Determination of Aortic Characteristic Impedance and Total Arterial Compliance From Regional Pulse Wave Velocities Using Machine Learning: An in-silico Study.
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SUBMITTER: Bikia V
PROVIDER: S-EPMC8155726 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Pulse wave velocity (PWV), a measure of arterial stiffness, is an independent risk factor for cardiovascular morbidity and mortality. We investigated the relationship of ambulatory brachial cuff-based oscillometric PWV (oPWV) to 2 known correlates: age and brachial systolic blood pressure (SBP). In 234 participants in the Masked Hypertension Study, we analyzed 7284 validated hourly ambulatory SBP and oPWV readings using the Mobil-O-Graph monitor, which uses a proprietary pulse wave analysis algorithm to determine oPWV. Carotid-femoral PWV (cfPWV) was also measured. Mixed linear models were developed to estimate oPWV from age and ambulatory SBP. Participants were 34% male, with mean (SD) age 52.8 (9.9) years, SBP 123.8 (18.4) mm Hg, and oPWV 7.6 (1.3) m/s and cfPWV of 7.7 (1.7) m/s. The relationship of oPWV to age and SBP is given below: [Formula: see text] Age uniquely accounted for an estimated 75% of the total variation of oPWV, whereas SBP uniquely accounted for 20%; these findings were confirmed in an external validation dataset. Together, age and SBP accounted for 99.1% of the total variance of oPWV but (only) 40.2% of the variance of cfPWV. The correlation between oPWV and cfPWV was 0.58 but was only 0.11 after controlling for age and SBP. We conclude that the Mobil-O-Graph's oPWV is nearly completely explained by age and SBP and its relationship to cfPWV is because of their shared associations with age and SBP. Other hemodynamic variables derived from oscillometric pulse wave analysis may be useful and deserve additional scrutiny.
| S-EPMC6679929 | biostudies-literature
Project description:Monitoring of the regional stiffening of the arterial wall may prove important in the diagnosis of various vascular pathologies. The pulse wave velocity (PWV) along the aortic wall has been shown to be dependent on the wall stiffness and has played a fundamental role in a range of diagnostic methods. Conventional clinical methods involve a global examination of the pulse traveling between two remote sites, e.g. femoral and carotid arteries, to provide an average PWV estimate. However, the majority of vascular diseases entail regional vascular changes and therefore may not be detected by a global PWV estimate. In this paper, a fluid-structure interaction study of straight-geometry aortas was carried out to examine the effects of regional stiffness changes on PWV. Five homogeneous aortas with increasing wall stiffness as well as two aortas with soft and hard inclusions were considered. In each case, spatio-temporal maps of the wall motion were used to analyze the regional pulse wave propagation. On the homogeneous aortas, increasing PWVs were found to increase with the wall moduli (R2 = 0.9988), indicating the reliability of the model to accurately represent the wave propagation. On the inhomogeneous aortas, formation of reflected and standing waves was observed at the site of the hard and soft inclusions, respectively. Neither the hard nor the soft inclusion had a significant effect on the velocity of the traveling pulse beyond the inclusion site, which supported the hypothesis that a global measurement of the average PWV could fail to detect regional abnormalities.
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Project description:OBJECTIVE:Assessment of local arterial properties has become increasingly important in cardiovascular research as well as in clinical domains. Vascular wall stiffness indices are related to local pulse pressure (?P) level, mechanical and geometrical characteristics of the arterial vessel. Non-invasive evaluation of local ?P from the central arteries (aorta and carotid) is not straightforward in a non-specialist clinical setting. In this work, we present a method and system for real-time and beat-by-beat evaluation of local ?P from superficial arteries-a non-invasive, cuffless and calibration-free technique. METHODS:The proposed technique uses a bi-modal arterial compliance probe which consisted of two identical magnetic plethysmograph (MPG) sensors located at 23 mm distance apart and a single-element ultrasound transducer. Simultaneously measured local pulse wave velocity (PWV) and arterial dimensions were used in a mathematical model for calibration-free evaluation of local ?P. The proposed approach was initially verified using an arterial flow phantom, with invasive pressure catheter as the reference device. The developed porotype device was validated on 22 normotensive human subjects (age = 24.5 ± 4 years). Two independent measurements of local ?P from the carotid artery were made during physically relaxed and post-exercise condition. RESULTS:Phantom-based verification study yielded a correlation coefficient (r) of 0.93 (p < 0.001) for estimated ?P versus reference brachial ?P, with a non-significant bias and standard deviation of error equal to 1.11 mmHg and ±1.97 mmHg respectively. The ability of the developed system to acquire high-fidelity waveforms (dual MPG signals and ultrasound echoes from proximal and distal arterial walls) from the carotid artery was demonstrated by the in-vivo validation study. The group average beat-to-beat variation in measured carotid local PWV, arterial diameter parameters-distension and end-diastolic diameter, and local ?P were 4.2%, 2.6%, 3.3%, and 10.2% respectively in physically relaxed condition. Consistent with the physiological phenomenon, local ?P measured from the carotid artery of young populations was, on an average, 22 mmHg lower than the reference ?P obtained from the brachial artery. Like the reference brachial blood pressure (BP) monitor, the developed prototype device reliably captured variations in carotid local ?P induced by an external intervention. CONCLUSION:This technique could provide a direct measurement of local PWV, arterial dimensions, and a calibration-free estimate of beat-by-beat local ?P. It can be potentially extended for calibration-free cuffless BP measurement and non-invasive characterization of central arteries with locally estimated biomechanical properties.
| S-EPMC6095577 | biostudies-literature
Project description:ObjectivesArterial stiffness and wave reflection parameters assessed from both invasive and non-invasive pressure and flow readings are used as surrogates for ventricular and vascular load. They have been reported to predict adverse cardiovascular events, but clinical assessment is laborious and may limit widespread use. This study aims to investigate measures of arterial stiffness and central hemodynamics provided by arterial tonometry alone and in combination with aortic root flows derived by echocardiography against surrogates derived by a mathematical pressure and flow model in a healthy middle-aged cohort.MethodsMeasurements of carotid artery tonometry and echocardiography were performed on 2226 ASKLEPIOS study participants and parameters of systemic hemodynamics, arterial stiffness and wave reflection based on pressure and flow were measured. In a second step, the analysis was repeated but echocardiography derived flows were substituted by flows provided by a novel mathematical model. This was followed by a quantitative method comparison.ResultsAll investigated parameters showed a significant association between the methods. Overall agreement was acceptable for all parameters (mean differences: -0.0102 (0.033 SD) mmHg*s/ml for characteristic impedance, 0.36 (4.21 SD) mmHg for forward pressure amplitude, 2.26 (3.51 SD) mmHg for backward pressure amplitude and 0.717 (1.25 SD) m/s for pulse wave velocity).ConclusionThe results indicate that the use of model-based surrogates in a healthy middle aged cohort is feasible and deserves further attention.
| S-EPMC4626380 | biostudies-literature
Project description:Although brachial-ankle pulse wave velocity (baPWV) has been widely used as an index of arterial stiffness, no consensus exists about whether baPWV can reflect central aortic stiffness. The authors investigated the association between baPWV and invasively measured aortic pulse pressure (APP) in a total of 109 consecutive patients (mean age, 62.3 ± 11.3 years; 67.9% men). Most patients (91%) had obstructive coronary artery disease, and mean baPWV and APP values were 1535 ± 303 cm/s and 66.8 ± 22.5 mm Hg, respectively. In univariate analysis, there was a significant linear correlation between baPWV and APP (r = .635, P < .001). The correlation between baPWV and APP remained significant even after controlling for potential confounders (β = 0.574, P < .001; R2 = .469). Arterial stiffness measured by baPWV showed a strong positive correlation with invasively measured APP, independent of clinical confounders. Therefore, baPWV can be a good marker of central aortic stiffness.
| S-EPMC8030939 | biostudies-literature
Project description:We present a novel analysis of arterial pulse wave propagation that combines traditional wave intensity analysis with identification of Windkessel pressures to account for the effect on the pressure waveform of peripheral wave reflections. Using haemodynamic data measured in vivo in the rabbit or generated numerically in models of human compliant vessels, we show that traditional wave intensity analysis identifies the timing, direction and magnitude of the predominant waves that shape aortic pressure and flow waveforms in systole, but fails to identify the effect of peripheral reflections. These reflections persist for several cardiac cycles and make up most of the pressure waveform, especially in diastole and early systole. Ignoring peripheral reflections leads to an erroneous indication of a reflection-free period in early systole and additional error in the estimates of (i) pulse wave velocity at the ascending aorta given by the PU-loop method (9.5% error) and (ii) transit time to a dominant reflection site calculated from the wave intensity profile (27% error). These errors decreased to 1.3% and 10%, respectively, when accounting for peripheral reflections. Using our new analysis, we investigate the effect of vessel compliance and peripheral resistance on wave intensity, peripheral reflections and reflections originating in previous cardiac cycles.
| S-EPMC4297358 | biostudies-literature
Project description:Modifiable risk factors, such as diet, are becomingly increasingly important in the management of cardiovascular disease, one of the greatest major causes of death and disease burden. Few studies have examined the role of diet as a possible means of reducing arterial stiffness, as measured by pulse wave velocity, an independent predictor of cardiovascular events and all-cause mortality. The aim of this study was to investigate whether dairy food intake is associated with measures of arterial stiffness, including carotid-femoral pulse wave velocity and pulse pressure. A cross-sectional analysis of a subset of the Maine-Syracuse Longitudinal Study sample was performed. A linear decrease in pulse wave velocity was observed across increasing intakes of dairy food consumption (ranging from never/rarely to daily dairy food intake). The negative linear relationship between pulse wave velocity and intake of dairy food was independent of demographic variables, other cardiovascular disease risk factors, and nutrition variables. The pattern of results was very similar for pulse pressure, whereas no association between dairy food intake and lipid levels was found. Further intervention studies are needed to ascertain whether dairy food intake may be an appropriate dietary intervention for the attenuation of age-related arterial stiffening and reduction of cardiovascular disease risk.
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Project description:The impact of brachial-ankle pulse wave velocity (baPWV) and heart-femoral pulse wave velocity (hfPWV) on rapid decline of estimated glomerular filtration rate (eGFR) has been inconclusive. The database of a multicenter prospective study of 2238 patients in Korea enrolled from 2011 to 2016 was reviewed. After excluding patients with missing baPWV (n?=?257) and eGFR change (n?=?180), the study included 1801 non-dialysis chronic kidney disease (CKD) patients. The eGFR change <-5ml/min/1.73?m2/year was defined as rapid decline. During a mean of 2.2 years, the mean eGFR change was -3.6?ml/min/1.73?m2/year, and 31.6% of patients were classified as having rapid decline. Older age, causes of CKD, increased heart rate, systolic blood pressures, and proteinuria were associated with the highest baPWV quintile. In multivariate logistic regression analyses, the odds of a rapid decline in eGFR was 1.9 times higher in the fifth quintile than in the first quintile (P?=?0.013). In a subset with baPWV and hfPWV (n?=?1182), high baPWV was associated with rapid eGFR decline only when accompanied by a high hfPWV. These findings suggest that central and peripheral PWVs may simultaneously affect rapid eGFR decline.
| S-EPMC5770427 | biostudies-literature
Project description:BackgroundAging of the proximal aorta can lead to increased pressure and flow pulsatility in the cerebral microcirculation, which may cause cognitive impairment. This study investigated the association between aortic characteristic impedance (Zc), an indicator of regional stiffness of the proximal aorta, and suspected mild cognitive impairment (MCI), compared with carotid-femoral pulse wave velocity (CFPWV).Methods and resultsA total of 1461 healthy community residents (46.4% men; age range, 35-96 years [mean±SD, 59.9±11.8 years]) without a history of cardiovascular events or stroke were included in the study. Zc was estimated using applanation tonometry and echocardiography. Cognitive function was assessed using the Mini-Mental State Examination. Education-adjusted cut points were used to define suspected MCI. Subjects with suspected MCI (n=493 [33.7%]) had significantly higher Zc and CFPWV than those without. In multivariable analysis, both Zc and CFPWV were inversely associated with Mini-Mental State Examination score. Zc (odds ratio per 1 SD, 1.22 [95% CI, 1.09-1.37] and CFPWV (odds ratio per 1 SD, 1.18 [95% CI, 1.01-1.38]) was also significantly associated with suspected MCI, after adjusting for age, sex, education level, mean arterial pressure, hypertension, diabetes, low-density lipoprotein cholesterol, and smoking status. In joint analysis, Zc was significantly associated with suspected MCI, but CFPWV was not. In the age subgroups of <50 years and 50 to 70 years, only Zc was significantly associated with suspected MCI.ConclusionsThis study found that Zc was significantly associated with Mini-Mental State Examination score and suspected MCI, especially in younger and middle-aged adults. These findings suggest that Zc may be a useful biomarker for identifying individuals at risk for MCI.
| S-EPMC10863810 | biostudies-literature
Project description:The abdominal aortic aneurysm (AAA) is a silent and often deadly vascular disease caused by the localized weakening of the arterial wall. Previous work has indicated that local changes in wall stiffness can be detected with pulse wave imaging (PWI), which is a non-invasive technique for tracking the propagation of pulse waves along the aorta at high spatial and temporal resolutions. The aim of this study was to assess the capability of PWI to monitor and stage AAA progression in a murine model of the disease. ApoE/TIMP-1 knockout mice (N = 18) were given angiotensin II for 30 days via subcutaneously implanted osmotic pumps. The suprarenal sections of the abdominal aortas were imaged every 2-3 d after implantation using a 30-MHz VisualSonics Vevo 770 with 15-?m lateral resolution. Pulse wave propagation was monitored at an effective frame rate of 8 kHz by using retrospective electrocardiogram gating and by performing 1-D cross-correlation on the radiofrequency signals to obtain the displacements induced by the waves. In normal aortas, the pulse waves propagated at constant velocities (2.8 ± 0.9 m/s, r(2) = 0.89 ± 0.11), indicating that the composition of these vessels was relatively homogeneous. In the mice that developed AAAs (N = 10), the wave speeds in the aneurysm sac were 45% lower (1.6 ± 0.6 m/s) and were more variable (r(2) = 0.66 ± 0.23). Moreover, the wave-induced wall displacements were at least 80% lower within the sacs compared with the surrounding vessel. Finally, in mice that developed fissures (N = 5) or ruptures (N = 3) at the sites of their AAA, higher displacements directed out of the lumen and with no discernible wave pattern (r(2) < 0.20) were observed throughout the cardiac cycle. These findings indicate that PWI can be used to distinguish normal murine aortas from aneurysmal, fissured and ruptured ones. Hence, PWI could potentially be used to monitor and stage human aneurysms by providing information complementary to standard B-mode ultrasound.
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