Prediction of long term restenosis risk after surgery in the carotid bifurcation by hemodynamic and geometric analysis
Thursday 12th July 2018
Domanin, M.; Gallo, D.; Vergara, C.; Biondetti, P.; Forzenigo, L.V.; Morbiducci, U.
Objective- Carotid restenosis is a common complication occurring after carotid endarterectomy (CEA). This study aimed to explore the potential of local hemodynamic disturbances and carotid bifurcation geometry to predict long-term restenosis at 60 months after CEA. Methods- Thirteen carotid bifurcations with a stenosis greater than 70% were submitted to CEA. Arteriotomy repair was performed with patch graft (PG) angioplasty in 9 cases, with primary closure (PC) in 4 cases. MRI acquisitions were performed within a month after surgery for hemodynamic and geometric characterization. Personalized computational fluid dynamic simulations were performed and hemodynamic disturbances were quantified in terms of exposure to low and oscillatory wall shear stress (WSS). Each carotid geometry was characterized automatically in terms of flare (i.e., the expansion at the carotid bulb) and tortuosity proximal to the bifurcation. Based on hemodynamics and geometry, cases were classified into three categories of “geometric” or “hemodynamic” restenosis risk. At 60 months after CEA, eligible participants underwent duplex ultrasound scan and peak systolic velocity measurement for the detection of restenosis, with extraction of intima-media thickness from five selected locations along the carotid bifurcation. Results- More unfavorable hemodynamic conditions established in PG than PC cases. Carotid flare was found to be significantly associated with the exposure to low WSS and therefore considered to define the geometric restenosis risk. No significant associations were found for tortuosity. The two cases characterized by the highest flare and the largest exposure to low WSS developed restenosis >50% at 60 months. A high correspondence was found between morphological DUS observations of myointimal thickening or new atheroma development and low and oscillatory WSS regions. Conclusions- The quantitative analysis of hemodynamics and geometry holds potential for the stratification of patients at risk for development of late restenosis after CEA. Moreover, it can help the understanding of the mechanistic processes underlying restenosis development, potentially guiding the clinical decision between PG vs. PC. Our findings suggest that arteriotomy repair should avoid an artificial flare, that is linked with restenosis via the generation of flow disturbances. Geometric characterization from imaging data is a convenient, fast and easy method that can be integrated in the clinical practice.