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 BBB PREEXISTENT BBB PREEXCITED SVT ANTIDROMIC AVRT AT OR AVNRT WITH BYSTANDER BYPASS TRACT ANTIARRYTHMIC DRUGS CLASS 1A,CLASS 1C AMIODARONE 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 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

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 VT ECG criteria: Brugada algorithm Brugada P. Ciculation 1991

Step 1

Step 2

Step 3

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

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 rSR’ configuration monophasic R wave qR (or Rs) complex V1 or R/S > 1 R/S ratio < 1 QS complex V6 or

“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 • Left axis deviation • AV dissociation   •   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 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 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

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 AVRT ECG criteria Brugada P. Ciculation 1991

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 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 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

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