VASCULAR HYPERTROPHY AND REMODELING IN SECONDARY HYPERTENSION

It has been proposed that several neurohumoral factors may be involved in the genesis of vascular structural changes (remodeling or hypertro phy) frequently observed in essential hypertension. Therefore, in this study we investigated vascular structural alterations of subcutaneous small resistance arteries in patients with secondary forms of hyperte nsion. The study included 70 participants: 11 with pheochromocytoma, 1 3 with primary aldosteronism, and 17 with renovascular hypertension; 1 3 normotensive subjects and 16 patients with essential hypertension se rved as controls. All subjects were submitted to a biopsy of subcutane ous fat. Small resistance arteries were dissected and mounted on a mic romyograph, and media-lumen ratio, media thickness, remodeling index, and growth index were evaluated. Endothelial function was evaluated ac cording to the dose-response curve to acetylcholine. In patients with either primary aldosteronism or renovascular hypertension, a marked in crease in media-lumen ratio was observed, whereas in patients with phe ochromocytoma, the extent of vascular structural alterations was simil ar to that observed in patients with essential hypertension. The incre ase in media-lumen ratio in patients with essential hypertension and w ith pheochromocytoma was mainly due to vascular remodeling (remodeling index, 93% to 94%), whereas in patients with renovascular hypertensio n, there was vascular growth (remodeling index, 70%; growth index, 53% ). Patients with primary aldosteronism had an intermediate pattern com pared with the other two forms of secondary hypertension. An evident i mpairment of endothelial function was observed in all four hypertensiv e groups. In conclusion, the renin-angiotensin-aldosterone system seem s to be more powerful than the adrenergic system in inducing vascular growth.