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Carotid-subclavian bypass and the carotid steal phenomenon
S Hadjipetrou1, R S Lord, J A Crozier
1Surgical Professorial Unit, St Vincent's Hospital, University of New South Wales, Sydney, Australia.
Insights
Carotid-subclavian bypass surgery is safe, as duplex imaging showed no detrimental impact on cerebral blood flow. This vascular procedure ensures adequate carotid inflow, preventing steal phenomena in most patients.
Area of Science:
- Vascular Surgery
- Diagnostic Imaging
- Hemodynamics
Background:
- Carotid-subclavian bypass grafts are utilized to restore arterial blood flow.
- Potential complications include "steal phenomena" where blood flow is diverted away from the brain.
- Assessing cerebral circulation post-surgery is crucial for patient safety.
Purpose of the Study:
- To investigate the hemodynamic effects of carotid-subclavian bypass grafts.
- To determine if carotid steal occurs after bypass surgery using colour flow duplex imaging.
- To evaluate the safety of carotid-subclavian bypass regarding cerebral blood inflow.
Main Methods:
- Color flow duplex imaging was performed on twelve patients with patent carotid-subclavian bypass grafts.
- Peak systolic flow velocities were measured in the common carotid arteries (proximal and distal to the graft).
- Measurements were taken at rest and during induced arm hyperemia to assess steal phenomena.
Main Results:
- Distal common carotid artery flow velocities were comparable to the contralateral side.
- Proximal carotid artery flow on the bypass side was nearly double the distal flow.
- No carotid steal phenomena were observed, though two cases showed vertebral artery flow reversal during hyperemia (subclavian steal).
Conclusions:
- Carotid-subclavian bypass can be safely performed without compromising cerebral circulation.
- Center-stream peak systolic velocity is a reliable index for assessing flow and graft patency.
- The procedure generally maintains adequate carotid inflow to the brain.
Abstract:
Twelve patients with patent carotid-subclavian bypass grafts were investigated by colour flow duplex imaging to look for a carotid steal. Centre-stream peak systolic flow velocities in the common carotid arteries distal to the take-off of the bypass graft were equivalent to those in the contralateral common carotid artery. On the side of the bypass, common carotid flow proximal to the graft was almost double that on the distal side. Steal phenomena were not identified in the carotid artery either with the arm at rest or during hyperaemia. However, in two instances arm hyperaemia caused reversal of flow in the ipsilateral vertebral artery, suggesting the induction of a subclavian steal. The method of centre-stream peak systolic velocity as an index of flow confirmed that carotid-subclavian bypass can be safely carried out without depriving the cerebral circulation of the normal carotid inflow.