Abstract: A method for detecting a site of interest in a gastrointestinal tract, wherein the method includes sensing a length traveled by a sensor in a gastrointestinal tract from a reference point to a site of interest in the gastrointestinal tract.

Abstract: A method and devices for timing the delivery of non-excitatory signals for modifying myocardial contractility of a portion of the heart are disclosed. The method includes the steps of applying electrodes to a plurality of cardiac sites, sensing electrical activity in a first cardiac site through a first electrode for detecting a first electrical depolarization event within a beat cycle, sensing electrical activity in a second cardiac site through a second electrode for detecting a second electrical depolarization event within the beat cycle, and applying a non-excitatory signal to the heart at or near at least the second cardiac site through at least one of the electrodes in response to detecting the second electrical depolarization event within an alert window period. The alert window period starts at a first delay from the time of detection of the first electrical depolarization event and has a first duration.