Shichen Xu

The impact of body mass index on pulse pressure in obesity.

Objective Pulse pressure, a marker of arterial vascular properties, has been linked to cardiovascular diseases and complications. This study examined the impact of excess body mass and cardiovascular disease risk factors on pulse pressure (PP). Design Cross-sectional and prospective study. Methods Baseline data consist of 219 obese African Americans, with mean ± SD age of 46.8 ± 10.9 years enrolled in a diet and exercise program of weight reduction. A non-invasive monitoring device was used to acquire 24 hourly ambulatory blood pressures. Pulse pressure was calculated as the difference between the average 24-h systolic and diastolic blood pressure and studied as a continuous variable and according to quartiles. The cross-sectional association of pulse pressure with body mass index (BMI) was examined using multivariate linear regression and proportional odds models that controlled for cardiovascular disease risk factors. In addition, we examined prospectively, in 36 participants, the effect of weight loss on pulse pressure, using the Wilcoxon signed ranked test. Results At baseline, a 5 kg/m2 increase in BMI was independently associated with a 35% risk [relative risk (RR) = 1.35, confidence interval (CI) = 1.10–1.65, P < 0.01] in the general study population and 19% (RR = 1.19, CI = 1.07–1.56, P = 0.04) in obese normotensives for increasing PP by one quartile after adjustment for other significant variables. After 3 months of diet and exercise intervention, BMI decreased by an average of 10.6% (P < 0.01) and resulted in an 8.8% (P < 0.01) reduction in PP. Conclusions In the context of obesity, increasing BMI is independently associated with decreasing arterial compliance, as reflected in PP. This association highlights the potential value to cardiovascular health of any reduction in body weight in obese individuals.

The Metabolically Healthy But Obese Phenotype in African Americans

J Clin Hypertens (Greenwich).

Effect of diet and exercise on pulse pressure and cardiac function in morbid obesity : Analysis of 24-hour ambulatory blood pressure

Blood pressure is a major risk factor for cardiovascular events, although the role of pulse pressure, an independent predictor of arterial stiffness, has recently been emphasized. This study examines the baseline relationship between body mass index (BMI) and blood pressure indexes in 215 obese African Americans enrolled in a diet—exercise program. The subject population was 77% female, with a mean ± SD age of 46.7±10.7 years and a mean BMI of 42.5±7.5 kg/m2. In addition, the authors prospectively examined the effect of weight loss on cardiovascular parameters in a subset of 25 participants. The results show a closer significant correlation between pulse pressure and BMI (β=1.97 kgm−1; p=0.001) than between systolic blood pressure and BMI (β=1.58 kgm1; p=0.020). After 3 months of diet and exercise, average reductions were as follows: BMI, 4.2 kg/m2 (p<0.01); systolic blood pressure, 7.2 mm Hg (p<0.01); pulse pressure, 4.8 mm Hg (p<0.01); and cardiac output, 975 mL/min (p<0.01). Compliance index increased by 0.1 mL/mm Hg/m2 (p=0.03). The results highlight the potential value to cardiovascular health of a modest reduction in body weight in obese individuals.

Effects of Lifestyle Modification on Telomerase Gene Expression in Hypertensive Patients: A Pilot Trial of Stress Reduction and Health Education Programs in African Americans

Background African Americans suffer from disproportionately high rates of hypertension and cardiovascular disease. Psychosocial stress, lifestyle and telomere dysfunction contribute to the pathogenesis of hypertension and cardiovascular disease. This study evaluated effects of stress reduction and lifestyle modification on blood pressure, telomerase gene expression and lifestyle factors in African Americans. Methods Forty-eight African American men and women with stage I hypertension who participated in a larger randomized controlled trial volunteered for this substudy. These subjects participated in either stress reduction with the Transcendental Meditation technique and a basic health education course (SR) or an extensive health education program (EHE) for 16 weeks. Primary outcomes were telomerase gene expression (hTERT and hTR) and clinic blood pressure. Secondary outcomes included lifestyle-related factors. Data were analyzed for within-group and between-group changes. Results Both groups showed increases in the two measures of telomerase gene expression, hTR mRNA levels (SR: p< 0.001; EHE: p< 0.001) and hTERT mRNA levels (SR: p = 0.055; EHE: p< 0.002). However, no statistically significant between-group changes were observed. Both groups showed reductions in systolic BP. Adjusted changes were SR = -5.7 mm Hg, p< 0.01; EHE = -9.0 mm Hg, p < 0.001 with no statistically significant difference between group difference. There was a significant reduction in diastolic BP in the EHE group (-5.3 mm Hg, p< 0.001) but not in SR (-1.2 mm Hg, p = 0.42); the between-group difference was significant (p = 0.04). The EHE group showed a greater number of changes in lifestyle behaviors. Conclusion In this pilot trial, both stress reduction (Transcendental Meditation technique plus health education) and extensive health education groups demonstrated increased telomerase gene expression and reduced BP. The association between increased telomerase gene expression and reduced BP observed in this high-risk population suggest hypotheses that telomerase gene expression may either be a biomarker for reduced BP or a mechanism by which stress reduction and lifestyle modification reduces BP. Trial Registration ClinicalTrials.gov NCT00681200

The Relationship Between Flow-Mediated Dilatation of the Brachial Artery and Intima-Media Thickness of the Carotid Artery to Framingham Risk Scores in Older African Americans

The objective of this study was to investigate the relationship of flow‐mediated dilatation and intima‐media thickness (IMT) with coronary risk in African Americans (AAs). Endothelial dysfunction and IMT of carotid arteries are considered early steps in atherosclerotic disease process and have been used as surrogate markers of subclinical atherosclerosis. Data were collected on 106 AAs with a mean age of 64.0±6.6 years. Carotid artery IMT was measured with B‐mode ultrasonography, as was brachial artery diameter at rest, during reactive hyperemia, and after nitroglycerin. Percent change in flow‐mediated dilatation (%FMD) was defined as 100×(diameter during reactive hyperemia – resting diameter)/resting diameter. Percent change in nitroglycerin‐mediated dilatation (%NMD) was defined as 100×(diameter with nitroglycerin‐resting diameter)/resting diameter. The Framingham 10‐year risk score (FRS) was calculated for each patient using the National Cholesterol Education Program (NCEP) risk score calculator and participants were categorized into 3 groups with FRS as <10%, 10% to 20%, and >20%. Thirty‐eight participants had risk scores <10%, 26 had 10% to 20%, and 42 >20%. There was a significant inverse relation between %FMD and FRS (P<.0001) and between %NMD and FRS (P<.001). IMT was not statistically different among the risk groups. Endothelial dysfunction assessed by FMD significantly correlates inversely with FRS in AAs. FMD, an index of arterial compliance, appears to be a sensitive and reliable index of cardiovascular disease.

Nocturnal blood pressure nondipping in obese African-Americans.

ObjectivesNondipping pattern of circadian blood pressure (BP) is associated with increased cardiovascular morbidity and mortality; however, limited data are available among obese African–Americans. We, therefore, aimed to evaluate the pattern of circadian BP variation and to identify clinical conditions associated with nondipping in this population. MethodsA total of 211 obese African–Americans enrolled in a weight-reduction program underwent 24-h ambulatory BP monitoring. Nondipping was defined as a nocturnal BP reduction of less than 10%. ResultsSystolic BP (SBP) nondipping was present in 158 participants (74.9%) and diastolic BP (DBP) nondipping was present in 93 participants (44.1%). In multivariate logistic regression analyses, diabetes was associated with SBP nondipping (adjusted OR, 2.53; CI: 1.16–5.76; P=0.02), and increasing BMI (5 kg/m2) was associated with DBP nondipping (adjusted OR, 1.46; CI: 1.17–1.83; P=0.001). In linear regression analyses, BMI was positively correlated to office, 24-h, daytime, and night-time SBP (P=0.03, 0.01, 0.03, and 0.005, respectively) and office, 24-h, daytime, and night-time PP (P=0.01, P<0.001, 0.001, and P=0.003, respectively). ConclusionThis study demonstrated an excessively high prevalence of nondippers and independent associations between diabetes and SBP nondipping and between BMI and DBP nondipping in an obese African–American population.

Effects of a low-calorie, low-salt diet and treadmill exercise on atherosclerotic risk factors in obese African-American women *

C disease risk factors encompass a multitude of conditions; however, certain factors are clearly related to the risk of heart disease, atherosclerosis, hypertension, and stroke, each of which affects millions of Americans each year. Obesity, an independent, modifiable major risk factor for the development of cardiovascular disease, is a complex multifactorial chronic condition. An estimated 97 million adults in the USA are overweight or obese: body mass index (BMI) 25 kg/m. Overweight and obesity are especially evident in some minority groups and in those with lower income and less education. According to the National Health and Nutrition Examination Survey of 1998, the prevalence is highest in non-Hispanic black women (66%). Clinical trials have demonstrated the effectiveness of behavior modification in reducing body weight, blood pressure, serum lipids, and blood glucose level. However, few studies or clinical trials conducted thus far have focused on blacks. There is a need for comprehensive programs targeting African-American women that can have lasting impact on cardiovascular risk factors. This study, conducted at the Howard University General Clinical Research Center (the study center), recruited subjects from the community to demonstrate the feasibility of achieving the intended goal.

Effect of Intensive Blood Pressure Control on Cardiovascular Remodeling in Hypertensive Patients with Nephrosclerosis

Pulse pressure (PP), a marker of arterial system properties, has been linked to cardiovascular (CV) complications. We examined (a) association between unit changes of PP and (i) composite CV outcomes and (ii) development of left-ventricular hypertrophy (LVH) and (b) effect of mean arterial pressure (MAP) control on rate of change in PP. We studied 1094 nondiabetics with nephrosclerosis in the African American Study of Kidney Disease and Hypertension. Subjects were randomly assigned to usual MAP goal (102–107 mmHg) or a lower MAP goal (≤92 mmHg) and randomized to beta-blocker, angiotensin converting enzyme inhibitor, or calcium channel blocker. After covariate adjustment, a higher PP was associated with increased risk of CV outcome (RR = 1.28, CI = 1.11–1.47, P < 0.01) and new LVH (RR = 1.26, CI = 1.04–1.54, P = 0.02). PP increased at a greater rate in the usual than in lower MAP groups (slope ± SE: 1.08 ± 0.15 versus 0.42 ± 0.15 mmHg/year, P = 0.002), but not by the antihypertensive treatment assignment. Observations indicate that control to a lower MAP slows the progression of PP, a correlate of cardiovascular remodeling and complications, and may be beneficial to CV health.

933 IMPACT OF DIABETES ON VASCULAR HEALTH

Background: Hypertension (HTN) and Diabetes (DM) constitute a potent duet for the development of atherosclerotic and hypertensive-renal cardiovascular diseases. Increase pulse pressure (PP), a marker of vascular health, is observed in some hypertensive subjects with DM. We investigate the impact of DM on vascular structure and function as reflected by carotid intima media thickness (IMT), brachial flow mediated dilatation (FMD) and the mechanism of a disproportionate increase in systolic and decrease in diastolic pressure resulting in an increase PP. Methods: We studied diabetic and non-diabetic African-Americans aged ≥ 55 years without clinical CVD and matched for age, gender, smoking, BMI, LDL, TG. Ischemic endothelial FMD was measured after testing for vascular dilatation with nitroglycerin, NMD. Differences in parameters are compared using the t-test. Results: Table. No title available. Conclusion: The significantly greater PP, a marker of vascular stiffness, and the diminished FMD, an index of vascular health in diabetics may indicate the onset of CVD before the development of clinical symptoms and/or signs.