WIDE COMPLEX TACHYCARDIA

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%

Causes of wide QRS TACHYCARDIA

VT MACROREENTRANT VT

FOCAL VT

SVT WITH ABERRANCY

FUNCTIONAL BBBPREEXISTENT BBB

PREEXCITED SVT ANTIDROMIC AVRTAT OR AVNRT WITH BYSTANDER BYPASS TRACT

ANTIARRYTHMIC DRUGS

CLASS 1A,CLASS 1CAMIODARONE

ELECTROLYTE ABNORMALITIES

HYPERKALEMIA

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.

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

RBBB morphology wide QRS tachycardia

VT

Structurally normal heart LVOT VT

Fasicular VT

Abnormal heart LV myocardial VT

Bundle Branch Reentrant VT

SVT

SVT with pre existing RBBB

SVT with functional RBBB

LBBB morphology wide QRS tachycardia

VT

Structurally normal heart RVOT VT

Abnormal heart Right ventricular myocardial VT

ARVD

SVT

Mahaim fibre mediated tachycardia

SVT with LBBB

SVT vs VT Clinical history

Medication Drug-induced tachycardia → Torsade de pointesDiureticsDigoxin-induced arrhythmia → [digoxin] ≥2ng/l or normal if hypokalemia

Age - ≥ 35 ys → VT (positive predictive value of 85%)

Underlying heart disease Previous MI → 90% VT

Pacemakers or ICD Increased risk of ventricular tachyarrhythmia

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

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

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

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.

Rate

Limited use in distinguishing VT from SVT.

Regularity

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

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 .

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 .

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) .

A QRS duration <140 msec does not exclude VT

SEPTAL VT

FASCICULAR VT

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.

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

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 %)

Negative concordance

Positive concordance

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.

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.

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

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%)

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

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)

Also look for….

VPCs

Evidence of prior MI

QT interval

ECG clues to any other structural heart disease

SVT vs VTECG criteria: Brugada algorithm

Brugada P. Ciculation 1991

Step 1

Step 2

Step 3

Step 4: LBBB - type wide QRS complex

SVT VT

small R wave notching of S waveR wave >30ms

fast downslopeof S wave

no Q wave

Q wave

> 70ms

V1

V6

V6 in LBBB type QRS

True LBBB

Monophasic R with slow upstroke

VT

qR or QS pattern

Step 4: RBBB - type wide QRS complex

SVT VT

V1

V6

or

or

R/S > 1 R/S ratio < 1 QS complex

rSR’ configuration monophasic R wave qR (or Rs) complex

“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

Josephson’s sign 

Notching near the nadir of the S-wave

Suggest VT

Rabbit’s ear

Wellens Criteria

  •   QRS width > 140 msec

  •   Left axis deviation

  •   AV dissociation

  •  Configurational characteristics of the QRS morphology

Ultrasimple Brugada criterion Joseph Brugada - 2010

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) 922-6.

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) 589-600.

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

Vi/Vt

aVR algorithmCriteria 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

Sensitivity Specificity PPV NPV

Brugada 89% 73% 92% 67%

Vereckei 97% 75% 93% 87%

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) 589-600.

Sensitivity & Specificity For VT

88% and 53% by aVR algorithm

VT vs AVRTECG criteria

Brugada P. Ciculation 1991

ELECTROPHYSIOLOGICAL TESTINGH-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 2) BBR VT

HV INTERVAL NEGATIVE (HIS POTENTIAL FOLLOWS QRS)

1)MYOCARDIAL VT

2)PREECXCITED SVT

IT RULES OUT

1)BBR VT

2) SVT WITH ABBERANCY

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

ELECTROPHYSIOLOGICAL TESTINGHIS 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

ELECTROPHYSIOLOGICAL TESTING

ATRIOVENTRICULAR RELATIONSHIP

ATRIAL RATE FASTER THAN VENTRICULAR

VT UNLIKELY

VENTRICULAR RATE FASTER THAN ATRIAL

VT

ELECTROPHYSIOLOGY ATRIAL ACTIVATION SEQUENCE

CONCENTRIC ATRIAL ACTIVATION- SVT AND VT

ECCENTRIC ATRIAL ACTIVATION -VT

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

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

Ventricular extra stimulation

IF IT RESETS NEXT QRS WITHOUT AFFECTING NEXT A-A INTERVAL------VT, EXCLUDES SVT