RT Journal Article SR Electronic T1 ECG phenomena: alternating QRS morphologies JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 596 OP 596 DO 10.1136/heartjnl-2013-305290 VO 100 IS 7 A1 Paech, Christian A1 Pfeil, Nicole A1 Gebauer, Roman Antonin YR 2014 UL http://heart.bmj.com/content/100/7/596.abstract AB