Ultrasound Evaluates The Influence On Subclavian Artery Steal Caused By Vertebral Artery Hypoplasia

ObjectiveTo analyze the influence of vertebral artery hypoplasia(VAH)on the degree of subclavian artery steal(SAS)in patients with severe unilateral subclavian artery stenosis or occlusion by color Doppler ultrasound(CDU).Methods563 patients with severe unilateral subclavian artery stenosis or occlusion confirmed by ultrasonic examination and digital subtraction angiography(DSA)from August 2019 to May 2022 were selected.Meanwhile,their intracranial collateral circulation was evaluated by DSA and magnetic resonance angiography(MRA).Exclusion criteria:(1)Patients with image quality not up to the diagnostic criteria;(2)Patients complicated with severe stenosis or occlusion of the carotid artery,vertebral artery,contralateral subclavian artery and intracranial vessels;(3)Patients who received radial arterio-cephalic venous fistula and were complicated with other upper extremity vascular lesions.A total of 169 patients with severe unilateral subclavian artery stenosis or occlusion,including 50 patients with VAH complicated with severe unilateral subclavian artery stenosis or occlusion(the VAH group)and 119 patients with nonvertebral artery hypoplasia(NVAH)complicated with severe unilateral subclavian artery stenosis or occlusion(the NVAH group),were included in this study.There were 32 patients complicated with ipsilateral VAH and 18 patients complicated with contralateral VAH.Epiq-5 and Epiq-7 color Doppler ultrasonic diagnostic instruments of Philips Netherlands were used with 5-12 MHz linear array probe and 3-5 MHz convex array probe for detection.Carotid artery system,vertebral artery system and bilateral subclavian arteries were routinely detected.First,the course of vertebral artery and subclavian artery,with or without plaque and stenosis of lumen was observed in 2D mode,and the inner diameter of bilateral vertebral artery was measured in V2 segment.The blood flow of bilateral vertebral arteries and the initial subclavian artery were shown by CDU.Pulsed doppler flow imaging was then used to measure the blood flow spectrum of bilateral vertebral arteries,the initial stenosis and the distal segment of the subclavian artery(measuring the blood flow velocity at the end of systole and the end of diastole in both locations).The influence of VAH on the degree of SAS was analyzed according to the characteristics of the blood flow spectrum of the affected vertebral artery in patients with severe subclavian artery stenosis or occlusion.Results1 Comparison of general conditions of patients between the VAH group and the NVAH group:1.1 The severe stenosis or occlusion of subclavian artery was the most common in patients aged 60-80 in either the VAH group or the NVAH group.The difference was not statistically significant.1.2 The incidence of severe unilateral subclavian artery stenosis or occlusion in male patients in the VAH and NVAH groups was 60%(30/50)and 63.9%(76/119),respectively.There was no statistically significant difference in the incidence between male and female patients in the two groups,indicating that severe subclavian artery stenosis or occlusion is more common in males.1.3 The incidence of severe stenosis or occlusion of the right subclavian artery in patients in the VAH group was 64.0%(32/50),which was significantly higher than that of the left subclavian artery.The incidence of severe stenosis or occlusion of the left subclavian artery in patients in the NVAH group was 71.4%(85/119),which was significantly higher than that of the right subclavian artery.There was a statistically significant difference between the two groups,indicating that severe subclavian artery stenosis or occlusion was more likely to occur on the right side in the VAH group but on the left in the NVAH group.1.4 The proportion of blood pressure asymmetry in both upper limbs in patients in the VAH and the NVAH groups was 96.0%(48/50)and 87.4%(104/119),respectively.The difference was not statistically significant.2 Comparison of clinical symptoms between the VAH group and the NVAH groupThe incidence of dizziness in patients in the two groups was 64.0%(32/50)and 32.8%(39/119),respectively.The incidence of upper limb weakness was 70.0%(35/50)and 25.2%(30/119),respectively.The difference was statistically significant,indicating that the patients in the VAH group were more likely to develop symptoms of posterior circulatory ischemia.3 Comparison of types of SAS between the VAH group and the NVAH groupLatent(30%)and partial(58%)steals were mainly identified in the VAH group,while partial(52.9%)and complete(32.8%)steals were mainly identified in the NVAH group.The difference was statistically significant,indicating that VAH could relieve the degree of SAS.There was no statistically significant difference in the types of SAS between the ipsilateral VAH and contralateral VAH groups.ConclusionVAH may relieve the degree of SAS in patients with severe unilateral subclavian artery stenosis or occlusion.The degree of subclavian artery stenosis in patients with VAH complicated with severe unilateral subclavian artery stenosis or occlusion may be underestimated by CDU.SignificanceWhen evaluating patients with VAH complicated with severe unilateral subclavian artery stenosis or occlusion by CDU,the degree of subclavian artery stenosis may be underestimated by the types of SAS.Therefore,the degree of subclavian artery stenosis should be judged according to various hemodynamic parameters to improve the accuracy in judging the severity of stenosis and provide more valuable information for clinical decisions.InnovationsTo explore the effect of VAH on the degree of SAS,which is beneficial to improve the accuracy of ultrasonic diagnosis of VAH in patients with severe stenosis or occlusion of unilateral subclavian artery,and provide more valuable information for clinical decision-making.Disadvantages1.This study is a single-center study.The cross-regional multi-center study may be carried out in the future.2.At present,there are no quantitative indicators in the literature reviewed on the imaging standards for the degree and type of SAS,so it is not possible to make a quantitative analysis in this paper.3.The prognosis of patients with severe stenosis or occlusion of the subclavian artery was not followed up in this study.This can be evaluated in the future.Objectives1.To compare the diagnostic value of transcranial color code sonography(TCCS)and DSA for basilar artery steal phenomenon(BSP).2.To compare the diagnostic value of TCCS,DSA and MRA for posterior communicating artery(PCoA)opening.3.To analyze the influence of VAH on anterior circulation in patients with SAS by TCCS.MethodsExcluding criteria for the 169 patients included in the above-mentioned CDU method:(1)18 patients whose PCoA cannot be shown due to no or poor sound transmission of temporal bone;(2)12 patients confirmed with embryonic posterior cerebral artery by DSA or MRA.A total of 139 patients with severe unilateral subclavian artery stenosis or occlusion were included in this study.There were 41 patients in the VAH group and 98 patients in the NVAH group.There were 25 patients complicated with ipsilateral VAH and 16 patients complicated with contralateral VAH in the VAH group.Epiq-5 and Epiq-7 color Doppler ultrasonic diagnostic instruments of Philips Netherlands were used with a 5-1 MHz phased array probe to detect the hemodynamic parameters of the basilar and PCoA of all patients enrolled.All patients with severe unilateral subclavian artery stenosis or occlusion were divided into two groups according to the diagnosis of BSP by DSA.The results of TCCS were compared with the "golden standard"(the results of DSA)to explore the diagnostic value of TCCS for BSP.All patients with severe unilateral subclavian artery stenosis or occlusion were divided into two groups according to the diagnosis of PCoA opening by DSA.The results of TCCS and MRA were compared with those of DSA to explore the diagnostic value of TCCS and MRA for PCoA opening.The diagnosis of BSP by TCCS was compared among the NVAH group,the ipsilateral VAH group and the contralateral VAH group.The diagnosis of PCoA opening by TCCS was also compared among the three groups.Meanwhile,the anterior circulation ischemia was compared among the three groups.The difference was statistically significant for P<0.05.Results1.Contrastive analysis of diagnosis of BSP by TCCS and DSA:The two were highly consistent(Kappa=0.821).The difference in the diagnosis of BSP by TCCS and DSA was not statistically significant.2.Contrastive analysis of diagnosis of PCoA opening by TCCS and DSA:The two were highly consistent(Kappa=0.796).The difference in the diagnosis of PCoA opening by TCCS and DSA was not statistically significant.3.Contrastive analysis of diagnosis of PCoA opening by MRA and DSA:The two were highly consistent(Kappa=0.799).The difference in the diagnosis of PCoA opening by MRA and DSA was not statistically significant.4.Comparison of BSP among the NVAH group,the ipsilateral VAH group and the contralateral VAH group:Compared with the NVAH group and the ipsilateral VAH group,the proportion of BSP in the contralateral VAH group(53.3%)was higher.The difference was statistically significant,indicating that BSP was more likely to occur in the contralateral VAH group.5.Comparison of PCoA opening among the NVAH group,the ipsilateral VAH group and the contralateral VAH group:Compared with the NVAH group and the ipsilateral VAH group,the proportion of PCoA opening in the contralateral VAH group(68.8%)was higher.The difference was statistically significant,indicating that PCoA opening was more likely to occur in the contralateral VAH group.6.Comparison of anterior circulation ischemia among the NVAH group,the ipsilateral VAH group and the contralateral VAH group:Compared with the NVAH group and the ipsilateral VAH group,the proportion of anterior circulation ischemia in the contralateral VAH group(68.8%)was higher.The difference was statistically significant,indicating that anterior circulation ischemia was more likely to occur in the contralateral VAH group.ConclusionsTCCS and DSA are highly consistent in diagnosing BSP and PCoA opening in patients with VAH complicated with severe stenosis or occlusion of the subclavian artery.TCCS showed that patients with severe unilateral subclavian artery stenosis or occlusion complicated with contralateral VAH are more likely to occur BSP and anterior circulation ischemia.Significances1.TCCS is consistent with DSA in evaluating BSP and PCoA opening in patients with VAH complicated with severe stenosis or occlusion of the subclavian artery.In addition,it is more suitable for extensive clinical application than DSA for it is noninvasive,convenient and highly repeatable.2.TCCS can properly evaluate the influence of VAH on the anterior circulation of patients with severe unilateral subclavian artery stenosis or occlusion.It can provide a good diagnostic basis for guiding the early diagnosis and treatment and reducing mortality and disability.Innovations1.In this study,the evaluation of BSP in patients with VAH complicated with severe stenosis or occlusion of the subclavian artery was compared between TCCS and DSA,and the evaluation of PCoA opening in patients with VAH complicated with severe stenosis or occlusion of the subclavian artery was compared among TCCS,DSA and MRA,providing a reference for clinicians to select the appropriate examination.2.TCCS was used to evaluate the BSP and PCoA opening in patients with VAH complicated with severe stenosis or occlusion of the subclavian artery,so as to determine the influence of VAH on anterior circulation in these patients and provide a reference for diagnosis,treatment and prognosis of patients.Disadvantages1.18 patients were excluded due to no or poor sound transmission of temporal bone when evaluating the influence of VAH on the anterior circulation of patients with SAS.Therefore,only 139 patients were analyzed.2.In this study,for cases with unshown PCoA,it could not be clearly that it is due to aplasia or unopen.3.Since there were few patients in the VAH group,the types of basilar steal were not further analyzed.More patients may be enrolled for further analysis.