Functional Subclavian Artery Compression Caused by Thoracic Outlet Syndrome
A 68-year-old hypertensive man was admitted to our center for a non-ST-elevation acute coronary syndrome with normal troponin value. The clinical history was remarkable for enabliting pain of the left upper arm. After a positive stress test, the patient was scheduled for coronary angiography. The coronary angiography revealed severe 3-vessel coronary artery disease and a slight impairment of left ventricular function. Because the patient appeared to be a candidate for coronary surgery via the left internal mammary artery, a subclavian artery angiography was performed in the same session to exclude any subclavian artery stenosis and assess the suitability of the internal mammary artery as an arterial conduit. A tight stenosis of the middle portion of the left subclavian artery was detected (Figure, A). Because we believed that the patient had thoracic outlet syndrome (TOS), the patient’s left arm was mildly adducted and a magnified subclavian angiogram performed. The angiogram revealed that the stenosis appeared to be mild (Figure, B). After maximally adducting the left arm, the stenosis completely disappeared (Figure, C), confirming a phasic compression of the subclavian artery. TOS uncommonly causes arterial vascular complications; bony or muscular abnormalities such as abnormal cervical ribs, fibrous bands, or other variations of scalene musculature can lead to chronic trauma to the subclavian artery or the brachial plexus. Diagnosis is made by Doppler ultrasound or MRI. Surgical excision of the first cervical ribs or scalene muscle with or without vascular reconstruction is the treatment of choice. In rare instances, the angiography of the subclavian artery may detect a previously undiagnosed TOS.