One Patent Intracranial Collateral Predicts Tolerance of Flow Reversal during Carotid Angioplasty and Stenting

Current understanding of chronic total occlusion of the internal carotid artery

At present, there is limited understanding of chronic total occlusion (CTO) of the internal carotid artery (ICA). Therefore, the present report collected related cases from PubMed and reviewed the literature. Cerebral vessels may form collateral circulation immediately or gradually following CTO of the ICA. The natural history of CTO of the ICA includes a variety of outcomes, all of which are biased toward a non-benign progressive process and are characterized by insufficient cerebral perfusion, embolus detachment and cognitive dysfunction. The majority of cases of CTO of the ICA require treatment. In early studies, the results of external-ICA bypass were unsatisfactory, while recanalization is now considered the only viable option. The current treatment indications mainly depend on the degree of injury to the cerebrovascular reserve and the extent to which the oxygen extraction fraction is increased. The length, height and duration of ICA occlusion are also relevant, though more frequently, the condition depends on multiple factors. Endovascular interventional recanalization, carotid endarterectomy (CEA) and hybrid surgery may be conducted in a select group of patients. As novel materials are developed, the success rate of simple recanalization may gradually increase; however, hybrid surgery may be more representative of the current trend, as advanced CEA can remove carotid atherosclerosis plaques, thus reducing the technological demands of the subsequent interventional recanalization. There are many complications that may result from recanalization following CTO of the ICA, including hyperperfusion and technical errors; therefore, the operation must be conducted carefully. If the recanalization is successful, it typically results in a stable improvement of patient condition in the long term. However, despite these conclusions, more studies are required in the future to further improve current understanding of CTO of the ICA.

Distinctive subcellular Akt-1 responses to shear stress in endothelial cells

Endothelial cells undergo a rapid cell-cell junction inclination following exposure to atheroprotective unidirectional flow. In contrast, atherosclerotic lesions correlate with a heterogeneous distribution of the junctional wall inclination in cells exposed to time-varying, reversing, and oscillatory flow as well as to low mean shear stress. However, the underlying biochemical events by which endothelial cells distinctively respond to unidirectional versus flow reversal remain unclear. Here, we show that the subcellular distribution of flow-induced Akt-1 phosphorylation in endothelial cells lining the mouse aorta varies depending on local hemodynamics. Activated Akt-1 accumulated in perinuclear areas of cells in regions predisposed to disturbed flow but were localized at the cell-cell junction in regions of high unidirectional laminar shear stress. In flow-adapted human endothelial cells, reversal in flow direction was associated within minutes with a subcellular concentration of phosphorylated Akt-1 at the upstream edge of cells. Interestingly, oscillatory flow (with a zero mean shear stress) failed to activate Akt-1, whereas a unidirectional pulsatile flow of similar amplitude induced an increase in Akt-1 phosphorylation. Finally, silencing of the G protein αq/11 subunit abrogated both flow-induced Akt-1 and GSK-3β activation. Together, these results characterize the existence of a Gαq/11-mediated Akt-1 signaling pathway that is dynamically responsive to flow direction, thereby offering a novel approach to regulating EC dysfunctions in regions subjected to flow reversal.

Surgical exposure of the carotid artery for endovascular interventional procedures

BACKGROUND

Transfemoral approach for endovascular interventions is not always possible in cases of unfavorable anatomy. We report our experience using a transcervical approach with carotid cut down and direct, controlled puncture of the carotid artery.

METHODS

Four patients underwent surgical exposure of the carotid artery for endovascular procedures. One patient had retrograde placement of a stent in the common carotid artery, and three patients had coiling of an intracranial aneurysm. After the endovascular procedure, the sheath was removed and the vessel was closed, under direct visualization.

RESULTS

The technique allowed access to extracranial and intracranial lesions. There were no access site complications. There were no access site-related cardiac, systemic, or neurologic events.

CONCLUSIONS

Transcervical access with surgical exposure of the carotid artery for direct and controlled vascular puncture is an effective alternative for endovascular extracranial and intracranial procedures in patients in whom the femoral route cannot be used.