WIDE QRS TACHYCARDIA

Wide QRS Tachycardia

MSN PAVAN KUMAR

Wide complex tachycardia

 Definitions
 Causes
 Features for differentiation
 Diagnostic approach/algorithms


Definition :
 A rhythm with QRS duration ≥ 120 ms and heart rate > 100/min.
 Sustained vs non sustained

Causes :
Regular :
1. Ventricular tachycardia(80% of WCT)
2. Any SVT with aberrancy (2nd MC WCT)
3. Any SVT with BBB
4. Any SVT with delayed conduction d/t drugs and electrolytes
a. Class IA,IC ; hyperkalemia.
5. Antidromic AVRT(1-5%)
6. Pacemaker mediated rhythm
Irregular :
1. AF with conduction on preexcitation pathway.
2. Any irregular SVT with aberrancy , BBB .
3. VT in the 1st 30 sec , pts on anti arrythmitic drugs – cycle length
varibility.

Features for differentiation :

 Pacemaker rhythm(<1% of WCT)
1. History and physical examination
2. ECG:
a. Stimulus artefact
b. LBBB with left superior axis(if RV apical pacing) , various
combinations ( biventricular pacing)

Features for differentiation :

VT vs Preexcited tachycardia
•VT
– Predominantly negative QRS complexes in V4-V6
– Presence of a QR complex in one or more leads V2-V6
– More QRS complex than P
•75% sensitivity & 100% specificity for VT (Stierer et al)

 Features for differentiation :
 History and physical examination:
1. H/o heart disease – previous MI , angina , CHF – have a PPA of 95%
for diagnosing VT
2. Pts with VT are older than SVT (> 35 yrs)
3. SVT-A often have h/o previous episode(>3years)
4. Pts with SVT-A are hemodynamically stable.
5. Examination for AV dissociation
a. Cannon A waves in JVP
b. Variable S1 intensity
c. Variation in SBP unrelated to respiration.
6. Termination of WCT with physical manoeuvres and medications

 Features for differentiation by ECG :
1. QRS duration
2. QRS axis
3. Concordant pattern
4. Precordial RS duration.
5. Morphological criteria - RBBB , LBBB , ambiguous chest lead pattern
6. Q wave presence
7. AV dissociation
8. Baseline QRS prolongation – QRS duration , QRS configuration.
9. aVR changes.
10.Lead II R-wave-peak-time (RWPT) criterion .

1. QRS duration :
 > 160 ms with LBBB , >140 ms with RBBB - VT
 Wellens et al . Showed that 69% of VT had QRS duration of
>140ms and none of SVT-A showed QRS duration of >140ms.
 Exceptions:
a. Anti arrythmitic drugs non specifically prolong QRS duration.
b. Pts with structurally normal heart may have VT with QRS
duration of 120-140ms.(<140ms in12% , < 120 ms in 4%)
c. QRS duration also depend site of origin of VT , septal VT

QRS duration has sensitivity of 70%

2. QRS axis :
 Frontal plane axis of -90 to +180 --- VT
 Shift in QRS axis of more than 40 from baseline --- VT(less
specific)
 RBBB with LAD, LBBB with RAD --- VT.
 LAFB (-30 to -90) ,
LPFB (+110 to150) and
RBBB (normal axis).

3.Concordant QRS in chest leads:
 Concordant QRS in chest leads is diagnostic of VT uncommon in
SVT-A.
 Exceptions:
 Positive concordance (ventricular activation begins left
posteriorly) seen in VT originating in Lt post wall or SVT using a
left posterior accessory pathway for AV conduction.
 If no additional criteria for WPW are absent don’t consider it
because of low incidence(<6%)

Specificity of 90%, Sensitivity of 20%

3.Concordant QRS in limb leads :
 The presence of predominantly negative QRS complexes in leads
1,2,3 is suggestive of VT
 This is another way to describe right superior axis
 Similar to RS axis it is considered as highly specific for VT

4.Pericardial RS duration criteria :
 If concordant QRS complexes are absent i.e with RS complex
onset of R wave to nadir of S wave > 100 ms.

Sensitivity – 66%
Specificity - 98%

5.RBBB – V1 :
 rSr , rSR , rR , rsr patterns consistent with SVT-A
 R , R>30ms with any negative QRS , qR --- VT
 This is because right ventricle doesn’t participate in initial QRS

Sensitivity – 30-80%
Specificity - 84-95%

5.RBBB – V6 :
 qRs , Rs , RS with R/S >1 --- SVT –A
 R , QR , QS , RS with R/S < 1 --- VT

Specificity - 80-100%

5. LBBB – V1,V6:

Sensitivity – 100% Sensitivity – 17%
Specificity - 89% Specificity - 100%


5.Ambiguous chest lead pattern:
 W and M pattern in V1 have been classified as LBBB & RBBB
 Because they are ambiguous in this way, they are unlikely to
represent typical aberration and are highly specific for VT.
 Sensitivity of 60-80% , specificity of 90-95%.

6. Q wave presence :
 Q during WCT --- suggest old MI --- VT most likely.
 In general pts with post MI VT maintain Q wave during WCT that
are present during baseline in the same lead.
 Exceptions :
1. Pts with DCMP will have Q wave during VT that are not present
during baseline.
2. PSEUDO Q wave with retrograde p wave deforming QRS can
be seen in SVT-A
3. Preexcited tachycardia with posterior AV connection can have Q
wave in inferior leads

7. AV dissociation :
 The most specific ECG finding for VT .
 Clues for AV dissociation:
1. Clinically by cannon A waves , variable intensity of S1 , Variation
in SBP unrelated to respiration.
2. AV dissociation
3. AV ratio of less than 1
4. 2:1 VA block(d/t retrograde conduction)
5. Variation in QRS amplitude during WCT
6. Fusion & capture beats
7. Recording separate atrial electro gram
(oesophageal/transvenous)
8. Echo (evaluating RA contraction in relation to ventricular)


V rate = 215/mt
A rate = 125/mt
A/V =0.58


VT with retrograde 2:1 VA conduction (seen in 15-20% of VT)


 Variation in amplitude of QRS during WCT
1. Scalar summation of P wave with QRS
2. Variable ventricular filling in the presence of AVD
 Presence of multiple WCT configuration has a sensitivity of 55%
for diagnosing VT


 The QRS complex is prolonged, and the R-R interval is regular
except for occasional capture beats (C) that have a normal contour
and are slightly premature. Complexes intermediate in contour
represent fusion beats (F).
 Thus, even though atrial activity is not clearly apparent,
atrioventricular dissociation is present during ventricular
tachycardia and produces intermittent capture and fusion beats

 Caveats while using AVD:
1. Low sensitivity (20-50%) is d/t fast heart rates , inadequate
duration of recording , observer inexperience.
2. 30% of pts , especially VT with low V rate , have 1:1 VA
conduction – differentiate by vagal maneuvers , adnosine.
3. AF and VT co exist AVD cannot be diagnosed .

Specificity – 98%

8. Base line QRS prolongation:
a. Pt with baseline QRS rhythm and WCT QRS different – VT
1. QRS during VT is narrower than baseline rhythm
2. Contra lateral BBB in baseline rhythm and during WCT
3. AV dissociation
4. Rarely other findings may be useful like precordial concordance ,
north-west axis , monophasic R wave in V1

Pts with BBRT Impulse originates in RBB Travels through LBB

Have typical features of LBBB

9. aVR changes :
1. Presence of initial ‘r’ wave in aVR
2. Presence of initial ‘r’ or ‘q’ wave of > 40ms duration
3. Presence of notch in descending limb of negative onset and
predominantly negative QRS
4. Vi/Vt ≤ 1
All the above features are indicative of VT

Sensitivity – 96.7%
Specificity – 99%

9. aVR changes : Initial ‘r’
wave in aVR
During SVT with aberrancy ,
initial septal activation and main
ventricular activation are
directed away from lead aVR
 negative QRS complex

Exceptions :
1. Inferior MI- initial r wave (rS complex) during NSR or SVT
2. VT originating from base of heart may not have initial r wave

9. aVR changes :

9. aVR changes : Vi/Vt ≤ 1
Vi = voltage in the initial 40ms of QRS
Vt = voltage in the terminal 40ms of QRS
In SVT-A only one portion is bundle branch is blocked --- so the
initial portion of QRS is rapid compared to terminal portion.
In VT slow muscle to muscle spread of impulse causes slower
voltage changes through out QRS complex
Can be applied to any lead
The vi/vt was > 1 (signifying supraventricular origin) in 88%
tracings with LBBB pattern, in 98% with RBBB pattern, and
90% with nonspecific IVCD.

9. aVR changes : Vi/Vt ≤ 1

10. Lead II R-wave-peak-time (RWPT) criterion : Pavas criteria

RWPT > or =50 ms at DII is a
simple and highly sensitive
criterion that discriminates VT
from SVT in patients with wide
QRS complex tachycardia.

Sensitivity and
specificity of 97%

Heart Rhythm. 2010 Jul;7(7):922-6. Epub 2010 Mar 4.

 Diagnostic approach/algorithms
1. Wellens(1978) , Akhtar(1988) ,
2. Brugada(1991)
3. Griffith(1994)
4. Bayesian(1995)
5. aVR algorithms(2007)
6. lead II R-wave-peak-time (RWPT) criterion(2010)
7. Combined .

Diagnostic approach/algorithms

WELLENS CRITERIA AKHTAR CRITERIA

Diagnostic approach/algorithms BRUGADA CRITERIA

Specificity – 96.5%

Brugada P, Brugada Jet al.A new approach to the
DD of a regular tachycardia with a wide QRS
complex. Circulation. 1991;83:1649-16595

Diagnostic approach/algorithms GRIFFITH CRITERIA
WCT

NO YES

VT YES
INDEPENDENT P WAVES

Sensitivity – 95%
Griffith MJ,Garratt Ci,et VT as default diagnosis in
Specificity – 64% broad complex tachycardia. Lancet 1994 feb

Diagnostic approach/algorithms BAYESIAN CRITERIA

CRITERIA LR V WAVE IN LBBB
QRS WIDTH r > 40MS 50
=140MS 0.31 NOTCH IN ‘S’ 50
140-160MS 0.48 R-S > 60MS 50
> 160MS 22.86 NONE 0.13
QRS AXIS INTRINSICOID IN V6
NW AXIS 7.86 = 60MS 19.3
RBBB + LAD 8.21 < 60MS 0.46
LBBB + RAD 3.93 V6 MORPHOLOGY
NONE 0.47 QS 50
V WAVE IN RBBB BIPHASIC RBBB R/S<1 50
TALLER LT PEAK 50 TRIPHASIC RBBB R/S<1 0.13
Rs OR qR 4.03
rsR OR rR 0.21
NONE 1.41 Sensitivity – 95%
Specificity – 52%

Diagnostic approach/algorithms aVR CRITERIA

Specificity – 99%

Heart Rhythm, , Vereckei, A. et al. New
algorithm using only lead aVR for DD of wide
QRS complex tachycardia., 2008


Sen.10% The sensitivity [95.7 vs.
Spe.100%
88.2, P < 0.001] and NPV
[83.5% vs. 65.3% for VT
Sen.48% diagnosis of the new
Spe.98% algorithm were superior to
those of the Brugada criteria
Sen.89%
Spe.89%

Application of a new algorithm in the DD
Sen.95% of wide QRS complex tachycardia Andra´s
Spe.80% Vereckei et al . EHJ 2007.


ALGORITHM ORIGINAL STUDY LAU & NG(2001) ISENHOUR(2000)
SEN. SPEF. SEN. SPE. SEN SPE.
BRUGADA 98.7 96.5 92 44 79-91 43-70

GRIFFITH 95 64 92 44

BAYESIAN 95 52 97 56


 Comparison of five electrocardiographic methods for differentiation
of wide QRS-complex tachycardias
 Brugada, Bayesian, Griffith, and aVR algorithms, and the lead II R-
wave-peak-time (RWPT) criterion
 All five algorithms/criteria had equal moderate diagnostic accuracy.
 The newer methods were not more accurate than the classic Brugada
algorithm

Comparison of five electrocardiographic methods for differentiation
of wide QRS-complex tachycardias.Jastrzebski.M Europace 2010 feb
14


Best algorithmic approach for diagnosing WCT
1. BRUGADA
2. aVR criteria
3. Vereckei combined criteria(old & aVR criteria)

WIDE QRS TACHYCARDIA

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