[Atraumatic diagnosis and semi-invasive therapy of subclavian steal syndrome using percutaneous transluminal angioplasty. A current concept].

Percutaneous transluminal angioplasty (PTA) is a semiinvasive, non-operative transvascular technique for dilatation of stenosed vessel segments by help of balloon catheters. This technique was applied to 30 out of 42 patients with a subclavian steal mechanism due to highgrade proximal subclavian artery (PSA) lesions. The transfemoral, transaxillary or both approaches were used. A staging of the severity of the subclavian steal mechanism on the basis of the pre-interventional Doppler ultrasound findings (Grade I-IV) was proposed for adequate selection of patients for angioplasty. During balloon dilatation of the subclavian artery permanent CW Doppler monitoring of the ipsilateral vertebral blood flow velocity was performed at the mastoid. Balloon dilatation failed to be effective in 4 patients with complete subclavian artery occlusions (Stage IV). In 26 patients with high-grade stenoses of the proximal subclavian artery (Stage II/III), angioplasty led to recanalisation of the vessel and abolishment of the steal mechanism. However, relief or improvement of the concomitant subclavian steal syndrome could not be achieved except in one-third or two-thirds of the patients, respectively. Long term follow-up with repeat Doppler sonography indicated a complete removal of the subclavian lesions in 50% of the cases, whereas the remaining patients produced some kind of re-stenosis. However, repeat angioplasty became necessary in only 5 cases and was permanently successful in two of them. If patients with complete subclavian artery occlusions were excluded, the complication rate due to angioplasty was very low. Embolism into the finger arteries could only be observed once. In another case, accidental dissection and complete occlusion of the distal subclavia artery occurred but underwent spontaneous recanalisation. Doppler monitoring of vertebral flow velocity was very useful for both control of the effectiveness of the dilatation procedure and deeper insight into the pathophysiology of the subclavian steal mechanism. An unexpected delay phenomenon concerning the re-establishment of cephalad vertebral flow direction was observed immediately after recanalisation of the subclavian artery and was thought to protect the posterior circulation against early embolism due to mobilisation of plaque debris within the proximal subclavian segment. From an angiological point of view, the outcome of percutaneous transluminal angioplasty does not yet meet the success rates of various modern extra-thoracic surgical procedures for operative treatment of subclavian steal mechanism. However, the rate of improvement of clinical signs and symptoms is equal with both methods.(ABSTRACT TRUNCATED AT 400 WORDS)