No P wave. Regular QRS. Tachycardic. = Junctional tachycardia
carotid sinus pressure
Reduced frequency of SAN discharge
Increase in the delay of conduction in the AVN
May make identification of underlying patholgy clearer. E.g. atrial flutter on image
high frequency ectopic ventricular depolarisiation focus
ventricular tachycardia (ectopic focus) and R/LBBB
Ventricular tachycardia
Broad QRS complexes
T waves difficult to identify
- if QRS is wider than 160 ms it is usually ventricular in origin
- if the QRS is very irregular thatn it is probably AF with BBB
- Does the patient have BBB in sinus rhythm as well (if you can see it - the QRS will be the same shape)
bradycardia
tachycardia
no focal point of depolarisation - muscel fibres are contracting independently.
AVN threshold - all or none conduction. Irregularly timed but of regular shape.
Atrial fibrillation
No P waves
irregular baseline
Irregular QRS
Normal shaped QRS
(looks a bit like flutter in lead v1 - normal)
presence of an accessory conducting bundle between the atria and ventricle - WITH NO AVN TO PAUSE CONDUCTION. (usually it runs down the left side of the heart).
[arrhythmias]: in WPW syndrome there is a ‘pre-excitation’ as a depolarisation wave reaches the ventricles before the main wave. what would be seen on ECG
Short PR interval
Delta wave on QRS (early slurred upstroke of QRS - 2nd part is normal - main depolarisation catches up )
Paroxysmal tachycardia
(depolarisation down the His then back up accessory to reactivate the atria = ‘re-entry’ circuit = sustained tachycardia.
Sustained tachycardia in the WPW syndrome (re-entry tachycardia - no P waves)
