Duplex ultrasound protocol and findings in common carotid artery dissection extending from the aortic arch

Abstract

Introduction. - Aortic dissection can extend into the brachiocephalic arteries. We analyzed carotid duplex ultrasound (CDU) in DeBakey I acute aortic dissection to identify characteristics and establish a protocol to ensure appropriate evaluation. Method. - From 2002 to 2011, patients with CDU and proximal aortic dissection were identified. The protocol included color Doppler in both long and short axis, spectral waveforms of true and false lumens, and imaging of the aortic arch, when appropriate. Imaging was performed on a Philips iE33 or iu22 using a 9-3 MHz linear array probe for the cervical carotid arteries and a curved array 5-1 MHz probe for the aortic arch. Waveforms were analyzed for signs of proximal dissection. Results. - CDU was performed in 87 of 288 patients and comprised the study group. Intimal flaps were noted in 26 common carotid arteries (CCAs) in 20 patients. The false lumen was thrombosed in nine arteries (35%). Eight CCAs had stenosis >50%, with seven having increased velocities >200 cm/sec. All patients with elevated velocities in the true lumen had false-lumen thrombosis. We noted that carotid artery dissections were not visualized in all planes and that more false lumens were found to be patent on CDU than on computed tomography. Characteristic waveforms included a second pulsed systolic waveform, a wide and jagged systolic peak, intermittent flow reversal, and visualization of a dissection flap. Conclusion. - Carotid imaging in transverse and axial planes is important in dissection cases. We found that a 5-1 MHz curved-array probe may be helpful in imaging the proximal brachiocephalic arteries and aortic arch. Several characteristic waveforms were noted. We recommend a standardized protocol that includes near-complete CCA visualization, multiplane views, and Doppler waveform analysis of both true and false lumens. The clinical significance of false-lumen patency or true-lumen stenosis remains unclear.