RT Journal Article SR Electronic T1 WILLIAM RITCHIE JF British Heart Journal JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 207 OP 209 DO 10.1136/hrt.7.4.207 VO 7 IS 4 A1 W. E. Hume YR 1945 UL http://heart.bmj.com/content/7/4/207.abstract AB