Simplified Distributed-Parametermodel of Brachial-Radial Arteries for Noninvasive Determination of Mechanical Characteristics of Vessel

Abstract

This paper proposes a simplified distributed-parameter model of the brachial-radial arteries segment for the determination of mechanical parameters of these arteries and compares it with a four-element Windkessel model. The comparison is performed using data collected noninvasively of pressure pulse waveforms at two different locations of the arterial segment, under physiological (normotensive) and pathological (primary hypertension) conditions. The results show, by Akaike Information Criterion, that the proposed model fits the real pressure pulse waveform better than classical Windkessel model, and that also gives mechanical parameters coherent with the clinical condition.

Mixed circuit training acutely reduces arterial stiffness in patients with chronic stroke: a crossover randomized controlled trial

“…Markers of arterial stiffness (i.e., br-PWV, AC, and IR1,2) also were evaluated by the noninvasive pulse wave detection and analysis system, as previously described (Ferreira et al 2006). Measurements were taken at baseline after a 10-min rest, and at 60-min post-MCT (or CTL), with participants in a supine position in the laboratory.…”

“…This pressure pulse wave is propagated with a given velocity, namely the pulse wave velocity (PWV), which is inversely related to AC (Cavalcante et al 2011). Part of the energy from the pressure pulse wave is reflected towards the heart once it finds some structural discontinuation or bifurcation, namely a pulse wave reflection, which can be measured even in peripheral arteries by the reflection index (RI1,2) (Ferreira et al 2006;Ferreira et al 2004). This index can be calculated as the difference between the second and first peak of the pressure pulse waveform, expressed as a percentage of the pulse pressure.…”

Avaliação de um modelo de parâmetros distribuídos aplicado à estimação da geometria arterial na hipertensão

“…Para contornar este fato, propusemos um modelo simplificado do segmento braquial-radial (B-R) que utiliza parâmetros distribuídos baseado na teoria das linhas de transmissão (Nichols e O'Rourke, 1998) e em informações anatômicas. Tal modelo se mostrou, de acordo com o critério de informação de Akaike, mais adequado para predição de pulsos reais completos do que o Wk-4 para a fase sistólica (sem reflexões) (Ferreira et al, 2006).…”

“…Os métodos de solução de problemas inversos geralmente necessitam de rotinas de minimização de erros ("otimização paramétrica"), as quais na maioria não possuem garantia de localização de mínimos globais (Press et al, 1992). Assim, este trabalho apresenta a validação do método de determinação dos parâmetros do modelo anteriormente proposto (Ferreira et al, 2006) utilizando simulações de pulsos distais do segmento arterial, gerados a partir de pulsos proximais reais.…”