User's Manual

Pacing and Sensing Functions



Lead Detection and Auto-Initialization

Lead Detection

Purpose

The lead detection function allows the implant to recognize the

connected leads as early as during implantation. This is also the basis

for being able to activate the auto-initialization function.

When the connected leads have been successfully detected, the pacing

and sensing polarities are automatically set. This depends on the type

of leads connected (be they unipolar or bipolar). The pacemaker uses

the lead impedance as a basis for the automatic polarity setting.

The pacemaker goes through the following phases:

— An initial lead detection

— Lead polarity is recognized

— Confirmation

The Initial Lead Detection

To detect a lead, the implant (depending on the type) provides unipolar

pacing both in the atrial and ventricular channel and measures the

impedance of each stimulus. If intrinsic events are detected, they

trigger a pulse in the same chamber in which the event was detected.

This mimics the pacing response of an implant in the DDT mode. If the

measured impedances lie within 200-3000 Ohm, the lead is considered

detected.

Recognizing Lead Polarity

After successful detection of the lead, the implant switches to bipolar

pacing. The impedance is also measured during pacing. If it lies

between 200-3000 Ohm, a bipolar lead is considered confirmed.