Figure 1.

(A) Single-port DF-4 cavity for both high and low voltage (DF4 LLHH). The two poles on the right are high-voltage poles, and the other two poles including the tip pole are for low-voltage connections. A single distal set screw to the tip electrode holds the lead in place. An IS-4 connector would look similar but could take in up to four low-voltage poles. (B) DF-1 (top) and IS-1 (bottom) connectors. The DF-1 port has a single distal set screw, whereas the IS-1 port may have two set screws (as shown) or a distal set screw with a proximal spring contact. In contrast to the DF-4 system, the seal rings are part of the lead and not the connector. Seal rings are shown in light blue and the poles in red. (Images reprinted with the permission of Biotronik SE, Berlin, Germany.)