[Critical comparison of uni- and bipolar pacemaker systems].

More than 90% of all implanted pacemaker systems in Germany up to the present were unipolar. Stimulation and sensing therein, take place between the cathodal electrode tip and the anodal pacemaker. A relatively large chance of noise interference is allowed by the large distance between the two poles. The high sensitivity, at is needed for correct function, enables intra- and extracorporal noise signals to interfere. This disadvantage of unipolar systems is mainly avoided when using bipolar systems. Since both poles are situated close to each other within the heart, there is only a very small chance of notice interference. However, there are many arguments in favour of both systems. In recent years there has been a slight trend towards bipolar pacing. By reducing the well-known disadvantages of bipolar pacing, such as increased conductor resistivity, as inferior energy function, greater coil diameter and reduced handling, the beneficial effects of bipolar pacing--mostly the clear discrimination between physiological cardiac and extraneous signals--become more important. A new 3.2 mm universal connector (VS-1) might help to realize bipolar pacing more easily. In the future, a pacemaker system with unipolar pacing and simultaneously a bipolar sensing function, might help to increase safety in pacing.