An Approach to the Management of Idiopathic Outflow Tract ...
Transcript of An Approach to the Management of Idiopathic Outflow Tract ...
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An Approach to the Management of Idiopathic Outflow Tract Ventricular
Tachycardia
Girish M Nair. MBBS, MD, FRCPC Arrhythmia Service
McMaster University and Hamilton Health Sciences
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Disclosures
• Speaker’s fees, honoraria and grants from- • St. Jude Medical • Boston Scientific • Biosense Webster • Medtronic
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Outline of Talk
• Approach to LBBB/RBBB, Right Axis VT • Epidemiology, clinical features • Anatomy of the outflow region of the heart • Cases from the EP lab to illustrate challenges
involved in diagnosis and ablation of outflow tachycardias
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DL
• 40 years old lady • Triathlete • Palpitations during exercise • EKG documentation post exercise • Normal echo/MRI • No syncope/family h/o SCD
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Question 1
• The mechanism of outflow tract VT is –
1. Triggered activity- Delayed after depolarizations
2. Enhanced automaticity 3. Reentry 4. Unknown
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Idiopathic OT VT
• Occur in patients without overt structural heart disease
• Surface EKG- LBBB/RBBB pattern and inferior axis (positive QRS in leads II, III and aVF.
• Discrete, focal origin from the outflow tract • Typical Electropharmacological response • Ventromedial cardiac nerve stimulation induces
RVOT VPBs- Enhanced automaticity
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Idiopathic OT VT
• Induced with Programmed Electrical Stimulation • Characteristic electro-pharmacologic response • Induced by adrenergic stimulation- exercise/Isuprel • Terminates in response to
– Adenosine – Beta blockers – Calcium blockers – Valsalva maneuvers
• Mechanism- Triggered activity secondary to c-AMP mediated delayed after depolarizations (phase 4)
• Somatic mutation in c-AMP protein detected in a patient
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LV Ostium
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OT VT
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Idiopathic VT- RBBB Morphology
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Important Questions
• Is the patient symptomatic enough to be ablated? – Symptomatic PVCs/VT – Tachycardiomyopathy – > 15,000 VPBs in a 24 hour period
• Is the outflow tract VT – – In the RVOT/PA – In the LVOT/ Ao Cusps – Epicardial/Aorto-Mitral Continuity
• Can the VT be ablated safely without causing collateral damage?
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EKG Localization
PA OT Tachycardia • Taller QRS in Leads 2,3,Avf • aVL > aVR • Earlier transition in V2 • R in V2 bigger Betensky BP et.al. V2 Transition Index. J Am Coll Cardiol 2011;57:2255–62)
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Activation Mapping
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Case 1
• 55 years old lady • Frequent palpitations • Ventricular bigeminy • 50,000 VPBs/24 hours; NS VT • Echo – Normal LV function valves • No response to beta-blockers/ flecainide
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Introduction
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Question 2
• Localize the origin of the VPBs 1. RVOT 2. LVOT 3. Aortic coronary cusp 4. Epicardial Aorto mitral continuity
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Introduction
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Case 2
• 42 yrs old male nurse • 2 episodes of rapid palpitations lasting 4 hrs;
precipitated by exertion (ice hockey) • Associated pre-syncope • Echo, MRI no abnormalities • 1st EP study 2006 no VT inducible with 8mcg of
Isuprel • 2nd EP study 2008 sustained VT inducible with
10mcg of Isuprel and programmed stimulation
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EGM- AoCusp- LVOT
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Question 3
• Will you ablate this at this site? - 1. Yes 2. No 3. Maybe 4. Will decide after further electrophysiologic testing
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Words of Wisdom
“Recognition of these ECG patterns may have considerable clinical significance, both in terms of procedural planning for left ventricular mapping and in counseling patients about the risk of inability to attempt ablation or the potential for heart block with LVOT pattern 2.”
Repetitive Monomorphic Tachycardia From the Left Ventricular Outflow Tract: Electrocardiographic Patterns Consistent With a Left Ventricular Site of Origin. Callans D et.al. J Am Coll Cardiol 1997;29:1023–7.
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Question 4
• What would you do next ? – 1. Give the patient a pacemaker 2. Give the patient an ICD 3. Perform further induction 4. Wait (hope) for recovery
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VT
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Case 3 ■ 31 years old school teacher ■ Exercise induced palpitations ■ Wide complex tachycardia (WCT) ■ Two prior EP studies and RF ablation attempts- unsuccessful ■ Referred for EP study and possible epicardial ablation if necessary ■ No comorbidities ■ Echo normal LV function and valves ■ Cardiac MRI- no abnormalities detected ■ No family history of sudden unexplained death/cardiomyopathy ■ Good Response to Flecainide and Bisoprolol ■ Incessant WCT on discontinuing Flecainide
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Presystolic Potentials
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Voltage Maps
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Example of textchart
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Outflow Tract VT
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Energy Sources in SOV/LVOT
Study pts energy settings AT-term Das 1 Cryo 6mm ? 30
1 irrig. RF ? 4 8 conv. RF 55°C, ≥20W 4-9 sec
Ouyang 9 conv. RF 55°C, ≥20W, 1-8 sec Yamada 1 conv. RF ? ? Raatikainen 1 conv. RF 55°C, 30W, 3 sec Marine 1 conv. RF 55°C, 20W, 4 sec
Das - JCE 2008; Ouyang - JACC 2006; Yamada - Heart Rhythm 2006; Raatikainen - Europace 2007
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Summary
• OT VT – triggered/automatic VT in structurally normal hearts
• Exceptions- scarring in the OT- ? Reentry • Can be ablated successfully in most patients • Remember- multiple exit sites, great vessels,
epicardial origin • Careful about collateral damage- AV node,
coronary arteries, valves • Pericarditis/constriction post epicardial mapping/
ablation
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Thank You