Triggered modes

When a triggered mode (VVT or AAT) is programmed, the sensing of a non-refractory event triggers an immediate pacing. This functional operation therefore corresponds to the opposite of the VVI-AAI modes where sensing inhibits pacing. This type of pacing mode is nowadays very sparsely programmed. Indeed, pacing during sensing is associated with an unnecessary increase in energy consumption with acceleration of battery wear. The triggered modes can be used in 2 special circumstances:

1. in the case of myopotential detection or electromagnetic interference, a pacemaker programmed in SST mode does not inhibit but induces pacing on each artifact detected outside the refractory period, thus avoiding a pause in pacemaker-dependent patients. This type of mode was of value on older pacemaker models which were more sensitive to external interference given their functioning in unipolar mode only.
2. to evaluate sensing in the chamber under consideration, to verify the absence of far-field oversensing and that the extrasystoles are also correctly sensed. On this tracing, for example, the AAT mode shows that the sensing of sinus activity is appropriate but that there is an oversensing of the far-field R wave.