Introduction Percutaneous transluminal angioplasty (PTA) has been used to treat stenoses of the vertebral (VA) and sub- clavian (SA) arteries with few complications [1±4]. However, the complication rate from embolisation of plaque material could be lowered by improving techni- que [4±6, 9, 10]. We analysed the site of plaques and stenoses in the SA and VA and used this knowledge to conceive and use a special PTA technique which may be helpful in high-risk situations. Materials and methods We analysed intra-arterial digital subtraction angiograms (i.a. DSA) of 35 patients with stenoses or occlusions of the internal carotid artery; 30 men, 5 women, mean age 68.8 ± 8.63 years, range 44±83 years. They were selected because they had stenoses or oc- clusions of the VA and SA in addition carotid stenoses. Six patients presented with vertebrobasilar symptoms or signs, and one with ªblue fingersº probably because of arterioarterial embolisation to her left hand. In 28 patients the SA and VA plaques were appar- ently asymptomatic. High-resolution (1024  1024 matrix) i. a. DSA of the aortic arch, including selective catherisation of the supraaortic arteries were performed in anteroposterior and lateral projections in all pa- tients. If necessary, oblique projections were added to clarify the findings. DSA was performed on a biplane system consisting of two tubes mounted on a G-ring at 90  to each other which are mechani- cally highly accurate. A special software package for precise mea- surement of vessel diameters was developed and integrated in the angiography system. In phantom studies the measurement error was found to be less than 0.05 mm on average and 0.50 mm at most [7]. The site of the plaques was classified as in Figure 1. When there was a plaque the residual diameter of the narrowed and the ad- jacent normal segments were measured using the software pack- age. If feasible, the normal proximal segment was used for calcu- lation of the degree of stenosis; if not, a normal vessel segment distal to the stenosis was used. The degree of stenosis was calcu- lated according to the formula: degree of stenosis = (1 ± residual diameter/normal diameter)  100 % Neuroradiology (1999) 41: 537±542 Ó Springer-Verlag 1999 INTERVENTIONAL NEURORADIOLOGY I. N. Staikov D. Dai Do L. Remonda H. Mattle R. Baumgartner G. Schroth The site of atheromatosis in the subclavian and vertebral arteries and its implication for angioplasty Received: 1 July 1998 Accepted: 15 December 1998 I. N. Staikov × D. Dai Do × R. Remonda × H. Mattle × R. Baumgartner × G. Schroth ( ) ) Department of Neuroradiology, University Hospital of Bern, Inselspital, Freiburgerstrasse 10, CH-3010 Bern, Switzerland, e-mail: gerhard.schroth@insel.ch Fax: + 41-31-6 32 48 72 Abstract We analysed the site of plaques and stenoses in the sub- clavian and vertebral arteries, to improve the safety of percutaneous transluminal angioplasty (PTA) in high-risk patients. These lesions were assessed on arteriograms of 35 patients with stenoses and occlu- sions of the subclavian and verte- bral arteries; the degree of stenoses was measured. Of 19 subclavian ar- tery stenoses 17 (89 %) were in the segment proximal to the vertebral artery; 30 (79%) of 38 vertebral ar- tery stenoses were on the medial wall. With this knowledge, a dou- ble-balloon technique using a si- multaneous transbrachial and transfemoral approach for angio- plasty of high-risk subclavian or combined subclavian and vertebral artery stenoses and occlusions was used successfully in seven patients. This new technique may broaden the endovascular therapeutic possi- bilities in the rare but dangerous situation where plaque extends di- rectly from the stenotic subclavian artery into the origin of the verte- bral artery. Key words Artery subclavian × Artery vertebral × Angioplasty percutaneous transluminal