ODO mode

Patient

69-year-old man implanted with a Medtronic dual-chamber pacemaker following repeated syncopes due to sinus node dysfunction; the 2 pacing leads are well positioned with normal pacing impedances, correct sensing and satisfactory pacing thresholds; 3 days after implantation, pacemaker evaluation; programming of various pacing modes and recording of tracings; for this first tracing, device programmed to ODO mode;

Trace

Spontaneous atria and sinus rhythm (positive P waves in leads I, II, V5, V6, negative in aVR); fixed and normal PR interval (< 200 ms); spontaneous ventricles with left anterior fascicular block pattern (left axis, q1S3 pattern);

Trace

This is the recording (simultaneously with the previous tracing) of the endocavitary electrograms (EGM) from the programmer; EGM 3 corresponds to an electrocardiographic lead, EGM2 to the ventricular EGM and EGM1 to the atrial EGM; spontaneous atrial and ventricular activities (AS-VS);

Exergue

In a dual-chamber pacemaker, there are different programmable modes, each with its respective specificities; DOO mode: no possibility of sensing, asynchronous pacing; ODO mode: no pacing; DDT mode: trigger mode, sensing triggers pacing; VDD mode: absence of atrial pacing; DDI mode: absence of ventricular pacing following an atrial sensing; DDD mode: ventricular synchronization upon atrial sensing and ventricular pacing; modes are specific to each manufacturer to avoid unnecessary ventricular pacing;