The effect of implantation of aortic stents on compliance and blood flow. An experimental study in pigs.

Balloon dilation of coarctation of the aorta has been found to be an effect ive modality for treatment. Recently, in the older child and adult, implant ation of endovascular stents has been considered a clinical alternative to dilation alone. Little is known, however, of the effect of implantation of stents on aortic compliance. To investigate this impact of implantation, we studied 18 piglets, divided into experimental and control groups. At media n weight of 14 kg, 2 pairs of ultrasonic crystals were implanted on the aor tic wall. After 1 week, all animals underwent catheterization. In the exper imental group, a 3 cm long balloon expandable stent was implanted in the de scending thoracic aorta between the pairs of crystals. Measurements of arte rial pressure and dimensions were performed before implantation and immedia tely thereafter, and at follow-up catheterization. The index of stiffness, beta, and the the elastic modulus of aortic pressure-strain, were calculate d as indexes of arterial compliance. The change in compliance during the pe riod of study was not different between groups. At follow-up, no difference was observed between groups in the velocity of the aortic pulse wave, the augmentation index, or the maximum velocity of now of blood. The stents rem ained patent and did not affect aortic growth or medial wall thickness. The re was no difference between groups in levels of plasma renin activity and serum aldosterone. In this animal model studied over the short term, theref ore, implantation of stents does not affect aortic compliance. Further stud ies are required to elucidate the long term effects of stents on the hemody namics affecting the aortic wall and local flow dynamics.