68 Stratos LV/LV-T Technical Manual

2.1.6 AAI and VVI

The pacing modes AAI and VVI provide atrial and ventricular demand pacing. The lower rate timer is started by a sense or pace event. A sense event outside of the refractory period inhibits pacing and resets the lower rate timer; in the absence of a sense event, a pulse generator pulse will be emitted at the end of the lower rate interval.

2.1.7 AAI, VVI

The AAI and VVI single-chamber pacing modes are used in atrial and demand pacing. In each case, pacing and sensing only occur in the atrium (AAI) or the ventricle (VVI).

The basic interval is started by a sense or pace event. If the sense event occurs before the basic interval has expired, pacing is inhibited. Otherwise, pacing occurs at the end of the basic interval.

2.1.8 AOO, VOO

In these modes, atrial, ventricular and AV sequential pulses, respectively, are emitted asynchronously. These modes primarily serve diagnostic purposes during follow-up. When programming to the VOO or VOO mode, the risks associated with asynchronous ventricular pacing should be considered.

2.1.9 DOO

Asynchronous, AV sequential pacing pulses are emitted in this pacing mode. When programming DOO mode, the risks of asynchronous ventricular pacing should be considered.

2.1.10 VDI

The VDI mode corresponds to the VVI mode, with the additional function of providing atrial sensing. However, the timing is the same as the VVI mode. The purpose of the VDI mode is to permit the use of the marker function with the IEGM for the atrial channel, for example, to measure the retrograde conduction time.

The VA conduction time between a ventricular pace or sense event (with marker) and the atrial sense event can be measured directly on the display or printout from the programmer or on an ECG strip chart recorder (IEGM/marker output function).