Antonia Perez-Martin

Abnormal vascular reactivity at rest and exercise in obese boys

Background  Obese children exhibit vascular disorders at rest depending on their pubertal status, degree of obesity, and level of insulin resistance. However, data regarding their vascular function during exercise remain scarce. The aims of the present study were to evaluate vascular morphology and function at rest, and lower limb blood flow during exercise, in prepubertal boys with mild‐to‐moderate obesity and in lean controls.

Flow-mediated dilation and exercise-induced hyperaemia in highly trained athletes: comparison of the upper and lower limb vasculature

Aim:  The main purpose of the present study was to assess whether similar vascular adaptive changes could be obtained by long‐term intensive training involving predominantly either the lower or the upper limb musculature.

Vascular smooth muscle function in type 2 diabetes mellitus: a systematic review and meta-analysis

Aims/hypothesisIn type 2 diabetes, in contrast to the well-documented endothelial dysfunction, studies assessing vascular smooth muscle (VSM) function have yielded discrepant results over the last two decades. We therefore sought to determine whether or not VSM function is impaired in individuals with type 2 diabetes.MethodsWe conducted a systematic search of MEDLINE, Cochrane, Scopus and Web of Science databases, from their respective inceptions until December 2012, for articles evaluating VSM function in individuals with type 2 diabetes. A meta-analysis was performed to compare the standardised mean difference (SMD) in VSM function between individuals with type 2 diabetes and age-matched controls. Subgroup analyses and meta-regression were used to identify sources of heterogeneity.ResultsTwenty-seven articles (1,042 individuals with type 2 diabetes and 601 control subjects) were included in this analysis. VSM function was significantly impaired in diabetic compared with control subjects (SMD −0.68, 95% CI −0.84, −0.52; p < 0.001). Although moderate heterogeneity among studies was found (I2 = 52%), no significant publication bias was detected. Subgroup analyses showed a further decline in VSM function assessed in the microcirculation compared with the macrocirculation of individuals with type 2 diabetes (p = 0.009). In meta-regression, VSM function in the microcirculation was inversely associated with BMI and triacylglycerols and was positively associated with HDL-cholesterol.Conclusions/interpretationIn addition to the endothelium, the VSM is a source of vascular dysfunction in type 2 diabetes. An exacerbation of VSM function in the microcirculation may be a distinctive feature in type 2 diabetes.

Exercise Response in Hypertrophic Cardiomyopathy: Blunted Left Ventricular Deformational and Twisting Reserve with Altered Systolic-Diastolic Coupling

Background— Abnormal left ventricular (LV) deformational mechanics have been demonstrated in patients with hypertrophic cardiomyopathy (HCM) at rest, but there is a lack of information on their adaptation to exercise. The aim of this study was to assess the adaptability of LV strains and torsional mechanics during exercise in HCM patients. Methods and Results— Twenty nonobstructive HCM patients (age, 48.3±12.3 years; 14 men) and 20 control subjects underwent speckle-tracking echocardiographic measurement of longitudinal, radial, and circumferential strains, systolic twist, and diastolic untwisting rate (UTR) at rest and submaximal exercise. HCM patients showed lower resting longitudinal (−15.7±5.0% versus −19.4±2.6%, P<0.001) and radial (38.1±11.3% versus 44.7±14.4%, P<0.05) strains but higher circumferential strain (−21.9±4.0% versus −18.8±2.3%, P<0.05) and twist (15.7±3.6° versus 9.3±2.6°, P<0.0001) than control subjects. Exercise induced an increase in all strains in control subjects but only a moderate increase in longitudinal strain (to −18.4±5.0%), without significant changes in radial and circumferential strains or twist in HCM patients. Exercise peak UTR was lower (−119.0±31.5°/s versus −137.3±41.1°/s) and occurred later (137±18% versus 125±11% systolic time, P<0.05) in HCM than in control subjects. A significant relationship between twist and UTR was obtained in control subjects (ß=−0.0807, P<0.001) but not in HCM patients (ß=−0.0051, P=0.68). Conclusions— HCM patients had severely limited strain adaptability and no LV twisting reserve at exercise. They had reduced and delayed UTR with reduced systolic-diastolic coupling efficiency by twist-untwist mechanics.Background— Abnormal left ventricular (LV) deformational mechanics have been demonstrated in patients with hypertrophic cardiomyopathy (HCM) at rest, but there is a lack of information on their adaptation to exercise. The aim of this study was to assess the adaptability of LV strains and torsional mechanics during exercise in HCM patients. Methods and Results— Twenty nonobstructive HCM patients (age, 48.3±12.3 years; 14 men) and 20 control subjects underwent speckle-tracking echocardiographic measurement of longitudinal, radial, and circumferential strains, systolic twist, and diastolic untwisting rate (UTR) at rest and submaximal exercise. HCM patients showed lower resting longitudinal (−15.7±5.0% versus −19.4±2.6%, P <0.001) and radial (38.1±11.3% versus 44.7±14.4%, P <0.05) strains but higher circumferential strain (−21.9±4.0% versus −18.8±2.3%, P <0.05) and twist (15.7±3.6° versus 9.3±2.6°, P <0.0001) than control subjects. Exercise induced an increase in all strains in control subjects but only a moderate increase in longitudinal strain (to −18.4±5.0%), without significant changes in radial and circumferential strains or twist in HCM patients. Exercise peak UTR was lower (−119.0±31.5°/s versus −137.3±41.1°/s) and occurred later (137±18% versus 125±11% systolic time, P <0.05) in HCM than in control subjects. A significant relationship between twist and UTR was obtained in control subjects (s=−0.0807, P <0.001) but not in HCM patients (s=−0.0051, P =0.68). Conclusions— HCM patients had severely limited strain adaptability and no LV twisting reserve at exercise. They had reduced and delayed UTR with reduced systolic-diastolic coupling efficiency by twist-untwist mechanics.

Cardiac function during exercise in obese prepubertal boys: effect of degree of obesity.

The purpose of the study was to evaluate the dynamics of diastolic and systolic function from rest to maximal exercise using conventional echocardiography and tissue Doppler imaging (TDI) in obese prepubertal boys compared to age‐matched lean controls. Eighteen obese (10 with first degree obesity and 8 with second degree obesity according to French curves, BMI: 23.3 ± 1.8 and 29.0 ± 2.0 kg/m2, respectively) and 17 lean controls (BMI = 17.6 ± 0.6 kg/m2, P < 0.001), aged 10–12 years were recruited. After resting echocardiography, all children performed a maximal exercise test. Regional diastolic and systolic myocardial velocities were acquired at rest and each workload. Stroke volume and cardiac output were calculated. At rest, obese boys had greater left ventricular (LV) diameters and LV mass. Boys in the first degree group showed no diastolic or systolic dysfunction, whereas boys with second degree obesity showed subtle diastolic dysfunction. During exercise, both obese groups showed greater stroke volume and cardiac output. First degree obese boys exhibited greater systolic and diastolic tissue Doppler velocities than controls, whereas second degree obese boys had lower diastolic tissue velocities irrespective of exercise intensity and lower fractional shortening at high exercise intensities than controls. In conclusion, no impairment in diastolic or systolic function is noticed in prepubertal boys with first degree of obesity. Enhanced regional myocardial function response to exercise was also demonstrated in this population, suggesting adaptive compensatory cardiac changes in mild obesity. However, when obesity becomes more severe, impaired global and regional cardiac function at rest and during exercise can be observed.

Diastolic Dysfunction and Intraventricular Dyssynchrony Are Restored by Low Intensity Exercise Training in Obese Men

The aim of this study was to evaluate the impact of a low‐intensity training program on subclinical cardiac dysfunction and on dyssynchrony in moderately obese middle aged men. Ten obese and 14 age‐matched normal‐weight men (BMI: 33.6 ± 1.0 and 24.2 ± 0.5 kg/m2) were included. Obese men participated in an 8‐week low‐intensity training program without concomitant diet. Cardiac function and myocardial synchrony were assessed by echocardiography with tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE). At baseline, obese men showed diastolic dysfunction on standard echocardiography, lower strain values (systolic strain: 15.9 ± 0.9 vs. 18.8 ± 0.3%, diastolic strain rate: 0.81 ± 0.09 vs. 1.05 ± 0.06 s−1), and significant intraventricular dyssynchrony (systolic: 13.3 ± 2.1 vs. 5.4 ± 2.1 ms, diastolic: 17.4 ± 3.2 vs. 9.1 ± 2.1 ms) (P < 0.05 vs. controls for all variables). Training improved aerobic fitness, decreased systolic blood pressure and heart rate, and reduced fat mass without weight loss. Diastolic function, strain values (systolic strain: 17.4 ± 0.9%, diastolic strain rate: 0.96 ± 0.12 s−1) and intraventricular dyssynchrony (systolic: 3.3 ± 1.7 ms, diastolic: 5.5 ± 3.4 ms) improved significantly after training (P < 0.05 vs. baseline values for all variables), reaching levels similar to those of normal‐weight men. In conclusion, in obese men, a short and easy‐to‐perform low intensity training program restored diastolic function and cardiac synchrony and improved body composition without weight loss.

Wall mechanics of the stented rabbit aorta: long-term study and correlation with histological findings.

Purpose: To evaluate long-term changes in arterial wall mechanics induced by stenting of the rabbit aorta. Methods: Eighteen New Zealand white rabbits had initial stent deployment (3×8 mm Multilink) at 110% of the pre-stenting abdominal aortic diameter. Group A (n=10) had no post-deployment stent expansion and group B (n=8) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed measurement of diameters at systole and diastole and the calculation of diameter compliance. Measurements were performed before stenting and compared to those recorded immediately after stenting and at 3 months at 3 locations: upstream from the stent, at the stent level, and downstream from the stent. Measurements were also compared among measurement sites. The pathological study included measurement of intimal thickening and calculation of an injury score. Results: At the stent level, diameter compliance was significantly lower after initial stenting and at 3 months than before stenting (group A: p<0.005; group B: p<0.001) and than downstream or upstream from the stent (group A: p<0.0001, group B: p<0.005). No significant difference in diameter compliance was found between groups A and B. In group B, intimal thickening and the injury score were greater than in group A (p<0.05 and p<0.0001, respectively). Conclusions: Endovascular stenting of the rabbit aorta impairs wall mechanics. Performing 30% overdilation of the stent does not worsen this impairment but induces greater in-stent intimal hyperplasia.

Effects of a Lifestyle Program on Vascular Reactivity in Macro- and Microcirculation in Severely Obese Adolescents

CONTEXT AND OBJECTIVE This study aimed to comprehensively assess the macro- and microcirculation of severely obese adolescents (SOA) and normal-weight counterparts and to determine the longitudinal effects of weight loss on vascular function in SOA. DESIGN, SETTING, PARTICIPANTS, AND OUTCOME MEASURES: Seventeen SOA (body mass index z-score = 4.22 ± 0.73) and 19 puberty-matched normal-weight counterparts (body mass index z-score = -0.02 ± 1.04) were included. The SOA participated in a 4 month weight loss program. Brachial artery flow-mediated dilation and response to sublingual nitrate (nitrate-mediated dilation [NMD]) were assessed by high-resolution ultrasound. Microvascular reactivity was evaluated by laser Doppler flowmetry in response to NMD, iontophoresis of acetylcholine and sodium nitroprusside, and local hyperthermia. Plasma insulin, leptin, resistin, C-reactive protein, myeloperoxidase, and tissue plasminogen activator were measured. RESULTS At baseline, SOA had similar flow-mediated dilation and impaired NMD in the brachial artery compared to normal-weight adolescents. Similarly, peak responses to acetylcholine and sodium nitroprusside iontophoresis and to local hyperthermia were unaltered, whereas cutaneous blood flow after NMD was lower in the forearm microcirculation of SOA. All plasma measurements were significantly higher in SOA. After the 4-month program, SOA presented a weight reduction of 7.4 ± 3.1%, but neither brachial artery nor microvascular reactivity variables were improved. Significant decreases were detected in plasma leptin, myeloperoxidase, and tissue plasminogen activator. CONCLUSIONS Macro- and microvascular endothelial function are preserved in adolescents with severe obesity. Conversely, weight loss does not improve their impaired smooth muscle response to exogenous organic nitrate in both vascular beds, despite reducing plasma markers adversely related to vascular homeostasis.

Decreased microvascular myogenic response to insulin in severely obese adolescents

By means of flowmotion analysis, it is mainly accepted that, in normal conditions, insulin specifically increases the activity of microvascular smooth muscle. The objective of this study was to compare this effect in severely obese and normal-weight adolescents. Laser Doppler measurements were used to assess cutaneous blood flux (CBF) and flowmotion in response to transdermal iontophoresis of insulin in 20 severely obese adolescents (SOA) aged 12-17 years (BMI = 33.34 ± 1.07 kg/m2), and 16 normal-weight adolescents (BMI = 18.85 ± 0.50 kg/m2). Fasting insulin levels were higher in SOA than in normal-weight adolescents (6.25 ± 1.03 vs. 3.11 ± 0.28 μU/ml, P = 0.007). Net insulin-induced increase of CBF did not significantly differ between SOA and normal-weight adolescents (422.41 ± 146.09 vs. 232.36 ± 80.98 %, P = 0.265). A significant impairment of myogenic flowmotion was detected in SOA compared to normal-weight adolescents in response to insulin delivery (5.91 ± 0.35 vs. 8.12 ± 0.63 %, P = 0.003). Severely obese adolescents exhibit decreased myogenic activity in response to insulin, which may be an early step in the development of insulin resistance.

Leg arterial stiffness after weight loss in severely obese adolescents

Severe obesity is one of the fastest growing obesity categories in childhood [1], and has been related to vascular stiffness in central elastic arteries [2]. However, recent reports have shown a preserved arterial compliance in obese adolescents compared to their normal-weight counterparts [3–5], thus suggesting that the mechanisms relating obesity-associated risk factors to the development of arterial morbidity in the young remain to be established. The purpose of this study was to identify differences in central and peripheral arterial stiffness in severely obese adolescents (SOA) and normal-weight counterparts, and to assess the effect of a conventional weight loss program in SOA.