VT stimulation
VT stim basics
Purpose
• Can be utilised for borderline ICD indications, as a positive VT study suggests that there is significant substrate to maintain ventricular arrhythmias.
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• May be utilised to induce VT to map during a VT ablation
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• To qualify as a positive VT stim study, VT must be
-Monomorphic and
-Sustained
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• VF is non specific
Complications
<0.5%
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Complications may include
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Induction of non clinical arrhythmia (VF)
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Hematoma
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Cardiac perforation/tamponade
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stroke
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death
VT stim assessment
Equipment
• 1 Venous access
• 1 RV pacing catheter (typically JSN)
Procedure
There will be some degree of variability of VT stimulation depending on the Consultant.
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A complete VT stiumlation study will involve a full protocol performed at 2 different sites (e.g., RVOT and RV apex) and with the S1 at 2 different rates (e.g., 600ms and 400ms).
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Each protocol involves performing a ventricular paced extras series, with decrementing of the S2 until tachycardia is induced or VERP is reached.
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An S3 and an S4 will be added with the previous stimuli programmed just above the ERP.
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Possible protocol
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S1 600ms x 8, S2 400ms down to 240ms (VERP 240ms)
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S1 600ms x 8, S2 260ms, S3 400ms down to 200ms (VERP 200ms)
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S1 600ms x 8, S2 260ms, S3 220ms, S4 400ms down to 220ms (VERP 220ms)
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