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TCD Finding Predicts Embolization From Stent Deployment During TCAR
Adam I Bardoczi, Nora F Kovacs, Lilla A Juhasz, Charudatta Bavare, Linda Le, Reka Vernes, Diana Husvethova, Alan Lumsden, Zsolt F Garami
Houston Methodist DeBakey CV Center, Houston, TX
Introduction: Transarterial carotid revascularization (TCAR) is a widely utilized treatment choice to resolve severe carotid artery stenosis. Despite its clever design to minimize intraprocedural embolization, accounting for its low perioperative stroke rates, embolic showers at various steps of the procedure can be observed with Transcranial Doppler (TCD). Although microembolization may not lead to increased risk of postoperative “overt stroke”, a broad body of literature informs us about the long-term complications of “covert stroke lesions” caused by microembolization, including increased dementia and depression in the elderly. Maximum efforts should therefore be made to minimize any embolization during TCAR.
Methods: This single center, retrospective study analyzed TCD data collected from 50 consecutive TCAR procedures performed on 49 patients (one patient underwent TCAR bilaterally) between January of 2019 and May of 2024. Nova Signal TCD machines with 2 MHz probes secured to headframes were used for intraoperative monitoring of the ipsilateral or bilateral middle cerebral arteries via the transtemporal bone window, according to standard TCD guideleines. Mean Flow Velocity, Delta Flow, Pulsatility Index and emboli count were recorded and analyzed. We hypothesized that if after the establishment of flow reversal and common carotid artery clamp placement we observe any emboli or a greater than 50% change in the delta flow on the TCD monitor, it would be associated with a higher chance of an embolic shower during stent deployment. Furthermore, that a higher degree of ipsilateral ICA or ECA stenosis might predict a greater chance of shower during stenting. Univariable and multivariable logistic regression models were used to assess the hypothesized variables of interest.
Results: Our data showed increased odds of an embolic shower during stent placement in patients with a greater than 50% decrease in Delta Flow after CCA clamp placement (30.85 [1.1-862.81]; p=0.044) and when more than 10 emboli were seen between clamping and stenting (HR: 340.08 [7.03-26303.79]; p=0.004). Interestingly, patients with Diabetes Mellitus showed lower odds of a shower during stenting (0.02 [0.01-0.68]; p=0.030). Neither ipsilateral ICA stenosis of greater than 70% (p=0.669) nor ipsilateral ECA stenosis of greater than 50% (p=0.854) showed significant increase in embolic shower occurrence.
Conclusion: A Delta Flow decrease of more than 50% in the ipsilateral MCA may point to hemodynamics that influence the robustness of the flow reversal system during TCAR, leading to suboptimal protection from microembolization. Further research is warranted to understand how the neuroprotective effect of flow reversal may be maximized on an individual level.
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