BACKGROUND: Development of retrograde blood flow may be observed in the vertebral artery and is associated with progressive ipsilateral proximal subclavian or innominate artery stenosis. The subclavian steal phenomenon is more prevalent in the left subclavian artery (LSA). The purpose of this study was to analyze the correlation between the degree of LSA stenosis and pulse Doppler waveforms of the left vertebral artery (LVA). METHODS: A retrospective analysis of LVA waveforms was performed in 22 cases with LSA proximal stenosis before the origin of the LVA in conventional angiograms. The degree of LSA stenosis was classified into 5 groups (<50, 50-59, 60-69, 70-89, 90-100%). Pulse Doppler waveforms of the LVA were also classified into 5 subtypes depending on the depth of the mid-systolic notch representing retrograde blood flow (normal, mid-systolic notch, retrograde flow smaller than antegrade flow, retrograde flow larger than antegrade flow, retrograde flow without antegrade flow). RESULTS: A statistically significant correlation (R(2) = 0.646, p < 0.0001) was found between the degree of LSA stenosis and the LVA waveform. CONCLUSIONS: The pattern analysis of LVA pulse Doppler waveforms seems to be useful in determining the degree of LSA stenosis.
BACKGROUND: Development of retrograde blood flow may be observed in the vertebral artery and is associated with progressive ipsilateral proximal subclavian or innominate artery stenosis. The subclavian steal phenomenon is more prevalent in the left subclavian artery (LSA). The purpose of this study was to analyze the correlation between the degree of LSA stenosis and pulse Doppler waveforms of the left vertebral artery (LVA). METHODS: A retrospective analysis of LVA waveforms was performed in 22 cases with LSA proximal stenosis before the origin of the LVA in conventional angiograms. The degree of LSA stenosis was classified into 5 groups (<50, 50-59, 60-69, 70-89, 90-100%). Pulse Doppler waveforms of the LVA were also classified into 5 subtypes depending on the depth of the mid-systolic notch representing retrograde blood flow (normal, mid-systolic notch, retrograde flow smaller than antegrade flow, retrograde flow larger than antegrade flow, retrograde flow without antegrade flow). RESULTS: A statistically significant correlation (R(2) = 0.646, p < 0.0001) was found between the degree of LSA stenosis and the LVA waveform. CONCLUSIONS: The pattern analysis of LVA pulse Doppler waveforms seems to be useful in determining the degree of LSA stenosis.