DIFFRENTIAL DIAGNOSIS OF WIDE QRS COMPLEX TACHYCARDIA

1. APPROACH TO WIDE QRS COMPLEX
TACHYCARDIA
KUSH KUMAR BHAGAT
DM CARDIO

2. DEFINITION
Wide QRS complex tachycardia is a rhythm with a rate of
more than 100 b/m and QRS duration of more than 120 ms
VT (80%)
SVT (20%)

3. WHY IS IT IMPORTANT TO DIAGNOSE….?
 Right diagnosis is important in management
 Incorrect decision or indecision can worsen the status

6. APPROACH TO THE EVALUATION OF WIDE
COMPLEX TACHYCARDIAS
 History
 Physical Examination
 The Electrocardiogram
 Algorithms
 Electrophysiologic Testing

7. POINTS IN HISTORY DIAGNOSIS
UTILITY OF HISTORY IN MAKING A DIAGNOSIS
H/O MI VT
H/O CHF VT
H/O ANGINA VT
Recurrent episodes SVT
Duration of illness >3 years SVT
Minimally symptomatic events including
palpitations and light headedness without syncope
SVT
Each has a
PPV of 95%

8. SVT VS VT
PHYSICAL EXAMINATION
 Physical findings that indicate presence of AV
dissociation (cannon A waves, variable-intensity
S1,variation in BP) if present are useful
 Termination of WCT in response to maneuvers like
Valsalva, carotid sinus pressure, or adenosine is
strongly in-favor of SVT but there are well-documented
cases of VT responsive to these

9. ELECTROCARDIOGRAPHIC FEATURES
Several features of the ECG in WCT have proven
diagnostic utility; the more important among these
include the following
1. QRS Duration - a wider QRS duration favors VT.
 In RBBB-like WCT, a QRS duration more than 140
milliseconds suggests VT, whereas in LBBB-like WCT, a
QRS duration more than 160 milliseconds suggests VT.
 Rarely, VT can have a relatively narrow QRS duration
(less than 120 to 140 milliseconds) can be observed in
fascicular (verapamil-sensitive) VT.

10. 2. QRS Axis-.
 A significant axis shift (more than 40 degrees) between the
baseline NSR and WCT is suggestive of VT.
 A right superior (northwest) is rare in SVT and strongly suggests
VT.
 In a patient with an RBBB-like WCT, a QRS axis to the left of
−30 degrees suggests VT.
 in a patient with an LBBB-like WCT, a QRS axis to the right of
+90 degrees suggests VT.
 RBBB with a normal axis is uncommon in VT (less than 3%)
and is suggestive of SVT

11. LBBB morphology with RAD

12. o 3. Precordial QRS Concordance- Concordance is present
when the QRS complexes in the six precordial leads (V1
through V6) are either all positive in polarity (tall R waves) or all
negative in polarity (deep QS complexes).
o Because concordant patterns are present in <20% of all VTs,
this criterion has low sensitivity.
o In some cases of LBBB aberration, R waves may not be seen
until V7 or later, leaving a concordant negative pattern.
o A more recent analysis found that a negative concordant pattern
had virtually no capacity to distinguish SVT-A from VT, but a
positive concordant pattern remained a strong differentiator.
Miller JM, Das MK, Yadav AV, et al.: Value of the 12-lead ECG in wide QRS tachycardia. Cardiol Clin. 24:439-451 2006 16939835

13. Concordant pattern.
The left panel shows a VT
arising in the apical area of the
left ventricle resulting in
negative concordancy of all
precordial leads.
In the right panel ventricular
activation starts in the left
posterior area, resulting in
positive concordancy of all
precordial leads.

14. 4. Atrioventricular Dissociation:
 When the P waves can be clearly seen and the atrial rate is
unrelated to and slower than the ventricular rate, AV dissociation
consistent with VT is present
 AV dissociation is the hallmark of VT (specificity is 100%;
sensitivity is 20% - 50%).

15.  Fusion Beats- Ventricular fusion occurs when a
ventricular ectopic beat and a supraventricular beat
(conducted via the AVN and HPS) simultaneously
activate the ventricular myocardium.
 The resulting QRS complex has a morphology
intermediate between the appearance of a sinus QRS
complex and that of a purely ventricular complex.
 Dressler Beats or a capture beat- is a normal QRS
complex identical to the sinus QRS complex, occurring
during the VT indicates that the normal conduction
system has momentarily captured control of ventricular
activation from the VT focus.

16. Fusion beat and capture beat

18. Ventriculoatrial conduction with block
Approximately 30% of VTs have 1 : 1 retrograde
ventriculoatrial (VA) conduction 15% to 20% have second-degree
(2 : 1 or Wenckebach) VA block.

19. 5. QRS Morphology- As a rule, if the WCT is caused by
SVT with aberration, then the QRS complex during the
WCT must be compatible with some form of BBB that
could result in that QRS configuration.
• If there is no combination of bundle branch or fascicular
blocks that could result in such a QRS configuration, then
the diagnosis by default is VT.

20. • WCTs can be classified as having an RBBB-like pattern or an
LBBB-like pattern.
• In the patient with a WCT and positive QRS polarity in lead V1
(RBBB pattern), a monophasic R, biphasic qR complex, or
broad R (more than 40 milliseconds) in lead V1 favors VT
• A double-peaked R wave in lead V1 favors VT if the left peak is
taller than the right peak (the rabbit ear sign)
• An rS complex in lead V6 is a strong predictor of VT (likelihood
ratio more than 50 : 1)

21. In RBBB pattern first “rabbit ear” is taller in VT while second “rabbit ear” is taller
in SVT.
In LBBB pattern the time from R-wave start to S-wave nadir is short in SVT and
long in VT.

22. • In the patient with a WCT and a negative QRS polarity in lead
V1 (LBBB pattern), a broad initial R wave of 40 milliseconds or
more in lead V1 or V2 favors VT,
• Notching in the downstroke of the S wave, or an RS interval
(from the onset of the QRS complex to the nadir of the S wave)
of more than 70 milliseconds in lead V1 or V2 favors VT.
• Any Q wave in V6 favours VT

23. FINDINGS IN LEAD V1 AND V2 DURING LBBB
SHAPED TACHYCARDIA POINTING TO A
VENTRICULAR ORIGIN
the presence of any
of these three
criteria in lead V1
(broad R wave,
slurred or notched
downstroke of the S
wave, and delayed
nadir of S wave) is a
strong predictor of
VT (likelihood ratio,
more than 50 : 1).

24. WELLEN’S CRITERIA
( VT FAVOURED IN THE PRESENCE OF )
 AV DISSOCIATION
 LEFT AXIS DEVIATION
 CAPTURE OR FUSION BEATS
 QRS ≥ 140 msec
 PRECORDIAL QRS CONCORDANCE
 RSR’ IN V1, MONO OR BIPHASIC QRS IN V1,OR
MONOPHASIC QS IN V6
Wellens HJJ, Bar FWHM, Lie KI. The value of the
electrocardiogram in the differential diagnosis of a tachycardia
with a widened QRS complex. Am J Med 1978;64:27-
33[Medline].

25. WELLEN’S CRITERIA

26. KINDWALL’S CRITERIA FOR VT IN
LBBB
 R wave in V1 or V2 >30 ms.
 Any Q wave in V6.
 Onset of QRS to nadir of S wave in V1 or V2 >
60 ms.
 Notching on the downstroke of the S wave in V1
or V2.
Kindwall KE, Brown J, Josephson ME: Electrocardiographic
criteria for ventricular tachycardia in wide
complex left bundle branch block morphology tachycardia.
Am J Cardiol 61:1279, 1988.

27. BRUGADA CRITERIA
SENSITIVITY 89.2%
SPECIFICITY 73.2%
NEGATIVE PREDICTIVE VALUE 67.2%
POSITIVE PREDICTIVE VALUE 91.2%

28. Step 1

29. ECG THAT DEMONSTRATES POSITIVE CONCORDANCE, STEP ONE OF
BRUGADA CRITERIA NOTE THE ABSENCE OF AN RS COMPLEX

30. Step 2

32. Step 3

34. STEP 4: LBBB - TYPE WIDE QRS COMPLEX
SVT VT
R wave >40ms
small R wave notching of S wave
fast downslope
of S wave
no Q wave
> 70ms
Q wave
V1
V6

35. STEP 4: RBBB - TYPE WIDE QRS COMPLEX
SVT VT
rSR’ configuration monophasic R wave qR (or Rs) complex
V1
V6
or
or
R/S > 1 R/S ratio < 1
QS complex

36. GRIFFITH ALGORITHM
VT UNLESS OTHERWISE PROVED!
SENSITIVITY FOR VT 90%
SPECIFICITY 67-85%
Lancet 1994 Feb. 12,343(8894)386-388

37. New aVR algorithm
 Vereckei et al;Heart Rhythm 2008
 483 WCT (351 VT, 112 SVT, 20 preexcited tachycardia)
analysed
 Greater sensitivity for VT diagnosis than Brugada
algorithm(96.5% vs 89.2%, P .001)
 Greater specificity for diagnosing SVT compared with Brugada
criteria
András Vereckei, MD et al Heart Rhythm, Vol 5, No 1, January 2008

38.  Vereckei proposed two algorithms incorporating lead aVR.
Reasons for using aVR:
During SVT w/ BBB, the initial rapid septal activation and the
later main ventricular activation wavefront move away from lead
aVR, creating a negative QRS complex in lead aVR
 Initial dominant R wave in aVR is incompatible w/ SVT, its
presence suggest VT, typically originating from the inferior or
apical region
The first had four steps (a positive result at any step makes a VT
diagnosis, with the remaining ECGs categorized as SVT-A)

39. VERECKEI ALGORITHM
NEGATIVE
PREDICTIVE VALUE
83.8%
POSITIVE
PREDICTIVE VALUE
92.4%
Vereckei A et al. Eur Heart J 2007

40. VENTRICULAR ACTIVATION VELOCITY RATIO VI/VT
 Vi – initial ventricular activation velocity
 Vt – terminal ventricular activation velocity
 Measured by the excursion (in mV) during the initial (Vi) and
terminal (Vt) 40 msec of the QRS complex
 Vi/Vt <= 1,supports VT
 Principle: Rapidity of initial septal activation with SVT as
compared to VT
 SVT with aberrancy-initial activation is rapid
 VT-initial ventricular activation slow due to muscle to muscle spread of activation

42.  This algorithm performed well in initial testing but is
somewhat cumbersome, and it is difficult to
remember how to make the measurements.
 The second proposed algorithm involves only aVR
and thus is generally simpler.
 It also consists of four steps:

43. AVR ALGORITHM
SENSITIVITY 96.5%
SPECIFICITY 75%
NEGATIVE PREDICTIVE VALUE 86.6%
POSITIVE PREDICTIVE VALUE 92.7%
András Vereckei, MD et al Heart Rhythm, Vol 5, No 1, January 2008

45. CAVEATS OF VI/VT CRITERIA
 A scar situated at a late activated ventricular site can
result in a decreased Vt in the presence of VT, leading
to the misdiagnosis of SVT
 In fascicular VT, the Vi is not slower than the Vt

46. MODIFIED BRUGADA/
PAVA CRITERIA
SENSITIVITY 93.2%
SPECIFICITY 99.3%
POSITIVE PREDICTIVE VALUE 98.2%
NEGATIVE PREDICTIVE VALUE 93.3 %
 Pava et al proposed another simple, one-step criterion:
the interval from QRS onset to peak amplitude (positive or
negative) in lead 2.
 Using a cutoff of 50 ms, almost all WCTs with a shorter
time to peak amplitude in lead 2 were SVT, whereas
almost all WCTs with intervals ≥50 ms were VT.
 The proposed rationale to analyze lead II is that it is a
lead that is easy to obtain and is commonly represented
as a rhythm strip on ECG or ECG monitors.
J Brugada/Pava et al Heart Rhythm
2010;7:922–926

49. CAVEATS OF PAVA CRITERIA
 Inability to accurately define the initiation and peak of QRS
complexes
 Fascicular VT and Bundle branch re-entry VT may have a
shorter RWPT due to their origin within or in close proximity to
the His-Purkinje network.
 Although this criterion appears to have many desirable
features—simplicity, ease of application, accuracy—its
performance in the hands of other investigators has been less
impressive (sensitivity 0.60, specificity 0.83).

50. BRUGADA/STUERER ALGORITHM FOR
VT V/S PRE EXCITED SVT
the predominant polarity of the QRS
complex in leads V4 through V6 is defined
as positive or negative
Positive
a qR complex in one or more of
precordial leads V2 through V6
1:1 AV relationship
Absent
SPECIFICITY
SENSITIVITY 75%
VT Sp 100%, Sn 64%
VT Sp 100%,Sn 75%
100%
V>A Waves VT Sp100%,Sn 75%
SVT
Negative
Present
Absent
Present/Absent with A >V waves
Sn75%/25% are still VT
Gunter Steurer ,Pedro Brugada et al Clin. Cardiol. 17, 306-308 (1994)

51. ACC/AHA ALGORITHM
Blomström-Lundqvist and Scheinman et al. Circulation 108:1871,2003,

52. IRREGULAR WCT
 AF + BBB
 Consistent QRS morphology
 Rate limited by AV node (usually < 200bpm)
 Atrial flutter with variable block + BBB
 Flutter waves present, some not conducted
 Consistent QRS morphology
 Consistent R-R interval in groups
 AF + WPW
 QRS morphology variation
 Rates can approach 300bpm

53.  MAT + BBB
 Irregular P waves of different morphology
 Consistent QRS morphology
 Inconsistent R-R interval
 Polymorphic VT
 QRS morphology variation (more chaotic than
WPW)
 Rates consistently rapid (often > 300bpm)
 Unstable

54. ELECTROPHYSIOLOGICAL
TESTING
 His Bundle–Ventricular Interval- When the His
bundle–ventricular (HV) interval is positive (i.e., the
His potential precedes the QRS onset), an HV
interval during the WCT shorter than that during
NSR (HVWCT less than HVNSR) indicates VT or
preexcited SVT
 an HVWCT equal to or longer than HVNSR
indicates SVT with aberrancy.
 When the HV interval is negative (i.e., the His
potential follows the QRS onset), SVT with
aberrancy are excluded.

55. SUMMARY
 Arriving at the correct diagnosis of tachycardia has obvious
clinical importance, in that current therapies can cure many
disorders thereby preventing further episodes.
 In cases of WCT, many algorithms have been proposed to
differentiate between the two major causes: VT and SVT-A.
Although each algorithm is introduced with great promise, each
has its limitations.
 The ideal algorithm would be one that is (1) easy to remember,
(2) universally applicable to all WCTs, (3) easy to apply with
unequivocal results, and (4) 100% sensitive and specific for VT
(or SVT).
 Until such a tool is developed, it is safest to treat the
patient with WCT that cannot be readily classified for
whatever reason as though the rhythm is VT, until proven
otherwise.

56. TAKE HOME MESSAGE
 VT>>SVT
 When in doubt treat as VT
 Do not hesitate to shock if hemodynamic instability is
present
 Brugada`s is not the only criteria, it`s time to move on!!
 Never make the mistake of rejecting VT because the broad
QRS tachycardia is haemodynamically well tolerated.

57. THANK YOU