“Not so wide” QRS tachycardia: Isn’t it a VT?iseindia.org/ecg_presentation/04.Dr.Satish...
Transcript of “Not so wide” QRS tachycardia: Isn’t it a VT?iseindia.org/ecg_presentation/04.Dr.Satish...
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“Not so wide” QRS tachycardia: Isn’t it a VT?
Mid Term ISECON, Thane, Nov 2017
Satish Toal
Director Cardiac Electrophysiology, New Brunswick Heart Centre,
Asst Prof., Dept of Medicine, Dalhousie University
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Disclosures
•No conflict of interest
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Objectives:
• Identify narrow and “not so wide” QRS tachycardia that can be VT • Identify features on ECG that help diagnose them •Understand acute and long term management of fascicular VT
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ARE THE QRS NARROW OR WIDE
•Cannot tell conclusively from a single monitor strip
•Get a 12 lead ECG, if clinically possible
•QRSd < 120 ms is narrow, < 145 ms relatively narrow
•Common things common - narrow complex rhythms are more likely to be supraventricular and wide complex ventricular
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•Remember arrhythmias can break rules - exceptions to both can happen
•Acute treatment – usually don’t have to break our rules !
•Than why bother?
• Important for long term management and prognosis
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• Idiopathic Fascicular VT
•VT post MI using His Purkinjee system or propagating into it very early
•Children (with a narrower baseline QRS in sinus rhythm)
•Digoxin toxicity - mechanism is enhanced automaticity in the region of the fascicles
Narrow Complex tachycardias that can be VT are unusual
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History
•34 year male
•H/o palpitations, previous ER visits
•Not feeling well for few days
•No h/o structural heart disease
•Normal echo
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After beta blockers in previous admission
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Most common idiopathic VT of the left ventricle.
It is a re-entrant tachycardia, typically seen in young patients without structural heart disease.
Only 10% of cases of VT occur in the absence of structural heart disease, termed idiopathic VT. The majority of idiopathic VTs (75-90%) arise from the right ventricle — e.g right ventricular outflow tract tachycardia.
Fascicular VT is the most common type of idiopathic VT arising from the left ventricle (10-15% of all idiopathic VTs).
Usually occurs in young healthy patients (15-40 years of age; 60-80% male). Most episodes occur at rest but may be triggered by exercise, stress and beta agonists. The mechanism is re-entrant tachycardia due to an ectopic focus within the left ventricle.
A similar ECG pattern of fascicular VT may occur with digoxin toxicity, but here the mechanism is enhanced automaticity in the region of the fascicles.
Fascicular VT
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Monomorphic ventricular tachycardia eg. fusion complexes, AV dissociation, capture beats.
QRS duration 100 – 140 ms — this is narrower than other forms of VT.
Short RS interval (onset of R to nadir of S wave) of 60-80 ms — the RS interval is usually > 100 ms in other types of VT.
RBBB Pattern.
Axis deviation depending on anatomical site of re-entry circuit (see classification). ◦ Posterior fascicular VT (90-95% of cases): RBBB morphology + left axis deviation; arises close
to the left posterior fascicle. ◦ Anterior fascicular VT (5-10% of cases): RBBB morphology + right axis deviation; arises close to
the left anterior fascicle. ◦ Upper septal fascicular VT (rare): atypical morphology – usually RBBB but may resemble LBBB
instead; cases with narrow QRS and normal axis have also been reported. Arises from the region of the upper septum
Fascicular VT
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After ablation – pt comes back
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Comes back again after “successful” ablation !
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Figure 2
HeartRhythm Case Reports 2016 2, 101-106DOI: (10.1016/j.hrcr.2015.11.011)
Copyright © 2016 Heart Rhythm Society Terms and Conditions
http://www.elsevier.com/termsandconditionshttp://www.elsevier.com/termsandconditionshttp://www.elsevier.com/termsandconditions
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• Diagnosis can be difficult and this rhythm is often misdiagnosed as SVT with RBBB;
• Use criteria other than QRS duration for diagnosis: • Characteristic pattern of QRS morphology
• Capture beats,
• Fusion beats,
• VA dissociation – remember there may be exceptions
• Never forget the clinical setting – • History
• Age,
• Structural heart disease
• Medications
Diagnosis – fascicular VT
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• Often unresponsive to adensoine, vagal maneouvers, and lidnocaine.
• However, it characteristically responds to verapamil.
• Digoxin-induced fascicular VT is responsive to Digoxin Immune Fab.
Management – fascicular VT Arrhythmia may break rules, do you?
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Recent AWMI, tachycardia 190 bpm, QRSd 110 ms
Miller JM. The many manifestation of ventricular tachycardia. J Cardiovasc Electrophysiol. 1992;3:88-107.
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Miller JM. The many manifestation of ventricular tachycardia. J Cardiovasc Electrophysiol. 1992;3:88-107.
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RBBB, Left axis, QRSd 135 ms
Bogun F, Good E, Reich S, et al. Role of Purkinje fibers in post-infarction ventricular tachycardia. J Am Coll Cardiol. 2006;48:2500–2507
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Narrow QRS VT post MI
• Abello et al - incidence of SMVT with a QRS complex
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• Purkinje fibers may participate in the re-entry circuit of post-infarction VT.
• Involvement of the Purkinje system accounts for the relatively narrow QRS complexes (≤145 ms) during these VTs. Usually have RBBB morphology
• VT with left bundle branch block morphology, the effective target site was near the His bundle - suggesting that a proximal portion of the His-Purkinje system, before the branch point of the right and left bundle branches, was involved.
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Bogun F, Good E, Reich S, et al. Role of Purkinje fibers in post-infarction ventricular tachycardia. J Am Coll Cardiol. 2006;48:2500–2507
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Bogun F, Good E, Reich S, et al. Role of Purkinje fibers in post-infarction ventricular tachycardia. J Am Coll Cardiol. 2006;48:2500–2507
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• 61 year male, HTN, DM
• No previous heart disease
• Normal coronaries
• Mild global LV dysfunction
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• Hemodynamically stable
• IV adenosine – no effect
• Spontaneous termination but repeated runs
• Given metoprolol, Verapamil – no effect
• Responded to fleicanide !
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Al’Aref et al Differentiation of Left Ventricular Arrhythmias Circ Arrhythm Electrophysiol.2015;8:616-624. DOI: 10.1161/CIRCEP.114.002619
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Take home message • Narrow complex VT can happen, but are uncommon, hence rule out SVT • Don’t just focus on QRS width • Analyze ECG completely - morphology, axis, VA association, capture/fusion
beats • Correlate ECG with clinical scenario • If pt has h/o MI
• Look for capture, fusion beats, VA dissociation
• If young healthy pt • Look for characteristic RBBB left axis deviation in addition to capture, fusion beats and
VA dissociation
• Treatment: • Fascicular VT responds to Verapamil. • Post MI pts always consider possibility of VT with sustained monomorphic tachycardia
in relatively narrow QRS • Digoxin-induced fascicular VT is responsive to Digoxin Immune Fab.