Pathogenesis of Essential Hypertension

T HE pathogenesis of essential hypertension, which accounts for 95 per cent of hypertensions seen clinically, is still unknown despite extensive research during the past 25 years. These studies, however, have indicated that there are neurogenic, electrolyte, endocrine, and renal changes in pathophysiology that may have pathogenetic significance for essential hypertension. These changes may be interpreted to mean either that essential hypertension is a generic classification consisting of several distinct types of hypertension or that it is a single.clinical entity with various degrees of functional alteration in different body systems. The former is presently the majority opinion, although only future research can determine which viewpoint is valid. The pathogenetic relation of malignant hypertension to essential hypertension is also controversial. Although some authorities regard the 2 conditions as qualitatively different, most probably malignant hypertension is usually a greatly accelerated and accentuated form of essential hypertension. The same may be said for arteriolonecrosis, the typical lesion of malignant hypertension, in relation to arteriolosclerosis, the typical lesion of essential hypertension. Recent reports confirm the role of heredity and body type in essential hypertension, but obviously these factors must operate through pathogenetic and pathophysiologic mechanisms that only future research can elucidate. Aging and obesity are contributory but not basic factors in the development of essential hypertension. The cardiac output, blood volume, viscosity of the blood, and elasticity of the arteries are within normal limits in early