Angiographic evaluation of the rat carotid balloon injury model.

Rationale: The rat carotid balloon-injury (BI) model is a widely used model of intimal hyperplasia (IH) and vascular remodeling. A variable degree of IH after BI has been previously reported, and we have encountered technical challenges and suboptimal results with the original method.

Objective: To evaluate the original rat carotid artery BI method with the use of micro-angiography. We tested the hypothesis that in order to obtain an optimal arterial response, BI should be limited to the common carotid artery with preservation of blood flow.

Methods And Results: The left common carotid artery (CCA) was injured by one of three different methods. Carotid angiograms and pathology were examined 14 days after BI. A 2F Fogarty balloon catheter inflated to 2 atm inside the aortic arch would not slide back into the common carotid artery until deflation to 0.5 to 0.7 atm. Four out of five (80%) vessels injured with this method developed excessive inflammation without discernible IH. Six out of nine (66%) arteries that underwent BI limited to the CCA at 2 atm developed the largest angiographic stenosis (p=0.003) and IH (0.20±0.03 mm(2), p=0.028). Ten out of eleven (91%) arteries injured with a variable pressure of 1.5 to 2.2 atm, based on the operator's feedback, developed considerable IH (0.12±0.02 mm(2)). All injured carotid arteries with preserved blood flow on angiography developed IH with intact histological boundaries.

Conclusions: Optimal IH with preservation of histological boundaries is achieved by graded BI limited to the CCA that preserves carotid blood flow.