WIDE QRS TACHYCARDIA

MSN PAVAN KUMAR

Wide QRS Tachycardia

Wide complex tachycardia

DefinitionsCauses Features for differentiationDiagnostic 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 BBB4.Any SVT with delayed conduction d/t drugs and

electrolytesa. Class IA,IC ; hyperkalemia.

5.Antidromic AVRT(1-5%)6.Pacemaker mediated rhythmIrregular :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.


Pacemaker rhythm(<1% of WCT) 1.History and physical examination2.ECG:

a. Stimulus artefactb. 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 :

Features for differentiation :History and physical examination:1.H/o heart disease – previous MI , angina , CHF –

have a PPA of 95% for diagnosing VT2.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 JVPb. Variable S1 intensityc. Variation in SBP unrelated to respiration.

6.Termination of WCT with physical manoeuvres and medications


Features for differentiation by ECG :1.QRS duration2.QRS axis3.Concordant pattern 4.Precordial RS duration.5.Morphological criteria - RBBB , LBBB , ambiguous

chest lead pattern6.Q wave presence7.AV dissociation8.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


Sensitivity – 30-60%

Specificity - 80-100%

5. LBBB – V1,V6:


Sensitivity – 100%

Specificity - 89%

Sensitivity – 17%

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-A3. 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 dissociation3. AV ratio of less than 14. 2:1 VA block(d/t retrograde conduction)5. Variation in QRS amplitude during WCT6. Fusion & capture beats7. Recording separate atrial electro gram

(oesophageal/transvenous)8. Echo (evaluating RA contraction in relation to

ventricular)


7. AV dissociation :


V rate = 215/mtA rate = 125/mtA/V =0.58



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

Variation in amplitude of QRS during WCT1.Scalar summation of P wave with QRS2.Variable ventricular filling in the presence of AVDPresence 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 .



Sensitivity – 20-50%Specificity – 98%

8. Base line QRS prolongation:a. Pt with baseline QRS rhythm and WCT QRS different –

VT1. QRS during VT is narrower than baseline rhythm2. Contra lateral BBB in baseline rhythm and during WCT3. AV dissociation4. 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 :10. Presence of initial ‘r’ wave in aVR11. Presence of initial ‘r’ or ‘q’ wave of > 40ms

duration12. Presence of notch in descending limb of

negative onset and predominantly negative QRS13. 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 SVT2. VT originating from base of heart may not have

initial r wave


9. aVR changes :

Vi = voltage in the initial 40ms of QRSVt = voltage in the terminal 40ms of QRSIn 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 leadThe 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


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.

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

Sensitivity and specificity of

97%

Diagnostic approach/algorithms1. 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



Sensitivity – 98.7%

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

BRUGADA CRITERIA

WCT



NO YES

INDEPENDENT P WAVES

YESVT

Griffith MJ,Garratt Ci,et VT as default diagnosis in broad complex tachycardia. Lancet 1994 feb

Sensitivity – 95%

Specificity – 64%

GRIFFITH CRITERIA


Diagnostic approach/algorithms BAYESIAN CRITERIA

CRITERIA LR

QRS WIDTH =140MS 140-160MS > 160MS

0.310.4822.86

QRS AXIS NW AXIS RBBB + LAD LBBB + RAD NONE

7.868.213.930.47

V WAVE IN RBBB TALLER LT PEAK Rs OR qR rsR OR rR NONE

504.030.211.41

V WAVE IN LBBB r > 40MS NOTCH IN ‘S’ R-S > 60MS NONE

5050500.13

INTRINSICOID IN V6 = 60MS < 60MS

19.30.46

V6 MORPHOLOGY QSBIPHASIC RBBB R/S<1TRIPHASIC RBBB R/S<1

50500.13

Sensitivity – 95%

Specificity – 52%


Diagnostic approach/algorithms aVR CRITERIA

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

Sensitivity – 96.7%

Specificity – 99%



Sen.10%Spe.100%Sen.48%Spe.98%

Sen.89%Spe.89%Sen.95%Spe.80%

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

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


ALGORITHM ORIGINAL STUDYSEN. SPEF.

LAU & NG(2001)SEN. SPE.

ISENHOUR(2000)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.BRUGADA2.aVR criteria3.Vereckei combined criteria(old & aVR criteria)


WIDE QRS TACHYCARDIA

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