narrow qrs tachy i.tammi raju

APPRAOCH TO NARROW COMPLEX TACHYCARDIA

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.

Atrial Flutter

REGULAR SVT

• 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

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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 Fibrillationmost 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

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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 SVTNARROW QRS TACHYCARDIA

• 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 (the Jaeggi algorithm),

• 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.


Summary of AVNRT subtypes

• 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

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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 conduction 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 AVRTInitiated by either an APB or VPBAV conduction is over the AV node & VA conduction over

accessory pathwayActivation 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

AVNRT AVRT

Incidence Most common Less than AVNRT

sex female males

Pathway Slow-fast,Ventricles not required for activation

AccesoryVentricles 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

WAYS TO DIFFERENTIATE

• 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 wavesAT & 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.

CAROTID SINUS MASSAGE

• 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.


• Carotid sinus massage 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.

• Carotid sinus massage


• 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-P INTERVAL


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


ST segment depression

• Represent either repolarization changes or a retrograde atrial activation

• More commonly seen in those with an AV reentrant tachycardia associated with an accessory pathway


LEAD aVLNARROW QRS TACHYCARDIA

• 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.

SUMMARY

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 anteriorpathway: The retrograde P wave is negative in lead V1 and positive inleads II, III and aVF.

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

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

Patient with a right posteroseptal pathway:The retrograde P wave is positive in lead V1, negative in leads II, IIIaVF 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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narrow qrs complex

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