2. WIDE COMPLEX TACHYCARDIA

3. Definitions
Wide QRS complex tachycardia is a rhythm with a rate of ≥100 b/m and QRS duration of ≥ 120 ms
VT – 80% of Wide QRS Complex Tachycardia
SVT with abberancy 15 to 20%
SVT with bystander preexcitation And antidromic reentrant tachycardia – 1% to 6%

4. Causes of wide QRS TACHYCARDIAVT
MACROREENTRANT VT
FOCAL VT
SVT WITH ABERRANCY
FUNCTIONAL BBB
PREEXISTENT BBB
PREEXCITED SVT
ANTIDROMIC AVRT
AT OR AVNRT WITH BYSTANDER BYPASS TRACT
ANTIARRYTHMIC DRUGS
CLASS 1A,CLASS 1C
AMIODARONE
ELECTROLYTE ABNORMALITIES
HYPERKALEMIA

5. Why QRS is wide?
A widened QRS (≥120 msec) occurs when ventricular activation is abnormally slow
Arrhythmia originates outside of the normal conduction system (ventricular tachycardia)
Abnormalities within the His-Purkinje system (supraventricular tachycardia with aberrancy).
Pre-excited tachycardias: supraventricular tachycardias with antegrade conduction over an accessory pathway into the ventricular myocardium.

6. MORPHOLOGY
LBBB morphology-QRS complex duration ≥ 120 ms with a predominantly negative terminal deflection in lead V1
RBBB morphology-QRS complex duration ≥ 120 ms with a predominantly positive terminal deflection in V1

7. RBBB morphology wide QRS tachycardiaVT
Structurally normal heart
LVOT VT
Fasicular VT
Abnormal heart
LV myocardial VT
Bundle Branch Reentrant VT

8. SVT
SVT with pre existing RBBB
SVT with functional RBBB

9. LBBB morphology wide QRS tachycardiaVT
Structurally normal heart
RVOT VT
Abnormal heart
Right ventricular myocardial VT
ARVD

10. SVT
Mahaim fibre mediated tachycardia
SVT with LBBB

11. SVT vs VT Clinical history
Age
- ≥ 35 ys → VT (positive predictive value of 85%)
Underlying heart disease
Previous MI → 90% VT
Pacemakers or ICD
Increased risk of ventricular tachyarrhythmia
Medication
Drug-induced tachycardia → Torsade de pointes
Diuretics
Digoxin-induced arrhythmia → [digoxin] ≥2ng/l or normal if hypokalemia

12. Duration of the tachycardia — SVT is more likely if the tachycardia has recurred over a period of more than three years

13. SVT vs VT
AV dissociation
-cannon A waves
-variable intensity of S1
Termination of WCT in response to maneuvers like Valsalva, carotid sinus pressure, or adenosine favor SVT

14. Maneuvers
The response of the arrhythmia to maneuvers may provide insight to the mechanism of the WCT
Carotid sinus pressure —  Enhances vagal tone , depresses sinus and AV nodal activity

15. VT
Unaffected by vagal maneuvers such as carotid sinus pressure or valsalva
May slow or block retrograde conduction.
Exposes AV dissociation
Rarely, VT terminates in response to carotid sinus pressure.

16. Rate
Limited use in distinguishing VT from SVT.

17. Regularity
Marked irregularity of RR interval occurs in atrial fibrillation (AF) with aberrant conduction and polymorphic VT

18. Axis
A right superior axis (axis from -90 to ±180º)- “northwest" axis, strongly suggests VT .
(sensitivity 20%,specificity 96%)
Exception -antidromic AVRT in Wolff- Parkinson-White (WPW) syndrome .

19. AXIS
Compared to the axis during sinus rhythm, an axis shift during the WCT of more than 40º suggests VT .
In a patient with a RBBB-like WCT, a QRS axis to the left of -30º suggests VT.
In a patient with an LBBB-like WCT, a QRS axis to the right of +90º suggests VT .

20. QRS duration In general, wider QRS favors VT.
In a RBBB-like WCT, a QRS duration >140 msec suggests VT
In a LBBB-like WCT, a QRS duration >160 msec suggests VT  
In an analysis of several studies, a QRS duration >160 msec was a strong predictor of VT (likelihood ratio >20:1) .

21. A QRS duration <140 msec does not exclude VT
SEPTAL VT
FASCICULAR VT

22. Concordance
Concordance is present when the QRS complexes in all six precordial leads (V1 through V6) are monophasic with the same polarity.
Either -entirely positive with tall, monophasic R waves, or entirely negative with deep monophasic QS complexes.
If any of the six leads has a biphasic QRS (qR or RS complexes), concordance is not present.

23. Negative concordance is strongly suggestive of VT
exception:SVT with LBBB aberrancy may demonstrate negative concordance
Positive concordance -also indicates VT
exception: antidromic AVRT with a left posterior accessory pathway

24. Presence of concordance strongly suggests VT (90 percent specificity)
Absence is not helpful diagnostically (approximately 20 percent sensitivity) 
Higher specificity for Positive concordance compared to negative concordance(specificity 95% vs 90 %)

25. Negative concordance

26. Positive concordance

27. AV dissociation
AV dissociation is characterized by atrial activity that is independent of ventricular activity
Atrial rate slower than the ventricular rate diagnostic of VT.
Atrial rate that is faster than the ventricular rate - SVTs.

28. Absence of AV dissociation in VT
AV dissociation may be present but not obvious on the ECG.
The ventricular impulses conduct backwards through the AV node and capture the atrium ( retrograde conduction), preventing AV dissociation.

29. Dissociated P waves PP and RR intervals are different
PR intervals are variable
There is no association between P and QRS complexes
The presence of a P wave with some , but not all, QRS complexes

30. Fusion beats
Fusion beat-produced by fusion of two ventricular activation wavefronts characterised by QRST morphology intermediate between normal and fully abnormal beat.
Fusion beats during a WCT are diagnostic of AV dissociation and therefore of VT.
Low sensitivity(5-20%)

32. Capture beats
Capture beats, or Dressler beats, are QRS complexes during a WCT that are identical to the sinus QRS complex .
Implies that the normal conduction system has momentarily "captured" control of ventricular activation from the VT focus.
Fusion beats and capture beats are more commonly seen when the tachycardia rate is slower

34. If old ecg available…
Ideal QRS configuration between baseline and WQRST-suggest SVT(exception :bundle branch reentrant VT)
Contralateral BBB patterns in baseline vs WQRST ECGs-suggest VT
WQRST complexes narrower than baseline ECG-suggest VT(the baseline ecg must have a bundle branch block pattern)

35. Also look for…. VPCs Evidence of prior MI QT interval
ECG clues to any other structural heart disease

36. SVT vs VT ECG criteria: Brugada algorithm
Brugada P. Ciculation 1991

37. Step 1

38. Step 2

39. Step 3

40. Step 4: LBBB - type wide QRS complex
SVT VT
R wave >30ms
small R wave
notching of S wave V1
fast downslope
of S wave
> 70ms V6
Q wave
no Q wave

41. V6 in LBBB type QRS True LBBB Monophasic R with slow upstroke VT
qR or QS pattern

42. Step 4: RBBB - type wide QRS complex
SVT VT
rSR’ configuration
monophasic R wave
qR (or Rs) complex V1 or
R/S > 1
R/S ratio < 1
QS complex V6 or

43. “R/S ratio in V6 rule”
R/S ratio in RBB type wide QRS tachycrdia less than one, favours VT
Sensitivity-0.73
Specificity-0.79
Positive predictive value 0.9

44. Josephson’s sign 
Notching near the nadir of the S-wave
Suggest VT

45. Rabbit’s ear

46. Wellens Criteria • Left axis deviation • AV dissociation
  •   QRS width > 140 msec
  •   Left axis deviation
  •   AV dissociation
  •  Configurational characteristics of the QRS morphology

47. Ultrasimple Brugada criterion
Joseph Brugada
R wave peak time in Lead II 
Duration of onset of the QRS to the first change in polarity (either nadir Q or peak R) in lead II.
If the RWPT is ≥ 50ms the likelihood of a VT very high (positive likelihood ratio 34.8)
Pava LF, Perafán P, Badiel M, Arango JJ, Mont L, Morillo CA, and Brugada J. R-wave peak time at DII: a new criterion for differentiating between wide complex QRS tachycardias. Heart Rhythm 2010 Jul; 7(7)

49. Vereckei A, Duray G, Szénási G, Altemose GT, and Miller JM
Vereckei A, Duray G, Szénási G, Altemose GT, and Miller JM.  Application of a new algorithm in the differential diagnosis of wide QRS complex tachycardia. Eur Heart J 2007 Mar; 28(5)

50. Vi –initial 40 ms in v1 (initial ventricular activation velocity)
Vt terminal 40ms in v1(late ventricular activation velocity)
Wct caused by svt-initial activation of the septum is rapid followed by conduction delay which manifest in later part of qrs vi/vt more than 1
In Vt vi/vt is less than 1
Vi/vt less than 1 in svt—svt with old anteroseptal MI
Vi/vt more than 1 in VT-FASCICULAR VT

51. Vi/Vt

52. aVR algorithm
Criteria looks ONLY at lead aVR (if answer is yes, then VT): 1. Is there an initial R wave? 2. Is there a r or q wave > 40 msec 3. Is there a notch on the descending limb of a negative QRS complex? 4. Measure the voltage change in the first (vi) and last 40 msec (vt). Is vi / vt < 1? Vereckei et al, Heart Rhythm 2008

53. Sensitivity Specificity PPV NPV Brugada 89% 73% 92% 67%
Vereckei 97% % % %
Vereckei A, Duray G, Szénási G, Altemose GT, and Miller JM.  Application of a new algorithm in the differential diagnosis of wide QRS complex tachycardia. Eur Heart J 2007 Mar; 28(5)

54. Sensitivity & Specificity For VT
88% and 53% by aVR algorithm

55. VT vs AVRT ECG criteria
Brugada P. Ciculation 1991

56. ELECTROPHYSIOLOGICAL TESTING
H-V INTERVAL (HIS BUNDLE TO VENTRICLE TIME)
POSITIVE H-V INTERVAL (HIS POTENTIAL PRECEDES QRS ON SET)
HV interval during WCT HV interval during WCT
shorter than HV interval same or longer than HV
In sinus rhythm interval in Sinus rhythm
1)SVT WITH ABBERANCY
SVT WITH PREEXCITATION ) BBR VT

57. HV INTERVAL NEGATIVE (HIS POTENTIAL FOLLOWS QRS)
1)MYOCARDIAL VT
2)PREECXCITED SVT
IT RULES OUT
1)BBR VT
2) SVT WITH ABBERANCY

58. ELECTROPHYSIOLOGICAL TESTING
PROLONGATION OF VA INTERVAL AND TACHYCARDIA CYCLE LENGTH
ANTIDROMIC AVRT
TACHYCARDIA CYCLE LENGTH OSCILLATIONS
VARIATION IN TACHYCARDIA CYCLE LENGTH(V-V INTERVAL) if dictated and preceded by similar variations in H-H INTERVAL SVT WITH ABBERANCY,BBR VT
if,variation IN V-V INTERVAL precedes similar changes in H-H INTERVAL---- MYOCARDIAL VT ,PREEXCITED VT

59. ELECTROPHYSIOLOGICAL TESTING
HIS BUNDLE – RBB POTENTIAL SEQUENCE
H-RB-V ACTIVATION SEQUENCE -SVT WITH ABBERANCY,BBR VT
RB-H-V SEQUENCE – ANTIDROMIC AVRT USING ATRIO FASCICULAR PATHWAY
RB-V-H SEQUENCE - ANTIDROMIC AVRT USING ATRIO FASCICULAR PATHWAY
V-RB-H –VT
V-H-RB -VT

60. ELECTROPHYSIOLOGICAL TESTING
ATRIOVENTRICULAR RELATIONSHIP
ATRIAL RATE FASTER THAN VENTRICULAR
VT UNLIKELY
VENTRICULAR RATE FASTER THAN ATRIAL VT

61. ELECTROPHYSIOLOGY ATRIAL ACTIVATION SEQUENCE
CONCENTRIC ATRIAL ACTIVATION- SVT AND VT
ECCENTRIC ATRIAL ACTIVATION -VT

62. Diagnostic maneuvers ATRIAL EXTRASTIMULATION
If advances next ventricular contraction similar in morphology with WCT --- EXCLUDES VT
delay in onset of next ventricular contraction -----EXCLUDES VT

63. DIAGNOSTIC MANEUVERS ATRIAL PACING
Ability to entrain WCT with similar morphology-----EXCLUDES MTOCARDIAL VT (CAN OCCUR IN BBR VT)
Ability to dissociate with rapid atrial pacing without influencing tachycardia cycle length and qrs morphology -----VT

64. Ventricular extra stimulation
IF IT RESETS NEXT QRS WITHOUT AFFECTING NEXT A- A INTERVAL------VT, EXCLUDES SVT