The influence of obesity on arterial compliance in adult men and women

Fluid-structure interactions of peripheral arteries using a coupled in silico and in vitro approach

Vascular compliance is considered both a cause and a consequence of cardiovascular disease and a significant factor in the mid- and long-term patency of vascular grafts. However, the biomechanical effects of localised changes in compliance cannot be satisfactorily studied with the available medical imaging technologies or surgical simulation materials. To address this unmet need, we developed a coupled silico-vitro platform which allows for the validation of numerical fluid-structure interaction results as a numerical model and physical prototype. This numerical one-way and two-way fluid-structure interaction study is based on a three-dimensional computer model of an idealised femoral artery which is validated against patient measurements derived from the literature. The numerical results are then compared with experimental values collected from compliant arterial phantoms via direct pressurisation and ring tensile testing. Phantoms within a compliance range of 1.4-68.0%/100 mmHg were fabricated via additive manufacturing and silicone casting, then mechanically characterised via ring tensile testing and optical analysis under direct pressurisation with moderately statistically significant differences in measured compliance ranging between 10 and 20% for the two methods. One-way fluid-structure interaction coupling underestimated arterial wall compliance by up to 14.7% compared with two-way coupled models. Overall, Solaris™ (Smooth-On) matched the compliance range of the numerical and in vivo patient models most closely out of the tested silicone materials. Our approach is promising for vascular applications where mechanical compliance is especially important, such as the study of diseases which commonly affect arterial wall stiffness, such as atherosclerosis, and the model-based design, surgical training, and optimisation of vascular prostheses.

The impacts of exercise on pediatric obesity

Over the last few decades, the rates of pediatric obesity have more than doubled regardless of sociodemographic categorization, and despite these rates plateauing in recent years there continues to be an increase in the severity of obesity in children and adolescents. This review will discuss the pediatric obesity mediated cardiovascular disease (CVD) risk factors such as attenuated levels of satiety and energy metabolism hormones, insulin resistance, vascular endothelial dysfunction, and arterial stiffness. Additionally, early intervention to combat pediatric obesity is critical as obesity has been suggested to track into adulthood, and these obese children and adolescents are at an increased risk of early mortality. Current suggested strategies to combat pediatric obesity are modifying diet, limiting sedentary behavior, and increasing physical activity. The effects of exercise intervention on metabolic hormones such as leptin and adiponectin, insulin sensitivity/resistance, and body fat in obese children and adolescents will be discussed along with the exercise modality, intensity, and duration. Specifically, this review will focus on the differential effects of aerobic exercise, resistance training, and combined exercise on the cardiovascular risks in pediatric obesity. This review outlines the evidence that exercise intervention is a beneficial therapeutic strategy to reduce the risk factors for CVD and the ideal exercise prescription to combat pediatric obesity should contain both muscle strengthening and aerobic components with an emphasis on fat mass reduction and long-term adherence.

Perioperative non-invasive versus semi-invasive cardiac index monitoring in patients with bariatric surgery - a prospective observational study

Background

In morbidly obese patients undergoing laparoscopic bariatric surgery, the combination of obesity-related comorbidities, pneumoperitoneum and extreme posture changes constitutes a high risk of perioperative hemodynamic complications. Thus, an advanced hemodynamic monitoring including continuous cardiac index (CI) assessment is desirable. While invasive catheterization may bear technical difficulties, transesophageal echocardiography is contraindicated due to the surgical procedure. Evidence on the clinical reliability of alternative semi- or non-invasive cardiac monitoring devices is limited. The aim was to compare the non-invasive vascular unloading to a semi-invasive pulse contour analysis reference technique for continuous CI measurements in bariatric surgical patients.

Methods

This prospective observational study included adult patients scheduled for elective, laparoscopic bariatric surgery after obtained institutional ethics approval and written informed consent. CI measurements were performed using the vascular unloading technique (Nexfin®) and semi-invasive reference method (FloTrac™). At 10 defined measurement time points, the influence of clinically indicated body posture changes, passive leg raising, fluid bolus administration and pneumoperitoneum was evaluated pre- and intraoperatively. Correlation, Bland-Altman and concordance analyses were performed.

Results

Sixty patients (mean BMI 49.2 kg/m²) were enrolled into the study and data from 54 patients could be entered in the final analysis. Baseline CI was 3.2 ± 0.9 and 3.3 ± 0.8 l/min/m², respectively. Pooled absolute CI values showed a positive correlation (r_s = 0.76, P < 0.001) and mean bias of of − 0.16 l/min/m² (limits of agreement: − 1.48 to 1.15 l/min/m²) between the two methods. Pooled percentage error was 56.51%, missing the criteria of interchangeability (< 30%). Preoperatively, bias ranged from − 0.33 to 0.08 l/min/m² with wide limits of agreement. Correlation of CI was best (r_s = 0.82, P < 0.001) and percentage error lowest (46.34%) during anesthesia and after fluid bolus administration. Intraoperatively, bias ranged from − 0.34 to − 0.03 l/min/m² with wide limits of agreement. CI measurements correlated best during pneumoperitoneum and after fluid bolus administration (r_s = 0.77, P < 0.001; percentage error 35.95%). Trending ability for all 10 measurement points showed a concordance rate of 85.12%, not reaching the predefined Critchley criterion (> 92%).

Conclusion

Non-invasive as compared to semi-invasive CI measurements did not reach criteria of interchangeability for monitoring absolute and trending values of CI in morbidly obese patients undergoing bariatric surgery.

Trial registration

The study was registered retrospectively on June 12, 2017 with the registration number NCT03184272.

Independent influences of maternal obesity and fetal sex on maternal cardiovascular adaptation to pregnancy: a prospective cohort study

Background/Objectives

Successful pregnancy requires the de novo creation of low-resistance utero-placental and feto-placental circulations and incomplete remodeling of this vasculature can lead to maternal or fetal compromise. Maternal BMI and fetal sex are known to influence vascular compliance and placental development, but it is unknown if these are independent or synergistic effects. Here we aim to investigate the impact of maternal obesity, fetal sex, and any interaction thereof on maternal cardiovascular adaptation to pregnancy, by assessing the physiological drop of uterine artery doppler pulsatility (UtA-PI) and umbilical artery doppler pulsatility index (UA-PI) over gestation.

Subjects/Methods

Nulliparous women with a singleton pregnancy participating in a prospective cohort study (n = 4212) underwent serial UtA-PI and UA-PI measurements at 20-, 28- and 36-weeks gestation. Linear mixed regression models were employed to investigate the influence of maternal BMI, fetal sex and interactions thereof on the magnitude of change in UtA-PI and UA-PI.

Results

Throughout gestation, UtA-PI was higher for male fetuses and UA-PI was higher for female fetuses. The physiological drop of UtA-PI was significantly smaller in overweight (change −24.3% [95%CI −22.3, −26.2]) and obese women (change −21.3% [−18.3, −24.3]), compared to normal-weight women (change −25.7% [−24.3, −27.0]) but did not differ by fetal sex. The physiological drop in UA-PI was greater for female than male fetuses (–32.5% [−31.5, −33.5] vs. −30.7% [−29.8, −31.7]) but did not differ by maternal BMI. No interactions between maternal BMI and fetal sex were found.

Conclusions

Maternal cardiovascular adaptation to pregnancy is independently associated with maternal BMI and fetal sex. Our results imply sexual dimorphism in both maternal cardiovascular adaptation and feto-placental resistance.

Maternal separation enhances anticontractile perivascular adipose tissue function in male rats on a high-fat diet

Clinical studies have shown that obesity negatively impacts large arteries' function. We reported that rats exposed to maternal separation (MatSep), a model of early life stress, display enhanced angiotensin II (ANG II)-induced vasoconstriction in aortic rings cleaned of perivascular adipose tissue (PVAT) under normal diet (ND) conditions. We hypothesized that exposure to MatSep promotes a greater loss of PVAT-mediated protective effects on vascular function and loss of blood pressure (BP) rhythm in rats fed a high-fat diet (HFD) when compared with controls. MatSep was performed in male Wistar-Kyoto rats from days 2 to 14 of life. Normally reared littermates served as controls. On ND, aortic rings from MatSep rats with PVAT removed showed increased ANG II-mediated vasoconstriction versus controls; however, rings from MatSep rats with intact PVAT displayed blunted constriction. This effect was exacerbated by an HFD in both groups; however, the anticontractile effect of PVAT was greater in MatSep rats. Acetylcholine-induced relaxation was similar in MatSep and control rats fed an ND, regardless of the presence of PVAT. HFD impaired aortic relaxation in rings without PVAT from MatSep rats, whereas the presence of PVAT improved relaxation in both groups. On an HFD, immunolocalization of vascular smooth muscle-derived ANG-(1-7) and PVAT-derived adiponectin abundances were increased in MatSep. In rats fed an HFD, 24-h BP and BP rhythms were similar between groups. In summary, MatSep enhanced the ability of PVAT to blunt the heightened ANG II-induced vasoconstriction and endothelial dysfunction in rats fed an HFD. This protective effect may be mediated via the upregulation of vasoprotective factors within the adipovascular axis.

Whole blood viscosity and cerebral blood flow velocities in obese hypertensive or obese normotensive adolescents

BACKGROUND

Obesity affects all major organ systems and leads to increased morbidity and mortality. Whole blood viscosity is an important independent regulator of cerebral blood flow. The aim of the present study was to evaluate the effect of whole blood viscosity on cerebral artery blood flow velocities using transcranial Doppler ultrasound in pediatric patients with obesity compared to healthy controls and analyze the effect of whole blood viscosity and blood pressure status to the cerebral artery blood flow velocities.

METHODS

Sixty patients with obesity diagnosed according to their body mass index (BMI) percentiles aged 13-18 years old were prospectively enrolled. They were grouped as hypertensive or normotensive according to their ambulatory blood pressure monitoring. Whole blood viscosity and middle cerebral artery velocities by transcranial Doppler ultrasound were studied and compared to 20 healthy same aged controls.

RESULTS

Whole blood viscosity values in hypertensive (0.0619±0.0077 poise) and normotensive (0.0607±0.0071 poise) groups were higher than controls (0.0616±0.0064 poise), with no significance. Middle cerebral artery blood flow velocities were higher in the obese hypertensive (73.9±15.0 cm/s) and obese normotensive groups (75.2±13.5 cm/s) than controls (66.4±11.5 cm/s), but with no statistical significance.

CONCLUSIONS

Physiological changes in blood viscosity and changes in blood pressure did not seem to have any direct effect on cerebral blood flow velocities, the reason might be that the cerebral circulation is capable of adaptively modulating itself to changes to maintain a uniform cerebral blood flow.

Pulse-contour derived cardiac output measurements in morbid obesity: influence of actual, ideal and adjusted bodyweight

The non-invasive Nexfin cardiac output (CO) monitor shows a low level of agreement with the gold standard thermodilution method in morbidly obese patients. Here we investigate whether this disagreement is related to excessive bodyweight, and can be improved when bodyweight derivatives are used instead. We performed offline analyses of cardiac output recordings of patient data previously used and partly published in an earlier study by our group. In 30 morbidly obese patients (BMI > 35 kg/m²) undergoing laparoscopic gastric bypass, cardiac output was simultaneously determined with PiCCO thermodilution and Nexfin pulse-contour method. We investigated if agreement of Nexfin-derived CO with thermodilution CO improved when ideal and adjusted—instead of actual- bodyweight were used as input to the Nexfin. Bodyweight correlated with the difference between Nexfin-derived and thermodilution-derived CO (r = −0.56; p = 0.001). Bland Altman analysis of agreement between Nexfin and thermodilution-derived CO revealed a bias of 0.4 ± 1.6 with limits of agreement (LOA) from −2.6 to 3.5 L min when actual bodyweight was used. Bias was −0.6 ± 1.4 and LOA ranged from −3.4 to 2.3 L min when ideal bodyweight was used. With adjusted bodyweight, bias improved to 0.04 ± 1.4 with LOA from −2.8 to 2.9 L min. Our study shows that agreement of the Nexfin-derived with invasive CO measurements in morbidly obese patients is influenced by body weight, suggesting that Nexfin CO measurements in patients with a BMI above 35 kg/m² should be interpreted with caution. Using adjusted body weight in the Nexfin CO-trek algorithm reduced the bias.

Whole grain consumption is negatively correlated with obesity-associated aortic stiffness: A hypothesis

OBJECTIVE

Obesity is a risk factor for cardiovascular disease that increases aortic stiffness, which predicts future cardiovascular events. Additionally, obesity is associated with overconsumption, which contributes to aortic stiffening. Recent work has highlighted the role of various foods and nutrients on aortic stiffness among the general population. The objective of the present study was to explore the influence of dietary factors on obesity-associated aortic stiffness, as food choices might be a potential explanation for accelerated aortic stiffening in obesity rather than overconsumption alone.

METHODS

Data collected in our laboratory were evaluated in aggregate considering obese men with available measures of aortic stiffness and habitual dietary intake (n = 22). Aortic stiffness was assessed with the gold standard carotid-femoral pulse wave velocity, and habitual dietary intake was determined with the National Institutes of Health's Dietary History Questionnaire-II.

RESULTS

Whole grain consumption predicted obesity-associated aortic stiffness in regression analyses (R² = 0.29, P = 0.010). This correlation remained significant after adjusting for traditional risk factors (age, body mass index, blood pressure) (R² = 0.27, P = 0.027). Overconsumption determined by daily caloric intake was not predictive of aortic stiffness (R² = 0.09, P = 0.17) nor was total fiber content (R² = 0.06, P = 0.29).

CONCLUSIONS

These findings suggest a potential role of whole grains to protect against aortic stiffness even when dietary overconsumption is present. Fiber content has been proposed as a major beneficial component in whole grains, but it did not correlate with obesity-related aortic stiffness, suggesting whole grains may have a unique and potentially synergistic role in the protection of obesity-associated aortic health.

Subclinical inflammation associated with prolonged TIMP-1 upregulation and arterial stiffness after gestational diabetes mellitus: a hospital-based cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) has significant implications for the future health of the mother. Some clinical studies have suggested subclinical inflammation and vascular dysfunction after GDM. We aimed to study whether concentrations of high-sensitivity C-reactive protein (hsCRP), tissue inhibitor of metalloproteinase-1 (TIMP-1), matrix metalloproteinase-8 (MMP-8) and -9, as well as values of arterial stiffness differ between women with and without a history of GDM a few years after delivery. We also investigated possible effects of obesity on the results.

METHODS

We studied two cohorts-120 women with a history of GDM and 120 controls-on average 3.7 years after delivery. Serum concentrations of hsCRP were determined by immunonephelometric and immunoturbidimetric methods, MMP-8 by immunofluorometric assay, and MMP-9 and TIMP-1 by enzyme-linked immunosorbent assays. Pulse wave velocity (PWV) was determined using the foot-to-foot velocity method from carotid and femoral waveforms by using a SphygmoCor device. Arterial compliance was measured non-invasively by an HDI/PulseWave™CR-2000 arterial tonometer. All 240 women were also included in subgroup analyses to study the effect of obesity on the results. Multiple linear regression analyses were performed with adjustment for confounding factors.

RESULTS

PWV after pregnancy complicated by GDM was significantly higher than after normal pregnancy, 6.44 ± 0.83 (SD) vs. 6.17 ± 0.74 m/s (p = 0.009). Previous GDM was also one of the significant determinants of PWV in multiple linear regression analyses. On the other hand, compliance indices of both large (p = 0.092) and small (p = 0.681) arteries did not differ between the study cohorts. Serum TIMP-1 levels were significantly increased after previous GDM (p = 0.020). However, no differences were found in the serum levels of MMP-8, MMP-9 or hsCRP. In subgroup analyses, there were significantly higher concentrations of hsCRP (p = 0.015) and higher PWV (p < 0.001) among obese women compared with non-obese ones.

CONCLUSIONS

PWV values were significantly higher after GDM compared with normoglycemic pregnancies and were associated with prolonged TIMP-1 upregulation. Cardiovascular risk factors were more common in participants with high BMI than in those with previous GDM.

Effects of Obesity and Hypertension on Pulse Wave Velocity in Children

Pulse wave velocity (PWV) is a biomarker of arterial stiffness. Findings from prior studies are conflicting regarding the impact of obesity on PWV in children. The authors measured carotid-femoral PWV in 159 children aged 4 to 18 years, of whom 95 were healthy, 25 were obese, 15 had hypertension (HTN), and 24 were both obese and hypertensive. Mean PWV increased with age but did not differ by race or sex. In adjusted analyses in children 10 years and older (n=102), PWV was significantly higher in children with hypertension (PWV±standard deviation, 4.9±0.7 m/s), obesity (5.0±0.9 m/s), and combined obesity-hypertension (5.2±0.6 m/s) vs healthy children (4.3±0.7 m/s) (each group, P<.001 vs control). In our study, obesity and HTN both significantly and independently increased PWV, while African American children did not have a higher PWV than Caucasian children.

Differences in galectin-3, a biomarker of fibrosis, between participants with peripheral artery disease and participants with normal ankle-brachial index

The aim of this study was to determine if galectin-3 levels were different between participants with peripheral artery disease (PAD) and controls, and to describe its relationship with markers of early atherosclerosis. Sixty participants were recruited into two groups: a PAD group (n=31), ankle-brachial index (ABI) ⩽0.90 and a normal ABI group (n=29), ABI 1.0-1.4. PAD participants were older (68.6 vs 61.8 years, p=0.037), more commonly men (68% vs 38%, p=0.02), and with more cardiovascular risk factors (p<0.001). Galectin-3 was 22% higher in PAD participants (mean±SD: 17.6±4.7 vs 14.4±4.1 ng/mL, p<0.01). The odds ratio for galectin-3 in PAD to be 1 ng/mL higher than the participants with normal ABI was 1.19, after adjusting by age and gender (p=0.014). High-sensitivity C-reactive protein (hs-CRP) and homeostatic model assessment (HOMA) were positively associated with galectin-3 in the age- and gender-adjusted model, while arterial elasticity and microalbuminuria were not. In conclusion, galectin-3 levels were higher in participants with PAD.

Reduced carotid baroreceptor distensibility-induced baroreflex resetting contributes to impairment of sodium regulation in rats fed a high-fat diet

Decreased carotid arterial compliance has been reported in obese subjects and animals. Carotid baroreceptors are located at the bifurcation of the common carotid artery, and respond to distension of the arterial wall, suggesting that higher pressure is required to obtain the same distension in obese subjects and animals. A hyperosmotic NaCl solution induces circulatory volume expansion and arterial pressure (AP) increase, which reflexively augment renal excretion. Thus, we hypothesized that sodium regulation via the baroreflex might be impaired in response to chronic hyperosmotic NaCl infusion in rats fed a high-fat diet. To examine this hypothesis, we used rats fed a high-fat (Fat) or normal (NFD) diet, and measured mean AP, water and sodium balance, and renal function in response to chronic infusion of hyperosmotic NaCl solution via a venous catheter. Furthermore, we examined arterial baroreflex characteristics with static open-loop analysis and distensibility of the common carotid artery. Significant positive water and sodium balance was observed on the 1st day of 9% NaCl infusion; however, this disappeared by the 2nd day in Fat rats. Mean AP was significantly higher during 9% NaCl infusion in Fat rats compared with NFD rats. In the open-loop analysis of carotid sinus baroreflex, a rightward shift of the neural arc was observed in Fat rats compared with NFD rats. Furthermore, distensibility of the common carotid artery was significantly reduced in Fat rats. These results indicate that a reduced baroreceptor distensibility-induced rightward shift of the neural arc might contribute to impairment of sodium regulation in Fat rats.

Arterial compliance in obese children: implications for cardiovascular health

Recent work showed that arterial compliance may be elevated unexpectedly in obese children, attributable to accelerated growth and maturation. We hypothesize that children with obesity or Type 2 diabetes may reach peak arterial maturation earlier in life and then experience an earlier, and potentially more rapid, decline in arterial compliance, leading toward earlier cardiovascular disease development.

Accuracy of Vigileo/Flotrac monitoring system in morbidly obese patients

PURPOSE

Our goal was to assess the accuracy of measuring cardiac output (CO) by the FloTrac/Vigileo (CO(V)) device in comparison with thermodilution technique through pulmonary artery catheterization (PAC(TD)) in morbidly obese patients.

MATERIAL AND METHODS

Cardiac output in 8 morbidly obese patients was assessed twice at upright and lying position breathing ambient air. At least 4 consecutive CO measurements with 10 mL of ice-cold saline injections were performed each time. Simultaneous CO measurements were recorded with both single-bolus thermodilution and CO(V).

RESULTS

One hundred thirty-two CO data pairs were collected. The overall mean single-bolus thermodilution 6.2 ± 1.1 L/min was lower than the overall mean CO(V) 7.8 ± 1.6 L/min (P < .001). Lin concordance coefficient indicated that overall agreement between PAC(TD) and CO(V) was poor, 0.29. Lin concordance coefficient in sitting position was 0.29, 95% confidence interval (0.17-0.40) and in lying position was 0.30, 95% confidence interval (0.15-0.44). The Bland-Altman plot analysis showed systematically higher values from CO(V) in comparison with PAC(TD). These differences increased in presence of high CO measurements. In 3 of 8 patients, the percentage error was lower than 20%, whereas in the other 5, it was higher than 20%. Of these 5, in 2 cases, the percentage error was greater than 50%.

CONCLUSION

Data obtained using CO(V) vs PAC(TD) measurements showed poor correlation. The results were not interchangeable.

The impact of overweight and obesity on health-related quality of life and blood pressure control in hypertensive patients

OBJECTIVE

Hypertension and obesity deteriorate patient health-related quality-of-life (HRQoL). This study assessed the impact of overweight and obesity on HRQoL and blood pressure (BP) control in hypertensive participants, according to sex.

METHODS

HRQoL was assessed using the 12-item Short Form Health Survey in 11,498 white patients treated for hypertension for at least 12 months. Nutritional status was diagnosed according to WHO criteria.

RESULTS

Overweight and obesity were associated with worse BP control, regardless of sex. In women, overweight and especially obesity were inversely associated with all analyzed HRQoL dimensions. Among men, obesity decreased all HRQoL dimensions, and overweight influenced only physical functioning, role physical, bodily pain, vitality, general health, and Physical Component Score (PCS) but not Mental Component Score (MCS). Overweight in men did not influence social functioning, or emotional and mental health. The BMI values associated with optimal PCS and MCS scores were higher for men than for women. Age-adjusted multivariate regression analysis revealed that PCS score was associated with obesity, higher education level, comorbidities, and antihypertensive therapy duration, whereas MCS score was associated with female sex. Polydrug BP control diminished PCS and MCS.

CONCLUSION

Overweight and obesity deteriorate BP control, regardless of age and polytherapy. BMI values associated with optimal HRQoL are higher for men than women treated for hypertension. Obesity more strongly diminishes the physical versus mental HRQoL component, regardless of sex. Overweight worsens HRQoL physical components in both sexes and mental component-only in women.

Vascular compliance in lean, obese, and diabetic children and adolescents: a cross-sectional study in a minority population

BACKGROUND

In adults, both obesity and type 2 diabetes mellitus (T2DM) are positively correlated with cardiovascular disease mortality and arterial stiffness. Several studies of adults have shown that both obesity and T2DM are independently associated with increased arterial stiffness. However, little is known about the relationship between arterial compliance and cardiovascular disease risk in children. We assessed whether large and small arterial compliance is impaired in obese and diabetic pubertal children.

METHODS

One hundred children of African-Caribbean ethnicity, aged 14-16 years, including 21 lean children (between the 25th and 75th percentile), 40 obese children (>95th percentile), and 39 children with T2DM diagnosed by American Diabetes Association criteria were studied. Arterial compliance of the large (C1) and small (C2) vessels was measured using radial arterial diastolic pulse wave contour analysis.

RESULTS

C1 did not differ significantly between lean, obese, and T2DM subjects. C2 was significantly greater in obese and T2DM subjects (10.9 ± 1 and 10.4 ± 0.7 ml/mm Hg × 100 ml, respectively) compared to lean subjects (7.8 ± 0.8 ml/mm Hg × 100 ml; p < 0.05). C2 was also significantly greater in T2DM subjects receiving antihypertensive drug therapy than in diabetic subjects not on antihypertensive treatment.

CONCLUSION

Increased compliance in diabetic and obese children compared to lean subjects could be secondary to premature maturation of the vascular system; whether this early maturation can translate into a subsequent rise in the incidence of cardiovascular events related to diabetes and obesity can only be determined by long-term follow-up of these patients.

Impact of pubertal development on endothelial function and arterial elasticity

OBJECTIVES

Little is known about the relation of pubertal development on endothelial function and arterial elasticity in children and adolescents; therefore, we compared brachial artery flow-mediated dilation and carotid artery elasticity across Tanner (pubertal) stages in children and adolescents.

STUDY DESIGN

Blood pressure, fasting lipids, glucose and insulin, body fat, insulin sensitivity adjusted for lean body mass, brachial flow-mediated dilation (percent dilation and area under the curve), endothelium-independent dilation (peak dilation and area under the curve), and carotid artery elasticity were evaluated across pubertal stages (Tanner I vs Tanner II-IV vs Tanner V) in 344 children and adolescents (184 males, 160 females; ages 6 to 21 years).

RESULTS

One hundred twenty-four subjects (mean age 8.23 ± 0.15 years; 52 females) were Tanner stage I; 105 subjects (mean age 13.19 ± 0.17 years; 47 females) were Tanner stages II-IV; and 115 subjects (mean age 17.19 ± 0.16 years; 61 females) were Tanner stage V. There were no significant differences for any of the measures of vascular structure and function across pubertal stages.

CONCLUSION

Results of the current study indicate that smooth-muscle and endothelial function, as well as carotid artery elasticity, do not differ throughout pubertal development and that accounting for pubertal stage when reporting vascular data in children and adolescents may be unnecessary.

Associations of aortic distensibility and arterial elasticity with long-term visit-to-visit blood pressure variability: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Although higher visit-to-visit variability (VVV) of blood pressure (BP) is associated with increased cardiovascular disease risk, the physiological basis for VVV of BP is incompletely understood.

METHODS

We examined the associations of aortic distensibility (assessed by magnetic resonance imaging) and artery elasticity indices (determined by radial artery pulse contour analysis) with VVV of BP in 2,640 and 4,560 participants, respectively, from the Multi-Ethnic Study of Atherosclerosis. Arterial measures were obtained at exam 1. BP readings were taken at exam 1 and at 3 follow-up visits at 18-month intervals (exams 2, 3, and 4). VVV was defined as the SD about each participant's mean systolic BP (SBP) across visits.

RESULTS

The mean SDs of SBP were inversely associated with aortic distensibility: 7.7, 9.9, 10.9, and 13.2mm Hg for quartiles 4, 3, 2, and 1 of aortic distensibility, respectively (P trend < 0.001). This association remained significant after adjustment for demographics, cardiovascular risk factors, mean SBP, and antihypertensive medication use (P trend < 0.01). In a fully adjusted model, lower quartiles of large artery and small artery elasticity (LAE and SAE) indices were also associated with higher mean SD of SBP (P trend = 0.02 for LAE; P trend < 0.001 for SAE).

CONCLUSIONS

In this multiethnic cohort, functional alterations of central and peripheral arteries were associated with greater long-term VVV of SBP.

Metabolic syndrome and arterial elasticity in youth

OBJECTIVE

To compare arterial elasticity in children, adolescents, and young adults with and without metabolic syndrome (MetS), and to assess which MetS components, demographic measures, and body composition measures are associated with arterial elasticity.

MATERIALS/METHODS

Two-hundred six subjects (107 females and 99 males) between the ages of 10 and 20years were recruited by local newspaper advertisements, university email advertisements, and informational flyers. Subjects were assessed on MetS components, demographic measures, body composition measures, and arterial elasticity via radial tonometry. Forty-five subjects (22%) had MetS, as defined by the International Diabetes Federation, and 161 subjects (78%) did not.

RESULTS

The primary novel finding was that group differences were not observed for large artery elasticity index (LAEI) (MetS=16.1±4.4 (ml×mmHg(-1))×10 (mean±SD), control=15.4±4.9, (ml×mmHg(-1))×10, p=0.349), and small artery elasticity index (SAEI) (MetS=9.2±2.7 (ml×mmHg(-1))×100, control=8.4±2.9, (ml×mmHg(-1))×100, p=0.063). In the MetS group, fat free mass was positively associated with arterial elasticity, and was the strongest multivariate predictor of LAEI (partial R(2)=0.41) and SAEI (partial R(2)=0.29).

CONCLUSIONS

Youth with MetS did not exhibit differences in LAEI and SAEI compared to controls. Furthermore, fat free mass of youth with MetS was positively associated with arterial elasticity, and was the strongest predictor of both LAEI and SAEI. The clinical implication is that exercise intervention designed to increase fat free mass might increase arterial elasticity in youth, particularly in youth with MetS.

The relationship between objectively measured physical activity, sedentary time, and vascular health in children

BACKGROUND

Physical activity (PA) is beneficially associated with arterial compliance in adults; however, whether this association persists in children is unclear. We examined the cross-sectional relationship of PA and sedentary time with arterial compliance in children.

METHODS

Large and small artery compliance was determined by diastolic pulse contour analysis in 102 children aged 8-11 years (43 boys). We used accelerometers and age-specific cut points to classify activity as sedentary, light, or moderate-to-vigorous (MVPA). We also categorized MVPA according to bout length (0-5, 5-10, 10-20, and ≥20 min). Hierarchical linear regression examined: (i) the contribution of activity to large and small artery compliance (controlling for body surface area, systolic blood pressure, and body mass index (BMI)) and (ii) whether bouted MVPA was associated with arterial compliance independent of total MVPA.

RESULTS

Activity variables did not explain any additional variance in large artery compliance beyond that captured by body surface area, BMI, and systolic blood pressure (P = 0.118 to P = 0.990). Light activity and MVPA explained an additional 5.8% (P = 0.003) and 2.7% (P = 0.043) of the variance in small artery compliance. MVPA accumulated in bouts was not significantly associated with small artery compliance after controlling for the total volume of MVPA (P = 0.784 to P = 0.923).

CONCLUSIONS

Objectively measured PA is associated with small, but not large artery compliance in children aged 8-11 years. Future research should explore the influence of bout frequency and the effect of a PA.intervention on arterial compliance.

Sex differences in cardiovascular disease risk in adolescents with type 1 diabetes

BACKGROUND

Cardiovascular disease is seen at a younger age and at a higher prevalence in patients with type 1 diabetes than in the general population. It is well described that women with type 1 diabetes have a higher relative risk of cardiovascular disease than men with type 1 diabetes, unlike that seen in the general population. The pathophysiology behind this is unknown.

OBJECTIVE

We performed a cross-sectional study to examine sex differences in cardiovascular disease risk factors in adolescents with type 1 diabetes between ages 13 and 20 years, compared with children of a similar age without type 1 diabetes.

METHODS

All patients underwent a dual energy x-ray absorptiometry scan to measure body composition and a pulse wave test measure of arterial elasticity. Fasting serum lipid levels, apolipoprotein B, and apolipoprotein C-III levels were measured in each patient. Twenty-nine children with type 1 diabetes (10 girls, 19 boys) and 37 healthy children (18 girls, 19 boys) participated.

RESULTS

Although no sex differences for body mass index (P = 0.91) and glycosylated hemoglobin (P = 0.69) were seen, girls with type 1 diabetes had a significantly higher percent trunk fat compared with boys (P = 0.004). No sex differences were found (P > 0.05) for percent trunk fat in adolescents without diabetes. There was no sex difference among any other cardiovascular risk factors in either children with or without diabetes.

CONCLUSIONS

Female adolescents with type 1 diabetes have more centrally distributed fat, which may contribute to their relatively higher cardiovascular disease risk. Attenuation of the central distribution of fat through exercise and dietary modifications may help ameliorate their subsequent cardiovascular disease burden.

Sex differences in vascular compliance in normal-weight but not obese boys and girls: the effect of body composition

Objectives. To determine the effect of sex and obesity on vascular function in children and explore potential mechanisms that account for differences in vascular function. Methods. Participants were 61 (30 boys) normal-weight (BMI 25-75% ile for age and sex) and 62 (30 boys) obese (BMI ≥ 95% ile) children of ages 8-18 years. Measurements of large and small artery elastic index (LAEI and SAEI, resp.) and reactive hyperemia index (RHI) were obtained at rest, along with anthropometric and biochemical information. Results. In normal-weight children, LAEI was 16% higher in males than females (P = 0.04) with a similar trend for SAEI (13% higher in males, P = 0.067). In obese children, no sex-related differences in vascular measures were observed. In multivariable models, sex differences in arterial compliance were explained by higher lean mass in normal-weight boys. Fat mass predicted LAEI and SAEI in both normal-weight and obese females, but fat mass predicted arterial compliance in boys when fat mass exceeded 24 kg (37% of the sample). Conclusions. Normal-weight males have higher arterial compliance than normal-weight females due to increased lean mass, but sex-related differences were not observed among obese children due to a lack of sex-related differences in lean or fat mass.

Cardiovascular responses to walking in patients with peripheral artery disease

PURPOSES

The study's purposes were to assess the cardiovascular responses during constant-load walking and to identify predictors of this response in peripheral artery disease (PAD) patients.

METHODS

Seventy-nine patients with PAD performed a constant-load treadmill test (2 mph, 0% grade). During the test, systolic blood pressure (BP), diastolic BP, and HR were obtained at the fourth minute to the last minute of exercise. Patients were also characterized by demographic measures, cardiovascular risk factors, baseline exercise performance, and vascular measures.

RESULTS

During constant-load walking, there was a significant increase (P < 0.01) in systolic BP (+12 ± 10 mm Hg), diastolic BP (+6 ± 9 mm Hg), and HR (+5 ± 5 bpm). The HR responses were negatively correlated with the ischemic window (r = -0.23, P < 0.05), expressed as an area under the curve of the resting ankle systolic BP and its recovery from a maximal graded treadmill test, and positively correlated with the HR during the first minute of recovery from the maximal graded treadmill test (r = 0.27, P < 0.05). The increase in cardiovascular variables during constant-load walking was greater in subjects with a higher body mass index and in men (P < 0.05).

CONCLUSIONS

Patients with PAD had an increased cardiovascular response during constant-load walking, and these responses were greater in obese patients and in men. The clinical implication is that PAD patients engaged in walking training programs, particularly men and those with obesity, require frequent assessment of cardiovascular parameters to avoid exaggerated increases in BP and HR during constant-load walking.

Changes in vascular function and structure in juvenile idiopathic arthritis

OBJECTIVE

Chronic inflammatory diseases in adults have been associated with increased cardiovascular risk and impaired vascular function. We aimed to assess the presence of early vascular dysfunction in patients with juvenile idiopathic arthritis (JIA) and investigate the role of inherent inflammatory process of JIA in vascular health.

METHODS

Thirty patients with JIA (age range 7-18 years) were compared to 33 age- and sex-matched controls. Endothelial function (brachial artery flow-mediated dilation [FMD]), carotid intima-media thickness (IMT), and arterial stiffness were examined. Endothelial inflammation was assessed by intercellular adhesion molecule 1 (ICAM-1) and P-selectin measurements.

RESULTS

Patients with JIA showed decreased FMD compared to controls (P = 0.001), independent of age (P = 0.9 among age subgroups). Baseline differences in erythrocyte sedimentation rate, ICAM-1, and glucose between the 2 groups accounted for the difference in FMD. The presence of systemic JIA was associated with greater IMT compared to patients with oligoarticular disease, polyarticular disease, or controls (P = 0.014, P = 0.069, and P = 0.046, respectively). The difference in IMT between systemic versus oligoarticular/polyarticular JIA was attributed to the following risk factors: age, body mass index, blood pressure, disease activity, and corticosteroids use. There were no differences in arterial stiffness indices between JIA patients and controls or between patients with systemic versus nonsystemic disease.

CONCLUSION

Endothelial function is impaired in patients with JIA at a very young age, while IMT is increased only in the presence of systemic JIA. Vascular dysfunction may be partly attributed to the effects of disease-related characteristics (inflammation, disease activity, and medications).

Arterial elasticity in American Indian and Caucasian children, adolescents, and young adults

We compared arterial elasticity in American Indian and Caucasian children, adolescents, and young adults, and we assessed whether demographic, body composition, and ambulatory activity measures were predictive of arterial elasticity within each group. Fifty-one American Indians and 66 Caucasians between the ages of 8 and 30 years were assessed on large artery elasticity index, small artery elasticity index, body fat percentage, and daily ambulatory activity during 7 consecutive days. American Indians had a higher percentage of body fat than Caucasians (p = 0.002), whereas daily ambulatory activity measures were similar (p > 0.05). American Indians had a 16% lower large artery elasticity index (p = 0.007) and a 19% lower small artery elasticity index (p < 0.001) than Caucasians. The regression model for large artery elasticity index included average cadence (p = 0.001), fat-free mass (p < 0.001), age component (Caucasian only) (p < 0.001), and sex (p = 0.025). The regression model for small artery elasticity index included fat-free mass (p < 0.001), maximum cadence for 30 continuous minutes (p = 0.009), race (p = 0.005), and average cadence (p = 0.049). Between 8 and 30 years of age, elasticity means for the large and small arteries is lower in American Indians than in Caucasians. A smaller difference was observed in children, with a trend to a much larger difference in young adults. Furthermore, greater fat-free mass and higher daily ambulatory cadence are associated with higher arterial elasticity in both American Indians and Caucasians.

Is Small Artery Elasticity Decreased Prior to Intima-Media Thickening in Patients with Longstanding Rheumatoid Arthritis?

Objective.

To determine small artery elasticity (SAE) in patients with longstanding rheumatoid arthritis (RA) in comparison to healthy controls, and to investigate its relation to markers of endothelial cell activation, disease activity, joint damage, and the presence of atherosclerosis.

Methods.

Forty-nine patients with RA and 50 age- and sex-matched healthy controls were studied. Traditional cardiovascular risk factors and disease-related factors were recorded. SAE was measured noninvasively by pulse-wave analysis (PWA). Endothelial activation was assessed by measuring levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) and von Willebrand factor (vWF). Carotid intima-media thickness (IMT), as an indicator of subclinical atherosclerosis, was assessed using ultrasonography.

Results.

Patients with RA had higher body mass index, blood pressure, and triglyceride levels and were more often cigarette smokers compared to controls. SAE was decreased in RA patients compared to controls and was inversely related with age, smoking, blood pressure, vWF, sVCAM-1, high sensitivity C-reactive protein, and IMT. Presence of RA was independently related to SAE in multivariate linear regression analysis. SAE was inversely related with the Health Assessment Questionnaire score. No correlation was found between SAE and other disease activity markers and damage. IMT in patients and controls was not different.

Conclusion.

Small artery elasticity was decreased in patients with longstanding RA. The presence of RA was independently associated with SAE. Whereas IMT in patients with RA was not increased, we hypothesize that endothelial dysfunction, reflected by decreased SAE, is present prior to IMT thickening in these patients.

Predictors of large and small artery elasticity in healthy subjects from 9 to 89 years old

BACKGROUND

We identified demographic variables, cardiovascular risk factors, and ambulatory activity measures that predict large and small artery elasticity in apparently healthy subjects between 9 and 89 years of age.

METHODS

A total of 480 subjects were assessed on large artery elasticity index (LAEI), small artery elasticity index (SAEI), demographic measures, cardiovascular risk factors, and daily ambulation during 7 consecutive days. All possible regression and Mallow's C(p) were used to select multivariate models for prediction of LAEI and SAEI.

RESULTS

In subjects 20 years of age and younger, LAEI model (R(2) = 0.25, P < 0.001) included age, average ambulatory cadence, and obesity. SAEI model (R(2) = 0.39, P < 0.001) contained body mass index (BMI), maximum daily ambulatory cadence for 30 continuous min, age, and total ambulatory strides. In subjects between 21 and 50 years, LAEI model (R(2) = 0.41, P < 0.001) included systolic blood pressure (SBP), gender, race, and diastolic blood pressure (DBP). SAEI model (R(2) = 0.42, P < 0.001) contained gender, BMI, DBP, race, dyslipidemia, and SBP. In subjects older than 50 years, LAEI model (R(2) = 0.54, P < 0.001) included SBP, gender, age, and BMI. SAEI model (R(2) = 0.45, P < 0.001) contained gender, age, BMI, DBP, current smoking, and SBP.

CONCLUSIONS

Daily ambulatory activity, particularly cadence of 30 continuous min of ambulation, is positively associated with arterial elasticity in children and adolescents. In contrast, the predominant factors related to the decline in arterial elasticity in adults are blood pressure and age.

Paradoxical Increase in Arterial Compliance in Obese Pubertal Children

We determined whether arterial compliance measured by pulse wave analysis is impaired in obese pubertal children compared to normal weight controls, and assessed whether arterial compliance is associated with ambulatory activity. Body fat percentage was significantly different between the normal (n = 33) and obese (n = 34) participants ( P < .001). Large ( P = .012) and small ( P < .001) arterial compliance were lower in the normal-weight group. After adjusting for height, systolic and diastolic blood pressure, race, sex, and Tanner stage, large arterial compliance was no longer different between groups ( P = .066), whereas small arterial compliance remained higher in the obese group ( P < .001). Obese pubertal children have paradoxically increased small arterial compliance compared to that of normal weight children, even after adjusting for height, blood pressure, race, sex, and Tanner stage. Thus, obesity in adolescence is not associated with impairments in small arterial compliance.

Effects of a single bout of exercise on arterial compliance in older adults

The effects of acute exercise on arterial compliance in older adults are unknown. Large and small arterial compliance were assessed during and 24 hours following a 30-minute bicycle ergometer test and on a nonexercise, control condition. The change in large artery compliance was similar between the exercise and nonexercise conditions (P = 0.876). Small artery compliance during the exercise day was higher than the nonexercise day at 45, 60, and 75 minutes following exercise (P < .001), was 17% higher 30 minutes postexercise than at rest (P < .001), and decreased by 20% between 30 minutes (4.5 ± 0.4 mL/mm Hg × 100) and 120 minutes (3.6 ± 0.3 mL/mm Hg × 100) after exercise (P = .027). The current study shows 30 minutes of moderate-intensity exercise transiently increases small arterial compliance 30 minutes after exercise but does not elicit more sustained increases in either large or small arterial compliance.

Gender and ethnic differences in arterial compliance in patients with intermittent claudication

OBJECTIVE

To assess the gender and ethnic differences in arterial compliance in patients with intermittent claudication.

METHODS

A total of 114 patients participated, including 38 Caucasian men, 32 Caucasian women, 16 African American men, and 28 African American women. Patients were assessed on large artery elasticity index (LAEI), small artery elasticity index (SAEI), age, weight, body mass index, ankle-brachial index (ABI), smoking status, and metabolic syndrome components.

RESULTS

Group differences were found for LAEI (P = .042), SAEI (P = .019), body mass index (P = .020), prevalence of elevated fasting glucose (P = .001), and prevalence of abdominal obesity (P = .025). Significant covariates for LAEI included age (P = .0002) and elevated triglycerides (P = .0719). LAEI (units = 10 mL x mm Hg) adjusted for age and triglycerides was 39% lower (P = .0005) in African Americans (11.4 +/- .90; mean +/- SE) than in Caucasians (15.8 +/- 0.72), whereas no significant difference (P = .7904) existed between men (13.8 +/- 0.81) and women (13.5 +/- 0.79). Significant covariates for SAEI included age (P = .0001), abdominal obesity (P = .0030), and elevated blood pressure (P = .0067). SAEI (units = 100 mL x mm Hg) adjusted for age, abdominal obesity, and elevated blood pressure was 32% lower (P = .0007) in African-Americans (2.8 +/- 0.3) than in Caucasians 4.1 +/- 0.2), and was 18% lower (P = .0442) in women (3.1 +/- 0.2) than in men (3.8 +/- 0.2).

CONCLUSION

African American patients with intermittent claudication have more impaired macrovascular and microvascular function than Caucasian patients, and women have more impaired microvascular function than men. These ethnic and gender differences in arterial compliance are evident even though ABI was similar among groups, suggesting that arterial compliance provides unique information to quantify vascular impairment in patients with intermittent claudication.

Dose-dependent increases in heart rate variability and arterial compliance in overweight and obese adults with DHA-rich fish oil supplementation

Heart rate (HR) variability and large arterial compliance can be improved using fish oils. DHA, a component of fish oil, has cardiovascular health benefits, but its effect on HR variability (HRV) and arterial compliance is yet to be quantified. Sixty-seven overweight or obese adults (thirty-six males and thirty-one females; 53 (sem 2) year; BMI 31.7 (sem 1.1) kg/m(2)) were randomly allocated to consume either 6 g/d sunola oil (control; n 17), fish oil (260 mg DHA+60 mg EPA per g) at doses of 2 g/d (n 16), 4 g/d (n 17) or 6 g/d (n 17). Blood pressure, HR and compliance of large and small arteries were measured while supine at baseline and after 12 weeks in all participants, and HRV was assessed in a subgroup of forty-six participants. There was no effect of fish oil on blood pressure, small artery compliance or HR. However, the low frequency:high frequency ratio of HRV decreased with increasing doses of fish oil (r - 0.34, P = 0.02), while large artery compliance increased (r 0.34, P = 0.006). Moreover, the changes in these biomarkers were significantly correlated (r - 0.31, P = 0.04) and may reflect fish oil-induced improvements in arterial function and cardiac autonomic regulation.

Association between arterial compliance and age in participants 9 to 77 years old

We characterized the age-related change in large and small artery compliance in 137 healthy participants between 9 and 77 years of age. Large artery compliance, measured by diastolic pulse contour analysis, had a sharp positive linear trend (0.89 mL x mm Hg( -1) x year(-1)) highly correlated with age in participants younger than 30 years (r = .76, p <.0001), had a slight negative trend (-0.10 mL x mm Hg(-1) x year(-1)) not significantly associated with age (r = -.11, p = .532) in middle-aged participants, and had a sharper negative trend (-0.19 mL x mm Hg(-1) x year(-1)) significantly associated with age (r = -.30, p =.023) in participants beyond 50 years. Similar results were found for small artery compliance. Large and small artery compliance increase in children, adolescents, and young adults, reach plateaus near age 30, and then decline beyond 30 years of age in those free of cardiovascular disease and risk factors.

Uncalibrated arterial pressure waveform analysis for less-invasive cardiac output determination in obese patients undergoing cardiac surgery

BACKGROUND

Uncalibrated arterial waveform analysis (FloTrac/Vigileo) uses standard arterial access to determine cardiac output (CO). Calculations are based on arterial waveform characteristics in combination with patient characteristic data to estimate individual arterial compliance. It has been shown that obesity is associated with altered arterial compliance independently of other risk factors. We conducted this study to assess the validity of measuring CO by the FloTrac/Vigileo device in obese patients undergoing cardiac surgery in comparison with bolus thermodilution technique.

METHODS

Fifteen obese patients with a BMI of > or = 30 and 23 non-obese patients (BMI 18-25) undergoing coronary artery bypass grafting (CABG) were included. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device (software version 1.10) were obtained intraoperatively after induction of anaesthesia, before cardiopulmonary bypass (CPB), after CPB, and after sternal closure. Measurements in the intensive care unit (ICU) were performed upon arrival in the ICU, after 4, 8, and 24 h after surgery. CO was indexed to the body surface area (cardiac index, CI).

RESULTS

The analysis of 262 data pairs revealed a bias and precision of 0.19 and +/-0.66 litre min(-1) m(-2), resulting in a percentage error of 26.6%. Thermodilution CI values ranged from 1.1 to 4.2 litre min(-1) m(-2) [mean 2.4 (0.52) litre min(-1) m(-2)]. Subgroup analysis resulted in a percentage error of 29.8% in obese patients and 24.4% in patients with normal BMI.

CONCLUSIONS

The semi-invasive FloTrac/Vigileo device was found to adequately agree with bolus pulmonary artery thermodilution in both obese and non-obese patients undergoing CABG.

Is adiposopathy (sick fat) an endocrine disease?

OBJECTIVE

To review current consensus and controversy regarding whether obesity is a 'disease', examine the pathogenic potential of adipose tissue to promote metabolic disease and explore the merits of 'adiposopathy' and 'sick fat' as scientifically and clinically useful terms in defining when excessive body fat may represent a 'disease'.

METHODS

A group of clinicians and researchers, all with a background in endocrinology, assembled to evaluate the medical literature, as it pertains to the pathologic and pathogenic potential of adipose tissue, with an emphasis on metabolic diseases that are often promoted by excessive body weight.

RESULTS

The data support pathogenic adipose tissue as a disease. Challenges exist to convince many clinicians, patients, healthcare entities and the public that excessive body fat is often no less a 'disease' than the pathophysiological consequences related to anatomical abnormalities of other body tissues. 'Adiposopathy' has the potential to scientifically define adipose tissue anatomic and physiologic abnormalities, and their adverse consequences to patient health. Adiposopathy acknowledges that when positive caloric balance leads to adipocyte hypertrophy and visceral adiposity, then this may lead to pathogenic adipose tissue metabolic and immune responses that promote metabolic disease. From a patient perspective, explaining how excessive caloric intake might cause fat to become 'sick' also helps provide a rationale for patients to avoid weight gain. Adiposopathy also better justifies recommendations of weight loss as an effective therapeutic modality to improve metabolic disease in overweight and obese patients.

CONCLUSION

Adiposopathy (sick fat) is an endocrine disease.

The effects of body mass index on cerebral blood flow velocity

OBJECTIVE

Obesity is a risk factor for cerebrovascular disease. We aimed to determine the effects of high body mass index (BMI) on cerebral blood flow regulation in patients with type-2 diabetes mellitus, hypertension, and stroke.

METHODS

We analyzed data from 90 controls, 30 diabetics, 45 hypertensives, and 32 ischemic stroke patients who underwent transcranial Doppler for evaluation of blood flow velocities (BFV) in the middle cerebral arteries (MCA) and cerebrovascular resistance (CVR) during supine rest and head-up tilt. This study was a cross-sectional analysis. We used a structural equation multiple indicators modeling to determine the effects of BMI and other background variables (age, sex, race, smoking, alcohol use, and systolic blood pressure) on cerebral BFV.

RESULTS

Higher BMI (P = 0.02) and age (P = 0.004) were associated with lower mean BFV during baseline, independent of diagnosis of diabetes mellitus, hypertension or stroke, and after adjusting for all background variables and vessel diameters. Men, especially those with stroke, had a lower mean BFV than women (P = 0.01). CVR increased with BMI (P = 0.001) at baseline and during head-up tilt (P = 0.02), and was elevated in obese subjects (P = 0.004) compared to normal weight subjects across all groups.

INTERPRETATION

High BMI is associated with a reduction in cerebral BFV and increased CVR. These findings indicate that obesity can adversely affect cerebral blood flow and resistance in the cerebrovascular bed, independent of diagnosis of type-2 diabetes, hypertension or stroke. Obesity may contribute to cerebromicrovascular disease, and affect clinical functional outcomes of the older population.

Pathogenic potential of adipose tissue and metabolic consequences of adipocyte hypertrophy and increased visceral adiposity

When caloric intake exceeds caloric expenditure, the positive caloric balance and storage of energy in adipose tissue often causes adipocyte hypertrophy and visceral adipose tissue accumulation. These pathogenic anatomic abnormalities may incite metabolic and immune responses that promote Type 2 diabetes mellitus, hypertension and dyslipidemia. These are the most common metabolic diseases managed by clinicians and are all major cardiovascular disease risk factors. 'Disease' is traditionally characterized as anatomic and physiologic abnormalities of an organ or organ system that contributes to adverse health consequences. Using this definition, pathogenic adipose tissue is no less a disease than diseases of other body organs. This review describes the consequences of pathogenic fat cell hypertrophy and visceral adiposity, emphasizing the mechanistic contributions of genetic and environmental predispositions, adipogenesis, fat storage, free fatty acid metabolism, adipocyte factors and inflammation. Appreciating the full pathogenic potential of adipose tissue requires an integrated perspective, recognizing the importance of 'cross-talk' and interactions between adipose tissue and other body systems. Thus, the adverse metabolic consequences that accompany fat cell hypertrophy and visceral adiposity are best viewed as a pathologic partnership between the pathogenic potential adipose tissue and the inherited or acquired limitations and/or impairments of other body organs. A better understanding of the physiological and pathological interplay of pathogenic adipose tissue with other organs and organ systems may assist in developing better strategies in treating metabolic disease and reducing cardiovascular disease risk.