Research utility of noninvasive methods for measurement of cardiac output

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109853/1/cptclpt198751.pd

Hemodynamics and Vascular Hypertrophy in African Americans and Caucasians With High Blood Pressure

BACKGROUND: Hypertension in African Americans is characterized by greater systemic vascular resistance (SVR) compared with Caucasian Americans, but the responsible mechanisms are not known. The present study sought to determine if peripheral vascular hypertrophy is a potential mechanism contributing to elevated SVR in African Americans with high blood pressure (BP). METHODS: In a biracial sample of 80 men and women between the ages of 25 and 45 years, with clinic BP in the range 130/85-160/99mm Hg, we assessed cardiac output and SVR, in addition to BP. Minimum forearm vascular resistance (MFVR), a marker of vascular hypertrophy, also was assessed. RESULTS: SVR was elevated in African Americans compared with Caucasians (P < 0.001). Regression models indicated that age, body mass index, 24-hour diastolic BP, and ethnicity were significant predictors of SVR. There was also a significant interaction between ethnicity and MFVR in explaining SVR in the study sample. In particular, there was a significant positive association between MFVR and SVR among African Americans (P = 0.002), whereas the association was inverse and not statistically significant among Caucasians (P = 0.601). CONCLUSION: Hypertrophy of the systemic microvasculature may contribute to the elevated SVR that is characteristic of the early stages of hypertension in African American compared with Caucasians

Effects of Exercise and Sertraline on Measures of Coronary Heart Disease Risk in Patients With Major Depression: Results From the SMILE-II Randomized Clinical Trial

To assess the effects of supervised and home-based aerobic exercise training, and antidepressant pharmacotherapy (sertraline) on coronary heart disease (CHD) risk factors in a sample of participants with major depressive disorder (MDD)

Effect of Glycemic Load on Peptide-YY Levels in a Biracial Sample of Obese and Normal Weight Women

Black women suffer a disproportionately higher rate of obesity than their white counterparts. Reasons for this racial disparity may reflect underlying differences in the appetite suppressing peptide-YY (PYY). The PYY response to food is differentially influenced by macronutrient content but the effect of glycemic load on PYY response is unknown. This study examined whether glycemic load influences fasting and postprandial PYY levels and whether fasting and postprandial PYY levels are lower in obese black women compared to normal weight black women and to white women. Data were collected from 40 women (20 black, 20 white; 10 each normal weight vs. obese) at the University of North Carolina Clinical and Translational Research Center (CTRC). Participants completed in counterbalanced order two 4½-day weight-maintenance, mixed macronutrient high vs. low glycemic load diets followed by a test meal of identical composition. Total PYY levels were assessed before and after each test meal. Results show no differences in fasting PYY levels but significantly less postprandial PYY area under the curve (PYYAUC) in the group of obese black women compared to each other group (race × obesity interaction, P 0.27). These findings indicate that postprandial PYY secretion is not affected by glycemic load but is blunted in obese black women compared with normal weight black women and with white women; additionally, they begin to address whether blunted PYY secretion contributes uniquely to the pathogenesis of obesity in black women

Examination of Several Physiological and Psychosocial Factors Potentially Associated With Masked Hypertension Among Low-Risk Adults

We examined the association of factors in addition to prehypertensive office blood pressure (BP) level that might improve detection of masked hypertension (MH, defined as non-elevated office BP with elevated out-of-office BP average) among those otherwise at low-risk. This sample of 340 untreated adults 30 years and older with office BP average <140/90 mmHg all had two sets of paired office BP measurements and 24-hour ambulatory BP monitoring (ABPM) sessions one week apart. Other than BP levels, the only factors that were associated (at P<0.10) with MH at both sets were male sex (75% vs 66%) and working outside the home (72% vs 59% first set; 71% vs 45% second set). Adding these variables to BP level in the model did not appreciably improve detection of MH. We found no demographic, clinical, or psychosocial measures that improved upon prehypertension as a potential predictor of MH in this sample

Diurnal blood pressure pattern and development of prehypertension or hypertension in young adults: the CARDIA study

Nondippers (people whose sleep systolic blood pressure [SBP] fails to decrease >10% from daytime SBP) have increased risk of cardiovascular disease. The prevalence of nondipping in younger adults has not been well studied, nor has its value for predicting hypertension. We examined the prevalence of nondipping in a substudy of the Coronary Artery Risk Development in Young Adults (CARDIA) Study. We used Cox regression to estimate the hazard ratio (HR) conferred by nondipping for incident prehypertension or hypertension (preHTN/HTN) over 15 years. Of the 264 nonhypertensive participants at baseline, 118 (45%) were nondippers. Blacks were more likely than whites to be nondippers (52% versus 33%, P = .004). The incidence rate of preHTN/HTN was 29.2/1000 person-years among dippers and 36.2/1000 person-years among nondippers. Compared with those in the lowest quartile of nighttime to daytime SBP, those in the highest quartile were more likely to develop preHTN/HTN (HR 1.61; P = .06), but this relationship was attenuated after adjustment (HR 1.34; P = .27). Our results demonstrate that nondipping is common in young, nonhypertensive adults, and is more common in blacks than whites. Nondipping might predate a meaningful clinically detected increase in BP in some people, but more research in larger study samples is needed

Ethnic Differences in the Effects of the DASH Diet on Nocturnal Blood Pressure Dipping in Individuals with High Blood Pressure

Ethnic differences in nocturnal blood pressure (BP) dipping may contribute to the increased risk for adverse cardiovascular events noted in African Americans (AAs). The DASH (Dietary Approaches to Stop Hypertension) diet has been shown to be efficacious in lowering clinic and ambulatory BP; however, the effect of the DASH diet on BP dipping is unclear

The effect of job strain on nighttime blood pressure dipping among men and women with high blood pressure

Blunted nighttime blood pressure dipping is an established cardiovascular risk factor. This study examined the effect of job strain on nighttime blood pressure dipping among men and women with high blood pressure

The DASH Diet and Insulin Sensitivity

Lifestyle modifications, including adoption of the Dietary Approaches to Stop Hypertension (DASH) dietary pattern, weight loss in individuals who are overweight or obese, and physical activity, are effective in the prevention and treatment of hypertension. A healthy lifestyle may also have beneficial effects on metabolic abnormalities, such as insulin resistance, that are associated with high blood pressure. This review examines the independent and combined effects of the DASH diet and weight loss plus exercise on blood pressure and insulin sensitivity, with a focus on recently published results from the ENCORE study. Our data suggest that the DASH eating plan alone lowers blood pressure in overweight individuals with higher than optimal blood pressure, but significant improvements in insulin sensitivity are observed only when the DASH diet is implemented as part of a more comprehensive lifestyle modification program that includes exercise and weight loss

GENDER DIFFERENCES IN THE ENDOTHELIAL FUNCTION OF UNTREATED HYPERTENSION

Vascular endothelial dysfunction is associated with increased risk for adverse cardiovascular (CV) events. However, less is known about sex differences in the endothelial function of untreated hypertensive individuals. The purpose of this study was to assess endothelial function in women and men with untreated hypertension. Ninety participants (35 women, 55 men), aged 40 to 60 years (mean age, 46.1±8.2 years), with untreated stage 1 hypertension (systolic blood pressure 140-159 mm Hg and/or diastolic blood pressure 90-99 mm Hg) underwent brachial artery endothelial-dependent flow-mediated dilation and endothelial-independent glyceryl trinitrate dilation. Women had a smaller flow-mediated dilation response than men (adjusted mean±standard error of the mean [SEM]; 1.8±0.6% vs 3.9±0.4%, P=.036), adjusting for baseline arterial diameter (P=.004), age (P=.596), ethnicity (P=.496), log shear stress ratio (P<.001), body mass index (P=.009), 24-hour diastolic blood pressure (P=.169), high-density lipoprotein (P=.225), log creatinine (P=.927), and log physical activity (P=.682). Glyceryl trinitrate dilation did not differ by sex in adjusted models. Women between the ages of 40 and 60 years with untreated stage 1 hypertension exhibited a greater impairment of endothelial function compared with their male counterparts. These findings raise the possibility that female sex may impart a greater risk of CV events in patients with untreated stage 1 hypertension potentially due to poorer endothelial function