[Contralateral occlusion of the internal carotid artery in the study of carotid stenosis using Doppler ultrasonography]. / Oclusión contralateral de la arteria carótida interna en el estudio por ecografía Doppler de las estenosis carotídeas.

INTRODUCTION AND AIMS: The degree of stenosis measured by Doppler ultrasonography in patients with contralateral occlusion of the internal carotid artery (ICA) is assumed to be overestimated. We propose to measure the extent to which this phenomenon affects the capacity of Doppler ultrasonography to classify stenoses. PATIENTS AND METHODS: A retrospective study of 47 patients was conducted using Doppler ultrasonography and digital subtraction angiography; all subjects had confirmed unilateral occlusion of the ICA and stenoses of the contralateral ICA. Curves were traced plotting the degree of stenosis against the peak systolic velocity (PSV) and its ratio in the ICA and in the common carotid artery (VICA/VCCA). The curves were compared with their equivalents with no contralateral occlusion found in the literature. Later, the cases of stenosis were classified into groups of less than 50, 50-69 and more than 70%, and the main statistical values were calculated. RESULTS: The PSV in the stenoses between 40-50% presents more than 1 standard deviation (SD) above the mean. There were no significant deviations in other degrees of stenosis (p > 0.4). The VICA/VCCA showed a similar parallelism, but with deviations lower than 1 SD (p = 0.56). Seventeen per cent of the stenoses were over-classified, and this conditioned a sensitivity of 84, 71 and 100%, and a specificity of 100, 94 and 88% for the groups of less than 50, 50-69 and over 70%, respectively. The VICA/VCCA over-classified 41% of the stenoses; sensitivity was seen to be 56, 43 and 100% and specificity was 90, 64 and 87%. Diagnostic accuracy of the PSV and VICA/VCCA stands at 83 and 57%, respectively. CONCLUSIONS: Contralateral occlusion leads to over-classification of the PSV. There is a tendency to over-classify, although this does not affect the overall diagnostic accuracy. The VICA/VCCA does not offer greater diagnostic accuracy in classifying stenoses with contralateral occlusion.

Oclusión contralateral de la arteria carótida interna en el estudio por ecografía Doppler de las estenosis carotídeas / Contralateral occlusion of the internal carotid artery in the study of carotid stenosis using doppler ultrasonography

Introducción y objetivo. Se presupone una sobreestimación del grado de estenosis medida por ecografía Doppler en pacientes con oclusión contralateral de la arteria carótida interna (ACI). Proponemos cuantificar el efecto de este fenómeno sobre la capacidad de la ecografía Doppler para clasificar las estenosis. Pacientes y métodos. Se estudiaron retrospectivamente 47 pacientes mediante ecografía Doppler y angiografía de sustracción digital, todos con oclusión unilateral de la ACI confirmada y estenosis de la ACI contralateral. Se crearon curvas que relacionan el grado de estenosis con la velocidad máxima sistólica (VMS) y su razón en la ACI y en la arteria carótida común (VACI/VACC). Las contrastamos con sus equivalentes sin oclusión contralateral anteriormente publicadas. Posteriormente, las estenosis se clasificaron en grupos de < 50, 50-69 y > 70%, y se calcularon los principales valores estadísticos. Resultados. La VMS en las estenosis entre el 40-50% presenta más de una desviación estándar sobre la media. No hay desviaciones significativas en otros grados de estenosis (p > 0,4). La VACI/VACC muestra un paralelismo semejante, pero inferior a una desviación estándar (p = 0,56). El 17% de las estenosis se sobreestimó, lo que condicionó una sensibilidad del 84, 71 y 100%, y una especificidad del 100, 94 y 88% para los grupos de < 50, 50-69 y > 70%, respectivamente. La VACI/VACC sobreestimó el 41% de las estenosis; así, mostró una sensibilidad del 56, 43 y 100% y una especificidad del 90, 64 y 87% en los respectivos grupos. La exactitud diagnóstica de la VMS y de la VACI/VACC se sitúa en el 83 y el 57%, respectivamente. Conclusiones. La oclusión contralateral provoca una sobrestimación de la VMS. Existe una tendencia a la sobreestimación, aunque sin repercusión en la exactitud diagnóstica global. La VACI/VACC no presenta mayor exactitud diagnóstica en la clasificación de las estenosis con oclusión contralateral (AU)

Introduction and aims. The degree of stenosis measured by Doppler ultrasonography in patients with contralateral occlusion of the internal carotid artery (ICA) is assumed to be overestimated. We propose to measure the extent to which this phenomenon affects the capacity of Doppler ultrasonography to classify stenoses. Patients and methods. A retrospective study of 47 patients was conducted using Doppler ultrasonography and digital subtraction angiography; all subjects had confirmed unilateral occlusion of the ICA and stenoses of the contralateral ICA. Curves were traced plotting the degree of stenosis against the peak systolic velocity (PSV) and its ratio in the ICA and in the common carotid artery (VICA/VCCA). The curves were compared with their equivalents with no contralateral occlusion found in the literature. Later, the cases of stenosis were classified into groups of less than 50, 50-69 and more than 70%, and the main statistical values were calculated. Results. The PSV in the stenoses between 40-50% presents more than 1 standard deviation (SD) above the mean. There were no significant deviations in other degrees of stenosis (p > 0.4). The VICA/VCCA showed a similar parallelism, but with deviations lower than 1 SD (p = 0.56). Seventeen per cent of the stenoses were over-classified, and this conditioned a sensitivity of 84, 71 and 100%, and a specificity of 100, 94 and 88% for the groups of less than 50, 50-69 and over 70%, respectively. The VICA/VCCA over-classified 41% of the stenoses; sensitivity was seen to be 56, 43 and 100% and specificity was 90, 64 and 87%. Diagnostic accuracy of the PSV and VICA/VCCA stands at 83 and 57%, respectively. Conclusions. Contralateral occlusion leads to over-classification of the PSV. There is a tendency to over-classify, although this does not affect the overall diagnostic accuracy. The VICA/VCCA does not offer greater diagnostic accuracy in classifying stenoses with contralateral occlusion (AU)