Use of an angle-independent doppler system for intraoperative carotid endarterectomy surveillance

For the first few decades following the development and refinement of carotid endarterectomy in the 1950s through 1970s cerebral arteriography was the sole preoperative diagnostic modality and was considered the gold standard for carotid artery imaging. Cerebral arteriography, however, carries a risk of cerebrovascular events of 4% and permanent neurological deficit of approximately 1%.1 Noninvasive techniques such as oculoplethysmography (OPG), Doppler waveform analysis, and supraorbital directional flow were extensively studied, showed poor or no correlation with arteriography, and were deemed unreliable for surgical decision making.2,3 The Echoflow (Diagnostic Electronic Corp., Lexington, MA), a continuous wave directional Doppler velocity flowmeter that provided a velocity-sensitive color-coded computer-generated image of the extracranial carotid arteries developed in the 1970s was evaluated by several authors and showed merit as a screening tool for carotid stenosis.3-7 It was not until the development of duplex ultrasonography (DUS) in the 1980s, however, that the supremacy of arteriography for surgical planning was seriously challenged.8-12 DUS has become the most widely used screening tool for the detection of carotid stenosis, and in the majority of patients preoperative imaging with DUS alone is accurate, safe, and cost effective.9,13-16