Tandem High-grade Stenoses in the Innominate and Right Internal Carotid Arteries Diagnosed with Carotid Duplex Ultrasound

Abstract

Peak systolic velocity criteria for assessing the severity of internal carotid artery (ICA) stenosis may be inadequate in the setting of a critical proximal lesion. A 54-year-old man with a history of panvascular atherosclerosis presented for re-evaluation of known carotid stenosis. Carotid duplex ultrasound was performed by using B-mode ultrasound (Philips) with color and pulsed Doppler. Velocities within the innominate artery were markedly increased (PSV 553 cm/sec; EDV 211 cm/sec), consistent with high-grade stenosis. Waveforms in the right subclavian and common carotid (CCA) arteries were poststenotic in appearance, and velocity in the distal right CCA was very low (PSV 39 cm/sec). There was an additional step-up in velocity in the proximal right ICA with extensive homogeneous plaque visualized (right ICA PSV 210 cm/sec; EDV 115 cm/sec). Although the ICA lesion did not meet peak systolic velocity or end diastolic velocity criteria for >80% stenosis in our laboratory, the lesion was interpreted as an 80–99% lesion on the basis of the markedly increased ICA/CCA ratio (ICA/CCA ratio 5.38). The left subclavian artery had low, monophasic flow and was likely occluded near its origin with filling from a retrograde vertebral artery. The patient was referred for percutaneous intervention. Angiography confirmed a 99% stenosis of the innominate artery and a 90% stenosis of the right ICA in its proximal portion. The left subclavian artery was occluded. The left CCA arose from a bovine aortic arch. The innominate and right ICA lesions were treated successfully with balloon angioplasty and stenting. Duplex ultrasound is an outstanding diagnostic tool for the evaluation of extracranial carotid and innominate lesions. In the setting of tandem lesions, critical stenosis of the ICA may be missed with reliance on traditional PSV criteria alone. In such cases, interpretation of secondary criteria, particularly the ICA/CCA ratio, is crucial to establish an accurate diagnosis.