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.
• May be utilised to induce VT to map during a VT ablation
• To qualify as a positive VT stim study, VT must be
-Monomorphic and
-Sustained
• VF is non specific
Complications
<0.5%
Complications may include
-
Induction of non clinical arrhythmia (VF)
-
Hematoma
-
Cardiac perforation/tamponade
-
stroke
-
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.
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).
Each protocol involves performing a ventricular paced extras series, with decrementing of the S2 until tachycardia is induced or VERP is reached.
An S3 and an S4 will be added with the previous stimuli programmed just above the ERP.
Possible protocol
-
S1 600ms x 8, S2 400ms down to 240ms (VERP 240ms)
-
S1 600ms x 8, S2 260ms, S3 400ms down to 200ms (VERP 200ms)
-
S1 600ms x 8, S2 260ms, S3 220ms, S4 400ms down to 220ms (VERP 220ms)
