18. Characteristics of the 12-lead ECG duringCharacteristics of the 12-lead ECG during
the tachycardia that suggest a ventricularthe tachycardia that suggest a ventricular
origin for the arrhythmiaorigin for the arrhythmia
• AA QRS complex >0.14 sQRS complex >0.14 s in the absence ofin the absence of
antiarrhythmic therapyantiarrhythmic therapy
• AV dissociationAV dissociation (with or without fusion or(with or without fusion or
captured beats) or variable retrogradecaptured beats) or variable retrograde
conductionconduction
• AA superior QRS axissuperior QRS axis in the presence of ain the presence of a
right bundle branch block patternright bundle branch block pattern
• Concordance of the QRS patternConcordance of the QRS pattern in allin all
precordial leads (i.e., all positive or allprecordial leads (i.e., all positive or all
negative deflections)negative deflections)
• OtherOther QRS patterns (morphology)QRS patterns (morphology) withwith
prolonged duration that are inconsistentprolonged duration that are inconsistent
with typical right or left bundle branch blockwith typical right or left bundle branch block
patternspatterns
19. ECG CRITERIA THAT FAVORECG CRITERIA THAT FAVOR
VENTRICULAR TACHYCARDIAVENTRICULAR TACHYCARDIA
• AV dissociationAV dissociation
• QRS width:QRS width:
>0.14 s with RBBB>0.14 s with RBBB configurationconfiguration
>0.16 s with LBBB>0.16 s with LBBB configuration configuration
• QRS axis:QRS axis:
Left axis deviation with RBBBLeft axis deviation with RBBB
morphologymorphology Extreme left axisExtreme left axis
deviationdeviation (northwest axis)(northwest axis) with LBBBwith LBBB
morphology morphology
• Concordance of QRSConcordance of QRS in precordialin precordial
leads
Harrison's Principles of internal Medicine, 16th Edition
20. ECG CRITERIA THAT FAVORECG CRITERIA THAT FAVOR
VENTRICULAR TACHYCARDIAVENTRICULAR TACHYCARDIA
• MorphologicMorphologic
patterns of the QRSpatterns of the QRS
complex RBBB:complex RBBB:
Mono- orMono- or
biphasicbiphasic
complex in V1complex in V1
RS (RS (only withonly with
left axisleft axis
deviationdeviation)) oror QSQS
in V6in V6
• LBBB:LBBB:
Broad R wave in V1Broad R wave in V1
or V2or V2 0.04 s0.04 s
• Onset of QRS toOnset of QRS to
nadir of S wave in V1nadir of S wave in V1
or V2 ofor V2 of 0.07 s0.07 s
• NotchedNotched
downslope of Sdownslope of S
wave in V1 or V2wave in V1 or V2
• Q waveQ wave in V6in V6
Harrison's Principles of internal Medicine, 16th Edition
21. Differential Diagnosis of WideDifferential Diagnosis of Wide
Regular QRS TachcardiaRegular QRS Tachcardia
Absence of an RS complex in all precordial leads
Favor VT
Yes No
R to S interval > 100 ms in one precordial lead?
Yes
Favor VT
No
Atrio-ventricular dissociation?
Yes
Favor VT
No
Morphology criteria
Four-step AlgorithmFour-step Algorithm (by(by BrugadaBrugada et al)et al)
1
2
3
4
22. Differential Diagnosis of WideDifferential Diagnosis of Wide
Regular QRS TachcardiaRegular QRS Tachcardia
Morphology criteria for VT present both in precordial leads V1-2 and V6?
RBBB LBBB
Yes
Yes
Favor VT
Four-step AlgorithmFour-step Algorithm (by(by BrugadaBrugada et al)et al)
23.
24.
25.
26.
27.
28.
29. Polymorphic VTPolymorphic VT
Torsade de pointTorsade de point
Congenital Long QT syndromeCongenital Long QT syndrome