Doppler Study of the Left Common Carotid Artery With Pre-Occlusive Stenosis

Abstract

Our case report titled Doppler Study of the Left Common Carotid Artery With Preocclusive Stenosis was published in the September 2022 issue of the Journal for Vascular Ultrasound (JVU). After publication, some comments and questions were raised by Joleen D. Rodriguez, MHA, RDCS, RVT regarding the bidirectional flow seen in partial steal, referring to Figures 5 and 6 in our report. Furthermore, they elaborated on their questions with the help of some examples of Doppler flow patterns associated with subclavian artery stenosis. It was also mentioned that collateral circulation can only be confirmed by contrast-enhanced examination. Ms. Rodriguez was of the opinion that if electrocardiogram (ECG) is performed with the Doppler waveform, that will add some additional valuable information. There was particular interest in Figure 5 from our case report, with the annotated version in the letter indicating systole and diastole with green and yellow colors. It was suggested that the region of the spectral waveform labeled as systole in our study would be diastole and vice versa. With regard to Figure 6 in our case report, it was believed that it probably would be depicting occult or pre-steal phenomenon. I am very thankful to Ms. Rodriguez and her team for their comments on our case report. An author is like a poet and appreciates those who are taking interest in his or her creation. First of all, the case presented in our article is not subclavian stenosis or steal syndrome, but rather focuses on a preocclusive stenosis of the left common carotid artery (CCA). It is a severe stenosis; theoretically, you can say more than 90% stenosis.1–3 With such a left CCA preocclusive stenosis, it is difficult for the left CCA to supply the left internal carotid artery (ICA) and external carotid artery (ECA) as it would in a normal individual. In the case presented, there was only trickle flow in the stenosis, as shown in Figure 1 with this letter (figure numbers from the case report are shown in the left-lower corner of the small images in Figure 1). On power Doppler, there was only a sliver of blood flow, while on spectral Doppler there was slow flow (15.5 cm/s); the velocity in the stenosis was decreased instead of increased as shown in Figures 2-4 from the case report. There was antegrade tardus-parvus flow4–6 in the left ICA (Figure 5) and retrograde flow in the left ECA (Figure 6). There was substantially low resistance flow in the left vertebral artery7 (Figure 7). The superior thyroid artery on the right side originating from the right ECA is acting as a collateral pathway8,9 in the thyroid gland (Figure 8) and carries blood to the left superior thyroid artery (right to left) and then to the left ECA. The blood flow direction in the left ECA is retrograde10,11 as shown in Figure 1 with this letter. Regarding the use of ECG, I think there is a great difference between spectral Doppler ultrasound and ECG.12 ECG is measuring the electric conductivity in the heart while spectral Doppler depicts blood flow including its velocities, resistance, pulsatility pattern, and so on.13,14 I think there is no relation between arterial stenosis with ECG.15 In our laboratory, there is only ultrasound, and I have been performing vascular, musculoskeletal, small parts, and general ultrasound since 2013. We have not felt the need for a contrast-enhanced study in the cases of extracranial carotid examination. As far as our case report is concerned, it was a left CCA preocclusive stenosis, and the left ICA was supplied by a collateral pathway from the right ECA through the thyroid gland. It was accurately diagnosed by Doppler ultrasound and later treated with endarterectomy. 1141953 JVUXXX10.1177/15443167221141953Journal for Vascular UltrasoundBacha letter2022