84 Stratos LV/LV-T Technical Manual

The Stratos CRT-Ps have a specially designed header that allows the CRT-Ps to simultaneously sense and pace in both the right and left ventricles. Biventricular pacing therapy requires programming of a bipolar pacing configuration in the ventricle. Refer to Section 8.1 for a summary of the sensing and pacing configurations in the ventricle.

If a bipolar lead is connected to the CRT-P, unipolar or bipolar configuration can be programmed for pacing and sensing. As compared to bipolar pacing, the unipolar pacing pulse has the advantage of being clearly identifiable on the ECG. Unipolar pacing occasionally results in muscle stimulation in the device pocket or diaphragm.

2.5Automatic Lead Check

When Lead Check is activated, the lead impedance is automatically measured with every pace. If the impedance values are consecutively greater or less than the limits (<200 Ω and >3000 Ω) for repeated measurements, the system automatically switches from bipolar to a unipolar lead configuration. A bipolar lead failure is verified if the lead impedance measurement falls outside of the acceptable range for three consecutive readings. When a lead failure has been detected, a message is displayed on the programmer screen at the next follow-up visit in order to notify the physician of the change.

Lead Check also may be activated with unipolar leads. The pass-fail criterion remains the same as with bipolar leads. In the event that a lead failure occurs, the Lead Check feature is disabled and a message is displayed on the programmer screen at the next follow-up visit to notify the physician of the lead status.