Wide complex tachycardia Definitions Causes Features for differentiation Diagnostic approach/algorithms
Wide complex tachycardiaDefinition : A rhythm with QRS duration ≥ 120 ms and heart rate > 100/min. Sustained vs non sustained
Wide complex tachycardiaCauses : 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.
Wide complex tachycardiaFeatures 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)
Wide complex tachycardiaFeatures 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)
Wide complex tachycardia 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 JVP b. Variable S1 intensity c. Variation in SBP unrelated to respiration.6. Termination of WCT with physical manoeuvres and medications
Wide complex tachycardia Features for differentiation by ECG :1. QRS duration2. QRS axis3. Concordant pattern4. 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 .
Wide complex tachycardia1. 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%
Wide complex tachycardia2. 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).
Wide complex tachycardia3.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%
Wide complex tachycardia3.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
Wide complex tachycardia4.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%
Wide complex tachycardia5.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%
Wide complex tachycardia5.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%
Wide complex tachycardia5.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%.
Wide complex tachycardia6. 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
Wide complex tachycardia7. 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)
Wide complex tachycardia7. AV dissociation : V rate = 215/mt A rate = 125/mt A/V =0.58
Wide complex tachycardia7. AV dissociation : VT with retrograde 2:1 VA conduction (seen in 15-20% of VT)
Wide complex tachycardia7. AV dissociation : 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
Wide complex tachycardia7. AV dissociation : 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
Wide complex tachycardia7. AV dissociation : 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%
Wide complex tachycardia8. 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
Wide complex tachycardia9. aVR changes :1. Presence of initial ‘r’ wave in aVR2. Presence of initial ‘r’ or ‘q’ wave of > 40ms duration3. Presence of notch in descending limb of negative onset and predominantly negative QRS4. Vi/Vt ≤ 1 All the above features are indicative of VT Sensitivity – 96.7% Specificity – 99%
Wide complex tachycardia 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 complexExceptions :1. Inferior MI- initial r wave (rS complex) during NSR or SVT2. VT originating from base of heart may not have initial r wave
Wide complex tachycardia 9. aVR changes : Vi/Vt ≤ 1Vi = 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 complexCan 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.
Wide complex tachycardia10. 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.
Wide complex tachycardiaDiagnostic approach/algorithms BRUGADA 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
Wide complex tachycardiaDiagnostic 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
Wide complex tachycardia Diagnostic approach/algorithms BAYESIAN CRITERIACRITERIA LR V WAVE IN LBBBQRS WIDTH r > 40MS 50 =140MS 0.31 NOTCH IN ‘S’ 50 140-160MS 0.48 R-S > 60MS 50 > 160MS 22.86 NONE 0.13QRS 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 50V 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%
Wide complex tachycardiaDiagnostic approach/algorithms aVR CRITERIA Sensitivity – 96.7% Specificity – 99% Heart Rhythm, , Vereckei, A. et al. New algorithm using only lead aVR for DD of wide QRS complex tachycardia., 2008
Wide complex tachycardiaDiagnostic approach/algorithms 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.
Wide complex tachycardiaDiagnostic approach/algorithmsALGORITHM ORIGINAL STUDY LAU & NG(2001) ISENHOUR(2000) SEN. SPEF. SEN. SPE. SEN SPE.BRUGADA 98.7 96.5 92 44 79-91 43-70GRIFFITH 95 64 92 44BAYESIAN 95 52 97 56
Wide complex tachycardiaDiagnostic approach/algorithms 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