Arterial hypertension and aneurysmal dilatation

Hemodynamic parameters and especially systemic hypertension are considered to be significant factors in the progression of aortic aneurysmal dilatation. We have recently described an original experimental model of aortic aneurysm induced by transparietal infusion of elastase in the rat abdominal aorta. In order to evaluate the effect of hypertension on the aneurysmal remodeling of the arterial wall induced by perfusion of elastase activity, this experimental model was applied to renovascular hypertensive (N = 17), spontaneously hypertensive (N = 18) and normotensive rats (N = 17). The aneurysms were induced by infusion of 15 units of hog pancreatic elastase of a one centimeter isolated aortic segment in anesthetized rats which were sacrificed two weeks later. The aneurysmal length and diameter were measured in vivo using a micrometer in a surgical microscope. The aortas were then fixed in formalin and embedded in paraffin for standard histological study. The animals which died during the experimental period were examined. All rats presented a macroscopic aneurysm two weeks after the infusion of elastase. Histologically, the aneurysmal area was characterized by the disappearance of the normal elastic network and by the presence of a collagenic wall. The dimensions of the aneurysms (transversal diameter and length) were greater in hypertensive than in normotensive animals (F = 11, P less than 0.001) and aneurysmal dimensions were positively correlated with the level of blood pressure (r = 0.56, P less than 0.001). Moreover, the frequency of aortic rupture was greater in renovascular hypertensive (4/17) than in spontaneously hypertensive (1/18) and normotensive (0/17) rats.(ABSTRACT TRUNCATED AT 250 WORDS)