Effect of hydrostatic dilation on the structure and patency of small arteries

The effect of hydrostatic dilation on the structure and patency of 40 rat femoral arteries was investigated. The femoral arteries were hydrostatically dilated, following cannulation of a side branch, with heparinized Ringer's lactate to a pressure of 300 mmHg. Arterial patency, morphometry, and histology were assessed immediately, 24 hours, 48 hours, 7 days, and 14 days following dilation. Hydrostatic dilation caused an immediate 85 percent increase in intraluminal diameter (p less than 0.001) and an immediate 39 percent decrease in wall thickness (p less than 0.001). All the dilated arteries remained patent, although two developed intraluminal thrombus that partially obstructed the lumen. Hydrostatic dilation did not disrupt the cell layers of the arterial wall. The smooth muscle cells of the media were lengthened and showed diffuse necrosis at 24 and 48 hours. Margination of white blood cells was observed in all specimens at 48 hours. Nuclear regeneration in the smooth muscle of the media was first observed at seven days and was present throughout the media at 14 days. Wall thickness increased between 7 and 14 days due to intimal hyperplasia (p less than 0.01). Hydrostatic dilation is shown to be an effective means of increasing intraluminal diameter, but the pathologic changes initiated in the arterial wall militate against its use in the clinical setting.