Download approach to wide qrs complex tachycardia

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
PREEXCITED SVT
FUNCTIONAL BBB
PREEXISTENT BBB
ANTIARRYTHMIC
DRUGS
CLASS 1A,CLASS 1C
AMIODARONE
ELECTROLYTE
ABNORMALITIES
HYPERKALEMIA
ANTIDROMIC AVRT
AT OR AVNRT WITH
BYSTANDER BYPASS TRACT
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 WolffParkinson-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
VT
SVT
small R wave
R wave >30ms
notching of S wave
V1
fast downslope
of S wave
> 70ms
Q wave
V6
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
VT
SVT
rSR’ configuration
monophasic R wave
V1
or
R/S > 1
V6
qR (or Rs) complex
R/S ratio < 1
QS complex
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
•
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 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)
(vt). Is vi / vt < 1?
and last 40 msec
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 AA INTERVAL------VT, EXCLUDES SVT