Obesity and cardiac function.

Abstract

SUMMARY We studied 10 obese volunteers, mean age 36.5 ± 10.3 years, who weighed 123.56 ± 28.7 kg and were 69.96 ± 22.5 kg overweight. The subjects did not have diabetes, arterial hypertension or signs of cardiac and respiratory failure or disease and all underwent right-and left-heart catheterization. Cardiac output and stroke volume were high, according to increased oxygen consumption and to the degree of obesity. Ventricular end-diastolic and atrial pressures ranged from normal to high and correlated with body weight, signs of volume overloading and reduced left ventricular (LV) compliance. The mean pulmonary artery pressure was elevated and correlated well with weight, pulmonary resistance being normal; mean aortic pressure did not correlate with weight, and systemic arterial resistance tended to have a negative correlation. The LV function curve showed impaired ventricular function, particularly for the heaviest subjects, in whom Vma, and the ratio of the stroke work index to LV end-diastolic pressure were reduced. These indexes correlated well with each other and both correlated negatively with the degree of obesity. In contrast, maximal dP/dt was normal and did not correlate with excess weight. These observations show that depressed LV function is already present in relatively young obese people, even if they are free from signs of cardiopathy and other associate diseases. The degree of impairment of heart function seems to parallel the degree of obesity.HEART FAILURE occurs frequently in obese patients and appears to be the predominant cause of death in grossly obese subjects.1`3 Hemodynamic features contributing to the development of cardiac failure have been identified; particularly in obese people, changes in the factors that determine the preload and afterload stresses of the heart are present before cardiac failure occurs.3"-Few studies on the contractile function of the ventricle have been done.3 However, many features that depend on conditions that are often associated with contractile function, including arterial hypertension, diabetes, arteriosclerotic changes and respiratory disease, can interfere directly or indirectly with cardiac function, adding their own variations to those deriving from obesity. Therefore, we studied the changes of cardiac function in 10 relatively young volunteers who had varying degrees of obesity and were free from such pathologic conditions. MethodsThe 10 obese subjects ( significant ECG changes, x-ray cardiothoracic ratio exceeding 0.55 and stable arterial diastolic hypertension (diastolic arterial pressure > 100 mm Hg). None of the patients had treatment with digitalis or antihypertensive or diuretic drugs. These subjects underwent both right-and left-heart catheterization. Ten patients gave informed consent for the procedure. Left-heart catheterization was performed through a brachial arteriotomy. The first derivative of left ventricular pressure was obtained simultaneously with the pressure curve by Millar microtip transducer catheter and was recorded at a paper sp...

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