Sonographic evaluation of plaque morphology in haemodynamic and non-haemodynamic symptomatic carotid artery stenoses

A prospective duplex ultrasound and Colour Doppler imaging studies were performed on 52 consecutive patients with 63 carotid arteries (11 patients with bilateral carotid interrogation). The cases were classified into two study groups--non-haemodynamically (< 50%) and haemodynamically (= 50%) significant stenoses in relation to clinical events and carotid plaque echomorphology. Of the 63 carotid arteries that were evaluated, 36 (57.1%) revealed non-haemodynamic and 27 (42.9%) haemodynamic stenoses. Our study confirmed that more than half of the cases with hemispheric symptoms (stroke and TIA) were related to nonhaemodynamic stenosis accounting for 53.7%. While heterogeneous and homogeneous plaques were seen in both study groups with hemispheric symptoms, no heterogeneous plaque was seen in haemodynamic stenosis with non-hemispheric symptoms. No statistically significant differences were seen between heterogeneous and homogeneous plaques in non-haemodynamic and haemodynamic cases. Predominantly hypoechoic stenoses, representing thrombotic materials are more common in haemodynamic cases of stroke accounting for 64.3% and in 76.9% of non-haemodynamic cases in TIA. Plaque surface irregularity and ulceration did not seem to be related to the severity of stenosis as there was no statistically significant difference in the frequencies. However, while irregularly surfaced plaques are of equal frequency in non-haemodynamic and haemodynamic cases in stroke, there was no ulceration in non-haemodynamic cases. There was preponderance of irregular surfaced plaques in non-haemodynamic and ulceration in haemodynamic cases in TIA. Our study showed higher frequency of smooth plaque in relation to hemispheric and non-hemispheric symptoms in non-haemodynamic stenosis and mainly ulceration/irregular plaques in haemodynamic stenosis. The trend of plaque echomorphology and surface characteristics in the study groups were highlighted. The pathogenesis of the symptoms was discussed. In conclusion, there is more to the occurrence hemispheric symptoms than the severity of the stenosis. While flow-limiting effects of stenosis in conjunction with or without embolic potentials are causes of symptoms in haemodynamic, embolic potentials are the main factors in non-haemodynamic cases.