Is the algorithm used to process heart rate variability data clinically relevant? Analysis in male adolescents

OBJECTIVE: To analyze whether the algorithm used for the heart rate variability assessment (fast Fourier transform versus autoregressive methods) influenced its association with cardiovascular risk factors in male adolescents. METHODS: This cross-sectional study included 1,152 male adolescents (aged 14 to 19 years). The low frequency, high frequency components (absolute numbers and normalized units), low frequency/high frequency ratio, and total power of heart rate variability parameters were obtained using the fast Fourier transform and autoregressive methods, while the adolescents were resting in a supine position. RESULTS: All heart rate variability parameters calculated from both methods were different (p<0.05). However, a low effect size (<0.1) was found for all parameters. The intra-class correlation between methods ranged from 0.96 to 0.99, whereas the variation coefficient ranged from 7.4 to 14.8%. Furthermore, waist circumference was negatively associated with high frequency, and positively associated with low frequency and sympatovagal balance (p<0.001 for both fast Fourier transform and autoregressive methods in all associations). Systolic blood pressure was negatively associated with total power and high frequency, whereas it was positively associated with low frequency and sympatovagal balance (p<0.001 for both fast Fourier transform and autoregressive methods in all associations). Body mass index was negatively associated with high frequency, while it was positively associated with low frequency and sympatovagal balance (p values ranged from <0.001 to 0.007). CONCLUSION: There are significant differences in heart rate variability parameters obtained with the fast Fourier transform and autoregressive methods in male adolescent; however, these differences are not clinically significant. OBJETIVO: Analisar se o algoritmo usado para avaliação da variabilidade da frequência cardíaca (transformada rápida de Fourier versus autoregressivo) influencia em sua associação com fatores de risco cardiovascular adolescentes do gênero masculino. MÉTODOS: Estudo transversal, que incluiu 1.152 adolescentes do gênero masculino (14 a 19 anos). Componentes de baixa e alta frequência (absolutos e unidades normalizadas), razão componente de baixa frequência/componente de alta frequência e poder total da variabilidade da frequência cardíaca foram obtidos em repouso, na posição supina, usando os métodos transformada rápida de Fourier e autorregressivo. RESULTADOS: Todos os parâmetros da variabilidade da frequência cardíaca para ambos os métodos foram diferentes (p<0,05). Entretanto, um pequeno tamanho do efeito (<0,1) foi observado para todos os parâmetros. Os coeficientes de correlação intraclasse entre os métodos variaram de 0,96 a 0,99, enquanto os coeficientes de variação foram de 7,4 a 14,8%. A circunferência abdominal foi negativamente associada com o componente de alta frequência, e positivamente associada com o componente de baixa frequência e o balanço simpatovagal (p<0,001 para a transformada rápida de Fourier e o autorregressivo em todas as associações). A pressão arterial sistólica foi negativamente associada com o poder total e o componente de alta frequência, enquanto foi positivamente associada com o componente de baixa frequência e o balanço simpatovagal (p<0,001 para a transformada rápida de Fourier e o autorregressivo em todas as associações). O índice de massa corporal foi negativamente associado com o componente de alta frequência, enquanto foi positivamente associado com o componente de baixa frequência e o balanço simpatovagal (valores de p variando de <0,001 a 0,007). CONCLUSÃO: Houve diferenças significantes nos parâmetros da variabilidade da frequência cardíaca obtidos com os métodos transformada rápida de Fourier e autorregressivo em adolescentes masculinos, mas essas diferenças não foram clinicamente significativas

Reproducibility of hemodynamic, cardiac autonomic modulation and blood flow assessments in patients with intermittent claudication

Objective: To identify, in patients with peripheral artery disease and intermittent claudication (IC), the reproducibility of heart rate (HR), blood pressure (BP), rate pressure product (RPP), heart rate variability (HRV), and forearm and calf blood flow (BF) and vasodilatory assessments. Methods: Twenty-nine patients with IC underwent test and retest sessions, 8-12 days apart. During each session, HR, BP, HRV, BF and vasodilatory responses were measured by electrocardiogram, auscultation, spectral analysis of HRV (low frequency, LFR-R; high frequency, HFR-R) and strain gauge plethysmography (baseline BF, post-occlusion BF, post-occlusion area under the curve, AUC). Reproducibility was determined by intraclass coefficient correlation (ICC), typical error, coefficient of variation (CV) and limits of agreement. Results: The ICC for HR and BP were > 0.8 with CV 0.9 while CV were 0.9 while CV were < 19%; variable ICC and CV for vasodilatory responses were exhibited for calf (0.653 – 0.770; 35.2 – 37.7%) and forearm (0.169 – 0.265; 46.2 – 55.5%). Conclusions: In male patients with IC, systemic hemodynamic (HR and BP), cardiac autonomic modulation (LFR-R and HFR-R) and forearm and calf baseline BF assessments exhibited excellent reproducibility, whereas the level of reproducibility for vasodilatory responses were moderate to poor. Assessment reproducibility has highlighted appropriate clinical tools for the regular monitoring of disease/intervention progression in patients with IC

Immobilization of CalB Lipase by adsorption on magnetic nanoparticles: A heterogeneous biocatalysis/ Imobilização da lipase CalB por adsorção em nanopartículas magnéticas: um biocatalisador heterogêneo

Iron magnetic nanoparticles (Fe3O4) were evaluated as adsorption preparative heterofunctional support for the immobilization of lipase B from Candida antarctica (CALB). Heterogeneous magnetic catalysts are easy to recover by the magnetic field, which may optimize operational cost and enhance the purity of the products. The nanoparticles were produced by the co-precipitation method. Modifications were carried out on the nanoparticles’ surfaces with aminopropyltriethoxysilane (APTS). The adsorption was evaluated for 3.0 mg protein/g of support in the presence of 5mM sodium phosphate buffer, pH 7.0, at 25 °C and 0.5h of immobilization. In a solvent-free medium, under 37 °C, the biocatalyst prepared has shown activity of 2.2 U/g for the esterification of oleic acid after 0.5h, 37 kHz, and 300 W. The results obtained with CALB adsorbed onto magnetic iron nanoparticles were compared with those of lipase B from Candida antartica adsorbed onto acrylic resin (Novozym® 435). In this regard, under the same reactional conditions, Novozym® 435 has presented activity of 2.9 U/g

Impact of hypertension on arterial stiffness and cardiac autonomic modulation in patients with peripheral artery disease: a cross-sectional study

To examine the impact of hypertension on cardiovascular health in patients with symptomatic peripheral artery disease and to identify factors associated with uncontrolled hypertension. A cross-sectional study including 251 patients with symptomatic peripheral artery disease (63.9% males, mean age 67±10 years). Following hypertension diagnosis, blood pressure was measured to determine control of hypertension. Arterial stiffness (carotid-femoral pulse wave velocity) and cardiac autonomic modulation (sympathovagal balance) were assessed. Hypertension was associated with higher carotid-femoral pulse wave velocity, regardless of sex, age, ankle-brachial index, body mass index, walking capacity, heart rate, or comorbidities (ß=2.59±0.76m/s, b=0.318, p=0.003). Patients with systolic blood pressure ≥120mmHg had higher carotid-femoral pulse wave velocity values than normotensive individuals, and hypertensive patients with systolic blood pressure of ≤119mmHg (normotensive: 7.6±2.4m/s=≤119mmHg: 8.1±2.2m/s 120-129mmHg:9.8±2.6m/s=≥130mmHg: 9.9±2.9m/s, p0.05). Hypertensive patients with symptomatic peripheral artery disease have increased arterial stiffness. Arterial stiffness is even greater in patients with uncontrolled high blood pressure

Low-intensity resistance exercise does not affect cardiac autonomic modulation in patients with peripheral artery disease

OBJECTIVE: To analyze the effect of a single bout of resistance exercise on cardiac autonomic modulation in patients with peripheral artery disease. METHODS: Fifteen patients with peripheral artery disease (age: 58.3±4.0 years) underwent the following sessions in a random order: resistance exercise (three sets of 10 repetitions of the six resistance exercises with a workload of 5-7 in the OMNI-RES scale) and control (similar to the resistance session; however, the resistance exercises were performed with no load). The frequency domain (low frequency, high frequency and sympathovagal balance) and symbolic analysis (0V, 1V and 2V patterns) of heart rate variability were obtained before and until one hour after the interventions. RESULTS: After the resistance exercise and control sessions, similar increases were observed in the consecutive heartbeat intervals (control: 720.8±28.6 vs. 790.9±34.4 ms; resistance exercise: 712.9±30.1 vs. 756.8±37.9 ms;

Mundos mesclados, espaços segregados: cultura material, mestiçagem e segmentação no sítio Aldeia em Santarém (PA)

This article discusses the processes of cultural exchange between Portuguese, Portuguese-Brazilian, Amerindians, and mestizos based on the analysis of the material culture from households of Santarém (PA), occupied during the eighteenth and nineteenth centuries,. Although these social groups manipulated material culture aiming to express different values, related to hierarchy, social segmentation, and affirmation of identities, ambiguity also characterizes these assemblages. This material ambiguity informs about the mixtures of both practices and cultural references that brought about the building of a mestizo society.Com base na análise da cultura material proveniente de unidades domésticas do núcleo urbano de Santarém (PA), ocupadas nos séculos XVIII e XIX, o presente artigo discute os processos de trocas culturais entre portugueses, luso-brasileiros, indígenas e mestiços. Embora esses grupos sociais tenham manipulado a cultura material visando expressar diferentes valores, relacionados à hierarquia, segmentação social e afirmação de identidades, a ambigüidade é uma característica das amostras analisadas, informando sobre as misturas de práticas e de referenciais culturais que levaram à construção de uma sociedade mestiça

A ideologia do corpo feminino perfeito: questões com o real

O presente artigo se propõe refletir sobre como na sociedade capitalista contemporânea algo da ordem do real se inscreve no corpo feminino. Para tanto discorreremos acerca das categorias “corpo feminino” e “Real” à luz da teoria psicanalítica para, por fim, apresentar de que modo eles se articulam no contexto social atual, mais especificamente no capitalismo de consumo. Discutiremos como a mulher tem aderido à ideologia do corpo perfeito, na tentativa de evitar deparar-se com sua falta. Nesse momento daremos destaque à submissão às cirurgias estéticas na atualidade, as quais, paradoxalmente, são possibilidade de gozo e lançam a mulher na sua condição de não toda e ao encontro com o Real. O artigo pretende apresentar como no corpo da mulher há uma marca denunciando algo que falha na sociedade capitalista, que, por sua vez, por meio da ideologia do gozo pleno, busca afastar, neste caso, a mulher do seu desejo