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Maintenance of blood flow to an organ despite obstruction of a principal vessel. Blood flow is maintained through small vessels.

Circulation established through anastomosis with other parts when the chief vein is obstructed.

That carried on through secondary channels after stoppage of the principal course.

See Circulation.

The circulation of blood through vessels which, being ordinarily small and of comparatively little importance, become enlarged to compensate for the complete or partial closure of the main vessels of a part, with which they communicate on both the proximal and the distal side of the obstruction.