Diámetro basal de la arteria braquial en la evaluación del paciente con hipertensión esencial / Basal diameter of brachial artery when assessing patients with essential hypertension

Introducción: Las enfermedades cardiovasculares de mayor prevalencia y la hipertensión arterial tienen como sustento la aterosclerosis y la disfunción endotelial. La evaluación no invasiva de aterosclerosis subclínica constituye un complemento para la estratificación del riesgo cardiovascular en la evaluación del paciente hipertenso. Objetivo: Determinar la utilidad del diámetro basal de la arteria braquial en la evaluación del paciente con hipertensión arterial esencial. Método: Se realizó un estudio transversal analítico que incluyó 30 pacientes con hipertensión arterial esencial, a quienes se les realizó ultrasonografía para medir el diámetro basal de la arteria braquial, la vasorreactividad dependiente del endotelio y el grosor íntima media carotídeo, así como se precisó su riesgo cardiovascular, el tiempo de evolución y grado de la hipertensión arterial. Para determinar la asociación entre el diámetro arterial y el resto de las variables se utilizaron pruebas estadísticas como ANOVA de una vía y el coeficiente de correlación de Pearson. Resultados: La disfunción endotelial estuvo presente en 83,3 por ciento de los pacientes estudiados. Tanto el grosor del complejo íntima media carotídeo como la vasorreactividad dependiente del endotelio fueron adecuados marcadores de la enfermedad aterosclerótica. El diámetro basal de la arteria braquial tuvo una correlación inversa con la vasorreactividad dependiente del endotelio, y mostró valores medios esperados en relación a la presencia del tabaquismo, y con los peores grados de la enfermedad hipertensiva y el riesgo cardiovascular. Conclusiones: El diámetro basal de la arteria braquial no mostró la asociación esperada para la evaluación del paciente hipertenso esencial en la población estudiada(AU)

Introduction: The most prevalent cardiovascular diseases and high blood pressure are supported by atherosclerosis and endothelial dysfunction. The non-invasive assessment of subclinical atherosclerosis complements the cardiovascular risk stratification when evaluating hypertensive patients. Objective: To determine the value of the basal diameter of the brachial artery in assessing patients suffering from essential arterial hypertension. Method: An analytical cross-sectional study was carried out in 30 patients with essential arterial hypertension. They underwent ultrasonography to measure the basal diameter of the brachial artery, endothelium-dependent vasoreactivity and carotid mean intima thickness, as well as the cardiovascular risk, time of evolution and degree of arterial hypertension. Statistical tests such as one-way ANOVA and Pearson's correlation coefficient were used to determine the association between arterial diameter and the rest of the variables. Results: Endothelial dysfunction was present in 83.3% of the studied patients. Both the thickness of the carotid media intima complex and endothelium-dependent vasoreactivity were adequate markers for atherosclerotic disease. The basal diameter of the brachial artery had inverse correlation with endothelium-dependent vasoreactivity, and it showed expected mean values in relation to the presence of smoking, and with the worst degrees of hypertensive disease and cardiovascular risk. Conclusions: The basal diameter of the brachial artery did not show the expected association for the evaluation of essential hypertensive patients in the studied population(AU)

Acute effect of Finnish sauna bathing on brachial artery flow-mediated dilation and reactive hyperemia in healthy middle-aged and older adults.

Regular Finnish sauna bathing is associated with a reduced risk of all-cause and cardiovascular mortality in middle-aged and older adults. Potential acute physiological adaptations induced by sauna bathing that underlie this relationship remain to be fully elucidated. The purpose of this study was to determine if typical Finnish sauna sessions acutely improve brachial artery flow-mediated dilation (FMD) and reactive hyperemia (RH) in healthy middle-aged and older adults. Using a randomized crossover design, FMD and RH were evaluated in 21 healthy adults (66 ± 6 years, 10 men/11 women) before and after each of the following conditions: (1) 1 × 10 min of Finnish sauna bathing (80.2 ± 3.2°C, 23 ± 2% humidity); (2) 2 × 10 min of sauna bathing separated by 10 min of rest outside the sauna; (3) a time control period (10 min of seated rest outside the sauna). FMD was taken as the peak change from baseline in brachial artery diameter following 5 min of forearm ischemia, whereas RH was quantified as both peak and area-under-the-curve forearm vascular conductance postischemia. FMD was statistically similar pre to post 1 × 10 min (4.69 ± 2.46 to 5.41 ± 2.64%, P = 0.20) and 2 × 10 min of sauna bathing (4.16 ± 1.79 to 4.55 ± 2.14%, P = 0.58). Peak and area-under-the-curve forearm vascular conductance were also similar following both sauna interventions. These results suggest that typical Finnish sauna bathing sessions do not acutely improve brachial artery FMD and RH in healthy middle-aged and older adults.

Reactivity to low-flow as a potential determinant for brachial artery flow-mediated vasodilatation.

Previous studies have reported a vasoconstrictor response in the radial artery during a cuff-induced low-flow condition, but a similar low-flow condition in the brachial artery results in nonuniform reactivity. This variable reactivity to low-flow influences the subsequent flow-mediated dilatation (FMD) response following cuff-release. However, it is uncertain whether reactivity to low-flow is important in data interpretation in clinical populations and older adults. This study aimed to determine the influence of reactivity to low-flow on the magnitude of brachial artery FMD response in middle-aged and older individuals with diverse cardiovascular risk profiles. Data were analyzed from 165 individuals, divided into increased cardiovascular risk (CVR: n = 115, 85M, 67.0 ± 8.8 years) and healthy control (CTRL: n = 50, 30M, 63.2 ± 7.2 years) groups. Brachial artery diameter and blood velocity data obtained from Doppler ultrasound were used to calculate FMD, reactivity to low-flow and estimated shear rate (SR) using semiautomated edge-detection software. There was a significant association between reactivity to low-flow and FMD in overall (r = 0.261), CTRL (r = 0.410) and CVR (r = 0.189, all P < 0.05) groups. Multivariate regression analysis found that reactivity to low-flow, peak SR, and baseline diameter independently contributed to FMD along with sex, the presence of diabetes, and smoking (total R(2) = 0.450). There was a significant association between reactivity to low-flow and the subsequent FMD response in the overall dataset, and reactivity to low-flow independently contributed to FMD These findings suggest that reactivity to low-flow plays a key role in the subsequent brachial artery FMD response and is important in the interpretation of FMD data.

Blood viscosity but not shear stress associates with delayed flow-mediated dilation.

PURPOSE: Flow-mediated dilation (FMD) is a complex mechanism involving several mediators, and different hemodynamic forces. Temporally distinct FMD patterns can be elicited by ischemic stimulus. Some subjects dilate early after cuff release, while others dilate later or do not dilate at all. Aim of the present research was to verify if hemorheological and hemodynamic factors might influence different FMD pattern. METHODS: 148 free-living subjects were studied. FMD was measured at 50 s, 2 min and 3 min. Blood viscosity was measured and shear stress calculated. Shear stress stimulus was quantified as the area under the curve after ischemia (SSAUC) over the first 40-s post-occlusion. RESULTS: Based on the timing or absence of arterial dilation, 82 subjects were classified as Early dilators, 37 as Late dilators and 29 as No dilators. Peak FMD was 7.9 ± 4.3 % in Early dilators, and 9.1 ± 5.7 in Late dilators (p = NS). SSAUC was not significantly different among three groups, while blood viscosity was significantly higher in Late FMD subjects. Regression analyses showed the independent predictive role of age and blood viscosity on FMD patterns, and the lack of any association between FMD pattern and the magnitude of SS. CONCLUSIONS: The present study demonstrates that age and blood viscosity but not the magnitude of SS explain the different timing of the dilatory response to ischemia.

Flow-mediated dilatation, using time course data, shows maturation of the brachial artery from young children to mid-adolescents.

Flow-mediated dilatation (FMD) is a tool widely used to measure arterial responsiveness to sheer stress. However, there is scant literature to show how the peripheral arterial response changes as the vascular system matures. One reason for this is that the feasibility of measuring FMD in younger children has not been established. The aim of the present study was to assess brachial artery function at rest and during the FMD response after 4 min ischaemia of the forearm in children aged 6-15 years. Time to reach maximum FMD (FMDmax ) was found to be correlated with age (r = 0.4, P < 0.05), resting brachial artery diameter (r = 0.4, P < 0.05), height (r = 0.4, P < 0.05), body mass index (BMI; r = 0.45, P < 0.05), body surface area (r = 0.44, P < 0.05) and resting blood flow (r = 0.37, P < 0.05). However, there was no correlation between the traditional FMD response at 60 s or FMD maximal dilation and age, resting brachial artery diameter, height, weight, BMI, body surface area and resting blood flow. In conclusion, the time taken to reach the maximal dilation response is related to age, brachial artery luminal diameter and body habitus, but not the traditional measure of FMD response at 60 s or the maximal dilatation percentage.

Insulin resistance and arterial stiffness in healthy adolescents and young adults.

AIMS/HYPOTHESIS: Increased arterial stiffness is a risk factor for adverse cardiovascular events in adults with obesity-related insulin resistance (IR) or type 2 diabetes mellitus. Adolescents with type 2 diabetes have stiffer vessels. Whether stiffness is increased in obesity/IR in youth is not known. We sought to determine if IR was a determinant of arterial stiffness in youth, independent of obesity and cardiovascular risk factors. METHODS: We measured cardiovascular risk factors, IR, adipocytokines and arterial stiffness (brachial artery distensibility [BrachD], pulse wave velocity [PWV]) and wave reflection (augmentation index [AIx]) in 343 adolescents and young adults without type 2 diabetes (15-28 years old, 47% male, 48% non-white). Individuals <85th percentile of BMI were classified as lean (n = 232). Obese individuals were grouped by HOMA index as not insulin resistant (n = 46) or insulin resistant (n = 65) by the 90th percentile for HOMA for lean. Mean differences were evaluated by ANOVA. Multivariate models evaluated whether HOMA was an independent determinant of arterial stiffness. RESULTS: Risk factors deteriorated from lean to obese to obese/insulin resistant (all p ≤ 0.017). Higher AIx, lower BrachD and higher PWV indicated increased arterial stiffness in obese and obese/insulin-resistant participants. HOMA was not an independent determinant. Age, sex, BMI and BP were the most consistent determinants, with HDL-cholesterol playing a role for BrachD and leptin for PWV (AIx R²= 0.34; BrachD R² = 0.37; PWV R² = 0.40; all p ≤ 0.02). CONCLUSIONS/INTERPRETATION: Although IR is associated with increased arterial stiffness, traditional cardiovascular risk factors, especially obesity and BP, are the major determinants of arterial stiffness in healthy young people.

Vascular remodeling in response to 12 wk of upper arm unilateral resistance training.

UNLABELLED: Participation in regular aerobic exercise has been shown to increase arterial size and that exercise-induced vascular remodeling may be regional rather than systemic. However, these issues have been minimally investigated concerning resistance training. PURPOSES: To determine whether 1) resistance training of the nondominant arm elicits an increase in diameter of the brachial artery and 2) unilateral training induces arterial remodeling in the contralateral arm. METHODS: Twenty-four previously untrained participants, consisting of 18 females (aged 22.3 +/- 5.1 yr) and 6 males (aged 21.7 +/- 1.8 yr), participated in unilateral strength training of the biceps and triceps for 12 wk using their nondominant arm. Isotonic (one-repetition maximum, 1RM) and isometric (ISO) strength of the biceps were assessed before and after training on both arms. Brachial artery diameter and biceps muscle cross-sectional area (CSA) of both arms were also measured before and after training using magnetic resonance imaging (MRI). RESULTS: Brachial artery diameter increased 5.47% (P < 0.05) in the nondominant trained arm with no change observed in the dominant untrained arm. Biceps CSA increased 18.3% (P < 0.05) in the trained arm with no change (P > 0.05) in the untrained limb. Nondominant 1RM and ISO strength increased by 35.1% and 16.8%, respectively (P < 0.05 for both), although there were no significant changes (P > 0.05) in the contralateral arm. A modest correlation was found between the increases in CSA and in brachial artery diameter (r2 = 0.19, P = 0.039). CONCLUSIONS: These results indicate that upper arm vascular remodeling, manifesting as increased brachial artery diameter, can result from resistance training and that these changes are localized to the trained limb and associated with increases in CSA.

Local shear stress and brachial artery functions in end-stage renal disease.

Physiologic laminar shear stress (SS) is crucial for normal vascular structure and function. As a result of anemia-related lower whole-blood viscosity (WBV), SS could be reduced in patients with ESRD and might be associated with arterial functional alterations. In 44 patients with ESRD and 25 control subjects, brachial artery (BA) compliance and BA diameter changes (flow-mediated dilation [FMD[) were evaluated in response to local shear rate and SS changes during hand warming-induced hyperemia. Patients with ESRD and control subjects had similar BA blood flow, but SS was lower in patients with ESRD (P < 0.001), with lower shear rate (P < 0.01) and lower WBV (P < 0.0001). In control subjects, SS was positively (and physiologically) correlated with arterial diameter (P < 0.001). In contrast, in patients with ESRD, larger arterial diameter was associated with low SS (P < 0.05) and increased arterial wall elastic modulus (P < 0.001). Anemia-associated low WBV aggravates low shear rate, further contributing to SS reduction. These abnormalities were associated with decreased vasodilating response to endothelial mechanical stimulation. Compared with control subjects, BA compliance and FMD increases in response to hand warming-induced increased SS were lower in ESRD patients (P < 0.01), whereas their BA diameter response to glyceryl trinitrate did not differ. The long-term WBV and SS increases after anemia correction improved FMD (P < 0.01) and BA compliance (P < 0.05) and heightened arterial wall sensitivity to mechanical stimulation. Maintenance low SS as a result of anemia could play an indirect role in arterial dysfunction in patients with ESRD.

Changes in arterial stiffness and wave reflection with advancing age in healthy men and women: the Framingham Heart Study.

With advancing age, arterial stiffness and wave reflections increase and elevate systolic and pulse pressures. An elevated central pulse pressure is generally ascribed to increased wave reflection and portends an unfavorable prognosis. Using arterial tonometry, we evaluated central (carotid-femoral) and peripheral (carotid-brachial) pulse wave velocity, amplitudes of forward and reflected pressure waves, and augmentation index in 188 men and 333 women in the Framingham Heart Study offspring cohort who were free of clinical cardiovascular disease, hypertension, diabetes, smoking within the past 12 months, dyslipidemia, and obesity. In multivariable linear regression models, advancing age was the predominant correlate of higher carotid-femoral pulse wave velocity; other correlates were higher mean arterial pressure, heart rate, and triglycerides and walk test before tonometry (model R2=0.512, P<0.001). A similar model was obtained for carotid-brachial pulse wave velocity (model R2=0.227, P<0.001), although the increase with advancing age was smaller. Owing to different relations of age to central and peripheral stiffness measures, carotid-femoral pulse wave velocity was lower than carotid-brachial pulse wave velocity before age 50 years but exceeded it thereafter, leading to reversal of the normal central-to-peripheral arterial stiffness gradient. In this healthy cohort with a minimal burden of cardiovascular disease risk factors, an age-related increase in aortic stiffness, as compared with peripheral arterial stiffness, was associated with increasing forward wave amplitude and pulse pressure and reversal of the arterial stiffness gradient. This phenomenon may facilitate forward transmission of potentially deleterious pressure pulsations into the periphery.

Arterial alpha-adrenergic responsiveness is decreased and SNS activity is increased in older humans.

We tested the hypotheses that 1) there is an age-associated decrease in arterial alpha-adrenergic responsiveness and 2) there is upregulation of this response during suppression of sympathetic nervous system (SNS) activity. We measured forearm blood flow (FABF) by plethysmography during brachial artery infusions of the alpha-adrenergic agonist norepinephrine (NE) and the nonadrenergic agonist angiotensin II (ANG II) in 15 young and 14 older healthy human subjects. Among the old (O) relative to the young (Y) we identified greater plasma NE levels (Y: 1.29 +/- 0.07 nM vs. O: 2.14 +/- 0.17 nM; P = 0.0001); a decrease in NE-mediated reduction in FABF [analysis of variance (ANOVA) P = 0.04]; and, in contrast, no difference in ANG II-mediated reduction in FABF (ANOVA P = 0.43). In the nine older subjects studied during guanadrel (G) to suppress SNS activity, we identified decreased plasma NE levels [placebo (P): 2.11 +/- 0.24 nM vs. G: 1.09 +/- 0.09 nM; P = 0.002], increased NE-mediated FABF response (ANOVA P = 0.01), and no difference in FABF response to ANG II (ANOVA: P = 0.69) compared with P. We conclude that there is appropriate desensitization of arterial alpha-adrenergic responsiveness among the older relative to the young subjects that is specific for the alpha-adrenergic system. Among the older subjects there is homologous upregulation of this response when SNS activity is suppressed.

Comparison between absorbable and nonabsorbable sutures in arterial anastomoses in growing dogs.

Five dogs, 10 weeks old, underwent operation using ketamin-HCl anesthesia and end-to-end anastomoses of the femoral and brachial arteries were made using polyfilament nonabsorbable material (Ethibond), monofilament nonabsorbable material (Prolene), polyfilament absorbable material (Vicryl) and monofilament absorbable material (PDS). The arterial diameter using a micrometer and blood flow using an electromagnetic flow meter were determined. After six months another operation was performed and diameter and blood flow were measured again. No statistically significant differences were found between the different materials used with respect to growth related increases either in arterial diameter or blood flow.