Obesity hypertension. Converting enzyme inhibitors and calcium antagonists.

Abstract

Exogenous obesity is characterized hemodynamically by expanded intravascular (plasma) volume associated with an increased cardiopulmonary volume and cardiac output. In contrast, essential hypertension is related to an increased total peripheral resistance that is more or less uniformly distributed throughout the component organ circulations associated with a contracted plasma volume in proportion to the height of arterial pressure. Thus, both cardiac output and total peripheral resistance are elevated in obesity hypertension, and both impose a load on the left ventricle, resulting in both a volume and a pressure overload left ventricular hypertrophy. Although renal vascular resistance is not as increased as it is in lean hypertensive patients, these patients are subjected to hyperfiltration and proteinuria. Additionally, these hemodynamic alterations coexist with carbohydrate intolerance, hyperinsulinemia, hyperlipidemia, and hyperuricemia. With weight reduction and associated pressure reduction, the hemodynamic and metabolic changes reverse toward normal. However, should this not be achievable, the angiotensin converting enzyme inhibitors and calcium antagonists provide rational physiological approaches to drug therapy. With these agents pressure reduction is achieved through a fall in vascular resistance without intravascular volume expansion, and this is associated with reduced left ventricular mass and preserved cardiac and renal function, and without exacerbation of preexisting metabolic perturbations. Hence, these two classes of antihypertensive agents may provide a rational and physiological means for reversing the pathophysiological alterations of hypertensive disease in those obese patients in whom weight control is not possible.