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The use of oscillometric methods to determine brachial blood pressure (bBP) can lead to a systematic underestimation of the invasively measured systolic (bSBP) and pulse (bPP) pressure levels, together with a significant overestimation of diastolic pressure (bDBP). Similarly, the agreement between brachial mean blood pressure (bMBP), invasively and non-invasively measured, can be affected by inaccurate estimations/assumptions. Despite several methodologies that can be applied to estimate bMBP non-invasively, there is no consensus on which approach leads to the most accurate estimation. Aims: to evaluate the association and agreement between: (1) non-invasive (oscillometry) and invasive bBP; (2) invasive bMBP, and bMBP (i) measured by oscillometry and (ii) calculated using six different equations; and (3) bSBP and bPP invasively and non-invasively obtained by applanation tonometry and employing different calibration methods. To this end, invasive aortic blood pressure and bBP (catheterization), and non-invasive bBP (oscillometry [Mobil-O-Graph] and brachial artery applanation tonometry [SphygmoCor]) were simultaneously obtained (34 subjects, 193 records). bMBP was calculated using different approaches. Results: (i) the agreement between invasive bBP and their respective non-invasive measurements (oscillometry) showed dependence on bBP levels (proportional error); (ii) among the different approaches used to obtain bMBP, the equation that includes a form factor equal to 33% (bMBP = bDBP + bPP/3) showed the best association with the invasive bMBP; (iii) the best approach to estimate invasive bSBP and bPP from tonometry recordings is based on the calibration scheme that employs oscillometric bMBP. On the contrary, the worst association between invasive and applanation tonometry-derived bBP levels was observed when the brachial pulse waveform was calibrated to bMBP quantified as bMBP = bDBP + bPP/3. Our study strongly emphasizes the need for methodological transparency and consensus for non-invasive bMBP assessment.
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Background: The non-invasive estimation of aortic systolic (aoSBP) and pulse pressure (aoPP) is achieved by a great variety of devices, which differ markedly in the: 1) principles of recording (applied technology), 2) arterial recording site, 3) model and mathematical analysis applied to signals, and/or 4) calibration scheme. The most reliable non-invasive procedure to obtain aoSBP and aoPP is not well established. Aim: To evaluate the agreement between aoSBP and aoPP values invasively and non-invasively obtained using different: 1) recording techniques (tonometry, oscilometry/plethysmography, ultrasound), 2) recording sites [radial, brachial (BA) and carotid artery (CCA)], 3) waveform analysis algorithms (e.g., direct analysis of the CCA pulse waveform vs. peripheral waveform analysis using general transfer functions, N-point moving average filters, etc.), 4) calibration schemes (systolic-diastolic calibration vs. methods using BA diastolic and mean blood pressure (bMBP); the latter calculated using different equations vs. measured directly by oscillometry, and 5) different equations to estimate bMBP (i.e., using a form factor of 33% ("033"), 41.2% ("0412") or 33% corrected for heart rate ("033HR"). Methods: The invasive aortic (aoBP) and brachial pressure (bBP) (catheterization), and the non-invasive aoBP and bBP were simultaneously obtained in 34 subjects. Non-invasive aoBP levels were obtained using different techniques, analysis methods, recording sites, and calibration schemes. Results: 1) Overall, non-invasive approaches yielded lower aoSBP and aoPP levels than those recorded invasively. 2) aoSBP and aoPP determinations based on CCA recordings, followed by BA recordings, were those that yielded values closest to those recorded invasively. 3) The "033HR" and "0412" calibration schemes ensured the lowest mean error, and the "033" method determined aoBP levels furthest from those recorded invasively. 4) Most of the non-invasive approaches considered overestimated and underestimated aoSBP at low (i.e., 80 mmHg) and high (i.e., 180 mmHg) invasive aoSBP values, respectively. 5) The higher the invasively measured aoPP, the higher the level of underestimation provided by the non-invasive methods. Conclusion: The recording method and site, the mathematical method/model used to quantify aoSBP and aoPP, and to calibrate waveforms, are essential when estimating aoBP. Our study strongly emphasizes the need for methodological transparency and consensus for the non-invasive aoBP assessment.
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INTRODUCTION: Measurement of central (aortic) systolic blood pressure has been shown to provide reliable information to evaluate target organ damage. However, non-invasive central blood pressure measurement procedures are still under analysis. AIM: To compare human pressure waveforms invasively obtained in the aorta, with the corresponding waveforms non-invasively recorded using an oscillometric device (Mobil-O-Graph). METHODS: In this research were included 20 subjects in which invasive percutaneous coronary interventions were performed. They were 10 males (68 ± 12 y. o. , BMI: 27.4 ± 4.6 kg/m2) and 10 females (77 ± 8 y. o. , BMI: 28.5 ± 5.3 kg/m2). During the invasive aortic pressure recording, a synchronized non-invasive Mobil-O-Graph acquisition beat by beat and reconstructed central pressure wave was performed. Both, invasive and non-invasive pressure waves were digitized and stored for subsequent analysis and calculations. A computerized interpolation procedure was developed in our laboratory to compare these pressure waves. RESULTS: A significant correlation between Mobil-O-Graph central blood pressure measurements and the corresponding invasive values was found in males (r < 0.81; p < 0.01) and females (r < 0.93; p < 0.01). However, in both genders, the slope of the regression lines was lesser than 1 (males: y = 0.7354x + 18.998; females: y = 0.9835x + 2.8432). In the whole population (n = 20), a significant correlation between Mobil-O-Graph central blood pressure measurements and the corresponding invasive values was found (r < 0.89; p < 0.01) and the regression line was lesser than 1 (y = 0.9774x + 1.7603). CONCLUSIONS: In this research, a high correlation between invasive central blood pressure values and those measured with the Mobil-O-Graph device was found in males, females and the whole population. However, a sub estimation of Mobil-O-Graph central blood pressure values was observed.
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Aorta/fisiopatologia , Pressão Arterial , Determinação da Pressão Arterial , Doença da Artéria Coronariana/diagnóstico , Hipertensão/diagnóstico , Análise de Onda de Pulso , Idoso , Idoso de 80 Anos ou mais , Doença da Artéria Coronariana/fisiopatologia , Doença da Artéria Coronariana/terapia , Feminino , Frequência Cardíaca , Humanos , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Oscilometria , Intervenção Coronária Percutânea , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
Adaptive identification systems focus on dynamical approaches based on the observed data from an experiment and/or clinical data. These systems establish a relationship between an input (arterial or vein instantaneous pressure) and an output (instantaneous arterial or vein diameter). Several dynamics relationships and applications can be established because of this adaptive identification as an arterial dynamic range (frequency response), biomechanical behavior of cryopreserved arteries, regional differences in veins as artery substitution, role of vascular smooth muscle in human hypertension and time invariance in the biomechanics of wall arteries. The aim of this review is to summarize some of those relevant results obtained from adaptive filter identification in cardiovascular dynamics research and clinical evaluation.
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Artérias/fisiopatologia , Hemodinâmica , Hipertensão/fisiopatologia , Modelos Cardiovasculares , Animais , Anti-Hipertensivos/uso terapêutico , Fenômenos Biomecânicos , Artérias Carótidas/fisiopatologia , Criopreservação , Módulo de Elasticidade , Hemodinâmica/efeitos dos fármacos , Humanos , Hipertensão/diagnóstico , Hipertensão/tratamento farmacológico , Músculo Liso Vascular/fisiopatologia , Fatores de Tempo , Veias/fisiopatologiaRESUMO
BACKGROUND: Pulse wave velocity ratio (PWV-ratio), a measure of central-to-peripheral arterial stiffness gradient, is calculated as a quotient between carotid-femoral and carotid-radial PWV (cf-PWV/cr-PWV). This new index has been reported to be significantly associated with increased mortality in hemodialyzed patients. Since several reports showed differences in arterial stiffness regarding the pathway where the vascular access (VA) is, the purpose of this research was: a) to compare arterial stiffness values obtained in the left and right sides of the body in hemodialyzed and non-hemodialyzed patients, and b) to analyze PWV-ratio values obtained on the side of the body where the VA was placed and compare them to its contralateral intact side. Since it is difficult to adequately measure cr-PWV in patients with a VA in the forearm, we measured the carotid- brachial PWV (cb-PWV) and used it to calculate PWV-ratio (cf-PWV/cb-PWV). METHODS: A Pearson's correlation and Bland & Altman analysis were performed in hemodialyzed (n=135) and non-hemodialyzed (n=77) patients, to quantify the equivalence between arterial stiffness parameters (cf-PWV, cb-PWV, PWV-ratio) obtained on each side of the body with respect to its contralateral side. RESULTS: We conclude that PWV-ratio values measured on the side where the VA is placed were significantly higher than those obtained in its contralateral side, in hemodialyzed patients included in this research. Moreover, cf-PWV, cb-PWV and PWV-ratio values obtained on one side of the body were always highly correlated with its contralateral side. CONCLUSION: According to this research, any research involving PWV-ratio should always consider the observed territory.
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Derivação Arteriovenosa Cirúrgica , Doenças Cardiovasculares/diagnóstico , Análise de Onda de Pulso , Diálise Renal , Insuficiência Renal Crônica/terapia , Extremidade Superior/irrigação sanguínea , Rigidez Vascular , Adulto , Idoso , Idoso de 80 Anos ou mais , Derivação Arteriovenosa Cirúrgica/efeitos adversos , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/fisiopatologia , Estudos de Casos e Controles , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Diálise Renal/efeitos adversos , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/fisiopatologia , Reprodutibilidade dos Testes , Fatores de Risco , Resultado do TratamentoRESUMO
Arterial pressure waves have been described in one dimension using several approaches, such as lumped (Windkessel) or distributed (using Navier-Stokes equations) models. An alternative approach consists of modeling blood pressure waves using a Korteweg-de Vries (KdV) equation and representing pressure waves as combinations of solitons. This model captures many key features of wave propagation in the systemic network and, in particular, pulse pressure amplification (PPA), which is a mechanical biomarker of cardiovascular risk. The main objective of this work is to compare the propagation dynamics described by a KdV equation in a human-like arterial tree using acquired pressure waves. Furthermore, we analyzed the ability of our model to reproduce induced elastic changes in PPA due to different pathological conditions. To this end, numerical simulations were performed using acquired central pressure signals from different subject groups (young, adults, and hypertensive) as input and then comparing the output of the model with measured radial artery pressure waveforms. Pathological conditions were modeled as changes in arterial elasticity (E). Numerical results showed that the model was able to propagate acquired pressure waveforms and to reproduce PPA variations as a consequence of elastic changes. Calculated elasticity for each group was in accordance with the existing literature.
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Determinação da Pressão Arterial/métodos , Modelos Cardiovasculares , Processamento de Sinais Assistido por Computador , Adulto , Idoso , Pressão Sanguínea/fisiologia , Feminino , Humanos , Hipertensão/diagnóstico , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
UNLABELLED: Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pulsatility is associated with various common diseases of aging and hypertension. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. OBJECTIVE: Arterial pressure and diameter time series were evaluated in order to assess the relationship between arterial stiffness and FD. METHODS: Three Corriedale male sheep were operated. Left anterior descending artery (LAD) was dissected and the external arterial diameter was measured trough sonomicrometry. Similarly, a pressure microtransducer was positioned in the upper third of the ascending aorta. Simultaneous pressure and diameter were measured in normal state and under smooth muscle activation. Each time series FD were assessed by the application of Higuchi's method while arterial wall elastic modulus was evaluated by means of the pressure-strain relationship. RESULTS: Coronary stiffness was increased from normal state to phenylephrine state (47.32%, 21.12%, 10.87%) while aortic pressure FD was decreased (2.11%, 2.57%, 6.85%), respectively. CONCLUSION: Acute hypertension induced by phenylephrine produces an increase in the coronary wall elastic modulus with a concomitant decrease in the fractal nature of the aortic pressure, suggesting that coronary stiffening is associated with an unwrinkled aortic pressure.
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Pressão Arterial , Doença da Artéria Coronariana/fisiopatologia , Vasos Coronários/fisiopatologia , Modelos Cardiovasculares , Animais , Simulação por Computador , Módulo de Elasticidade , Fractais , Masculino , OvinosRESUMO
Study of humans aging has presented difficulties in separating the aging process from concomitant disease and/or in defining normality and abnormality during its development. In accordance with this, aging associates structural and functional changes evidenced in variations in vascular parameters witch suffer alterations during atherosclerosis and have been proposed as early markers of the disease. The absence of adequate tools to differentiate the expected (normal) vascular changes due to aging from those related with a vascular disease is not a minor issue. For an individual, an early diagnosis of a vascular disease should be as important as the diagnosis of a healthy vascular aging. Recent studies have proposed that the capacitive or reservoir function of the aorta and large elastic arteries plays a major role in determining the pulse wave morphology. The arterial pressure waveform can be explained in terms of a reservoir pressure, related to the arterial system compliance, and an "excess" or wave-related pressure, associated with the traveling waves. The aim of this study was to evaluate, by means of a mathematical approach, age-related changes in measured, reservoir and excess central aortic pressure in order to determine if age-related changes are concentrated in particular decades of life. Central aortic pressure waveform was non-invasively obtained in healthy subjects (age range: 20-69 years old). Age-related profiles in measured, reservoir and excess pressure were calculated.
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Envelhecimento , Aorta/patologia , Pressão Sanguínea , Adulto , Fatores Etários , Idoso , Aorta/fisiologia , Aterosclerose/patologia , Velocidade do Fluxo Sanguíneo , Doenças Cardiovasculares/fisiopatologia , Sistema Cardiovascular , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Cardiovasculares , Modelos Estatísticos , Pressão , Pulso Arterial , RiscoRESUMO
Gender-related difference in cardiovascular diseases is one of the most investigated and still unsolved issues. Finding an explanation to this topic might have important implications for the understanding of the differences between men and women in diseases and possibly lead to the development of gender-specific strategies for its management. Recent studies have proposed that the capacitive or reservoir function of the aorta and large elastic arteries plays a major role in determining the pulse wave morphology. The pressure waveform can be explained in terms of a reservoir pressure related to arterial compliance and an "excess" or wave-related pressure associated with traveling waves. Gender-differences in the ascending aorta pressure waveform reservoir and excess components are to be characterized. The aim of this study was to evaluate, by means of a mathematical approach, gender-related differences in the central aortic pressure waveform components. Central aortic pressure waveform was non-invasively obtained in 22 healthy subjects (Age: 20 years old; 11 female). Males and females showed differences in the level and time to maximal excess pressure component, but no gender-related differences were found in the reservoir one.
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Aorta/fisiologia , Pressão Sanguínea/fisiologia , Modelos Cardiovasculares , Simulação por Computador , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores Sexuais , Adulto JovemRESUMO
INTRODUCTION AND OBJECTIVES: The structural and functional changes observed in the left ventricle in professional soccer players could cause alterations in ventricular rotation (Rv) and ventricular torsion (Tv). Our aim was to characterize the changes in Tv that occur in professional soccer players. METHODS: In total, 17 professional soccer players and 10 healthy volunteers who had not undergone training (control subjects) were investigated by M-mode, B-mode and Doppler echocardiography. Left ventricular systolic and diastolic functional and structural parameters were measured. Basal and apical Rv, and Tv were determined using specially developed software (EchoPAC, GE Medical Systems). In addition, Tv was characterized in the time domain. RESULTS: In all subjects, left ventricular structural and functional parameters were within the normal ranges. Both left ventricular ejection fraction and shortening were greater in soccer players (P< .05). The magnitude of apical and basal Rv and the magnitude and velocity of Tv were all lower in soccer players (P< .05). In soccer players, there were negative correlations between the maximum Tv achieved and left ventricular shortening and ejection fraction (P< .05). CONCLUSIONS: The magnitude and velocity of Tv were lower in soccer players. A reduction in Tv might take place under certain physiological conditions and could represent an adaptive response that contributes to increased ventricular efficiency.