Use of dynamic flow reversal when performing transcervical carotid artery stent placement “demonstrated a significant reduction in embolisation to the brain” compared with transfemoral carotid artery stenting using distal filters, according to a Belgian study published in the Journal of Endovascular Therapy.
Several studies have shown that carotid artery stenting with distal protection filters is associated with higher incidences of stroke and postoperative lesions on diffusion-weighted magnetic resonance imaging (MRI). As a result, proximal protection methods are becoming more popular. One such method is dynamic flow reversal during transcervical stenting, which “has the additional advantage of avoiding manipulations in the arch and has been associated with low stroke and death rates and significantly fewer new diffusion-weighted MRI lesions compared with distal protection filter usage,” write Maarten Plessers and colleagues at Ghent University, Ghent, Belgium. “As manipulation within the aortic arch and origin of the common carotid artery is avoided and angioplasty is performed during flow reversal, emboli should not be able to flow to the brain.”
Although carotid artery stenting with dynamic flow reversal “is capable of reducing the embolic showers that are typically observed in embologenic phases of stenting with distal protection filters, such as stenting and balloon dilation, no direct comparison has yet been performed between stenting with dynamic flow reversal and the other common revascularisation procedures as regard their effects on embolisation,” Plessers and colleagues note, explaining the justification for their study.
Thirty-four patients (mean age 67.6 years; 24 male, 10 female) with significant carotid stenosis underwent successful transcranial Doppler monitoring during the revascularisation procedure—10 carotid endarterectomy, eight carotid artery stenting with distal protection and 16 stenting with flow reversal. Ipsilateral microembolic signals were segregated into three phases: pre-protection (until internal carotid artery cross-shunted or clamped if no shunt was used, filter deployed, or flow reversal established), protection (until clamp/shunt was removed, filter retrieved, or antegrade flow re-established), and post-protection (after clamp/shunt or filter removal or restoration of normal flow). In transfemoral stenting, the same distal filter embolic protection was always used (Emboshield; Abbott Vascular), while in transcervical stenting, dynamic flow reversal was created between the common carotid artery and the contralateral common femoral vein using the ENROUTE neuroprotection system (Silk Road Medical).
The authors report that stenting with distal protection showed higher embolisation rates than endarterectomy or stenting with flow reversal in both the pre-protection and protection phases (p<0.001). In the post-protection phase, no differences between the revascularisation therapies were observed. Stenting with flow reversal and endarterectomy showed no significant differences in intraoperative embolisation during any of the phases.
“Although studies on carotid artery stenting with flow reversal are still scarce, it has been shown that transcervical stenting with dynamic flow reversal is able to overcome many limitations of transfemoral carotid stenting with distal protection filters, revealing stroke and new diffusion-weighted MRI lesion rates that are comparable with endarterectomy,” suggest Plessers et al . “This study is consistent with these findings, since the embolic load during stenting with flow reversal was comparable with that during endarterectomy.”
While the authors believe that endarterectomy “is still considered the gold standard,” they suggest that “when for any reason stenting is preferred as a better treatment option, stenting with flow reversal appears to be a safer method than with distal protection in appropriately selected cases.”