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October 03, 2020
10/3/2020 2:00:00 PM - 10/3/2020 3:00:00 PM
Room Virtual
Understanding The Intracranial Effects Of Flow Reversal During Transcarotid Artery Revascularization
Busra Tok Cekmecelioglu, M.D., Peter Legeza, M.D., Pooja Tekula, M.D., Kavya Sinha, M.D., N. M. Giesecke, M.D., Zsolt Garami, M.D., Alan B. Lumsden, M.D.
Houston Methodist Hospital, Houston, Texas, United States
Disclosures: B. Tok Cekmecelioglu: None. P. Legeza: None. P. Tekula: None. K. Sinha: None. N.M. Giesecke: None. Z. Garami: Consulting Fees; Self; Silkroad Medical Teaching/Consultation. A. Lumsden: None.
Objective: Ischemic stroke is a major cause of morbidity and mortality and carotid stenosis is a major risk factor. Transcarotid artery revascularization (TCAR) is increasingly preferred by vascular surgeons as an alternative to transfemoral carotid stenting (CAS) and carotid endarterectomy (CEA), especially for high-risk patients with carotid artery stenosis. Previously published data have shown a low 30 days stroke rate of TCAR of 0% to 4%. The concept of “flow reversal” can be better understood by studying changes in intracranial circulation and the occurrence of emboli with transcranial doppler (TCD) (figure1).

Methods: Twelve consecutive cases over a 14 month period of patients undergoing TCAR were studied. All procedures were performed under general anesthesia. Patients’ demographic data, preoperative characteristics and perioperative TCD parameters were evaluated. Mean flow velocity (MFV) and pulsatility index (PI) of the ipsilateral middle cerebral artery (MCA), cerebral oximetry via Near-infrared spectroscopy (NIRS), bispectral index (BIS), and mean arterial pressure (MAP) values were monitored in the following phases: baseline, before flow reversal, flow reversal, and after flow reversal. The middle cerebral artery (MCA) was observed through the temporal window.

Results: We evaluated 5 female and 7 male patients with a mean age of 73 (63-91). 7 patients (58%) had previous ipsilateral CEA. Hypertension (83%) and diabetes mellitus (58%) were seen most as comorbidities.

Mean flow velocity of MCA, NIRS, BIS values had statistically significant decreases with flow reversal [40.58±10.57 to 20.58±14.34 cm/s, p=0.001; 71±4.40 to 66±6.27, p=0.0004; 45.71±8.51 to 40.14±8.09, p=0.0004], respectively while MAP change was not significant (p>0.05). After flow reversal was terminated, MFV in MCA increased significantly compared to MFV in MCA during flow reversal (24.50±15.25 to 53.33±17.69 cm/s, p=0.001.); however, there was no significant change when compared to baseline values (46±11.64 to 53.33±17.69 cm/s, p>0.05). In regards, NIRS and BIS values increased significantly after flow reversal as 66±6.27 to 70.71±4.19 and 40.14±8.09 to 46.42±10.48 (p=0.0004 and p=0.006). Mean flow velocity and pulsatility index of MCA parameters and MAP alterations with in the phases are shown in Table 1.

Postoperatively there was no stroke in any patient. During follow up, transient the ischemic attack, which immediately resolved without any deficit, was observed in 1 patient.

Conclusions: TCAR is a new, innovative, minimally invasive procedure alternative for carotid artery revascularization. However, the cerebrovascular flow impact of TCAR procedures is still not well described. While decreasing MCA flow during flow reversal, our TCD results show that flow increased with flow reversal cessation. Cerebrovascular monitoring with TCD is highly recommended for TCAR procedures as a safe and efficient tool to learn more about a new procedure.
Figure 1
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