Narrow qrs tachy i.tammi raju

APPRAOCHTO
NARROWCOMPLEXTACHYCARDIA
NARROW QRS TACHYCARDIA

• DEFINITION
• Tachycardia with a QRS complex width of < 120msec.
• A narrow QRS complex (<120 msec) reflects rapid activation
of the ventricles via the normal His-Purkinje system.
• The site of origin may be in the
– sinus node,
– the atria,
– the atrioventricular node,
– the His bundle, or
– some combination of these.

Classification of SVT by site of origin and regularityNARROW QRS TACHYCARDIA

• Sinus Tachycardia
• frequency between 100 and 180 beats/min, but it can be higher
with extreme exertion and in young individuals.
• Sinus tachycardia generally has a gradual onset and
termination.
• The P-P interval can vary slightly from cycle to cycle,
especially at slower rates.
• P waves have a normal contour, a larger amplitude can
develop, and the wave can become peaked.
• They appear before each QRS complex with a stable PR
interval unless concomitant AV block ensues
REGULAR SVT

With very fast heart rates the P waves may be hidden in the preceding T
wave, producing a ‘camel hump’ appearance.
Sinus Tachycardia
REGULAR SVT

• Inappropriate Sinus Tachycardia
• Typically seen in young healthy female adults.
• Sinus rate persistently elevated above 100 bpm in absence of
physiological stressor.
• Exaggerated rate response to minimal exercise.
• ECG indistinguishable from sinus tachycardia.
REGULAR SVT

• Sinus Node Reentrant Tachycardia (SNRT)
• Caused by reentry circuit close to or within the sinus node.
• Abrupt onset and termination.
• P wave morphology is normal.
• Rate usually 100 – 150 bpm.
• May terminate with vagal manoeuvres.
REGULAR SVT

Atrial Tachycardia
• Tachycardia resultant from one ectopic foci within
the atria, distinguished by a consistent p-wave of
abnormal morphology that fall before a narrow,
regular QRS complex.

Atrial Tachycardia
• Includes various conditions such as
– automatic AT,
– macroreentrant AT,
– scar-related AT,
– atrial flutters.
• Automatic AT usually presents with long RP tachycardia.
• A single site located anywhere in atria exhibits inherent
automaticity at a cycle length shorter than that of sinus node.
• P wave morphology pattern depends on exact site of origin.
• AV nodal blocking agents do not terminate the tachycardia.

• Typical Atrial Flutter (Common, or Type I Atrial Flutter)
• Involves the inferior vena cava – tricuspid isthmus in the
reentry circuit. Can be further classified based on the direction
of the circuit:
• Anticlockwise Reentry
– Commonest form of typical atrial flutter 90% cases
– Positive flutter waves in V1
– Negative flutter waves in leads II,III, aVF
• Clockwise Reentry (Reversed Typical Atrial Flutter)
– Wide negative flutter waves in V1
– Positive flutter waves in leads II, III, aVF
REGULAR SVT

• Atypical atrial flutter (Uncommon, or Type II Atrial Flutter)
• Does not fulfil criteria for either type of typical atrial flutter.
• Often associated with higher atrial rates and rhythm instability.
• Less amenable to treatment with ablation.
REGULAR SVT

• ECG Features
• Regular rhythm in presence of fixed AV block.
• Ventricular rate ~150 bpm in presence of 2:1 AV block.
• Flutter waves / ‘saw-tooth pattern’ best seen in leads II, III,
aVF and V1.
• Flutter wave morphology depending on type of atrial flutter
(see above).
• QRS complexes usually < 120 ms unless pre-existing bundle
branch block, accessory pathway, or rate related aberrant
conduction.
• Variable AV block will result in an irregular rhythm.
• Absence of an isoelectric baseline
REGULAR SVT

• Atrial flutter should be considered in all regular narrow
complex tachycardia with a ventricular rate of ~150 bpm.
• Vagal manoeuvres may help differentiate sinus
tachycardia from atrial flutter. In atrial flutter vagal
manoeuvres may be ineffective or result in a rapid decrease in
rate allowing flutter waves to be more easily seen.
• In atrial flutter with variable block the R-R distances will be
multiples of each other unlike atrial fibrillation in which no
relationship exists e.g. assuming atrial rate of 300bpm the R-R
distance in 2:1 block is 400ms, in 3:1 block 600ms, in 4:1
block 800ms.
REGULAR SVT

Atrial flutter with 2:1 block:

• ECG Features Of Atrial Fibrillation
• Irregularly irregular rhythm.
• No P waves.
• Absence of an isoelectric baseline.
• Variable ventricular rate.
• QRS complexes usually < 120 ms unless pre-existing bundle
branch block, accessory pathway, or rate related aberrant
conduction.
• Fibrillatory waves may be present and can be either fine
(amplitude < 0.5mm) or coarse (amplitude >0.5mm).
• Fibrillatory waves may mimic P waves leading to
misdiagnosis.
Atrial Fibrillation
most common sustained arrhythmia.
IRREGULAR SVT

• First episode – initial detection of AF regardless of symptoms
or duration
• Recurrent AF – More than 2 episodes of AF
• Paroxysmal AF – Self terminating episode < 7 days
• Persistent AF – Not self terminating, duration > 7 days
• Long-standing persistent AF – > 1 year
• Permanent (Accepted) AF – Duration > 1 yr in which rhythm
control interventions are not pursued or are unsuccessful
Classification Of Atrial Fibrillation

• A rapid, irregular atrial rhythm arising from multiple ectopic
foci within the atria.
• Most commonly seen in patients with severe COPD or
congestive heart failure.
• It is typically a transitional rhythm between frequent
premature atrial complexes (PACs) and atrial flutter /
fibrillation.
Multifocal Atrial Tachycardia
IRREGULAR SVT

Multifocal Atrial Tachycardia
IRREGULAR SVT

• Commonest cause of palpitations in patients with structurally normal
hearts.
• AVNRT is typically paroxysmal and may occur spontaneously or
provocation).
• It is more common in women than men (~ 75% of cases occurring in
women)
• complain of the sudden onset of rapid, regular palpitations, presyncope.
angina.
• The patient may complain of shortness of breath, anxiety and occasionally
polyuria.
• The tachycardia typically ranges between 140-280 bpm and is regular in
nature. It may cease spontaneously (and abruptly) or continue indefinitely
until medical treatment is sought.
• The condition is generally well tolerated and is rarely life threatening in
patients with pre-existing heart disease.
AVNRT
REGULAR SVT

• The slow pathway (alpha): a slowly-conducting pathway
with a short refractory period.
• The fast pathway (beta): a rapidly-conducting pathway with
a long refractory period.
REGULAR SVT
AVNRT

AVNRT - ECG
• Presence of a narrow complex tachycardia with regular R-R
intervals and no visible p waves.
• P waves are retrograde and are inverted in leads II,III,AVF.
• P waves are buried in the QRS complexes –simultaneous
activation of atria and ventricles – most common presentation
of AVNRT –66%.
• If not synchronous –pseudo s wave in inferior leads ,pseudo r’
wave in lead V1---30% cases .
• P wave may be farther away from QRS complex distorting the
ST segment ---AVNRT ,mostly AVRT.
REGULAR SVT

• Slow-Fast AVNRT (common type)
REGULAR SVT

REGULAR SVT

• Accounts for 10% of AVNRT
• Associated with Fast AV nodal pathway for anterograde
conduction and Slow AV nodal pathway for retrograde
conduction.
• Due to the relatively long ventriculo-atrial interval, the
retrograde P wave is more likely to be visible after the
corresponding QRS.
Fast-Slow AVNRT (Uncommon AVNRT)
REGULAR SVT

• Slow-Slow AVNRT (Atypical AVNRT)
• 1-5% AVNRT
• Associated with Slow AV nodal pathway for anterograde
conduction and Slow left atrial fibres as the pathway for
retrograde conduction.
• ECG features:
• Tachycardia with a P-wave seen in mid-diastole… effectively
appearing “before” the QRS complex.
• Confusing as a P wave appearing before the QRS complex in
the face of a tachycardia might be read as a sinus tachycardia.
REGULAR SVT

AVNRT(theJaeggialgorithm),
• Pseudo S/R waves,
• RP interval,
• Lack of significant ST depression in multiple leads
• A correct diagnosis of typical AVNRT can be made by ECG
analysis 76% of the time

Slow-Fast (Typical) AVNRT:
•Narrow complex tachycardia at ~ 150 bpm.
•No visible P waves.
•There are pseudo R’ waves in V1-2.

• PR interval <120ms
• Delta wave – slurring slow rise of
initial portion of the QRS
• QRS prolongation >110ms
• ST Segment and T wave
discordant changes – i.e. in the
opposite direction to the major
component of the QRS complex
• Pseudo-infarction pattern can be
seen in up to 70% of patients –
due to negatively deflected delta
waves in the inferior / anterior
leads (“pseudo-Q waves”), or as a
prominent R wave in V1-3
(mimicking posterior infarction).
WPW in sinus rhythm
REGULAR SVT-AVRT

Atrioventricular Reentry Tachycardias .AVRT
• AVRT is a form of paroxysmal
supraventricular tachycardia.
• A reentry circuit is formed by the
normal conduction system and the
accessory pathway resulting in circus
movement.
• During tachyarrythmias the features
of pre-excitation are lost as the
accessory pathway forms part of the
reentry circuit.
• AVRT often triggered by premature
atrial or premature ventricular beats.
• AVRT are further divided in
to orthodromic or antidromic con
duction based on direction of reentry
conduction and ECG morphology.
REGULAR SVT

• AVRT With Orthodromic Conduction
• In orthodromic AVRT antegrade conduction occurs via the
AV node with retrograde conduction occurring via the
accessory pathway. This can occur in patients with a concealed
pathway.
REGULAR SVT

Orthodromic AVRT using a rapidly conducting accessory pathway:
Most common type of AVRT
Initiated by either an APB or VPB
AV conduction is over the AV node & VA conduction over accessory
pathway
Activation of ventricle & atrium follow sequentially  P waves are
separated from the QRS complex.
Retrograde conduction is rapid  P wave closer to the preceding QRS
 RP < PR.
The QRS may be narrow or if aberrant conduction occurs, a typical
BBB will be present.

• AVRT With Antidromic Conduction
• In antidromic AVRT antegrade conduction occurs via the
accessory pathway with retrograde conduction via the AV
node. Much less common than orthodromic AVRT occuring in
~5% of patients with WPW.
• ECG features of AVRT with antidromic conduction are:
– Rate usually 200 – 300 bpm.
– Wide QRS complexes due to abnormal ventricular depolarisation via
accessory pathway.
REGULAR SVT

REGULAR SVTNARROW QRS TACHYCARDIA

AVNRT AVRT
Incidence Most common Less than AVNRT
sex female males
Pathway Slow-fast,
Ventricles not required for
activation
Accesory
Ventricles required for
activation
Activation Simultaneous activation Sequential activation
Rate <200 >200
P-wave Burried in QRS Will be seen after QRS
Pseudo-r,pseudo-s,pseudo-q present absent
RP-interval <70msec >70msec
ST-T changes Less common more
ST elevation in aVR lesss more
Notch in aVL more less
QRS alternans Rare common
Abberancy Rare common
BBB Doesnot alter rate Alters rate(coumel’s law)
AV block Possible Not possible in its presence

WAYSTODIFFERENTIATE
• Physical examination
• Carotid sinus massage
• Adenosine
• ECG

Physical examination during SVT
• Pulse, BP, S1 : they are regular & constant in regular
tachycardias. In AF & A.flutter with variable AV block, pulse,
BP & loudness of S1 varies.
• Neck veins :
SVT – rapid, regular pulsations (frog sign)
A.Flutter – flutter waves
AT & sinus tachycardia – no abnormal pulsations
The Frog sign: in AVNRT or AVRT, the atria contract against
closed AV valves  rapid, regular, expansive venous
pulsations in the neck (that resemble the rhythmic puffing
motion of a frog). It is due to simultaneous activation of atria
& ventricles.

CAROTIDSINUSMASSAGE
• Site-
• At the level of cricoid cartilage
and at the angle of mandible.
• Procedure-
• Gentle pressure is applied over
the carotid sinus for 5 -10
seconds.
• In case of no response – try on
the other side.
• Precaution-
– Check for carotid bruit
before massage.
– Ecg monitor must
– Simultaneous pressure
not to be applied both
sides.
• Alternative manuevres are
valsalva, gag reflex, ice water
pouring over the face.

Contraindications
• A carotid bruit.
• Prior stroke or transient ischemic attack, unless imaging has
shown no significant carotid disease.
• A history of serious cardiac arrhythmias (ventricular
tachycardia or fibrillation).

• RESPONSE
• The slowing of SA nodal activity can cause a temporary
decrease in the atrial rate (in patients with sinus tachycardia).
• The slowing of AV nodal conduction can lead to AV nodal
block, which may "unmask" atrial electrical activity (ie, reveal
P waves or flutter waves) by decreasing the number of QRS
complexes that obscure the electrical baseline.

• With some narrow QRS complex tachycardias that require AV
nodal conduction (especially AVNRT and AVRT), the
transient slowing of AV nodal conduction can terminate the
arrhythmia by interrupting the reentry circuit.
• Less commonly, CSM can cause some atrial tachycardias to
slow and terminate.
• In some cases, no response is obtained.
Carotid sinus massage

• Termination of the arrhythmia
• Termination with a P wave after the last QRS complex is
– most common in AVRT or AVNRT and is rarely seen with
AT.
• Termination with a QRS complex can be seen with
– AVRT, AVNRT, or AT.
• If the tachycardia continues despite successful induction of at
least some degree of AV nodal blockade, the rhythm is almost
certainly AT or atrial flutter; AVRT is excluded and AVNRT
is very unlikely

ADENOSINE
• MECHANISM OF ACTION
• Adenosine interacts with A1 receptors present on the
extracellular surface of cardiac cells, activating K+ channels.
• The increase in K+ conductance shortens atrial APD,
hyperpolarizes the membrane potential, and decreases atrial
contractility.
• Similar changes occur in the sinus and AV nodes.
• Adenosine antagonizes catecholamine-stimulated adenylate
cyclase to decrease cyclic adenosine monophosphate
accumulation and to decrease ICa.L and the pacemaker current
If in sinus node cells .

• Adenosine slows the sinus rate in humans, which is followed
by a reflex increase in sinus rate.
• In the region of the AV node, conduction is depressed, along
with decreases in action potential amplitude, duration, .
• Adenosine does not affect conduction in normal accessory
pathways. Conduction may be blocked in accessory pathways
that have long conduction times.
• A 6-6-12 mg dose of adenosine, administered intravenously in
rapid fashion, terminates the nodal-dependent SVT (i.e.,
AVRT and AVNRT) over 90% of the time

ECG
• The atrial rate
• Rhythm
• The P wave morphology (ie, identical to normal sinus rhythm,
retrograde, or abnormal).
• The position of the P wave in relation to the preceding and
following QRS complexes (ie, the RP relationship).
• The relationship between atrial and ventricular rates (1:1 or
otherwise).
• QRS alternance
• Lead Avr, and aVL
• ST – T changes

Narrow qrs tachycardia rate
Sinus tachy 100-180
SVT
Reentrant-
AVNRT,AVRT,sinoatrial
Automatic
Atrial tachy
Junctional tachy
200±50
Atrial flutter 300 ± 50
Atrial fibrillation 400±50
ATRIAL RATE

• IRREGULAR
• AF,
• Atrial tachycardia with
variable AV conduction,
• MAT
• REGULAR
• Atrial flutter
• Atrial atchycardia
• AVNRT
• AVRT
• PJRT
RHYTHM

P wave morphology
• Present or not -Absent in AF,AVNRT
• If present
– Similar to sinus rhythm
– Retrograde
– Abnormal

• SIMILAR TO SINUS RHYTHM
• Inappropriate sinus tachycardia
• SNRT
• Atrial tachycardia originating near the sinus node

Retrograde P waves
• AVNRT,
• AVRT, and,
• Abnormal P waves
• Atrial tachycardia

Pwaves
no
Irregular
R-R interval
ATRIAL
FIBRILLATION
Regular
R-R interval
AVNRT
yes
NORMAL
MORPHOLOGY
SINUS TACHYCARDIA
SINUS NODE REENTRY
INAPPROPRIATE
SINUS TACHYCARDIA

P wave present but
not of same
morphology as
sinus rhythm
Pseudo r’
wave in
V1
AVNRT
Pseudo S
wave on lead
II
AVNRT
Pwave
ST-T changes
Positive in
lead I
AVRT
Right
posteroseptal
Accessory
pathway
Negative in
lead I
AVRT
Left sided
accessory
pathway

R-PINTERVAL

NARROW COMPLEX QRS
TACHYCARDIA
SHORT RP
INTERVAL
TYPICAL
AVNRT
AVRT
LONG RP
INTERVAL
ATYPICAL
AVNRT
AVRT slow
retrograde
conduction
Permanent Form
junctional
tachycardia
ATRIAL TACHYCARDIA
SANRT
INAPPROPRIATE ST

STsegmentdepression
• Represent either repolarization changes or a retrograde atrial
activation
• More commonly seen in those with an AV reentrant
tachycardia associated with an accessory pathway

LEADaVL

• aVL notch: any positive deﬂection at the end of the QRS
during tachycardia and its absence during sinus rhythm.
• The aVL notch was found during AVNRT in 51.3 vs. 7.4% in
AVRT

• ST-segment elevation in aVR lead.
• The percentage of patients with aVR ST-segment elevation
was significantly greater in AVRT than in AVNRT
• The ST segment elevation in this lead is thought to be due to
deformation of the ST segment by retrograde atrial activation
rather than from a true repolarization abnormalit

• QRS Alternans
• QRS alternans describes a beat-to-beat variation in the
morphology of the QRS complex, most easily seen as a
difference in amplitude from one beat to the next.
• This finding is most often associated with accessory pathway-
mediated SVTs, such as orthodromic AVRT,
• solely a rate-related phenomenon and is independent of
tachycardia mechanism.
• In summary, its use as a discriminating factor is limited

The mechanism of QRS alternans during narrow
QRS tachycardia is not known.
It has been attributed to non-specific
intraventricular conduction abnormalities.
QRS alternans has been considered to be
strongly suggestive of AV re-entrant
tachycardia.
However, it may also occur during AV nodal re-
entrant tachycardia and can also be induced by
abrupt rapid atrial pacing.

AV ACCESSORY PATHWAYS
• 46 to 60 percent of
accessory pathways are
found within the left free
wall space
• 25 percent are within the
posteroseptal space
• 13 to 21 percent of
pathways are within the
right free wall space
• 2 percent are within the
anteroseptal space

• Pathways located between
annulus fibrosus and
epicardial reflection of
atrium
• Variable depth from
epicardium/endocardium
• LCX,CS-in left free wall
space
• CS, MCV,PDA- in
posterolat space
• RCA-anteroseptal and
right free wall spaces

A, Patient with a right anterior
pathway: The retrograde P wave is
negative in lead V1 and positive in
leads II, III and aVF.

Patient with a right posterior
pathway: The
retrograde P wave is negative in
leads V1, II, III and aVF.

Patient with a right midseptal
pathway: The retrograde P wave is
biphasic in lead V1 and negative in
leads II, III and aVF.

Patient with a right posteroseptal
pathway:
The retrograde P wave is positive in
lead V1, negative in leads II, III
aVF and biphasic in lead I.

• The software used for T-wave subtraction is a
customdesigned software incorporated in the
Bard EP recording system (Labsystem Pro).
• the rapid identification of the localization of an
accessory pathway during an EP study just by
analyzing P-wave polarity during AVRT,

• However, the presented algorithm may
virtually also be applied to the analysis of
retrograde P-wave polarity without the use of
this specific software.

• Lead V1 was used to differentiate right
(negative or isoelectric) from left (solely
positive) APs.
• Retrograde P-wave in lead I was negative in
left posterior APs exclusively and became
more positive with an AP location shifting
towards right anterior.

Narrow qrs tachy i.tammi raju

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