A multi-chamber cardiac pacing systems for providing synchronous pacing to at least the two upper heart chambers or the two lower heart chambers or to three heart chambers or to all four heart chambers employing one or more field density clamp (FDC) sense amplifiers for accurately sensing and timing...http://www.google.com.tw/patents/US5902324?utm_source=gb-gplus-share專利 US5902324 - Bi-atrial and/or bi-ventricular sequential cardiac pacing systems
