Sick vessel syndrome. Recovery of atherosclerotic and hypertensive vessels.

This review describes vascular changes in atherosclerotic and hypertensive vessels as well as effects of treatment. Changes in vascular structure in both atherosclerosis and hypertension are characterized by thickening of the vessel wall and vascular "remodeling." Remodeling tends to preserve the size of the lumen in atherosclerotic vessels and results in a smaller lumen in hypertensive vessels. Changes in vascular function are characterized by preservation of smooth muscle relaxation, with the exception of activity of ATP-sensitive potassium channels, and dysfunction of endothelium. Regression of atherosclerosis, by treatment of hyperlipidemia, results in quite rapid removal of lipid from the vessel wall but with inconsistent improvement in maximal vasodilator capacity. In contrast, endothelial function improves during regression of atherosclerosis, and hyperresponsiveness to serotonin subsides rapidly. Effective treatment of hypertension produces regression of vascular hypertrophy, and some approaches (especially angiotensin-converting enzyme inhibitors) are effective in correcting vascular remodeling. Endothelium-dependent relaxation generally improves during antihypertensive treatment. Reduction in pulse pressure may be more important than reduction in mean arterial pressure in reversing the structural and functional abnormalities of hypertensive vessels.