“…Dow et al (1966) encountered such changes in nine of their 17 cases, a greater frequency than for other branches, but did not quote the relative incidence in dissections beginning in the ascending aorta and in those with a more distal origin and a normal aortic root. Shuford et al (1969) found these vessels implicated in twoofeight cases in the former group, but did not mention this feature in the latter. In a series of 17 dissecting aneurysms studied by the author there were brachiocephalic artery abnormalities in five of seven originating in the ascending aorta, but in only two of 10 commencing adjacent the left subclavian, including the subject of the present report (Syme, 1972a); if five earlier cases omitted from this group are also considered (Syme, 1971), the major branches of the arch were involved in five of nine dissections in the former group, but in only two of 13 in the latter.…”