What does caudal flow in the left vertebral artery typically indicate?

Caudal flow in the left vertebral artery often indicates a left subclavian occlusion. When there is an occlusion or significant stenosis in the left subclavian artery, it can create a pressure gradient that causes blood to flow in a direction typically not expected. In this case, blood might flow from the vertebral artery toward the affected subclavian artery instead of the normal cranial direction. This is known as caudal flow and serves as a compensatory mechanism to ensure some level of perfusion occurs despite the blockage.

Understanding the anatomy and flow dynamics is essential for vascular technologists. The vertebral arteries normally provide blood flow upward (cranially) toward the brain. In contrast, when an occlusion is present in a neighboring vessel like the left subclavian artery, it disrupts this normal pattern, resulting in caudal flow. Therefore, recognizing caudal flow in the left vertebral artery is critical as it signals underlying vascular pathology, particularly involving the left subclavian artery.