Development of systemic arterial mechanical properties from infancy to adulthood interpreted by four-element windkessel models

2007 ◽  
Vol 103 (1) ◽  
pp. 66-79 ◽  
Author(s):  
Roberto Burattini ◽  
Paola Oriana Di Salvia
Keyword(s):  
Arterial Compliance ◽  
Peripheral Resistance ◽  
New Paradigm ◽  
Rapid Reduction ◽  
Cross Sectional ◽  
Total Arterial Compliance ◽  
In Series ◽  
Aortic Impedance ◽  
Age Range ◽  
Bell Shaped Curve

Aortic impedance data of infants, children and adults (age range 0.8–54 yr), previously reported by others, were interpreted by means of three alternative four-element windkessel models: W4P, W4S, and IVW. The W4P and W4S are derived from the three-element windkessel (W3) by connecting an inertance ( L) in parallel or in series, respectively, with the aortic characteristic resistance ( Rc). In the IVW, L is connected in series with a viscoelastic windkessel (VW). The W4S and IVW (same input impedance) fit the data best. The W4S, however, suffers from the assumption that Rc is part of total peripheral resistance ( Rp). The IVW model offers a new paradigm for interpretation of resistive properties in terms of viscous ( Rd) properties of vessel wall motion, distinguished from Rp. Results indicated that rapid reduction of Rd/ Rp during early development is functional to modulation of decay time constant (τd) of pressure in diastole, such that normalization over heart period (τd/T) is independent of body size. Estimates of total arterial compliance ( C) vs. age were fitted by a bell-shaped curve with a maximum at 33 yr. With body weight (BW) factored out by normalization, the C/BW data scattered about a bell-shaped curve centered at 66 mmHg. Inertance was significantly higher in pediatric patients than in adults, in accordance with a lower cross-sectional area of the vasculature, commensurate to a lower aortic flow. Changes of arterial properties appear functional to control the ratio of pulsatile power to active power and keep arterial efficiency as high as 97% in infants and children.

Estimating arterial resistance and compliance during transient conditions in humans

1989 ◽  
Vol 257 (1) ◽  
pp. H190-H197 ◽  
Author(s):  
F. C. Yin ◽  
Z. R. Liu
Keyword(s):  
Pressure Difference ◽  
Arterial Compliance ◽  
Quantitative Difference ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Hemodynamic Parameters ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Highly Correlated ◽  
Almost All

Almost all existing methods for estimating hemodynamic parameters are valid only during steady-state conditions. There is often a need, however, for estimating peripheral resistance and total arterial compliance during beat-to-beat transients such as during atrial fibrillation. During such transients the pressure at the onset and end of a cardiac cycle usually differ. This pressure difference necessitates a modification of usual methods used for estimating these hemodynamic parameters. In this paper we formulate a method for estimating resistance and total arterial compliance during such beat-to-beat transients. For simplicity the expressions are derived for a two-element windkessel model of the circulation. The method is a generalization of one we previously proposed. Rather than using parameter estimation techniques or having to assume a monoexponential pressure decay during diastole, our method uses the areas under the systolic and diastolic portions of the aortic pressure versus time tracing to obtain explicit expressions for compliance; both for the case where it is constant and when it is assumed to be nonlinear (exponential) function of pressure. Aortic pressure and flow data from patients undergoing cardiac catheterization are employed to illustrate the method. Results illustrate the quantitative difference between uncorrected and corrected estimates of both resistance and compliance as a function of the pressure difference between the onset and end of each beat. The uncorrected parameters were found to be linearly and highly correlated with these pressure differences. Regressions of pressure difference against normalized values revealed that the pooled data for all patients defined a single relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

Propofol Alters Left Ventricular Afterload as Evaluated by Aortic Input Impedance in Dogs

1996 ◽  
Vol 84 (2) ◽  
pp. 368-376. ◽  
Author(s):  
Dermot Lowe ◽  
Douglas A. Hettrick ◽  
Paul S. Pagel ◽  
David C. Warltier
Keyword(s):  
Input Impedance ◽  
Arterial Compliance ◽  
Left Ventricular ◽  
High Dose ◽  
Left Ventricular Afterload ◽  
Arterial Resistance ◽  
Ventricular Afterload ◽  
Total Arterial Compliance ◽  
Aortic Input Impedance ◽  
Aortic Impedance

Background Systemic vascular resistance incompletely describes left ventricular afterload because of the phasic nature of arterial pressure and blood flow. Aortic input impedance is an experimental description of left ventricular afterload that incorporates the frequency- dependent characteristics and viscoelastic properties of the arterial system. The effects of propofol on aortic input impedance were examined using three variables derived from the three-element Windkessel model: characteristic aortic impedance, total arterial compliance, and total arterial resistance. Methods Eight dogs were chronically instrumented for measurement of aortic pressure, left ventricular pressure, +dP/dt, subendocardial segment length, and aortic blood flow. Systemic hemodynamics and aortic blood pressure and flow waveforms were recorded in the conscious state and after a bolus of 5 mg x kg(-1) propofol and infusion for 15 min at 25, 50 and 100 mg x kg(-1) x h(-1). Aortic input impedance spectra were generated using power spectral analysis of aortic pressure and flow waveforms corrected for the phase responses of the pressure and flow transducers. Characteristic aortic impedance, total arterial resistance, and total arterial compliance were calculated from the aortic input impedance spectrum and the aortic pressure waveform. Parameters describing the net site and magnitude or arterial wave reflection were determined from aortic impedance. Results Propofol decreased total arterial resistance (3.05 +/- 0.20 during control to 2.29 +/- 0.18 dynes x s x cm(-5) x 10(3) at the high dose) and increased total arterial compliance (0.53 +/- 0.04 during control to 1.15 +/- 0.17 ml x mmHg(-1) at the high dose) in a dose- related manner. Propofol increased characteristic aortic impedance (1.49 +/- 0.15 during control to 2.20 +/- 0.20 dynes x s x cm(-5) x 10(2) at the high dose). The net site and the magnitude of arterial wave reflection were unchanged by the propofol. Conclusions In chronically instrumented dogs, propofol decreased total arterial resistance, a property of arteriolar resistance vessels, consistent with the known actions of this drug on systemic vascular resistance. Propofol also increased total arterial compliance and characteristic aortic impedance, indicating that this anesthetic affects the mechanical properties of the aorta. Propofol had no effect on arterial wave reflection patterns. The results indicate that propofol reduces left ventricular afterload via decreases in peripheral resistance and increases in arterial compliance.

Apparent arterial compliance

1998 ◽  
Vol 274 (4) ◽  
pp. H1393-H1403 ◽  
Author(s):  
Christopher M. Quick ◽  
David S. Berger ◽  
Abraham Noordergraaf
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Arterial Compliance ◽  
Complex Function ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Lumped Model ◽  
Total Arterial Compliance

Recently, there has been renewed interest in estimating total arterial compliance. Because it cannot be measured directly, a lumped model is usually applied to derive compliance from aortic pressure and flow. The archetypical model, the classical two-element windkessel, assumes 1) system linearity and 2) infinite pulse wave velocity. To generalize this model, investigators have added more elements and have incorporated nonlinearities. A different approach is taken here. It is assumed that the arterial system 1) is linear and 2) has finite pulse wave velocity. In doing so, the windkessel is generalized by describing compliance as a complex function of frequency that relates input pressure to volume stored. By applying transmission theory, this relationship is shown to be a function of heart rate, peripheral resistance, and pulse wave reflection. Because this pressure-volume relationship is generally not equal to total arterial compliance, it is termed “apparent compliance.” This new concept forms the natural counterpart to the established concept of apparent pulse wave velocity.

Evaluation of hypercholesterol diet-induced changes in viscoelastic properties of carotid circulation in pigs

1992 ◽  
Vol 263 (6) ◽  
pp. H1919-H1926 ◽  
Author(s):  
R. Burattini ◽  
L. Montanari ◽  
L. J. Mulligan ◽  
M. S. Cannon ◽  
D. R. Gross
Keyword(s):  
Control Diet ◽  
Peripheral Resistance ◽  
Dynamic Mechanical Properties ◽  
Lumped Parameter Model ◽  
Mean Flow ◽  
Static Compliance ◽  
Cross Sectional ◽  
Pulsatile Pressure ◽  
In Series ◽  
Carotid Circulation

Measurements of pulsatile pressure and flow at the input of the left and right carotid arteries and a new lumped parameter model were used to quantify changes in the overall dynamic mechanical properties of the carotid circulation between five control diet-fed pigs and five pigs fed a hyperlipidemic diet for 16 wk. The model represents the portion of the circulation supplied by either the left or the right carotid artery and is characterized by five parameters: peripheral resistance (Rp), an overall inertance (L), and an overall frequency-dependent compliance constituted by a capacitor C (static compliance) in series with a Maxwell section, i.e., a capacitor Cd, in parallel with a resistor Rd. Rp was calculated as the ratio between mean pressure (P) and mean flow (Q). The other four parameters were estimated by fitting measured to model predicted flows. The average static compliance was reduced by 40% (P = 0.01) between normal (P = 62.0 +/- 4.3 mmHg) and hyperlipidemic diet-fed pigs (P = 62.7 +/- 4.7 mmHg). A significant reduction in the overall cross-sectional area was inferred from a 53% increase (P = 0.05) in L, whereas resistance vessel tone was unchanged as judged from estimates of Rp. No signs of occlusive disease were found in any of the animals.

Beat-to-beat estimation of peripheral resistance and arterial compliance during pressure transients

1987 ◽  
Vol 252 (6) ◽  
pp. H1275-H1283 ◽  
Author(s):  
G. P. Toorop ◽  
N. Westerhof ◽  
G. Elzinga
Keyword(s):  
Heart Rate ◽  
Arterial Compliance ◽  
Peripheral Resistance ◽  
Estimation Method ◽  
Aortic Pressure ◽  
Autonomous Nervous System ◽  
Mean Flow ◽  
Arterial Tree ◽  
Total Arterial Compliance

We have used a computer-based parameter estimation method to obtain peripheral resistance, total arterial compliance, and characteristic resistance from the measurement of aortic pressure and flow in the open-thorax cat, assuming the three-element windkessel as a model of the systemic arterial tree. The method can be applied on a beat-to-beat basis in the steady state and in transients. We have validated this method by analyzing nonsteady-state data obtained from an electrical analog with fixed values of the resistances and compliance and by showing that the values obtained by this procedure were within 5% of the fixed values of the circuit. Changes in total peripheral resistance and arterial compliance were studied before, during, and after acute heart rate changes in five open-thorax cats with blocked autonomous nervous system. As expected, the peripheral resistance, estimated during the heart rate transient [3.93 +/- 0.94 (SE) kPa X ml-1 X s] was the same as before the transient (3.53 +/- 0.83 kPa X ml-1 X s); total arterial compliances were also identical (0.28 +/- 0.04 vs. 0.27 +/- 0.03 ml/kPa). In six cats without nervous blockade we obtained similar results. Calculation of peripheral resistance during transients from the mean pressure-to-mean flow ratio, i.e., without correction for arterial compliance, suggested changes in resistance values of less than or equal to 57%, which shows that correction is necessary. The findings indicate that peripheral resistance and total arterial compliance can be estimated in vivo on a beat-to-beat basis, even during hemodynamic transients.

scholarly journals Determination of Aortic Characteristic Impedance and Total Arterial Compliance From Regional Pulse Wave Velocities Using Machine Learning: An in-silico Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Vasiliki Bikia ◽  
Georgios Rovas ◽  
Stamatia Pagoulatou ◽  
Nikolaos Stergiopulos
Keyword(s):  
In Silico ◽  
Pulse Wave ◽  
Cuff Pressure ◽  
Arterial Compliance ◽  
Characteristic Impedance ◽  
Cross Sectional ◽  
Non Invasive ◽  
Total Arterial Compliance ◽  
Aortic Characteristic Impedance

In-vivo assessment of aortic characteristic impedance (Zao) and total arterial compliance (CT) has been hampered by the need for either invasive or inconvenient and expensive methods to access simultaneous recordings of aortic pressure and flow, wall thickness, and cross-sectional area. In contrast, regional pulse wave velocity (PWV) measurements are non-invasive and clinically available. In this study, we present a non-invasive method for estimating Zao and CT using cuff pressure, carotid-femoral PWV (cfPWV), and carotid-radial PWV (crPWV). Regression analysis is employed for both Zao and CT. The regressors are trained and tested using a pool of virtual subjects (n = 3,818) generated from a previously validated in-silico model. Predictions achieved an accuracy of 7.40%, r = 0.90, and 6.26%, r = 0.95, for Zao, and CT, respectively. The proposed approach constitutes a step forward to non-invasive screening of elastic vascular properties in humans by exploiting easily obtained measurements. This study could introduce a valuable tool for assessing arterial stiffness reducing the cost and the complexity of the required measuring techniques. Further clinical studies are required to validate the method in-vivo.

Echocardiographic assessment of aortic elastic properties with automated border detection in an ICU: in vivo application of the arctangent Langewouters model

2005 ◽  
Vol 288 (5) ◽  
pp. H2504-H2511 ◽  
Author(s):  
Jan R. Heerman ◽  
Patrick Segers ◽  
Carl D. Roosens ◽  
Frank Gasthuys ◽  
Pascal R. Verdonck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Arterial Compliance ◽  
Ascending Aorta ◽  
Border Detection ◽  
Cross Sectional ◽  
Ultrasound Monitoring ◽  
Total Arterial Compliance ◽  
Pressure Area ◽  
Echocardiographic Assessment

We studied whether combined pressure and transesophageal ultrasound monitoring is feasible in the intensive care unit (ICU) setting for global cardiovascular hemodynamic monitoring [systemic vascular resistance (SVR) and total arterial compliance (CPPM)] and direct estimation of local ascending and descending aortic mechanical properties, i.e., distensibility and compliance coefficients (DC and CC). Pressure-area data were fitted to the arctangent Langewouters model, with aortic cross-sectional area obtained via automated border detection. Data were measured in 19 subjects at baseline, during infusion of sodium nitroprusside (SNP), and after washout. SNP infusion lowered SVR from 1.15 ± 0.40 to 0.80 ± 0.32 mmHg·ml−1·s ( P < 0.05), whereas CPPM increased from 0.87 ± 0.46 to 1.02 ± 0.42 ml/mmHg ( P < 0.05). DC and CC increased from 0.0018 ± 0.0007 to 0.0025 ± 0.0009 l/mmHg ( P < 0.05) and from 0.0066 ± 0.0028 to 0.0083 ± 0.0026 cm2/mmHg ( P < 0.05), respectively, at the descending, but not ascending, aorta. The Langewouters model fitted the descending aorta data reasonably well. Assessment of local mechanical properties of the human ascending aorta in a clinical setting by automated border detection remains technically challenging.

scholarly journals Use of the Kalman Filter for Aortic Pressure Waveform Noise Reduction

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Frank Lam ◽  
Hsiang-Wei Lu ◽  
Chung-Che Wu ◽  
Zekeriya Aliyazicioglu ◽  
James S. Kang
Keyword(s):  
Kalman Filter ◽  
Arterial Compliance ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Hemodynamic Parameters ◽  
Windkessel Model ◽  
Estimation Algorithms ◽  
Intensive Care Patients ◽  
Aortic Impedance ◽  
Aortic Blood Pressure

Clinical applications that require extraction and interpretation of physiological signals or waveforms are susceptible to corruption by noise or artifacts. Real-time hemodynamic monitoring systems are important for clinicians to assess the hemodynamic stability of surgical or intensive care patients by interpreting hemodynamic parameters generated by an analysis of aortic blood pressure (ABP) waveform measurements. Since hemodynamic parameter estimation algorithms often detect events and features from measured ABP waveforms to generate hemodynamic parameters, noise and artifacts integrated into ABP waveforms can severely distort the interpretation of hemodynamic parameters by hemodynamic algorithms. In this article, we propose the use of the Kalman filter and the 4-element Windkessel model with static parameters, arterial compliance C, peripheral resistance R, aortic impedance r, and the inertia of blood L, to represent aortic circulation for generating accurate estimations of ABP waveforms through noise and artifact reduction. Results show the Kalman filter could very effectively eliminate noise and generate a good estimation from the noisy ABP waveform based on the past state history. The power spectrum of the measured ABP waveform and the synthesized ABP waveform shows two similar harmonic frequencies.

scholarly journals YI 1.1 Aortic Impedance and Total Arterial Compliance from Regional Pulse Wave Velocities

2020 ◽  
Vol 26 (Supplement 1) ◽  
pp. S1
Author(s):  
Vasiliki Bikia ◽  
Georgios Rovas ◽  
Stamatia Pagoulatou ◽  
Nikolaos Stergiopulos
Keyword(s):  
Pulse Wave ◽  
Arterial Compliance ◽  
Wave Velocities ◽  
Total Arterial Compliance ◽  
Aortic Impedance

scholarly journals Exploring Why Adult Mexican Males Do Not Get Vaccinated: Implications for COVID-19 Preventive Actions

2020 ◽  
Vol 42 (4) ◽  
pp. 515-527
Author(s):  
V. Nelly Salgado de Snyder ◽  
Deliana Garcia ◽  
Roxana Pineda ◽  
Jessica Calderon ◽  
Dania Diaz ◽  
...  
Keyword(s):  
Preventive Medicine ◽  
Age Groups ◽  
Adult Males ◽  
Cross Sectional ◽  
Administrative Services ◽  
Minority Males ◽  
Socially Disadvantaged ◽  
Preventive Actions ◽  
Socially Excluded ◽  
Age Range

Vaccination is the single most important preventive medicine action worldwide. However, there are inequalities in the procurement of vaccines particularly among US ethnic and racial minority males when compared to the rest of the US population. This study explored the reasons given by adult Mexican-origin males residing in Texas, for obtaining or not, immunizations. This was a cross-sectional, exploratory study with a sample of convenience of 401 adult males (age range 18–79) who were invited to participate in the study while waiting their turn to receive administrative services at the Mexican Consulate in Austin Texas. Data was collected in Spanish with a seven-item multiple choice questionnaire, using electronic tablets. The majority of respondents received their last vaccination longer than 5 years earlier. A higher percentage of individuals in the older age groups received a vaccine in the last year, as opposed to their younger counterparts who obtained their last immunization 3 to 5 years earlier. Among the reasons given for not getting vaccinated were lack of time or money, feared injections and side effects, insufficient information, interest or motivation. Others did not get vaccines because they perceived themselves to be healthy and did not feel sick. Findings from this study have important implications for future preventive medicine and vaccination practices that reach socially excluded groups in times of COVID-19. Recommendations are made to facilitate access to vaccines to the target group of this study and other socially disadvantaged populations in the global health context.

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