[Hemodynamic adaptation in severe obesity with or without arterial hypertension]

Hypertension and obesity are 2 common pathological conditions that have been directly related. The incidence of hypertension in an obese population is far greater than in otherwise normal people. Nevertheless, a causal relationship between the 2 disorders has not been established. But their coincidence in the same patient carries increased risk of cardiovascular morbidity and mortality. In the present study we have studied a group of normotensive obese patients (21 patients, Group A), a group of hypertensive obese patients (19 patients, Group B) and a group of normal subjects (11 patients, Group C) by radionuclide ventriculography with Tc 99m to visualize the different hemodynamic adaptation to these different conditions. Overweight causes an increased preload while hypertension causes an increased afterload. In response to the increase in preload the heart of obese patient undergoes eccentric hypertrophy; when an increase in afterload is present at the same time, the left ventricle develops concentric hypertrophy. We found an increased preload in both the obese groups (A and B) testified by increased blood volume and end diastolic volume. Heart rate was higher in the 2 populations of obese patients. As a result, cardiac output was significantly increased in Group A and B. But the stroke index is decreased in Group A and B with respect to Group C. The ejection fraction is reduced in Group A with respect to Group B and C. The contractility index (systolic blood pressure/end systolic volume) is higher in Group B in comparison with Group A. Thus, hypertensive obese patients seem to have a better cardiac performance respect to the normotensive obese patients.(ABSTRACT TRUNCATED AT 250 WORDS)