A lead assembly having a ring electrode is adapted for implant and for connection to a system for monitoring or stimulating cardiac activity. The lead assembly includes a first porous member disposed around the ring electrode at the distal end of the lead assembly, which can be used as a sensing or pacing...http://www.google.es/patents/US6263250?utm_source=gb-gplus-sharePatente US6263250 - Ring electrode with porous member
