Bipolar versus unipolar issues in DDD pacing.

The relative merits of unipolar and bipolar systems are reviewed in the context of DDD pacing. In order to allow reliable atrial sensing in the presence of myopotentials and exogenous noise, bipolar atrial sensing is desirable. Bipolar ventricular sensing will reduce the incidence of myopotential sensing and may reduce susceptibility to cross-talk. Unipolar systems, however, generally offer better stimulation characteristics. Considerations have led to the development of a new DDD pacemaker with bipolar sensing and unipolar pacing characteristics. The bipolar-sense/unipolar-pace pulse generator is simple to implement based upon a unipolar design and retains the simplicity, convenience, and reliability inherent in that mode.