Symposium
Obesity, Hypertension, and the Heart

https://doi.org/10.1097/00000441-200104000-00005Get rights and content

ABSTRACT

Hypertension occurs more commonly in obese than in lean persons at virtually every age. A variety of endocrine, genetic, and metabolic mechanisms have been linked to the development of obesity hypertension. These include insulin resistance and hyperinsulinemia, increased serum aldosterone levels, salt sensitivity and expanded plasma volume in the presence of increased peripheral vascular resistance, a genetic predisposition, and possibly increased leptin levels. Pressure and volume overload are present in obese hypertensives. This leads to a mixed eccentric-concentric form of left ventricular hypertrophy and increases the predisposition to congestive heart failure. Weight loss, even in modest decrements, is effective in reducing obesity-hypertension, possibly by ameliorating several of the proposed pathophysiologic mechanisms. There are currently no specific recommendations concerning pharmacotherapy of obesity-hypertension because each drug group has pros and cons.

Section snippets

Pathogenesis of Obesity-Hypertension

A series of endocrine, genetic, and metabolic mechanisms have been linked to the development of obesity-hypertension. These include insulin resistance/ hyperinsulinemia, overactivity of sympathetic nervous system, the renin-angiotensin-aldosterone system, salt retention, genetic predisposition, and leptin levels. A schematic review of these mechanisms and their probable interaction in causation of obesity hypertension is presented in Figure 1, and each mechanism is discussed below.

Obesity-Hypertension and The Heart

Because of the high blood volume in the obese, venous return to the right atrium, preload to the left atrium, left ventricular (LV) filling pressure, LV volume, and cardiac output are all shown to be increased.47 Afterload is also increased because of increased LV wall tension caused by increased LV volume.30 The LV adapts to these changes by increasing muscle mass, thereby producing thickening of the myocardial wall.48 In addition to the echocardiographic evidence cited above, autopsy study

Obesity-Hypertension and The Kidneys

Hall et al studied dogs with diet-induced obesity.58., 59. They demonstrated that sodium retention at the level of loop of Henle that may be caused by insulin resistance and hyperinsulinemia, increased sympathetic activity, activation of renin-angiotensin-aldosterone system, and/or higher renal interstitial fluid hydrostatic pressure. Microscopic examination of the animal kidneys revealed an increase in the interstitial cells and expansion of the extracellular matrix between tubules in the

Weight Reduction

It is well documented that reduction of weight is effective in reducing obesityhypertension. 65., 66. This reduction in blood pressure is seen whether or not salt restriction is instituted at the same time. Modest reduction in weight (5 to 10 kg) was effective in up to 75% of the subjects. In addition to better blood pressure control, weight loss is associated with reduction of insulin levels, sympathetic activity, possibly renin and aldosterone levels, and intracellular sodium levels. Cardiac

Summary

Several epidemiological studies have demonstrated a direct relationship between central obesity and hypertension. A series of endocrine and metabolic mechanisms have been linked to the development of obesity-hypertension. These include insulin resistance, hyperinsulinemia, increased adrenergic activity and aldosterone levels, and increased salt and water retention. Low levels of leptin and genetic predisposition may also be important. Hemodynamically, the cardiac output is increased with

References (68)

  • J. Duflou et al.

    Sudden death as a result of heart disease in morbid obesity

    Am Heart J

    (1995)
  • G. Bray

    Obesity in America. An overview

  • Rr Kuczmarski et al.

    Increasing prevalence of overweight among US adults. The National Health and Nutrition Examination Surveys (NHANES)

    JAMA

    (1994)
  • W. Kannel et al.

    The relation of adiposity to blood pressure and development of hypertension: the Framingham study

    Ann Intern Med

    (1967)
  • R. Stamler et al.

    Weight and blood pressure findings in hypertension screening of 1 million Americans

    JAMA

    (1978)
  • R. Levi et al.

    Overweight: a prognostic significant in relation to hypertension and cardiovascular renal diseases

    JAMA

    (1946)
  • T. Van Itallie

    The problem of obesity: Health implications of overweight and obesity in United States

    Ann Intern Med

    (1985)
  • M. Krotkiewski et al.

    Impact of obesity on metabolism in men and women: Importance of regional adipose tissue distribution

    J Clin Invest

    (1983)
  • W. Istfan et al.

    Insulin resistance versus insulin secretion in the hypertension of obesity

    Hypertension

    (1983)
  • R. DeFronzo et al.

    The effect of insulin on renal handling of sodium, potassium, calcium and phosphate in man

    J Clin Invest

    (1975)
  • R. Feldman et al.

    Parallel regulation of the local vascular and systemic metabolic effects of insulin

    J Clin Endocrinol Metab

    (1995)
  • M. Maxwell et al.

    Role of insulin and norepinephrine in the hypertension of obesity

    Am J Hypertens

    (1995)
  • J. Hall et al.

    Insulin resistance, hyperinsulinemia, and hypertension: causes, consequences, or merely correlations?

    Proc Soc Exp Biol Med

    (1995)
  • K. Hiramatzu et al.

    Changes in endocrine activities relative to obesity in patients with essential hypertension

    J Am Geriatr Soc

    (1981)
  • F. Messerli et al.

    Obesity and essential hypertension, intravascular volume, sodium excretion and plasma renin activity

    Arch Intern Med

    (1981)
  • A. Rocchini et al.

    The effect of weight loss on the sensitivity of blood pressure to sodium on obese adolescents

    N Engl J Med

    (1981)
  • C. Ward et al.

    Influence of insulin, sympathetic nervous system and obesity on blood pressure: The normotensive aging study

    J Hypertens

    (1996)
  • A. Rocchini

    The relationship of sodium sensitivity to insulin resistance

    Am J Med Sc

    (1994)
  • K. Dahl et al.

    Role of salt in fall of blood pressure accompanying reduction of obesity

    N Engl J Med

    (1958)
  • V. Campese

    Salt sensitivity in hypertension. Renal and cardiovascular implication

    Hypertension

    (1994)
  • A. Avenel et al.

    Sodium intake, inhibition of Na+-K+-ATPase, and obesity

    Lancet

    (1981)
  • M. De Luise et al.

    Reduced activity of the red-cell sodium-potassium pump in human obesity

    N Engl J Med

    (1980)
  • K. Boehringer et al.

    Pressor factors and cardiovascular responsiveness in lean and overweight normal or hypertensive subjects

    Hypertension

    (1982)
  • E. Reisen et al.

    Hemodynamics in obesity

  • Cited by (0)

    View full text