View
98
Download
2
Category
Preview:
Citation preview
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
NARROW QRS TACHYCARDIA
• 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
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
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 SVTNARROW QRS TACHYCARDIA
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
NARROW QRS TACHYCARDIA
Slow-Fast (Typical) AVNRT:•Narrow complex tachycardia at ~ 150 bpm.•No visible P waves.•There are pseudo R’ waves in V1-2.
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
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
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
NARROW QRS TACHYCARDIA
• 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.
NARROW QRS TACHYCARDIA
• 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
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.
NARROW QRS TACHYCARDIA
• 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).
NARROW QRS TACHYCARDIA
• 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
NARROW QRS TACHYCARDIA
• 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
NARROW QRS TACHYCARDIA
Carotid sinus massage
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
• 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
Carotid sinus massage
NARROW QRS TACHYCARDIA
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
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
NARROW QRS TACHYCARDIA
P wave morphology
• Present or not -Absent in AF,AVNRT• If present
– Similar to sinus rhythm– Retrograde– Abnormal
NARROW QRS TACHYCARDIA
• 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
NARROW QRS 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
NARROW QRS 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
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
R-P INTERVAL
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
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
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
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
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
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
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
• 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
NARROW QRS TACHYCARDIA
NARROW QRS TACHYCARDIA
• 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.
Recommended