Doppler Ultrasonography in Suspected Subclavian Artery Obstruction and in Patient Monitoring after Subclavian Stenting

Abstract

Subclavian or innominate artery (SIA) stenosis affects up to 5% of patients referred to coronary bypass grafting; it is symptomatic in less than half of these. This study aimed to assess the Doppler ultrasonography (DU) findings in SIA obstruction and patients' follow-up after percutaneous angioplasty (PTA). The study enrolled 118 patients (68 men, 50 women), aged 61.3 +/- 8.7 years, with suspected SIA obstruction, in whom peak systolic velocity (PSV) in the SIA and subclavian steal grade were assessed on DU and verified by quantitative angiography (QA). Serial follow-up DU was performed in patients treated with PTA. Grade I-III of subclavian steal from the vertebral artery (VA) was found in 89.8% of patients. In the remaining 10.2% only a PSV increase in the SIA was observed. QA confirmed the presence of SIA obstruction in all patients (stenosis grade: 80.9 +/- 17.3%). In patients with one-sided SIA obstruction, the ultrasonographic steal grade correlated with the QA stenosis grade (p < 0.001, r = 0.648). Lack of subclavian steal was noted in the case of distal subclavian stenosis, VA obstruction, VA originating from the aortic arch, and bilateral SIA obstruction. Successful PTA was performed in 77 of 83 patients referred to that procedure. PSV was reduced from 4.4 +/- 1.2 (2.2-6.5) m/sec to 1.34 +/- 0.51 (0.5-2.5) m/sec and flow in the VA was normalized. During the mean follow-up time of 24.7 +/- 15.6 months, there was a gradual increase in the in-stent PSV as well as gradual VA flow alterations, resulting in symptom recurrence. More than a twofold PSV increase, compared with the post-PTA values, was an indicator of restenosis in 11 of 12 patients. Careful DU evaluation enables the recognition of SIA obstruction in all patients. Ninety percent of them have subclavian steal correlating with the stenosis grade. Restenosis can be reliably detected with DU based on in-stent PSV and VA flow alterations.