Case #1a
Lateral left subclavian angiogram
The vertebral artery has a severe stenosis at the origin. The majority of the vertebral blood flow is supplied by the ascending cervical artery. The pharyngeal branches of the subclavian artery are also enlarged and providing collateral flow. The occipital artery is filling retrograde from the vertebral artery and reconstituting the external carotid.
Case #1b
AP left subclavian angiogram
The vertebral origin stenosis is better seen on the AP view. The large tangle of collateral vessels in the left neck include the ascending cervical artery and pharyngeal branches of the subclavian artery. Again, the occluded external carotid is being filled via retrograde occipital artery flow from the vertebral artery.