This document provides information on various types of arrhythmias including: - Supraventricular arrhythmias like atrial flutter and atrial fibrillation which involve rapid and irregular atrial rhythms. - Re-entry supraventricular tachycardia which is caused by an extra connection between the atria and ventricles. - Wolff-Parkinson-White syndrome which results from an abnormal accessory pathway that can cause supraventricular tachycardia. - Ventricular arrhythmias like ventricular tachycardia and ventricular fibrillation which involve rapid and life-threatening rhythms originating in the ventricles. - Bradyarrhythmias including different

1. Type Name What is it? ECG – Rhythm Strip
Supraventricular
arrythmias:
SVT
Atrial Flutter
“Shockable
rhythm”
An atrial contraction rate of over 250-300 bpm.
Rapid and regular form of atrial tachycardia.
Atria depolarize in an organised circular
movement caused by a re-entrant circuit of
excitation i.e.it goes straight back into the atria
instead of the impulsesjust travellingto the
ventricles.
Usuallyparoxysmal –sometimespersistent.
Patients presenting with paroxysms of atrial flutter
often have normal hearts, whereas patients with
chronic atrial flutter usually haveunderlyingheart
disease. Chronic atrial flutter eventually converts to
chronic atrial fibrillation.
“sawtoothpattern”of ECG esp.inLead II
Clinical Features:
Palpitations,ChestPain, Dyspnoea
125-160bpm
Episodescanlastfrom secondstoyears
Signsof heart failure (raisedJVP,peripheral oedemaetc)
Do U&Es, TFTs and Echocardiography.
Ischaemic heart disease, hyperthyroidism, cardiomyopathy and
rheumatic heart disease can all cause it but sometimes, no cause is found
Arial Fibrillation This is an atrial rhythm which is ineffective,
chaotic and irregular, usually of around 300-
600 bpm.
Paroxysmal - Lastinglessthan48 hour - Often
recurrent
Persistent- Anepisode of AFlastinggreaterthan
48 hours,whichcan still be cardiovertedtoNSR.
UnlikelytospontaneouslyreverttoNSR
Permanent- Inabilityof pharmacologicornon-
pharmacologicmethodstorestore NSR
Lone (idiopathic) AF: Absence of anyheart
disease andnoevidence of ventricular
dysfunction.A diagnosisof exclusion.Couldbe
genetic(~30%have familyhistory).Significant
stroke rate if > 75 years of age.
FBC, U&Es, TFTs, CXR,Echocardigraphy.
ECG Interpretation:
No Pwaves
IrregularQRS complexes(some maybe normal)
TransientflutterwavesinV1
Irregularlyirregularheartrate
Symptoms:
Asymptomatic. Palpitations, Chest pain, Pre-syncope (dizziness),
Dyspnea, Syncope, Sweatiness, Fatigue. Symptomsoftenworse atthe
onsetof AF. Suddencardiacdeath.Worseningpre-existingcondition:
angina,CHF

2. Re-entry
supraventricular
tachycardia
An arrhythmia caused by a second connection
between atria and ventricles,in addition to the
normal conduction system. There are two
types:
AVRNT (Atrio-Ventricular Node Re-entry
Tachycardia) - the second connection is closely
related to the AV
Rate of 130-250. Narrow QRS complex (except in bundle branch block), P
waves are: inverted, masked by QRS complex (AVNRT) or occur halfway
between complexes (AVRT), one P wave per QRS complex.
AVRT (Atrio-Ventricular Re-entry Tachycardia) - the second connection is
not related to the AV node.
node.
Wolff-Parkinson-
White syndrome
Usually
asymptomatic
buy may
experience:
palpitations,
dizziness,
syncope,
dyspnoea during
episodes
WPW is caused by the presence of an
abnormal accessory electrical conduction
pathway between the atria and
the ventricles. Electrical signals travelling
down this abnormal pathway (known as
the bundle of Kent) may stimulate the
ventricles to contract prematurely (pre-
excitation syndrome), resulting in
supraventricular tachycardia -
atrioventricular reciprocating tachycardia.
Sinusrhythmandveryshort PR interval
DominantR wave inV1 – “Type A” WPW and isassociatedwithaleftsided
accessorypathway
Notshown – DominantSwave in V1 – “Type B” WPW and indicatesaright
sidedaccessorypathway
Ventricular
arrythmias:
Narrow complex
tachycardia
Atrial Flutter
Atrial Fibrillation
SVT
It can alsobe causedby sinus tachycardia i.e.the normal physiological
response tocertainstimuli whichcause the heartrate torise.

3. Broad Complex
Tachycardia
Ventricular
fibrillation
Chaoticdepolarisationof the ventricles.
Mechanicallythisresultsinanarrestedcardiac
pumpfunctionandimmediate death.
VFcan onlybe treatedby
immediate defibrillation.
ECG requiredasap.
Bloods– cardiac enzymes(TroponinTandI, CK-
MB
Irregularrhythm
Usuallyoccurs duringan MI.  symptomschestpain,tiredness,palpitations
Ventricular
tachycardia
“shockable
rhythm”
QRS >120ms/3 small squares whichoriginatesin
the ventricles.
Symptoms:
Presentswithfeaturesof ischaemicheart
disease orhaemodynamiccompromise. Chest
pain, palpitations, dyspnoea,dizziness,syncope
and possibly symptomsof heartfailure.
The QRS complexesare rapid,wide,anddistorted.
The T wavesare large withdeflectionsopposite the QRScomplexes.
P wavesare usuallynotvisible.  The PRinterval isnotmeasurable.
A-V dissociationmaybe present.
V-A conductionmayor may notbe present
Bradyarrythmias: Heart Block 1st degree – slowdownof conduction. Notreally
“block”.JustP-R interval longerthan normal (>
0.2 sec).Treatment:none
Long termfollowuprecommended,asmore
advancedblockmaydevelopovertime.
2nd degree – some conductionbutnotothers.
Intermittentblockatthe AVN (droppedbeats)

4. MobitzI:
Progressive lengtheningof the PRinterval,
eventuallyresultinginadroppedQRS.
Usuallyvagal inorigin
Must see PR prolongationtomake diagnosisof
MobitzI
MobitzII:
Pathological,mayprogresstocomplete heart
block(3rd
degree HB)
Usually2:1, or 3:1, but may be variable
Permanentpacemakerindicated
3rd degree –complete blockbetweenatriaand
ventricle
P wavesare independentof the wide QRScomplex
not usingnormal conductingsystemsoitisan escaped
focus
Permanentpacemakerneedsfitted
Figure 1. Mobitz I
Figure 2. Mobitz II
Figure 3. 3rd degree/complete heart block
Bundle branch
block
Cessationof appropriate electrical conduction
downeitherthe R or L bundle branch.
In bothcasesthere is a wide QRScomplex.
RBBB- M shapein V1 and an N shape in V6 (the N can
also stand for "normal"). The "M" wave here has a
small rise(r),a big drop (S) and an even bigger rise(R)
givingan rSR wave. Finally,theN is your normal QRS
complex but justwider.
LBBB - V shape in V1 and an M shapein V6. The "V"
wave is also called an rS wave because ithas a very
slightrise(r) and a big drop (S) in amplitude.The "M"
Figure 4. RBBB

5. wave, also called R,is justa largerise(R) with a tiny
dip and tiny rise.
Can justbe left unless severe and a cardiac pacemaker
will berequired.
Figure 5. LBBB