Study on overestimation of blood flow velocity after bilateral internal carotid artery stenosis with color Doppler ultrasound

Objective To investigate the influence of unilateral internal carotid artery(ICA)stenosis (70-99%)or occlusion evaluated by color Doppler ultrasound(CDU)and transcranial Doppler (TCD)on ICA hemodynamics of contralateral carotid artery(50-69% stenosis)in patients with bilateral infernal carotid artery stenosis.Methods A total of 102 consecutive patients with bilateral ICA stenosis (unilateral stenosis 50-69%,contralateral stenosis 70-99% or occlusion)were enrolled from June 2005 to June 2011 and they were used as study group(group A).The patients were screened by color Doppler flow imaging(CDFI)and TCD,and they were confirmed as bilateral ICA stenosis by DSA.At the same time,89 patients with unilateral ICA stenosis 50-69% and normal contralateral ICA were used as control group(group B).The differences of ICA stenosis 50-69% in the two groups and the peak systolic velocity (PSV),end-diastolic flow velocity(EDV),resistance index(RI)and pulsatility index(PI)of anterior cerebral artery(ACA)in both groups were compared.Group A was redivided into an anterior communicating antery patent group(A1 group,n=54)and an anterior communicating artery occluded group(A2 group,n=48)according to the results of TCD and DSA examinations.The differences of the hemodynamic parameters of the 50-69% stenotic ICA and ACA stenosis,and the correlations of the hemodynamic changes in both groups were further compared.Results(T)The PSV and EDV of unilateral stenotic ICA stenosis and ACA with 50-69% stenosis in group A were significantly higher than those in group B(all P 0.05),RI and PI were significantly lower(P=0.001,P=0.000).?PSV and EDV of unilateral ICA and ACA with 50-69% stenosis in group A1 were higher than those in group A2(all P0.01),but RI of ICA and PI of ACA in group A1 were lower than those in group A2(P=0.000,P=0.000),the differences were statistically significant.③The velocity of ICA was positively correlated with that of ACA(r= 0.327,0.422,P=0.007,P=0.000).Conclusion When one side of internal carotid artery is severely stenotic,the measured value of velocity of the other side of ICA(50-69% stenosis)is significantly higher than the diagnostic criteria of the actual lesion.The anterior communicating artery patency is the basis of hemodynamic changes of the bilateral stenotic ICA.The identification of the degree of bilateral ICA stenosis should be evaluated comprehensively in combination with the extracranial and intracranial hemodynamic changes.