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Yim IHW, Parker KH, Drury NE, Lim HS. Pulmonary artery wave intensity analysis in pulmonary hypertension associated with heart failure and reduced left ventricular ejection fraction. Pulm Circ 2024; 14:e12345. [PMID: 38348196 PMCID: PMC10859878 DOI: 10.1002/pul2.12345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/27/2023] [Accepted: 01/26/2024] [Indexed: 02/15/2024] Open
Abstract
Wave intensity analysis (WIA) uses simultaneous changes in pressure and flow velocity to determine wave energy, type, and timing of traveling waves in the circulation. In this study, we characterized wave propagation in the pulmonary artery in patients with pulmonary hypertension associated with left-sided heart disease (PHLHD) and the effects of dobutamine. During right heart catheterization, pressure and velocity data were acquired using a dual-tipped pressure and Doppler flow sensor wire (Combowire; Phillips Volcano), and processed offline using customized Matlab software (MathWorks). Patients with low cardiac output underwent dobutamine challenge. Twenty patients with PHLHD (all heart failure with reduced left ventricular ejection fraction) were studied. Right ventricular systole produced a forward compression wave (FCW), followed by a forward decompression wave (FDW) during diastole. Wave reflection manifesting as backward compression wave (BCW) following the FCW was observed in 14 patients. Compared to patients without BCW, patients with BCW had higher mean pulmonary artery pressure (28.7 ± 6.12 vs. 38.6 ± 6.5 mmHg, p = 0.005), and lower pulmonary arterial capacitance (PAC: 2.88 ± 1.75 vs. 1.73 ± 1.16, p = 0.002). Pulmonary vascular resistance was comparable. Mean pulmonary artery pressure of 34.5 mmHg (area under the curve [AUC]: 0.881) and PAC of 2.29 mL/mmHg (AUC: 0.833) predicted BCW. The magnitude of the FCW increased with dobutamine (n = 11) and correlated with pulmonary artery wedge pressure. Wave reflection in PHLHD is more likely at higher pulmonary artery pressures and lower PAC and the magnitude of reflected waves correlated with pulmonary artery wedge pressure. Dobutamine increased FCW but did not affect wave reflection.
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Affiliation(s)
- Ivan H. W. Yim
- Department of Cardiac SurgeryUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUK
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
| | - Kim H. Parker
- Department of Biomedical EngineeringImperial CollegeLondonUK
| | - Nigel E. Drury
- Department of Cardiac SurgeryUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUK
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
| | - Hoong Sern Lim
- Department of Cardiac SurgeryUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUK
- Institute of Cardiovascular SciencesUniversity of BirminghamBirminghamUK
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2
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Moulton MJ, Secomb TW. A fast computational model for circulatory dynamics: effects of left ventricle-aorta coupling. Biomech Model Mechanobiol 2023; 22:947-959. [PMID: 36639560 PMCID: PMC10167185 DOI: 10.1007/s10237-023-01690-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 01/05/2023] [Indexed: 01/15/2023]
Abstract
The course of diseases such as hypertension, systolic heart failure and heart failure with a preserved ejection fraction is affected by interactions between the left ventricle (LV) and the vasculature. To study these interactions, a computationally efficient, biophysically based mathematical model for the circulatory system is presented. In a four-chamber model of the heart, the LV is represented by a previously described low-order, wall volume-preserving model that includes torsion and base-to-apex and circumferential wall shortening and lengthening, and the other chambers are represented using spherical geometries. Active and passive myocardial mechanics of all four chambers are included. The cardiac model is coupled with a wave propagation model for the aorta and a closed lumped-parameter circulation model. Parameters for the normal heart and aorta are determined by fitting to experimental data. Changes in the timing and magnitude of pulse wave reflections by the aorta are demonstrated with changes in compliance and taper of the aorta as seen in aging (decreased compliance, increased diameter and length), and resulting effects on LV pressure-volume loops and LV fiber stress and sarcomere shortening are predicted. Effects of aging of the aorta combined with reduced LV contractile force (failing heart) are examined. In the failing heart, changes in aortic properties with aging affect stroke volume and sarcomere shortening without appreciable augmentation of aortic pressure, and the reflected pressure wave contributes an increased proportion of aortic pressure.
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Affiliation(s)
- Michael J Moulton
- Department of Surgery, Cardiothoracic Surgery, University of Nebraska Medical Center, 982315 Nebraska Medical Center, Omaha, NE, 68198, USA.
| | - Timothy W Secomb
- Program in Applied Mathematics, University of Arizona, Tucson, AZ, 85724, USA
- Department of Physiology, University of Arizona, Tucson, AZ, 85724, USA
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3
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Tyberg JV. Wave propagation and reflection in the aorta and implications of the aortic Windkessel. EXPLORATION OF MEDICINE 2021. [DOI: 10.37349/emed.2021.00042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Some have said that it is inappropriate and perhaps impossible to consider wave and Windkessel phenomena simultaneously. For 50 years, arterial hemodynamics has been dominated by the frequency-domain “impedance analysis” in which it was assumed that all variations in aortic pressure and flow were caused only by forward- and backward-going waves. This paper is a review of the results of incorporating the effects of Frank’s Windkessel. We have taken the view that measured aortic pressure is the sum of a Windkessel component and forward-going and backward-going wave components. When the Windkessel component is initially subtracted out, the pattern of propagation and reflection of wave components becomes clear. Furthermore, this analysis obviates the implications of impedance analysis that have not been explained satisfactorily.
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Affiliation(s)
- John V. Tyberg
- Emeritus Professor of Cardiac Sciences and Physiology/Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Pomella N, Rietzschel ER, Segers P, Khir AW. Impact of varying diastolic pressure fitting technique for the reservoir-wave model on wave intensity analysis. Proc Inst Mech Eng H 2020; 234:1300-1311. [PMID: 32996433 PMCID: PMC7675780 DOI: 10.1177/0954411920959957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 08/27/2020] [Indexed: 01/09/2023]
Abstract
The reservoir-wave model assumes that the measured arterial pressure is made of two components: reservoir and excess. The effect of the reservoir volume should be excluded to quantify the effects of forward and backward traveling waves on blood pressure. Whilst the validity of the reservoir-wave concept is still debated, there is no consensus on the best fitting method for the calculation of the reservoir pressure waveform. Therefore, the aim of this parametric study is to examine the effects of varying the fitting technique on the calculation of reservoir and excess components of pressure and velocity waveforms. Common carotid pressure and flow velocity were measured using applanation tonometry and doppler ultrasound, respectively, in 1037 healthy humans collected randomly from the Asklepios population, aged 35 to 55 years old. Different fitting techniques to the diastolic decay of the measured arterial pressure were used to determine the asymptotic pressure decay, which in turn was used to determine the reservoir pressure waveform. The corresponding wave speed was determined using the PU-loop method, and wave intensity parameters were calculated and compared. Different fitting methods resulted in significant changes in the shape of the reservoir pressure waveform; however, its peak and time integral remained constant in this study. Although peak and integral of excess pressure, velocity components and wave intensity changed significantly with changing the diastolic decay fitting method, wave speed was not substantially modified. We conclude that wave speed, peak reservoir pressure and its time integral are independent of the diastolic pressure decay fitting techniques examined in this study. Therefore, these parameters are considered more reliable diagnostic indicators than excess pressure and velocity which are more sensitive to fitting techniques.
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Affiliation(s)
- Nicola Pomella
- Biomedical Engineering Research Group, Brunel University London, UK
- Centre for Genomics and Child Health, Blizard Institute, Queen Mary University of London, UK
- Current affiliation: Centre for Genomics and Child Health, Blizard Institute, Queen Mary University of London, UK
| | - Ernst R Rietzschel
- Department of Cardiovascular Diseases, Ghent University Hospital, Ghent, Belgium
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Armstrong MK, Schultz MG, Picone DS, Black JA, Dwyer N, Roberts-Thomson P, Sharman JE. Associations of Reservoir-Excess Pressure Parameters Derived From Central and Peripheral Arteries With Kidney Function. Am J Hypertens 2020; 33:325-330. [PMID: 32006010 DOI: 10.1093/ajh/hpaa013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 12/17/2019] [Accepted: 01/30/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Central artery reservoir-excess pressure parameters are clinically important but impractical to record directly. However, diastolic waveform morphology is consistent across central and peripheral arteries. Therefore, peripheral artery reservoir-excess pressure parameters related to diastolic waveform morphology may be representative of central parameters and share clinically important associations with end-organ damage. This has never been determined and was the aim of this study. METHODS Intra-arterial blood pressure (BP) waveforms were measured sequentially at the aorta, brachial, and radial arteries among 220 individuals (aged 61 ± 10 years, 68% male). Customized software was used to derive reservoir-excess pressure parameters at each arterial site (reservoir and excess pressure, systolic and diastolic rate constants) and clinical relevance was determined by association with estimated glomerular filtration rate (eGFR). RESULTS Between the aorta and brachial artery, the mean difference in the diastolic rate constant and reservoir pressure integral was -0.162 S-1 (P = 0.08) and -0.772 mm Hg s (P = 0.23), respectively. The diastolic rate constant had the strongest and most consistent associations with eGFR across aortic and brachial sites (β = -0.20, P = 0.02; β = -0.20, P = 0.03, respectively; adjusted for traditional cardiovascular risk factors). Aortic, but not brachial peak reservoir pressure was associated with eGFR in adjusted models (aortic β = -0.48, P = 0.02). CONCLUSIONS The diastolic rate constant is the most consistent reservoir-excess pressure parameter, in both its absolute values and associations with kidney dysfunction, when derived from the aorta and brachial artery. Thus, the diastolic rate constant could be utilized in the clinical setting to improve BP risk stratification.
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Affiliation(s)
| | - Martin G Schultz
- Menzies Institute for Medical Research, University of Tasmania, Australia
| | - Dean S Picone
- Menzies Institute for Medical Research, University of Tasmania, Australia
| | - J Andrew Black
- Department of Cardiology, Royal Hobart Hospital, Australia
| | - Nathan Dwyer
- Department of Cardiology, Royal Hobart Hospital, Australia
| | | | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania, Australia
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Changes in hemodynamics associated with metabolic syndrome are more pronounced in women than in men. Sci Rep 2019; 9:18377. [PMID: 31804574 PMCID: PMC6895092 DOI: 10.1038/s41598-019-54926-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 11/18/2019] [Indexed: 01/09/2023] Open
Abstract
The increase in cardiovascular risk associated with metabolic syndrome (MS) seems higher in women than in men. We examined hemodynamics during head-up tilt in 252 men and 250 women without atherosclerosis, diabetes, or antihypertensive medication, mean age 48 years, using whole-body impedance cardiography and radial pulse wave analysis. MS was defined according to Alberti et al. 2009. Men and women with MS presented with corresponding elevations of systolic and diastolic blood pressure (10-14%, p ≤ 0.001) versus controls. Supine pulse wave velocity (16-17%, p < 0.001) and systemic vascular resistance (7-9%, p ≤ 0.026), and upright cardiac output (6-11%, p ≤ 0.008) were higher in both MS groups than controls. Elevation of supine aortic characteristic impedance was higher in women than in men with MS (16% vs. 8%, p = 0.026), and in contrast to men, no upright impedance reduction was observed in women. When upright, women but not men with MS showed faster return of reflected pressure wave (p = 0.036), and smaller decrease in left cardiac work (p = 0.035) versus controls. The faster upright return of reflected pressure, lower upright decrease in left cardiac work, and higher elevation of aortic characteristic impedance may contribute to the greater increase in MS-related cardiovascular risk in women than in men.
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Michail M, Narayan O, Parker KH, Cameron JD. Relationship of aortic excess pressure obtained using pressure-only reservoir pressure analysis to directly measured aortic flow in humans. Physiol Meas 2018; 39:064006. [DOI: 10.1088/1361-6579/aaca87] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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8
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de Tombe PP, Tyberg JV. Frank's law of the heart: Found in translation. J Mol Cell Cardiol 2018; 121:33-35. [PMID: 29908919 DOI: 10.1016/j.yjmcc.2018.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 05/17/2018] [Accepted: 06/06/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Pieter P de Tombe
- Magdi Yacoub Institute, Harefield, United Kingdom; University of Illinois at Chicago, Chicago, USA; Freiburg University, Freiburg, Germany; Imperial College London, London, UK.
| | - John V Tyberg
- Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Canada
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Huang JT, Cheng HM, Yu WC, Lin YP, Sung SH, Wang JJ, Wu CL, Chen CH. Value of Excess Pressure Integral for Predicting 15-Year All-Cause and Cardiovascular Mortalities in End-Stage Renal Disease Patients. J Am Heart Assoc 2017; 6:JAHA.117.006701. [PMID: 29187389 PMCID: PMC5779003 DOI: 10.1161/jaha.117.006701] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The excess pressure integral (XSPI), derived from analysis of the arterial pressure curve, may be a significant predictor of cardiovascular events in high-risk patients. We comprehensively investigated the prognostic value of XSPI for predicting long-term mortality in end-stage renal disease patients undergoing regular hemodialysis. METHODS AND RESULTS A total of 267 uremic patients (50.2% female; mean age 54.2±14.9 years) receiving regular hemodialysis for more than 6 months were enrolled. Cardiovascular parameters were obtained by echocardiography and applanation tonometry. Calibrated carotid arterial pressure waveforms were analyzed according to the wave-transmission and reservoir-wave theories. Multivariable Cox proportional hazard models were constructed to account for age, sex, diabetes mellitus, albumin, body mass index, and hemodialysis treatment adequacy. Incremental utility of the parameters to risk stratification was assessed by net reclassification improvement. During a median follow-up of 15.3 years, 124 deaths (46.4%) incurred. Baseline XSPI was significantly predictive of all-cause (hazard ratio per 1 SD 1.4, 95% confidence interval 1.15-1.70, P=0.0006) and cardiovascular mortalities (1.47, 1.18-1.84, P=0.0006) after accounting for the covariates. The addition of XSPI to the base prognostic model significantly improved prediction of both all-cause mortality (net reclassification improvement=0.1549, P=0.0012) and cardiovascular mortality (net reclassification improvement=0.1535, P=0.0033). XSPI was superior to carotid-pulse wave velocity, forward and backward wave amplitudes, and left ventricular ejection fraction in consideration of overall independent and incremental prognostics values. CONCLUSIONS In end-stage renal disease patients undergoing regular hemodialysis, XSPI was significantly predictive of long-term mortality and demonstrated an incremental value to conventional prognostic factors.
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Affiliation(s)
- Jui-Tzu Huang
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Hao-Min Cheng
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan .,Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Medical Education, Center for Evidence-Based Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Wen-Chung Yu
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yao-Ping Lin
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shih-Hsien Sung
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jiun-Jr Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Chung-Li Wu
- Department of Medical Education, Center for Evidence-Based Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chen-Huan Chen
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan .,Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Medical Education, Center for Evidence-Based Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
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10
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Hydren JR, Richardson RS, Symons JD, Mynard JP, Smolich JJ, Ramos JS, Dias KA, Dalleck LC, Drummond C, Westerhof B, Westerhof N, Zuo L, Zhou T. Commentaries on Viewpoint: Origin of the forward-going "backward" wave. J Appl Physiol (1985) 2017; 123:1408-1410. [PMID: 29167201 DOI: 10.1152/japplphysiol.00758.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 11/22/2022] Open
Affiliation(s)
| | | | | | | | | | | | - Katrin A Dias
- Institute for Exercise and Environmental Medicine.,University of Texas Southwestern Medical Center
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11
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Tyberg JV, Burrowes LM, Bouwmeester JC, Wang JJ, Shrive NG, Parker KH. Last Word on Viewpoint: Origin of the forward-going "backward" wave. J Appl Physiol (1985) 2017; 123:1411. [PMID: 29167202 DOI: 10.1152/japplphysiol.00759.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 11/22/2022] Open
Affiliation(s)
- John V Tyberg
- Departments of Cardiac Sciences and Physiology/Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada;
| | - Lindsay M Burrowes
- Departments of Cardiac Sciences and Physiology/Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | | | - Jiun-Jr Wang
- Department of Medicine, School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Nigel G Shrive
- Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; and
| | - Kim H Parker
- Department of Biomedical Engineering, Imperial College, London, United Kingdom
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12
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On aortic pressure waveforms and a happy or unhappy marriage between wave propagation and Windkessel models. J Hypertens 2017; 35:1955-1957. [PMID: 28858197 DOI: 10.1097/hjh.0000000000001448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Tyberg JV, Burrowes LM, Shrive NG, Wang JJ. Origin of the forward-going "backward" wave. J Appl Physiol (1985) 2017; 123:1406-1407. [PMID: 28663376 DOI: 10.1152/japplphysiol.00350.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 06/13/2017] [Accepted: 06/27/2017] [Indexed: 01/09/2023] Open
Affiliation(s)
- John V Tyberg
- Departments of Cardiac Sciences and Physiology/Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada;
| | - Lindsay M Burrowes
- Departments of Cardiac Sciences and Physiology/Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Nigel G Shrive
- Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; and
| | - Jiun-Jr Wang
- Department of Medicine, School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
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14
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Cheng HM, Chuang SY, Wang JJ, Shih YT, Wang HN, Huang CJ, Huang JT, Sung SH, Lakatta EG, Yin FCP, Chou P, Yeh CJ, Bai CH, Pan WH, Chen CH. Prognostic significance of mechanical biomarkers derived from pulse wave analysis for predicting long-term cardiovascular mortality in two population-based cohorts. Int J Cardiol 2016; 215:388-95. [PMID: 27128568 PMCID: PMC10617614 DOI: 10.1016/j.ijcard.2016.04.070] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/11/2016] [Indexed: 11/26/2022]
Abstract
BACKGROUND Numerous mechanical biomarkers derived from pulse wave analysis (PWA) have been proposed to predict cardiovascular outcomes. However, whether these biomarkers carry independent prognostic value and clinical utility beyond traditional cardiovascular risk factors hasn't been systematically evaluated. We aimed to investigate the additive utility of PWA-derived biomarkers in two independent population-based cohorts. METHODS PWA on central arterial pressure waveforms obtained from subjects without a prior history of cardiovascular diseases of two studies was conducted based on the wave transmission and reservoir-wave theory: firstly in the Kinmen study (1272 individuals, a median follow-up of 19.8years); and then in the Cardiovascular Disease Risk Factors Two-Township Study (2221 individuals, median follow-up of 10years). The incremental value of the biomarkers was evaluated by net reclassification index (NRI). RESULTS In multivariate Cox analyses accounting for age, gender, body mass index, systolic blood pressure, fasting glucose, high-density- and low-density-lipoprotein cholesterol, and smoking, only systolic (SC) and diastolic rate constant (DC) of reservoir pressure could independently and consistently predict cardiovascular mortality in both cohorts and the combined cohort (SC: hazard ratio 1.18 [95% confidence interval 1.08-1.28, p<0.001; DC: 1.18 [1.09-1.28], p<0.001]. Risk prediction estimates in traditional risk prediction models were significantly more accurate when incorporating peak of reservoir pressure (NRI=0.049, p=0.0361), SC (NRI=0.043, p=0.0236) and DC (NRI=0.054, p=0.047). CONCLUSIONS Of all PWA-derived biomarkers, SC and DC were consistently identified as valuable parameters for incremental cardiovascular risk prediction in two large prospective cohorts.
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Affiliation(s)
- Hao-Min Cheng
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan; Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan; Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Public Health, National Yang-Ming University, Taipei, Taiwan
| | - Shao-Yuan Chuang
- Division of Preventive Medicine and Health Service, Research Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan
| | - Jiun-Jr Wang
- School of Medicine, Fu Jen Catholic University, Xinzhuang District, New Taipei City, Taiwan
| | - Yuan-Ta Shih
- Molecular Imaging Center, National Taiwan University, Taipei, Taiwan
| | - Hsin-Ning Wang
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chi-Jung Huang
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jui-Tzu Huang
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Hsien Sung
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Edward G Lakatta
- The Laboratory of Cardiovascular Science in the National Institute on Aging Intramural Research Program in Baltimore, MD, USA
| | - Frank C P Yin
- Department of Biomedical Engineering, Washington University, St Louis, MO, USA
| | - Pesus Chou
- Department of Public Health, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Jung Yeh
- Department of Public Health, Chung-Shan Medical University, Taichung, Taiwan
| | | | - Wen-Harn Pan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chen-Huan Chen
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan; Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan; Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Public Health, National Yang-Ming University, Taipei, Taiwan.
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Mynard JP. Assessment of conceptual inconsistencies in the hybrid reservoir-wave model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2013:213-6. [PMID: 24109662 DOI: 10.1109/embc.2013.6609475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The reservoir-wave paradigm separates pressure into windkessel-related 'reservoir' and wave-related 'excess' components, however the conceptual validity of this approach has not been sufficiently scrutinized. This paper assesses two logical implications of the reservoir-wave concept. First, parameters defining the reservoir (resistance and compliance) should be independent of wave effects. Second, wave analysis performed using excess pressure should provide a more accurate and physically intuitive representation of wave propagation and reflection in a vascular system, compared with the traditional wave analysis based on unseparated pressure. These issues were investigated with one-dimensional numerical models. Using a single vessel model, reservoir parameters were shown to be highly influenced by wave propagation effects. In a single bifurcation model, wave analysis based on excess pressure underestimated the reflection coefficient of the known impedance mismatch at the junction, overestimated the distance to this reflection site, and exhibited backward expansion waves suggestive of multiple negative impedance mismatches that did not exist in the system. Traditional wave analysis accurately and intuitively described waves. The identified conceptual inconsistencies in the reservoir-wave paradigm may arise from the use of hybrid (0D and 1D) dimensionality, rather than a hierarchical approach to model dimensionality.
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Hughes AD, Davies JE, Parker KH. The importance of wave reflection: A comparison of wave intensity analysis and separation of pressure into forward and backward components. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2013:229-32. [PMID: 24109666 DOI: 10.1109/embc.2013.6609479] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Waves and wave reflections play an undoubted role in arterial hemodynamics. Wave intensity analysis and separation of pressure into forward and backward components can both be used to analyze wave phenomena in arteries, but result in different interpretations regarding the contribution of wave reflections to the aorta blood pressure waveform. We compare these approaches using pressure and flow measurements made in the human aorta and discuss why the interpretations might differ.
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Capoccia M. Development and Characterization of the Arterial Windkessel and Its Role During Left Ventricular Assist Device Assistance. Artif Organs 2015; 39:E138-53. [DOI: 10.1111/aor.12532] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Massimo Capoccia
- Cardiothoracic Surgery; Royal Stoke University Hospital; Stoke-on-Trent UK
- Biomedical Engineering; University of Strathclyde; Glasgow UK
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Climie RED, Srikanth V, Keith LJ, Davies JE, Sharman JE. Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus. Am J Physiol Heart Circ Physiol 2015; 308:H1136-42. [DOI: 10.1152/ajpheart.00739.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 02/18/2015] [Indexed: 12/21/2022]
Abstract
Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise ( P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P < 0.01 all). In T2DM (but not controls), exercise Pexcess was associated with postexercise ACR ( r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcess could be important for appropriate renal function in T2DM.
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Affiliation(s)
- Rachel E. D. Climie
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia
| | - Velandai Srikanth
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia
- Stroke and Ageing Research Group, Monash Medical Centre, Department of Medicine, Southern Clinical School, Monash University, Melbourne, Australia; and
| | - Laura J. Keith
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia
| | - Justin E. Davies
- International Centre for Circulatory Health, Imperial College, London, United Kingdom
| | - James E. Sharman
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia
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19
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Narayan O, Davies JE, Hughes AD, Dart AM, Parker KH, Reid C, Cameron JD. Central aortic reservoir-wave analysis improves prediction of cardiovascular events in elderly hypertensives. Hypertension 2014; 65:629-35. [PMID: 25534707 DOI: 10.1161/hypertensionaha.114.04824] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Several morphological parameters based on the central aortic pressure waveform are proposed as cardiovascular risk markers, yet no study has definitively demonstrated the incremental value of any waveform parameter in addition to currently accepted biomarkers in elderly, hypertensive patients. The reservoir-wave concept combines elements of wave transmission and Windkessel models of arterial pressure generation, defining an excess pressure superimposed on a background reservoir pressure. The utility of pressure rate constants derived from reservoir-wave analysis in prediction of cardiovascular events is unknown. Carotid blood pressure waveforms were measured prerandomization in a subset of 838 patients in the Second Australian National Blood Pressure Study. Reservoir-wave analysis was performed and indices of arterial function, including the systolic and diastolic rate constants, were derived. Survival analysis was performed to determine the association between reservoir-wave parameters and cardiovascular events. The incremental utility of reservoir-wave parameters in addition to the Framingham Risk Score was assessed. Baseline values of the systolic rate constant were independently predictive of clinical outcome (hazard ratio, 0.33; 95% confidence interval, 0.13-0.82; P=0.016 for fatal and nonfatal stroke and myocardial infarction and hazard ratio, 0.38; 95% confidence interval, 0.20-0.74; P=0.004 for the composite end point, including all cardiovascular events). Addition of this parameter to the Framingham Risk Score was associated with an improvement in predictive accuracy for cardiovascular events as assessed by the integrated discrimination improvement and net reclassification improvement indices. This analysis demonstrates that baseline values of the systolic rate constant predict clinical outcomes in elderly patients with hypertension and incrementally improve prognostication of cardiovascular events.
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Affiliation(s)
- Om Narayan
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - Justin E Davies
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - Alun D Hughes
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - Anthony M Dart
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - Kim H Parker
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - Christopher Reid
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.)
| | - James D Cameron
- From the Monash Cardiovascular Research Centre, School of Clinical Sciences at Monash, Monash University, Melbourne Australia (O.N., J.D.C.); International Centre for Circulatory Health (J.E.D.), and Department of Bioengineering (K.H.P.), Imperial College, London, United Kingdom; UCL Institute of Cardiovascular Science, University College London, United Kingdom (A.D.H.); Baker IDI Heart and Diabetes Institute, Melbourne, Australia (A.M.D.); Department of Epidemiology & Preventative Medicine, Monash University, Melbourne, Australia (C.R.); and MonashHeart, Monash Health, Victoria, Australia (O.N., J.D.C.).
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20
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Climie RED, Srikanth V, Beare R, Keith LJ, Fell J, Davies JE, Sharman JE. Aortic reservoir characteristics and brain structure in people with type 2 diabetes mellitus; a cross sectional study. Cardiovasc Diabetol 2014; 13:143. [PMID: 25338824 PMCID: PMC4221700 DOI: 10.1186/s12933-014-0143-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 10/06/2014] [Indexed: 01/09/2023] Open
Abstract
Background Central hemodynamics help to maintain appropriate cerebral and other end-organ perfusion, and may be altered with ageing and type 2 diabetes mellitus (T2DM). We aimed to determine the associations between central hemodynamics and brain structure at rest and during exercise in people with and without T2DM. Methods In a sample of people with T2DM and healthy controls, resting and exercise measures of aortic reservoir characteristics (including excess pressure integral [Pexcess]) and other central hemodynamics (including augmentation index [AIx] and aortic pulse wave velocity [aPWV]) were recorded. Brain volumes (including gray matter volume [GMV] and white matter lesions [WML]) were derived from magnetic resonance imaging (MRI) scans. Multivariable linear regression was used to study the associations of hemodynamic variables with brain structure in the two groups adjusting for age, sex, daytime systolic BP (SBP) and heart rate. Results There were 37 T2DM (63 ± 9 years; 47% male) and 37 healthy individuals (52 ± 8 years; 51% male). In T2DM, resting aPWV was inversely associated with GMV (standardized β = −0.47, p = 0.036). In healthy participants, resting Pexcess was inversely associated with GMV (β = −0.23, p = 0.043) and AIx was associated with WML volume (β = 0.52, p = 0.021). There were no associations between exercise hemodynamics and brain volumes in either group. Conclusions Brain atrophy is associated with resting aortic stiffness in T2DM, and resting Pexcess in healthy individuals. Central vascular mechanisms underlying structural brain changes may differ between healthy individuals and T2DM.
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21
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Tyberg JV, Bouwmeester JC, Parker KH, Shrive NG, Wang JJ. Response to the letter of Mynard and Smolich. Int J Cardiol 2014; 176:1391. [DOI: 10.1016/j.ijcard.2014.08.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 08/02/2014] [Indexed: 10/24/2022]
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model. J Physiol 2014; 592:3801-12. [PMID: 25015922 DOI: 10.1113/jphysiol.2014.272963] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in 'excess' quantities which were treated as wave-related.Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)).Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e.pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nigel G Shrive
- Department of Civil Engineering, University of Calgary, Calgary, Alberta, Canada
| | - John V Tyberg
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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23
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Schultz MG, Davies JE, Hardikar A, Pitt S, Moraldo M, Dhutia N, Hughes AD, Sharman JE. Aortic Reservoir Pressure Corresponds to Cyclic Changes in Aortic Volume. Arterioscler Thromb Vasc Biol 2014; 34:1597-603. [DOI: 10.1161/atvbaha.114.303573] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Objective—
Aortic reservoir pressure indices independently predict cardiovascular events and mortality. Despite this, there has never been a study in humans to determine whether the theoretical principles of the mathematically derived aortic reservoir pressure (RP
derived
) and excess pressure (XP
derived
) model have a real physiological basis. This study aimed to directly measure the aortic reservoir (AR
direct
; by cyclic change in aortic volume) and determine its relationship with RP
derived
, XP
derived
, and aortic blood pressure (BP).
Approach and Results—
Ascending aortic BP and Doppler flow velocity were recorded via intra-arterial wire in 10 men (aged 62±12 years) during coronary artery bypass surgery. Simultaneous ascending aortic transesophageal echocardiography was used to measure AR
direct
. Published mathematical formulae were used to determine RP
derived
and XP
derived
. AR
direct
was strongly and linearly related to RP
derived
during systole (
r
=0.988;
P
<0.001) and diastole (
r
=0.985;
P
<0.001). Peak cross-correlation (
r
=0.98) occurred at a phase lag of 0.004 s into the cardiac cycle, suggesting close temporal agreement between waveforms. The relationship between aortic BP and AR
direct
was qualitatively similar to the cyclic relationship between aortic BP and RP
derived
, with peak cross-correlations occurring at identical phase lags (AR
direct
versus aortic BP,
r
=0.96 at 0.06 s; RP
derived
versus aortic BP,
r
=0.98 at 0.06 s).
Conclusions—
RP
derived
is highly correlated with changes in proximal aortic volume, consistent with its physiological interpretation as corresponding to the instantaneous volume of blood stored in the aorta. Thus, aortic reservoir pressure should be considered in the interpretation of the central BP waveform.
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Affiliation(s)
- Martin G. Schultz
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Justin E. Davies
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Ashutosh Hardikar
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Simon Pitt
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Michela Moraldo
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Niti Dhutia
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - Alun D. Hughes
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
| | - James E. Sharman
- From the Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia (M.G.S., A.H., J.E.S.); International Centre for Circulatory Health, Imperial College London, London, United Kingdom (J.E.D., M.M, N.D.); Royal Hobart Hospital, Hobart, Tasmania, Australia (S.P.); and Institute of Cardiovascular Science, University College London, London, United Kingdom (A.D.H.)
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24
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Wave reflections in the pulmonary arteries analysed with the reservoir-wave model. J Physiol 2014; 592:3053-62. [PMID: 24756638 DOI: 10.1113/jphysiol.2014.273094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conventional haemodynamic analysis of pressure and flow in the pulmonary circulation yields incident and reflected waves throughout the cardiac cycle, even during diastole. The reservoir-wave model provides an alternative haemodynamic analysis consistent with minimal wave activity during diastole. Pressure and flow in the main pulmonary artery were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading and positive end-expiratory pressure were observed. The reservoir-wave model was used to determine the reservoir contribution to pressure and flow and once subtracted, resulted in 'excess' quantities, which were treated as wave-related. Wave intensity analysis quantified the contributions of waves originating upstream (forward-going waves) and downstream (backward-going waves). In the pulmonary artery, negative reflections of incident waves created by the right ventricle were observed. Overall, the distance from the pulmonary artery valve to this reflection site was calculated to be 5.7 ± 0.2 cm. During 100% O2 ventilation, the strength of these reflections increased 10% with volume loading and decreased 4% with 10 cmH2O positive end-expiratory pressure. In the pulmonary arterial circulation, negative reflections arise from the junction of lobar arteries from the left and right pulmonary arteries. This mechanism serves to reduce peak systolic pressure, while increasing blood flow.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Medicine
| | | | - John V Tyberg
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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25
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Tyberg JV, Bouwmeester JC, Parker KH, Shrive NG, Wang JJ. The case for the reservoir-wave approach. Int J Cardiol 2014; 172:299-306. [DOI: 10.1016/j.ijcard.2013.12.178] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/07/2013] [Accepted: 12/31/2013] [Indexed: 01/09/2023]
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26
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Hametner B, Wassertheurer S, Hughes AD, Parker KH, Weber T, Eber B. Reservoir and excess pressures predict cardiovascular events in high-risk patients. Int J Cardiol 2013; 171:31-6. [PMID: 24315153 DOI: 10.1016/j.ijcard.2013.11.039] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/14/2013] [Accepted: 11/17/2013] [Indexed: 01/09/2023]
Abstract
BACKGROUND Analysis of the arterial pressure curve plays an increasing role in cardiovascular risk stratification. Measures of wave reflection and aortic stiffness have been identified as independent predictors of risk. Their determination is usually based on wave propagation models of the circulation. Another modeling approach relies on modified Windkessel models, where pressure curves can be divided into reservoir and excess pressure. Little is known of their prognostic value. METHODS AND RESULTS The aim of this study is to evaluate the predictive value of parameters gained from reservoir theory applied to aortic pressure curves in a cohort of high-risk patients. Furthermore the relation of these parameters to those from wave separation analysis is investigated. Central pressure curves from 674 patients with preserved ejection fraction, measured by radial tonometry and a validated transfer function, were analyzed. A high correlation between the amplitudes of backward traveling pressure waves and reservoir pressures was found (R=0.97). Various parameters calculated from the reservoir and excess pressure waveforms predicted cardiovascular events in univariate Cox proportional hazards modeling. In a multivariate model including several other risk factors such as brachial blood pressure, the amplitude of reservoir pressure remained a significant predictor (HR=1.37 per SD, p=0.016). CONCLUSIONS Based on very different models, parameters from reservoir theory and wave separation analysis are closely related and can predict cardiovascular events to a similar extent. Although Windkessel models cannot describe all of the physiological properties of the arterial system, they can be useful to analyze its behavior and to predict cardiovascular events.
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Affiliation(s)
- Bernhard Hametner
- Health & Environment Department, AIT Austrian Institute of Technology, Vienna, Austria; International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College London, United Kingdom.
| | - Siegfried Wassertheurer
- Health & Environment Department, AIT Austrian Institute of Technology, Vienna, Austria; Department of Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Alun D Hughes
- UCL Institute of Cardiovascular Science, University College London, United Kingdom
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, United Kingdom
| | - Thomas Weber
- Cardiology Department, Klinikum Wels-Grieskirchen, Wels, Austria
| | - Bernd Eber
- Cardiology Department, Klinikum Wels-Grieskirchen, Wels, Austria
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27
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Westerhof N, Westerhof BE. CrossTalk proposal: Forward and backward pressure waves in the arterial system do represent reality. J Physiol 2013; 591:1167-9; discussion 1177. [PMID: 23457373 DOI: 10.1113/jphysiol.2012.249763] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Nico Westerhof
- Department of Pulmonary Diseases, Institute for Cardiovascular Research, ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands.
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28
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Tyberg JV, Bouwmeester JC, Shrive NG, Wang JJ. CrossTalk opposing view: Forward and backward pressure waves in the arterial system do not represent reality. J Physiol 2013; 591:1171-3; discussion 1175. [PMID: 23457374 DOI: 10.1113/jphysiol.2012.249557] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- John V Tyberg
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
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29
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Tyberg JV, Bouwmeester JC, Shrive NG, Wang JJ. Rebuttal from John V. Tyberg, J. Christopher Bouwmeester, Nigel G. Shrive and Jiun-Jr Wang. J Physiol 2013. [DOI: 10.1113/jphysiol.2012.250357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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30
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31
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Wang JJ, Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Alterations in Aortic Wave Reflection With Vasodilation and Vasoconstriction in Anaesthetized Dogs. Can J Cardiol 2013; 29:243-53. [DOI: 10.1016/j.cjca.2012.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 03/11/2012] [Accepted: 03/11/2012] [Indexed: 11/15/2022] Open
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32
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33
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King SG, Ahuja KDK, Wass J, Shing CM, Adams MJ, Davies JE, Sharman JE, Williams AD. Effect of whole-body mild-cold exposure on arterial stiffness and central haemodynamics: a randomised, cross-over trial in healthy men and women. Eur J Appl Physiol 2012; 113:1257-69. [DOI: 10.1007/s00421-012-2543-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 10/31/2012] [Indexed: 01/23/2023]
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34
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35
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Mohiuddin MW, Rihani RJ, Laine GA, Quick CM. Increasing pulse wave velocity in a realistic cardiovascular model does not increase pulse pressure with age. Am J Physiol Heart Circ Physiol 2012; 303:H116-25. [PMID: 22561301 DOI: 10.1152/ajpheart.00801.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (C(tot)) and increases in total peripheral resistance (R(tot)) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because increases in pulse wave velocity (c(ph)) make the reflected pressure wave arrive earlier, augmenting systolic pressure. It has recently been shown, however, that increases in c(ph) do not have a commensurate effect on the timing of the reflected wave. We therefore used a validated, large-scale, human arterial system model that includes realistic pulse wave transmission to determine whether increases in c(ph) cause increased PP with age. First, we made the realistic arterial system model age dependent by altering cardiac output (CO), R(tot), C(tot), and c(ph) to mimic the reported changes in these parameters from age 30 to 70. Then, c(ph) was theoretically maintained constant, while C(tot), R(tot), and CO were altered. The predicted increase in PP with age was similar to the observed increase in PP. In a complementary approach, C(tot), R(tot), and CO were theoretically maintained constant, and c(ph) was increased. The predicted increase in PP was negligible. We found that increases in c(ph) have a limited effect on the timing of the reflected wave but cause the system to degenerate into a windkessel. Changes in PP can therefore be attributed to a decrease in C(tot).
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Affiliation(s)
- Mohammad W Mohiuddin
- Michael E. DeBakey Institute, Texas A&M University, College Station, 77843-4466, USA
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Sridharan SS, Burrowes LM, Bouwmeester JC, Wang JJ, Shrive NG, Tyberg JV. Classical electrical and hydraulic Windkessel models validate physiological calculations of Windkessel (reservoir) pressure. Can J Physiol Pharmacol 2012; 90:579-85. [DOI: 10.1139/y2012-027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Our “reservoir–wave approach” to arterial hemodynamics holds that measured arterial pressure should be considered to be the sum of a volume-related pressure (i.e., reservoir pressure, Preservoir) and a wave-related pressure (Pexcess). Because some have questioned whether Preservoir (and, by extension, Pexcess) is a real component of measured physiological pressure, it was important to demonstrate that Preservoir is implicit in Westerhof’s classical electrical and hydraulic models of the 3-element Windkessel. To test the validity of our Preservoir determinations, we studied a freeware simulation of the electrical model and a benchtop recreation of the hydraulic model, respectively, measuring the voltage and the pressure distal to the proximal resistance. These measurements were then compared with Preservoir, as calculated from physiological data. Thus, the first objective of this study was to demonstrate that respective voltage and pressure changes could be measured that were similar to calculated physiological values of Preservoir. The second objective was to confirm previous predictions with respect to the specific effects of systematically altering proximal resistance, distal resistance, and capacitance. The results of this study validate Preservoir and, thus, the reservoir–wave approach.
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Affiliation(s)
- Sarup S. Sridharan
- Department of Cardiac Sciences and Department of Physiology and Pharmacology, and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Lindsay M. Burrowes
- Department of Cardiac Sciences and Department of Physiology and Pharmacology, and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - J. Christopher Bouwmeester
- Department of Cardiac Sciences and Department of Physiology and Pharmacology, and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Jiun-Jr Wang
- Department of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Nigel G. Shrive
- Department of Civil Engineering, University of Calgary, Calgary, AB, Canada
| | - John V. Tyberg
- Department of Cardiac Sciences and Department of Physiology and Pharmacology, and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
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Dwyer N, Yong AC, Kilpatrick D. Variable open-end wave reflection in the pulmonary arteries of anesthetized sheep. J Physiol Sci 2012; 62:21-8. [PMID: 22102164 PMCID: PMC10717878 DOI: 10.1007/s12576-011-0182-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 11/09/2011] [Indexed: 01/09/2023]
Abstract
The aim of this study was to re-evaluate wave reflection in the healthy pulmonary arteries of sheep utilizing the time-domain-based method of wave intensity analysis. A thorough understanding of patterns of wave reflection during health and disease may provide future sensitive markers of early pulmonary vascular disease. Wave intensity was calculated from the simultaneous acquisition of proximal pulmonary arterial pressure and velocity in 12 anesthetized open-chest sheep. Normal pulmonary arterial wave speed was 2.1 ± 0.3 m s(-1). The incident forward compression wave generated by right ventricular systole was reflected in an open-end manner as a backward expansion wave from a site 3 cm downstream, corresponding to the main pulmonary bifurcation, and in a closed-end manner as a backward compression wave from a site 21 cm downstream, corresponding to the pulmonary microcirculation. The proximal open-end reflection site was not present throughout the entire cardiac cycle. Wave reflection was minimal with only 1% of the incident forward compression wave energy reflected as a backward expansion wave and 2% as a backward compression wave. The normal pulmonary artery in open-chest sheep is characterized by variable proximal open-end reflection from the main pulmonary bifurcation and fixed closed-end reflection from the microcirculation, generating backward-travelling waves of minimal intensity.
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Affiliation(s)
- Nathan Dwyer
- Discipline of Medicine, University of Tasmania Clinical School, Hobart, TAS, Australia.
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