User's Manual

50
Pacing and Sensing Functions
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Lead Configuration
In a unipolar configuration, the negative pole (the cathode) is situated
in the heart, while the positive pole (the anode) is formed by the
housing of the pacemaker. In a bipolar configuration, both poles of the
leads are situated in the heart.
The pacemakers allow you to program separate lead polarities for
pacing and sensing.
Compared with bipolar pacing, unipolar pacing has the advantage of
being clearly identifiable on the surface ECG, and its energy
consumption is a bit lower. Because one pole is formed by the
pacemaker housing in this case, unipolar pacing at high pulse
amplitudes can occasionally result in muscle stimulation in this area.
Because of its lower susceptibility to interference signals, i.e., skeletal
myopotentials, bipolar sensing offers a much better “signal-to-noise-
ratio” than unipolar sensing. Therefore, you can program higher
sensitivities (which are expressed as lower numerical values).
Caution! If a unipolar lead is used in one of the chambers,
that lead configuration has to be programmed to
“unipolar.” Otherwise entrance and/or exit block
will result.
Continuous Measurement and Recording of Lead
Impedance
Cylos implants are also able to continuously measure the existing lead
impedance and record it as a short-term or a long-term trend.