Reversed vertebral artery blood flow in subclavian artery obstruction (subclavian steal)

Abstract

Three cases are presented illustrating reversal of blood flow in a vertebral artery following occlusion or stenosis of the corresponding subclavian artery proximal to the origin of the vertebral. This provides a collateral circulation to the upper limb and may result in reduction in total cerebral blood flow leading to neurological symptoms. Retrograde filling of other collateral vessels, notably the thyro-cervical and costo-cervical trunks, has also been demonstrated in one case and the anatomy of the total possible collateral circulation to the arm from the cerebral vessels is discussed. Much has still to be learned about cerebral haemodynamics in health and in disease. The effects of single or multiple occlusions or stenoses may be far-reaching and stress is laid on the importance of simultaneous examination of all major cerebral vessels when cerebral or upper limb ischaemia is suspected. The syndrome may be created artificially following operative procedures on the innominate or subclavian arteries. This may produce immediate or late effects, particularly in the presence of atherosclerosis, or following its development in later years. Three cases are presented illustrating reversal of blood flow in a vertebral artery following occlusion or stenosis of the corresponding subclavian artery proximal to the origin of the vertebral. This provides a collateral circulation to the upper limb and may result in reduction in total cerebral blood flow leading to neurological symptoms. Retrograde filling of other collateral vessels, notably the thyro-cervical and costo-cervical trunks, has also been demonstrated in one case and the anatomy of the total possible collateral circulation to the arm from the cerebral vessels is discussed. Much has still to be learned about cerebral haemodynamics in health and in disease. The effects of single or multiple occlusions or stenoses may be far-reaching and stress is laid on the importance of simultaneous examination of all major cerebral vessels when cerebral or upper limb ischaemia is suspected. The syndrome may be created artificially following operative procedures on the innominate or subclavian arteries. This may produce immediate or late effects, particularly in the presence of atherosclerosis, or following its development in later years.