RT Journal Article SR Electronic T1 Pacing in heart failure: how many leads and where? JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 10 OP 12 DO 10.1136/hrt.2007.119404 VO 94 IS 1 A1 S Serge Barold A1 Bengt Herwerg YR 2008 UL http://heart.bmj.com/content/94/1/10.abstract AB