ARTERIO-VENOUS ANEURYSM
An abnormal communication between an artery and a vein constitutes an
arterio-venous aneurysm. Two varieties are recognised--one in which the
communication is direct--_aneurysmal varix_; the other in which the
vein communicates with the artery through the medium of a sac--_varicose
aneurysm_.
Either variety may result from pathological causes, but in the majority
of cases they are traumatic in origin, being due to such injuries as
stabs, punctured wounds, and gun-shot injuries which involve both artery
and vein. In former times the most common situation was at the bend of
the elbow, the brachial artery being accidentally punctured in
blood-letting from the median basilic vein. Arterio-venous aneurysm is a
frequent result of injuries by modern high-velocity bullets--for
example, in the neck or groin.
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