Low shear stress and balloon injury in arterial remodeling

Arteries remodel in response to low shear stress (τ) or balloon injury through the process of neointimal thickening (NIT). The purpose of this study was to determine whether low τ, balloon injury or a combination of the two would result in the development of NIT approximating that seen in clinical arterial restenosis. Methods Using standard aseptic techniques, the common carotid artery of 12 NZ White Rabbits was exposed. For the “low τ” group (n=4), the common carotid was ligated distal to cranial thyroid branch. For the “balloon injury” group (n=4), injury was created using 3 passes of a 3F balloon catheter inflated with 0.1ml fluid and the arteriotomy was repaired. For the “low τ with balloon injury” group (n=4) the artery was balloon injured as described and the artery restricted by ligating over a 0.018 guide wire distal to the cranial thyroid branch. Flow and pressure were measured at the initial surgery and harvest. After 4 weeks, the arteries were perfusion‐fixed and NIT measured and compared using OneWay ANOVA (p<0.05). Results All arteries were patent at sacrifice. Although NIT observed in the “low τ” (63± 27 μm, τ = 0.40 ± 0.17 dyne/cm 2 ) and “balloon injury” groups was not significantly different (51 ± 17 μm, τ = 4.32 ± 1.92 dyne/cm 2 ), a considerably greater NIT was observed with the combination of “low τ and balloon injury” (176 ± 17 μm, τ = 1.83 ± 0.48 dyne/cm 2 ) p=0.001. Conclusion Low τ and balloon injury alone result in minimal NIT. However, the combination of the two, synergistically increase NIT approximating that seen in clinical restenosis. This model can serve as an excellent platform to assess the response of therapeutic strategies to arterial restenosis. Source: NIH # HL67109 1:Effect of balloon injury (A,a), low shear (B,b) and balloon injury with low shear (C,c) with on NIT. A,B, C – 4X, a,b,c – 40X