The differences in systolic and diastolic velocity measurements in a healthy population can range widely along the common carotid artery. A similar phenomenon in patients with occlusive disease could cause inaccurate assessment of carotid stenosis and variation in recommendations on which patients undergo endarterectomy.
Radiologists at Duke University Medical Center in Durham, NC, and New York University Medical Center in New York City examined the variability of velocity measurements in the common carotid artery (CCA) to determine whether these measurements had an effect on the assessment of blockage in the internal carotid artery (ICA) (Radiology, February 2000, Vol. 214:2, pp.387-392).
The group focused on 98 carotid arteries of 57 patients who had undergone conventional carotid angiography between September 1996 and October 1997. Bilateral carotid ultrasound was performed with standard equipment and 7-4 MHz linear transducers (HDI 3000 from ATL Ultrasound and Acuson 128 from Acuson). Ultrasound imaging on all patients also included gray-scale, pulsed Doppler, and color-flow Doppler examinations of the CCA, ICA, external carotid artery, and vertebral arteries.
Angiography of the carotid arteries was performed with an intraarterial digital technique (Integris BV 3000, Philips Medical Systems, and CAS-30B, Toshiba Medical Systems) with biplane imaging capabilities and a 1024 x 1024 digital matrix. For all angiographic studies, ICA stenosis and CCA disease was assessed.
Of the 57 patients, seven had unilateral ICA occlusion, while 35 of the 98 ICAs had stenosis of 60%.
"Variability of peak systolic velocity (PSV) measurements along the course of each individual CCA was considerable," the authors wrote. "Using a threshold of 60% stenosis (and) a published threshold of ICA/CCA PSV ratio greater than 1.8 to indicate ICA stenosis of 60% of more, nine patients had values that would have resulted in discrepant recommendations."
In addition, the variabilities in CCA velocities of 16 patients could have resulted in a different therapeutic recommendation.
One problem with measuring CCA/ICA velocities is that a standard sampling site has not been established, the authors said. For this study, sampling sites in the CCA were defined as proximal, middle, or distal. The ICA was sampled proximally, just beyond the bulb widening, and distally. The authors concluded that clearly prescribed measurement locations would be beneficial for future research.
By Shalmali Pal
AuntMinnie.com staff writer
March 14, 2000
Copyright © 2000 AuntMinnie.com
Let AuntMinnie.com know what you think about this story.
