SVT ALOGARYTHM

1. Narrow QRS Complex
Tachycardia
Dr Vijay Amarnath
NIMS,Hyderabad

2. Narrow QRS Complex Tachycardia
• A narrow QRS complex (<120 msec)- rapid
activation of the ventricles via the normal His-
Purkinje system,
• above or within the atrioventricular (AV)
node (ie, a supraventricular tachycardia).
• origin may be in the sinus node, the atria, the
atrioventricular node, the His bundle, or some
combination of these sites.

3. Classification of narrow QRS complex tachycardias by
structures required for initiation and maintenance
Atrial tissue only AV junction
Sinus tachycardia AV nodal reentrant tachycardia
Inappropriate sinus tachycardia Atrioventricular reentrant
tachycardia
Sinus nodal reentrant tachycardia Junctional tachycardia
Atrial tachycardia Junctional ectopic tachycardia in
children
Multifocal atrial tachycardia Nonparoxysmal junctional
tachycardia in adults
Atrial fibrillation
Atrial flutter

4. Paroxysmal SVT
• applied to intermittent SVTs other than AF,
atrial flutter, and MAT. PSVT occurs with an
incidence of 35 per 100,000 person-years

5. Physical examination during SVT
• Pulse, BP, S1 : they are regular & constant in
regular tachycardia. 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.

8. ASSESSMENT OF REGULARITY OF
RHYTHM
• If the rhythm is irregular,scrutinize for discrete
atrial activity and for any evidence of a
pattern to the irregularity .
• atrial flutter with Mobitz type I second degree
AV block (Wenckebach) will exhibit an
irregular ventricular rhythm with the pattern
of "grouped beating" typical of a Wenckebach
rhythm

9. IDENTIFICATION OF ATRIAL
ACTIVITY
• If P waves cannot be clearly identified, the
Valsalva maneuver, carotid sinus massage
(CSM), or the administration of intravenous
adenosine may help to clarify the diagnosis

10. • Valsalva maneuver
• Carotid sinus massage
Contraindications
• A carotid bruit.
• Prior stroke or transient ischemic attack, unless imaging has
shown no significant carotid disease.
• A myocardial infarction within the previous six months.
• A history of serious cardiac arrhythmias (ventricular
tachycardia or fibrillation).

11. four possible results
• 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

12. • 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.

17. 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

18. CHARACTERIZATION OF ATRIAL
ACTIVITY
• The atrial rate.
• 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).

19. Atrial rate
• in isolation is rarely diagnostic
• very fast atrial rates (eg >250 beats/minute)-
atrial flutter or atrial tachycardia (AT).

21. P wave morphology
• Similar to sinus rhythm
• Retrograde
• Abnormal

22. • Sinus tachycardia (ST)
• Inappropriate sinus tachycardia (IST) — IST is
an unusual condition occurring in patients
without apparent heart disease or other cause
for sinus tachycardia, such as hyperthyroidism
or fever. Affected patients have an elevated
resting heart rate and/or an exaggerated
heart rate response to exercise; many patients
have both. The cause of IST is unknown, but
abnormal autonomic control is thought to be

23. • Sinoatrial (SA) nodal reentrant tachycardia
(SNRT) — SNRT is uncommon, accounting for
fewer than 5 percent of patients referred for
electrophysiologic testing. In SNRT, the rate
typically ranges from 100 to 150 beats/minute
• Atrial tachycardia (AT), usually originating
near the sinus node.

24. Retrograde P waves
suggest certain diagnoses, specifically AVNRT,
AVRT, and less commonly, JET or NPJT.

25. Abnormal P waves
• most consistent with atrial tachycardias,
although some AVRTs have abnormal P waves.

27. RP relationship
• Short RP tachycardias
Abnormal P wave : atrial tachycardia with AV
nodal conduction delay

29. Slow-fast form of AVNRT

30. Generation of ECG in common
form of AVNRT

32. Uncommon atrioventricular nodal
reentrant tachycardia

36. AVNRT
• 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.

39. Atrioventricular node reentrant
tachycardia (the Jaeggi algorithm),
• pseudo S/R waves,
• the RP interval,
• the lack of significant ST depression in
multiple leads
a correct diagnosis of typical AVNRT can be
made by ECG analysis 76% of the time

46. 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.

47. The mechanism of QRS alternans during narrow QRS
It has been attributed to non-specific intraventricula
QRS alternans has been considered to be strongly su
However, it may also occur during AV nodal re-entra
.

53. 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

56. • aVL notch: any positive deflection at the end
of the QRS during tachycardia and its absence
during sinus rhythm.

61. relevant ECG parameters.
• Heart rate
– There were no difference in the heart rate during tachycardia
between AVNRT and AVRT.
• Pseudo r wave, pseudo Q wave and pseudo S wave.
– A pseudo r wave in lead V1 was present more frequently in AVNRT
than in AVRT .
– The presence of pseudo S wave or pseudo Q wave in the inferior leads
was exclusively found during AVNRT.
• Retrograde P waves and RP interval-----------.
– A retrograde P wave separate from the QRS complex was discernible
more often in AVRT than in AVNRT.
– The RP interval was longer in AVRT than in AVNRT.
• ST-segment elevation in aVR lead.
– According to the definition, the percentage of patients with aVR ST-
segment elevation was significantly greater in AVRT than in AVNRT

62. • Cycle length alternans.
– Cycle length alternans was present in only four of
the initial 104 patients and all of them were AVRT.
• QRS alternans.
– By contrast, QRS alternans was present in both
AVNRT and AVRT, and the difference between the
two tachycardias was not statistically significant

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

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

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

75. 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.

82. Short and long RP

83. topograghy

84. CLASSIFICATION AND MECHANISMS
• European Society ofCardiology and the North American
Society of Pacing and Electrophysiology
• Atrial tachycardias were classified as tachycardia arising from
the atrium with a regular atrial rate
– focal or macroreentrant
• Focal AT-automatic, triggered, or microreentrant mechanisms.
– characterized by radial, circular, or centrifugal spread of activation from a
single focus and lack of electrical activation spanning the tachycardia cycle
length.
• Macroreentrant atrial tachycardias- reentry through relatively
large, potentially well-characterized circuits.
– characterized by a repetitive pattern of electrical activation encompassing the
entire cardiac cycle.

85. • The predominant areas of origin of focal atrial
tachycardia
– 1.the area along the crista terminalis,
– 2.near or aside the four pulmonary veins (superior
veins more commonly),
– 3.around or inside the coronary sinus os,
– 4.superior vena cava,
– 5.atrial septum, and
– 6.Koch's triangle.

87.  FOCI
 RA-
 1.CT,
 2.the tricuspid annulus (TA)
 3. the ostium of the coronary sinus (CS)
 4.the perinodal region.
 LA-
 1.pulmonary vein (PV) ostia
 2.mitral annulus (MA)
 3.LAA
 4.leftsided septum

88. topography

90. • Lead V1 is located to the right and anteriorly in relation to the
atria, which should be considered as right anterior and left
posterior.
• Tachycardias originating from the tricuspid annulus were
negative in V1 because of the anterior and rightward location
of this structure.
• The P-wave in V1 is universally positive for tachycardias
originating at the PVs, because of the posterior location of
these structures.

91.  The major limitation in the use of a positive P-wave in lead
V1 to predict left atrial origin was in distinguishing foci at the
superior CT from the RSPV.
 This is an important consideration given the relatively
common occurrence of AT from both sites, which are known
to be in close anatomic proximity.
 Tang et al.made the important observation that RSPV foci
showed a change in configuration from biphasic in SR to
upright in AT, a change not observed for right-sided
tachycardias.
 The predictive value of PWM for localizing the atrium of
origin was more limited when tachycardia foci arose from
the interatrial septum

92. alogarithm

93. alogarithm

94. Atrioventricular node reentrant
tachycardia (the Jaeggi algorithm),
• pseudo S/R waves,
• the RP interval,
• the lack of significant ST depression in
multiple leads
a correct diagnosis of typical AVNRT can be
made by ECG analysis 76% of the time

96. • aVL notch: any positive deflection at the end
of the QRS during tachycardia and its absence
during sinus rhythm.

103. relevant ECG parameters.
• Heart rate
– There were no difference in the heart rate during tachycardia
between AVNRT and AVRT.
• Pseudo r wave, pseudo Q wave and pseudo S wave.
– A pseudo r wave in lead V1 was present more frequently in AVNRT
than in AVRT .
– The presence of pseudo S wave or pseudo Q wave in the inferior leads
was exclusively found during AVNRT.
• Retrograde P waves and RP interval-----------.
– A retrograde P wave separate from the QRS complex was discernible
more often in AVRT than in AVNRT.
– The RP interval was longer in AVRT than in AVNRT.
• ST-segment elevation in aVR lead.
– According to the definition, the percentage of patients with aVR ST-
segment elevation was significantly greater in AVRT than in AVNRT

104. • Cycle length alternans.
– Cycle length alternans was present in only four of
the initial 104 patients and all of them were AVRT.
• QRS alternans.
– By contrast, QRS alternans was present in both
AVNRT and AVRT, and the difference between the
two tachycardias was not statistically significant

108. algorithm

109. New step

110. alogarithm

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

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

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

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