Sympathovagal balance, nighttime blood pressure, and QT intervals in normotensive obese women

OBJECTIVE: We describe associations among the heart-rate-corrected QT (QTc) interval, QTc dispersion (QTc-d), circadian BP variation, and autonomic function in obese normotensive women and the effect of sustained weight loss. RESEARCH METHODS AND PROCEDURES: In 71 obese (BMI = 37.14 +/- 2.6 kg/m(2)) women, 25 to 44 years of age, circadian BP variations (24-hour ambulatory BP monitoring), autonomic function (power spectral analysis of RR interval oscillations), and cardiac repolarization times (QTc-d and QTc interval) were recorded at baseline and after 1 year of a multidisciplinary program of weight reduction. RESULTS: Compared with nonobese age-matched women (n = 28, BMI = 23 +/- 2.0 kg/m(2)), obese women had higher values of QTc-d (p < 0.05) and QTc (p < 0.05), an altered sympathovagal balance (ratio of low-frequency/high-frequency power, p < 0.01), and a blunted nocturnal drop in BP (p < 0.01). In obese women, QTc-d and the QTc interval correlated with diastolic nighttime BP (p < 0.01) and sympathovagal balance (p < 0.01). Waist-to-hip ratio, free fatty acids, and plasma insulin levels correlated with QT intervals and reduced nocturnal drops in both systolic and diastolic BP and sympathovagal balance (p < 0.01). After 1 year, obese women lost at least 10% of their original weight, which was associated with decrements of QTc-d (p < 0.02), the QTc interval (p < 0.05), nighttime BP (p < 0.01), and sympathovagal balance (p < 0.02). DISCUSSION: Sustained weight loss is a safe method to ameliorate diastolic nighttime BP drop and sympathetic overactivity, which may reduce the cardiovascular risk in obese women

Myocardial wall thickness and left ventricular geometry in hypertensives. Relationship with insulin

In hypertensive patients the presence of left ventricular (LV) hypertrophy has been associated with a more severe degree of insulin resistance. Whether myocardial wall thickness or LV geometry are associated with a different degree of insulin resistance is still unknown in essential hypertensives. For this reason 26 men with new diagnosed essential hypertension were enrolled. All patients underwent echocardiographic examination and euglycemic hyperinsulinemic glucose clamp combined with indirect calorimetry. According to LV mass and relative wall thickness data, all patients were categorized in four groups: 1) patients with a normal geometric LV pattern (n = 8) (PAT = 0); 2) patients with concentric remodeling LV mass (n = 8) (PAT = 1); 3) patients with eccentric LV hypertrophy (n = 3) (PAT = 2); and 4) patients with concentric LV hypertrophy (n = 7) (PAT = 3). All groups were similar for anthropometric characteristics. Patients with normal echocardiographic LV pattern (PAT = 0) had higher whole body glucose disposal (WBGD), oxidative and nonoxidative glucose metabolism, and lower lipid oxidation than patients with abnormal echocardiographic LV patterns (PAT = 1 to 3). Nevertheless, no significant differences among the groups with abnormal echocardiographic patterns were found. After controlling for age, body mass index (BMI), waist/hip ratio (WHR), and mean arterial blood pressure, only sum of the wall thickness was significantly correlated with fasting plasma insulin (r = -0.38, P < .05), WBGD (r = - 0.50, P < .009), and NOGM (r = - 0.48, P < .02). In multivariate analysis, a model made by age, BMI, WHR, systolic and diastolic blood pressure, and WBGD explained 38% of the echocardiographic pattern variability. In this model, WBGD (P < .02) was significantly and independently associated with echocardiographic patterns explaining 19% of the echocardiographic pattern variability. In conclusion, our data demonstrate that in arterial hypertension hyperinsulinemia/insulin resistance mainly affects myocardial wall thickness, whereas only a trivial association with LV geometry occurs