Abnormal radial artery in Down's syndrome.

Abnormal arterial patterns in the forearm were discovered in 12 of 77 patients (16%) with Down's syndrome. Eight patients had an enlarged anterior interosseous artery, the distal portion of which was palpable over the dorsum of the hand; in seven it was associated with absence of the radial artery and in one it coexisted with the radial and ulnar arteries. Three patients had a hypoplastic radial artery and a relatively dominant ulnar artery. One patient had a vestigial radial artery that ended as muscular branches in the forearm. The developmental aspects of these aberrations are discussed.