[dissecting Aneurysm of the Aorta].

Dissecting aneurysm is the cause of about ona in a hundred of sudden deaths and about one in four hundred of all hospital deaths. Men are affected much more commonly than women in a proportion of between two and three to one, except in extreme old age when the sex difference is less, partly because there are more old women than old men. Dissecting aneurysm can occur at any age. The heaviest incidence is in later life, particularly between the ages of 50 and 70, but one case in five occurs under the age of 40. This contrasts with an equivalent figure for cardiac infarction under the age of 40 of about one case in fifty. Of cases occurring in young women, about half are in late pregnancy or soon after delivery. It is uncommon for dissecting aneurysm to develop during labour.