Triggered modes

When the VVT mode is programmed, pacing occurs at the programmed minimum rate, although a sensed non-refractory event triggers an immediate pacing in the absolute refractory period of the ventricular myocardium. This operational mode therefore corresponds to the opposite of the VVI mode where sensing inhibits pacing. This type of pacing mode is very seldom programmed today. 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 event of detection of myopotentials 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 useful on older pacemaker models that were more sensitive to external interference since only functioning in unipolar mode.
2. this mode enables evaluating sensing in the chamber under consideration as well as verifying that there is no crosstalk and that the extrasystoles are also properly sensed. In this tracing, for example, the AAT mode allows verifying that a) the sensing of sinus activity is correct, b) the sensing of the atrial extrasystoles is also correct, c) there is no far-field R wave oversensing.