An EC-IC bypass is a surgically created connection between branches of the External carotid artery and the Internal carotid artery.
Classification
EC-IC bypasses are classified as either low-flow bypasses or high-flow bypasses[^1].
Low-Flow EC-IC Bypass
In a low-flow EC-IC bypass, a branch of the STA is sutured to an M4 branch of the [MCA](\/lexikon\/arteria-cerebri-media-mca), a so-called STA-MCA bypass.
High-Flow EC-IC Bypass
In a high-flow EC-IC bypass, a direct connection is created between the ICA and another cerebral artery using a graft, such as a segment of the saphenous vein or radial artery[^1].
Surgical Technique
An end-to-side microanastomosis is performed during an intracranial low-flow STA-MCA bypass. A 10-0 monofilament interrupted suture is typically used for this purpose, allowing the microanastomosis to enlarge over time, unlike with a running suture[^2].