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Smiseth OA, Belenkie I, Ter Keurs HEDJ, Smith ER. In Memoriam: John Victor Tyberg, MD, PhD. Can J Cardiol 2023; 39:1041-1043. [PMID: 36646282 DOI: 10.1016/j.cjca.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Affiliation(s)
- Otto A Smiseth
- Institute for Surgical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Israel Belenkie
- Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Henk E D J Ter Keurs
- Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Eldon R Smith
- Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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Zylinski M, Occhipinti E, Mandic D. Generalization Error of a Regression Model for Non-Invasive Blood Pressure Monitoring using a Single Photoplethysmography (PPG) Signal. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:i-iv. [PMID: 38083115 DOI: 10.1109/embc40787.2023.10340929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Photoplethysmography (PPG) sensors integrated in wearable devices offer the potential to monitor arterial blood pressure (ABP) in patients. Such cuffless, non-invasive, and continuous solution is suitable for remote and ambulatory monitoring. A machine learning model based on PPG signal can be used to detect hypertension, estimate beat-by-beat ABP values, and even reconstruct the shape of the ABP. Overall, models presented in literature have shown good performance, but there is a gap between research and potential real-world use cases. Usually, models are trained and tested on data from the same dataset and same subjects, which may lead to overestimating their accuracy. In this paper: we compare cross-validation, where the test data are from the same dataset as training data, and external validation, where the model is tested on samples from a new dataset, on a regression model which predicts diastolic blood pressure from PPG features. The results show that, in the cross-validation, the predicted and the real values are linearly dependent, while in the external validation, the predicted values are not related to the real ones, but probably just through an average value.
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Parker KH, de Tombe P, van der Velden J, Westerhof BE. The nature of waves in the arteries in memoriam: Nico Westerhof and John Tyberg. J Physiol 2022; 600:4045-4050. [PMID: 35929767 DOI: 10.1113/jp283558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/28/2022] [Indexed: 11/08/2022] Open
Abstract
This memorial remembers the lives of two distinguished researchers who made major contributions to cardiovascular physiology; Nico Westerhof (1937-2022) and John Tyberg (1938-2022). It is a joint memorial not because they collaborated closely but because they held very different views about the nature of waves in the arteries. Their papers and particularly their lively discussions at many scientific meetings stimulated interest in the subject. Both were thoughtful and articulate about their views and the debates were polite and dignified. They never resolved their differences and, after outlining what these differences were, we will suggest that perhaps there is no resolution. The authors of this memorial were close to one or the other protagonist; a son, a son-in-law and two close collaborators. We all have different views about the nature of waves in the arteries but we all share great respect for both men and felt that a joint memorial was a fitting way to remember them and their many contributions. All of the authors knew the subjects of this memorial as 'Nico' and 'John' and we will use these informal names throughout. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kim H Parker
- Department of Bioengineering, Imperial College, Exhibition Road, London, SW7 2AZ, UK
| | - Pieter de Tombe
- Department of Physiology and Biophysics, The University of Illinois at Chicago, Chicago, USA
| | | | - Berend E Westerhof
- Department of Pulmonary Medicine, Amsterdam Universitair Medische Centra, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands
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Aortic Biomechanics and Clinical Applications. Anesthesiology 2022; 137:351-363. [PMID: 35904358 DOI: 10.1097/aln.0000000000004313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The aorta contributes to cardiovascular physiology and function. Understanding biomechanics in health, disease, and after aortic interventions will facilitate optimization of perioperative patient care.
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Paré M, Goupil R, Fortier C, Mac-Way F, Madore F, Hametner B, Wassertheurer S, Schultz MG, Sharman JE, Agharazii M. Increased Excess Pressure After Creation of an Arteriovenous Fistula in End-Stage Renal Disease. Am J Hypertens 2022; 35:149-155. [PMID: 34655294 PMCID: PMC8807157 DOI: 10.1093/ajh/hpab161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/12/2021] [Accepted: 10/14/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Reservoir-wave analysis (RWA) separates the arterial waveform into reservoir and excess pressure (XSP) components, where XSP is analogous to flow and related to left ventricular workload. RWA provides more detailed information about the arterial tree than traditional blood pressure (BP) parameters. In end-stage renal disease (ESRD), we have previously shown that XSP is associated with increased mortality and is higher in patients with arteriovenous fistula (AVF). In this study, we examined whether XSP increases after creation of an AVF in ESRD. METHODS Before and after a mean of 3.9 ± 1.2 months following creation of AVF, carotid pressure waves were recorded using arterial tonometry. XSP and its integral (XSPI) were derived using RWA through pressure wave analysis alone. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (CF-PWV). RESURLTS In 38 patients (63% male, age 59 ± 15 years), after AVF creation, brachial diastolic BP decreased (79 ± 10 vs. 72 ± 12 mm Hg, P = 0.002), but the reduction in systolic BP, was not statistically significant (133 ± 20 vs. 127 ± 26 mm Hg, P = 0.137). However, carotid XSP (14 [12-19] to 17 [12-22] mm Hg, P = 0.031) and XSPI increased significantly (275 [212-335] to 334 [241-439] kPa∙s, P = 0.015), despite a reduction in CF-PWV (13 ± 3.6 vs. 12 ± 3.5 m/s, P = 0.025). CONCLUSIONS Creation of an AVF resulted in increased XSP in this population, despite improvement in diastolic BP and aortic stiffness. These findings underline the complex hemodynamic impact of AVF on the cardiovascular system.
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Affiliation(s)
- Mathilde Paré
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec City, Québec, Canada
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Université Laval, Québec, Québec, Canada
| | - Rémi Goupil
- Hôpital du Sacré-Cœur de Montréal, Department of Medicine, Montréal, Québec, Canada
| | - Catherine Fortier
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec City, Québec, Canada
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Université Laval, Québec, Québec, Canada
- INSERM-U970-Paris Cardiovascular Research Center (PARCC), Paris, France
| | - Fabrice Mac-Way
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec City, Québec, Canada
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Université Laval, Québec, Québec, Canada
| | - François Madore
- Hôpital du Sacré-Cœur de Montréal, Department of Medicine, Montréal, Québec, Canada
| | - Bernhard Hametner
- Center for Health & Bioresources, Department of Health and Environment, AIT Austrian Institute of Technology, Vienna, Austria
| | - Siegfried Wassertheurer
- Center for Health & Bioresources, Department of Health and Environment, AIT Austrian Institute of Technology, Vienna, Austria
| | - Martin G Schultz
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Mohsen Agharazii
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec City, Québec, Canada
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Université Laval, Québec, Québec, Canada
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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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Michel JB. Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells. Physiol Rev 2020; 100:1779-1837. [DOI: 10.1152/physrev.00022.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.
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Quantification of Pulsed Operation of Rotary Left Ventricular Assist Devices with Wave Intensity Analysis. ASAIO J 2020; 65:324-330. [PMID: 29863632 DOI: 10.1097/mat.0000000000000821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The current generation of left ventricular assist devices (LVADs) provides continuous flow and has the capacity to reduce aortic pulsatility, which may be related to a range of complications associated with these devices. Pulsed LVAD operation using speed modulation presents a mechanism to restore aortic pulsatility and potentially mitigate complications. We sought to investigate the interaction of axial and centrifugal LVADs with the LV and quantify the effects of continuous and pulsed LVAD operations on LV generated wave patterns under different physiologic conditions using wave intensity analysis (WIA) method. The axial LVAD created greater wave intensity associated with LV relaxation. In both LVADs, there were only minor and variable differences between the continuous and pulsed operations. The response to physiologic stress was preserved with LVAD implantation as wave intensity increased marginally with volume loading and significantly with infusion of norepinephrine. Our findings and a new approach of investigating aortic wave patterns based on WIA are expected to provide useful clinical insights to determine the ideal operation of LVADs.
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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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Balmer J, Pretty CG, Davidson S, Mehta-Wilson T, Desaive T, Smith R, Shaw GM, Chase JG. Clinically applicable model-based method, for physiologically accurate flow waveform and stroke volume estimation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 185:105125. [PMID: 31698169 DOI: 10.1016/j.cmpb.2019.105125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 08/10/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND OBJECTIVES Cardiovascular dysfunction can be more effectively monitored and treated, with accurate, continuous, stroke volume (SV) and/or cardiac output (CO) measurements. Since direct measurements of SV/CO are highly invasive, clinical measures are often discrete, or if continuous, can require recalibration with a discrete SV measurement after hemodynamic instability. This study presents a clinically applicable, non-additionally invasive, physiological model-based, SV and CO measurement method, which does not require recalibration during or after hemodynamic instability. METHODS AND RESULTS The model's ability to predict flow profiles and SV is assessed in an animal trial, using endotoxin to induce sepsis in 5 pigs. Mean percentage error between beat-to-beat SV measured from an aortic flow probe and estimated by the model was -2%, while 90% of estimations fell within -24.2% and +27.9% error. Error between estimated and measured changes in mean SV following interventions was less than 30% for 4 out of the 5 pigs. Correlations between model estimated and probe measured flow, for each pig and hemodynamic interventions, was r2 = 0.58 - 0.96, with 21 of the 25 pig intervention stages having r2 > 0.80. CONCLUSION The results demonstrate the model accurately estimates and tracks changes in flow profiles and resulting SV, without requiring model recalibration.
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Affiliation(s)
- Joel Balmer
- Department of Mechanical Engineering, University of Canterbury, New Zealand.
| | | | - Shaun Davidson
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | | | - Thomas Desaive
- GIGA Cardiovascular Science, University of Liège, Liège, Belgium
| | - Rachel Smith
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | | | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, New Zealand
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Paré M, Goupil R, Fortier C, Mac-Way F, Madore F, Marquis K, Hametner B, Wassertheurer S, Schultz MG, Sharman JE, Agharazii M. Determinants of Increased Central Excess Pressure in Dialysis: Role of Dialysis Modality and Arteriovenous Fistula. Am J Hypertens 2020; 33:137-145. [PMID: 31419806 DOI: 10.1093/ajh/hpz136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/31/2019] [Accepted: 08/12/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Arterial reservoir-wave analysis (RWA)-a new model of arterial hemodynamics-separates arterial wave into reservoir pressure (RP) and excess pressure (XSP). The XSP integral (XSPI) has been associated with increased risk of clinical outcomes. The objectives of the present study were to examine the determinants of XSPI in a mixed cohort of hemodialysis (HD) and peritoneal dialysis (PD) patients, to examine whether dialysis modality and the presence of an arteriovenous fistula (AVF) are associated with increased XSPI. METHOD In a cross-sectional study, 290 subjects (232 HD and 130 with AVF) underwent carotid artery tonometry (calibrated with brachial diastolic and mean blood pressure). The XSPI was calculated through RWA using pressure-only algorithms. Logistic regression was used for determinants of XSPI above median. Through forward conditional linear regression, we examined whether treatment by HD or the presence of AVF is associated with higher XSPI. RESULTS Patients with XSPI above median were older, had a higher prevalence of diabetes and cardiovascular disease, had a higher body mass index, and were more likely to be on HD. After adjustment for confounders, HD was associated with a higher risk of higher XSPI (odds ratio = 2.39, 95% confidence interval: 1.16-4.98). In a forward conditional linear regression analysis, HD was associated with higher XSPI (standardized coefficient: 0.126, P = 0.012), but on incorporation of AVF into the model, AVF was associated with higher XSPI (standardized coefficient: 0.130, P = 0.008) and HD was excluded as a predictor. CONCLUSION This study suggests that higher XSPI in HD patients is related to the presence of AVF.
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Affiliation(s)
- Mathilde Paré
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec, Quebec, Canada
- Division of Nephrology, Faculty of Medicine, Université Laval, Québec, Quebec, Canada
| | - Rémi Goupil
- Hôpital du Sacré-Cœur de Montréal, Montréal, Quebec, Canada
| | - Catherine Fortier
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec, Quebec, Canada
- Division of Nephrology, Faculty of Medicine, Université Laval, Québec, Quebec, Canada
| | - Fabrice Mac-Way
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec, Quebec, Canada
- Division of Nephrology, Faculty of Medicine, Université Laval, Québec, Quebec, Canada
| | | | - Karine Marquis
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec, Quebec, Canada
| | - Bernhard Hametner
- Center for Health and Bioresources, AIT Austrian Institute of Technology, Vienna, Austria
| | | | - Martin G Schultz
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - Mohsen Agharazii
- CHU de Québec Research Center, L’Hôtel-Dieu de Québec Hospital, Québec, Quebec, Canada
- Division of Nephrology, Faculty of Medicine, Université Laval, Québec, Quebec, Canada
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Fortier C, Côté G, Mac-Way F, Goupil R, Desbiens LC, Desjardins MP, Marquis K, Hametner B, Wassertheurer S, Schultz MG, Sharman JE, Agharazii M. Prognostic Value of Carotid and Radial Artery Reservoir-Wave Parameters in End-Stage Renal Disease. J Am Heart Assoc 2019; 8:e012314. [PMID: 31220992 PMCID: PMC6662378 DOI: 10.1161/jaha.119.012314] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background Reservoir-wave approach is an alternative model of arterial hemodynamics based on the assumption that measured arterial pressure is composed of volume-related (reservoir pressure) and wave-related components (excess pressure). However, the clinical utility of reservoir-wave approach remains debatable. Methods and Results In a single-center cohort of 260 dialysis patients, we examined whether carotid and radial reservoir-wave parameters were associated with all-cause and cardiovascular mortality. Central pulse pressure and augmentation index at 75 beats per minute were determined by radial arterial tonometry through generalized transfer function. Carotid and radial reservoir-wave analysis were performed to determine reservoir pressure and excess pressure integral. After a median follow-up of 32 months, 171 (66%) deaths and 88 (34%) cardiovascular deaths occurred. In Cox regression analysis, carotid excess pressure integral was associated with a hazard ratio of 1.33 (95% CI , 1.14-1.54; P<0.001 per 1 SD) for all-cause and 1.45 (95% CI : 1.18-1.75; P<0.001 per 1 SD) for cardiovascular mortality. After adjustments for age, heart rate, sex, clinical characteristics and carotid-femoral pulse wave velocity, carotid excess pressure integral was consistently associated with increased risk of all-cause (hazard ratio per 1 SD, 1.30; 95% CI : 1.08-1.54; P=0.004) and cardiovascular mortality (hazard ratio per 1 SD, 1.31; 95% CI : 1.04-1.63; P=0.019). Conversely, there were no significant associations between radial reservoir-wave parameters, central pulse pressure, augmentation index at 75 beats per minute, pressure forward, pressure backward and reflection magnitude, and all-cause or cardiovascular mortality after adjustment for comorbidities. Conclusions These observations support the clinical value of reservoir-wave approach parameters of large central elastic vessels in end-stage renal disease.
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Affiliation(s)
- Catherine Fortier
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada.,2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
| | - Gabrielle Côté
- 2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
| | - Fabrice Mac-Way
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada.,2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
| | - Rémi Goupil
- 3 Hôpital du Sacré-Cœur de Montréal Montréal Quebec Canada
| | - Louis-Charles Desbiens
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada.,2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
| | - Marie-Pier Desjardins
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada.,2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
| | - Karine Marquis
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada
| | - Bernhard Hametner
- 4 Center for Health & Bioresources AIT Austrian Institute of Technology Vienna Austria
| | | | - Martin G Schultz
- 5 Menzies Institute for Medical Research University of Tasmania Hobart Australia
| | - James E Sharman
- 5 Menzies Institute for Medical Research University of Tasmania Hobart Australia
| | - Mohsen Agharazii
- 1 CHU de Québec Research Center L'Hôtel-Dieu de Québec Hospital Québec Quebec Canada.,2 Division of Nephrology Faculty of Medicine Université Laval Québec Quebec Canada
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Westerhof BE, Westerhof N. Uniform tube models with single reflection site do not explain aortic wave travel and pressure wave shape. Physiol Meas 2018; 39:124006. [DOI: 10.1088/1361-6579/aaf3dd] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Gregory A, Kruger M, Maher N, Moore R, Dobson G. Non-invasive Determination of Aortic Mechanical Properties and Their Effects on Left Ventricular Function Following Endovascular Abdominal Aneurysm Repair. J Med Biol Eng 2018. [DOI: 10.1007/s40846-018-0455-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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16
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Wave Intensity Analysis of Right Ventricular Function during Pulsed Operation of Rotary Left Ventricular Assist Devices. ASAIO J 2018; 65:465-472. [PMID: 29863635 DOI: 10.1097/mat.0000000000000835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.
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Reservoir pressure analysis of aortic blood pressure: an in-vivo study at five locations in humans. J Hypertens 2018; 35:2025-2033. [PMID: 28582283 DOI: 10.1097/hjh.0000000000001424] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
INTRODUCTION The development and propagation of the aortic blood pressure wave remains poorly understood, despite its clear relevance to major organ blood flow and potential association with cardiovascular outcomes. The reservoir pressure model provides a unified description of the dual conduit and reservoir functions of the aorta. Reservoir waveform analysis resolves the aortic pressure waveform into an excess (wave related) and reservoir (compliance related) pressure. The applicability of this model to the pressure waveform as it propagates along the aorta has not been investigated in humans. METHODS We analysed invasively acquired high-fidelity aortic pressure waveforms from 40 patients undergoing clinically indicated coronary catheterization. Aortic waveforms were measured using a solid-state pressure catheter at five anatomical sites: the ascending aorta, the transverse aortic arch, the diaphragm, the level of the renal arteries, and at the aortic bifurcation. Ensemble average pressure waveforms were obtained for these sites for each patient and analysed to obtain the reservoir pressure [Pr(t)] and the excess pressure [Px(t)] at each aortic position. RESULTS Systolic blood pressure increased at a rate of 2.1 mmHg per site along the aorta, whereas diastolic blood pressure was effectively constant. Maximum Pr decreased only slightly along the aorta (changing by -0.7 mmHg per site), whereas the maximum of Px increased from the proximal to distal aorta (+4.1 mmHg per site; P < 0.001). The time, relative to the start of systolic upstroke, of the occurrence of the maximum excess pressure did not vary along the aorta. Of the parameters used to derive the reservoir pressure waveform the systolic and diastolic rate constants showed divergent changes with the systolic rate constant (ks) decreasing and the diastolic rate constant (kd) increasing along the aorta. CONCLUSIONS This analysis confirms the proposition that the magnitude of the calculated reservoir pressure waveform, despite known changes in aortic structure, is effectively constant throughout the aorta. A progressive increase of excess pressure accounts for the increase in pulse pressure from the proximal to distal aorta. The reservoir pressure rate constants seem to behave as arterial functional parameters. The accompanying decrease in ks and increase in kd are consistent with a progressive decrease in aortic compliance and increase in impedance. The reservoir pressure waveform therefore provides a model that might have utility in understanding the generation of central blood pressure and in specific cases might have clinical utility.
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Arterial reservoir characteristics and central-to-peripheral blood pressure amplification in the human upper limb. J Hypertens 2018; 35:1825-1831. [PMID: 28505065 DOI: 10.1097/hjh.0000000000001400] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Arterial reservoir characteristics are related to blood pressure (BP) and independently predict cardiovascular events. It is unknown if arterial reservoir characteristics are modified from the central-to-peripheral large arteries and whether there is a contributory role to BP amplification. The aim of this study was to assess central-to-peripheral changes in arterial reservoir characteristics and determine associations with BP. METHODS Reservoir pressure (RP) and excess pressure (XSP) were derived from intra-arterial BP waveforms among 51 participants (aged 63 ± 13 years, 63% men) undergoing clinically indicated cardiac angiography. BP waveforms were recorded in the ascending aorta, brachial (mid-humerus) and radial (wrist) arteries via catheter pull-back. RESULTS There was no significant difference in RP between arterial sites (54 ± 15, 53 ± 15 and 52 ± 17 mmHg for the aorta, brachial and radial artery, respectively; P = 0.68). Conversely, XSP increased stepwise from the aorta to the brachial and radial arteries (24 ± 11, 42 ± 14 and 53 ± 16 mmHg; P < 0.001), as did SBP (134 ± 18, 141 ± 16 and 146 ± 19 mmHg; P = 0.004). There were highly significant associations between RP and SBP at all arterial sites (r = 0.821, 0.649 and 0.708; P < 0.001 for all), but the strength of associations between peak XSP and SBP increased significantly from the aorta to the radial artery (r = 0.121 and 0.508; z = 3.04; P = 0.004). CONCLUSION Arterial reservoir characteristics are modified through the large arteries of the upper limb. Although RP remains relatively constant, XSP increases significantly and is highly related to BP (SBP and pulse pressure) amplification. These data provide a new understanding on arterial reservoir characteristics and large-artery BP physiology.
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Mei CC, Zhang J, Jing HX. Fluid mechanics of Windkessel effect. Med Biol Eng Comput 2018; 56:1357-1366. [PMID: 29308546 DOI: 10.1007/s11517-017-1775-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 12/13/2017] [Indexed: 10/18/2022]
Abstract
We describe a mechanistic model of Windkessel phenomenon based on the linear dynamics of fluid-structure interactions. The phenomenon has its origin in an old-fashioned fire-fighting equipment where an air chamber serves to transform the intermittent influx from a pump to a more steady stream out of the hose. A similar mechanism exists in the cardiovascular system where blood injected intermittantly from the heart becomes rather smooth after passing through an elastic aorta. In existing haeodynamics literature, this mechanism is explained on the basis of electric circuit analogy with empirical impedances. We present a mechanistic theory based on the principles of fluid/structure interactions. Using a simple one-dimensional model, wave motion in the elastic aorta is coupled to the viscous flow in the rigid peripheral artery. Explicit formulas are derived that exhibit the role of material properties such as the blood density, viscosity, wall elasticity, and radii and lengths of the vessels. The current two-element model in haemodynamics is shown to be the limit of short aorta and low injection frequency and the impedance coefficients are derived theoretically. Numerical results for different aorta lengths and radii are discussed to demonstrate their effects on the time variations of blood pressure, wall shear stress, and discharge. Graphical Abstract A mechanistic analysis of Windkessel Effect is described which confirms theoretically the well-known feature that intermittent influx becomes continuous outflow. The theory depends only on the density and viscosity of the blood, the elasticity and dimensions of the vessel. Empirical impedence parameters are avoided.
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Affiliation(s)
- C C Mei
- Department of Civil and Environmental Engineering, Massacheusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - J Zhang
- Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - H X Jing
- Institute of Water Resources and Hydro-electric Engineering, Xi'an University of Technology, Xi'an, 710048, China
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Balmer J, Pretty C, Davidson S, Desaive T, Habran S, Chase JG. Effect of arterial pressure measurement location on pulse contour stroke volume estimation, during a rapid change in hemodynamic state. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.ifacol.2018.11.649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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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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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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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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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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25
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Abstract
PURPOSE OF REVIEW Arterial pulse waveform analysis has a long tradition but has not pervaded medical routine yet. This review aims to answer the question whether the methodology is ready for prime time use. The current methodological consensus is assessed, existing technologies for waveform measurement and pulse wave analysis are discussed, and further needs for a widespread use are proposed. RECENT FINDINGS A consensus document on the understanding and analysis of the pulse waveform was published recently. Although still some discrepancies remain, the analysis using both pressure and flow waves is favoured. However, devices which enable pulse wave measurement are limited, and the comparability between devices is not sufficiently given. Pulse waveform analysis has the potential for prime time. It is currently on a way towards broader use, but still needs to overcome challenges before settling its role in medical routine.
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26
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de Waard G, Di Mario C, Lerman A, Serruys P, van Royen N. Instantaneous wave-free ratio to guide coronary revascularisation: physiological framework, validation and differences from fractional flow reserve. EUROINTERVENTION 2017; 13:450-458. [DOI: 10.4244/eij-d-16-00456] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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27
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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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Kamoi S, Pretty C, Balmer J, Davidson S, Pironet A, Desaive T, Shaw GM, Chase JG. Improved pressure contour analysis for estimating cardiac stroke volume using pulse wave velocity measurement. Biomed Eng Online 2017; 16:51. [PMID: 28438216 PMCID: PMC5404318 DOI: 10.1186/s12938-017-0341-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 04/19/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Pressure contour analysis is commonly used to estimate cardiac performance for patients suffering from cardiovascular dysfunction in the intensive care unit. However, the existing techniques for continuous estimation of stroke volume (SV) from pressure measurement can be unreliable during hemodynamic instability, which is inevitable for patients requiring significant treatment. For this reason, pressure contour methods must be improved to capture changes in vascular properties and thus provide accurate conversion from pressure to flow. METHODS This paper presents a novel pressure contour method utilizing pulse wave velocity (PWV) measurement to capture vascular properties. A three-element Windkessel model combined with the reservoir-wave concept are used to decompose the pressure contour into components related to storage and flow. The model parameters are identified beat-to-beat from the water-hammer equation using measured PWV, wave component of the pressure, and an estimate of subject-specific aortic dimension. SV is then calculated by converting pressure to flow using identified model parameters. The accuracy of this novel method is investigated using data from porcine experiments (N = 4 Pietrain pigs, 20-24.5 kg), where hemodynamic properties were significantly altered using dobutamine, fluid administration, and mechanical ventilation. In the experiment, left ventricular volume was measured using admittance catheter, and aortic pressure waveforms were measured at two locations, the aortic arch and abdominal aorta. RESULTS Bland-Altman analysis comparing gold-standard SV measured by the admittance catheter and estimated SV from the novel method showed average limits of agreement of ±26% across significant hemodynamic alterations. This result shows the method is capable of estimating clinically acceptable absolute SV values according to Critchely and Critchely. CONCLUSION The novel pressure contour method presented can accurately estimate and track SV even when hemodynamic properties are significantly altered. Integrating PWV measurements into pressure contour analysis improves identification of beat-to-beat changes in Windkessel model parameters, and thus, provides accurate estimate of blood flow from measured pressure contour. The method has great potential for overcoming weaknesses associated with current pressure contour methods for estimating SV.
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Affiliation(s)
- Shun Kamoi
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Christopher Pretty
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Joel Balmer
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Shaun Davidson
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Antoine Pironet
- GIGA Cardiovascular Science, University of Liege, Liege, Belgium
| | - Thomas Desaive
- GIGA Cardiovascular Science, University of Liege, Liege, Belgium
| | - Geoffrey M. Shaw
- Intensive Care Unit, Christchurch Hospital, Christchurch, New Zealand
| | - J. Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
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Wang WT, Sung SH, Wang JJ, Wu CK, Lin LY, Lee JC, Cheng HM, Chen CH. Excess Pressure Integral Predicts Long-Term All-Cause Mortality in Stable Heart Failure Patients. Am J Hypertens 2017; 30:271-278. [PMID: 27838626 DOI: 10.1093/ajh/hpw133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/06/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Excess pressure integral (XSPI) derived from reservoir-excess pressure analysis is proposed as a novel indicator of cardiovascular dysfunction in hypertensives. Our study investigated the prognostic value of XSPI for stable heart failure (HF) patients. METHODS In total, 238 subjects (mean age 63 ± 18 years, 111 male), comprising 168 stable HF patients with either reduced (SHF; n = 64) left ventricular (LV) ejection fraction (EF) or isolated diastolic dysfunction (DHF, n = 104), and 70 healthy controls, were enrolled. Tonometry-derived carotid pressure waveforms were analyzed with the reservoir pressure theory. XSPI was calculated by subtracting the reservoir pressure from carotid pressure waveform. RESULTS XSPI in SHF and DHF (14.01 ± 5.16 and 13.90 ± 5.05 mm Hg•s) were significantly higher than that in controls (11.01 ± 3.67 mm Hg•s, both P < 0.001). During a median follow-up of 9.9 years, 56 deaths occurred. XSPI was a significant independent predictor of total mortality after adjusting for age, sex, left ventricular ejection fraction (LVEF), glomerular filtration rate (GFR), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) (hazard ratio = 4.37 per 1 SD, 95% confidence interval, 1.31-14.58). In subgroup analysis by different baseline characteristics including age, gender, NT-proBNP, LVEF, and GFR, higher XSPI was consistently associated with greater risk of total mortality. CONCLUSION In patients with stable HF, XSPI, a novel maker of cardiovascular dysfunction, was associated with long-term risk of total mortality.
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Affiliation(s)
- Wei-Ting Wang
- Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shih-Hsien Sung
- Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan
- Department of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Jiun-Jr Wang
- School of Medicine, Fu Jen Catholic University, Xinzhuang District, New Taipei City, Taiwan
| | - Cho-Kai Wu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Lian-Yu Lin
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jia-Chun Lee
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Hao-Min Cheng
- Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan
- Department of Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chen-Huan Chen
- Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan
- Department of Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan
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31
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Mynard JP, Smolich JJ. Wave potential: A unified model of arterial waves, reservoir phenomena and their interaction☆. Artery Res 2017. [DOI: 10.1016/j.artres.2017.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Ghimire A, Andersen MJ, Burrowes LM, Bouwmeester JC, Grant AD, Belenkie I, Fine NM, Borlaug BA, Tyberg JV. The reservoir-wave approach to characterize pulmonary vascular-right ventricular interactions in humans. J Appl Physiol (1985) 2016; 121:1348-1353. [DOI: 10.1152/japplphysiol.00697.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/03/2016] [Accepted: 10/19/2016] [Indexed: 01/08/2023] Open
Abstract
Using the reservoir-wave approach (RWA) we previously characterized pulmonary vasculature mechanics in a normal canine model. We found reflected backward-traveling waves that decrease pressure and increase flow in the proximal pulmonary artery (PA). These waves decrease right ventricular (RV) afterload and facilitate RV ejection. With pathological alterations to the pulmonary vasculature, these waves may change and impact RV performance. Our objective in this study was to characterize PA wave reflection and the alterations in RV performance in cardiac patients, using the RWA. PA pressure, Doppler-flow velocity, and pulmonary arterial wedge pressure were measured in 11 patients with exertional dyspnea. The RWA was employed to analyze PA pressure and flow; wave intensity analysis characterized PA waves. Wave-related pressure was partitioned into two components: pressures due to forward-traveling and to backward-traveling waves. RV performance was assessed by examining the work done in raising reservoir pressure and that associated with the wave components of systolic PA pressure. Wave-related work, the mostly nonrecoverable energy expended by the RV to eject blood, tended to vary directly with mean PA pressure. Where PA pressures were lower, there were pressure-decreasing/flow-increasing backward waves that aided RV ejection. Where PA pressures were higher, there were pressure-increasing/flow-decreasing backward waves that impeded RV ejection. Pressure-increasing/flow-decreasing backward waves were responsible for systolic notches in the Doppler flow velocity profiles in patients with the highest PA pressure. Pulmonary hypertension is characterized by reflected waves that impede RV ejection and an increase in wave-related work. The RWA may facilitate the development of therapeutic strategies.
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Affiliation(s)
- Anukul Ghimire
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Mads J. Andersen
- Department of Cardiology, University of Aarhus, Aarhus, Denmark; and
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Rochester, Minnesota
| | - Lindsay M. Burrowes
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - J. Christopher Bouwmeester
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Andrew D. Grant
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Israel Belenkie
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Nowell M. Fine
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Barry A. Borlaug
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Rochester, Minnesota
| | - John V. Tyberg
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
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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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The aortic reservoir-wave as a paradigm for arterial haemodynamics: insights from three-dimensional fluid-structure interaction simulations in a model of aortic coarctation. J Hypertens 2016; 33:554-63; discussion 563. [PMID: 25479031 DOI: 10.1097/hjh.0000000000000449] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The reservoir-wave paradigm considers aortic pressure as the superposition of a 'reservoir pressure', directly related to changes in reservoir volume, and an 'excess' component ascribed to wave dynamics. The change in reservoir pressure is assumed to be proportional to the difference between aortic inflow and outflow (i.e. aortic volume changes), an assumption that is virtually impossible to validate in vivo. The aim of this study is therefore to apply the reservoir-wave paradigm to aortic pressure and flow waves obtained from three-dimensional fluid-structure interaction simulations in a model of a normal aorta, aortic coarctation (narrowed descending aorta) and stented coarctation (stiff segment in descending aorta). METHOD AND RESULTS We found no unequivocal relation between the intraaortic volume and the reservoir pressure for any of the simulated cases. When plotted in a pressure-volume diagram, hysteresis loops are found that are looped in a clockwise way indicating that the reservoir pressure is lower than the pressure associated with the change in volume. The reservoir-wave analysis leads to very high excess pressures, especially for the coarctation models, but to surprisingly little changes of the reservoir component despite the impediment of the buffer capacity of the aorta. CONCLUSION With the observation that reservoir pressure is not related to the volume in the aortic reservoir in systole, an intrinsic assumption in the wave-reservoir concept is invalidated and, consequently, also the assumption that the excess pressure is the component of pressure that can be attributed to wave travel and reflection.
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Schultz MG, Hughes AD, Davies JE, Sharman JE. Associations and clinical relevance of aortic-brachial artery stiffness mismatch, aortic reservoir function, and central pressure augmentation. Am J Physiol Heart Circ Physiol 2015; 309:H1225-33. [PMID: 26276816 DOI: 10.1152/ajpheart.00317.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/12/2015] [Indexed: 01/09/2023]
Abstract
Central augmentation pressure (AP) and index (AIx) predict cardiovascular events and mortality, but underlying physiological mechanisms remain disputed. While traditionally believed to relate to wave reflections arising from proximal arterial impedance (and stiffness) mismatching, recent evidence suggests aortic reservoir function may be a more dominant contributor to AP and AIx. Our aim was therefore to determine relationships among aortic-brachial stiffness mismatching, AP, AIx, aortic reservoir function, and end-organ disease. Aortic (aPWV) and brachial (bPWV) pulse wave velocity were measured in 359 individuals (aged 61 ± 9, 49% male). Central AP, AIx, and aortic reservoir indexes were derived from radial tonometry. Participants were stratified by positive (bPWV > aPWV), negligible (bPWV ≈ aPWV), or negative stiffness mismatch (bPWV < aPWV). Left-ventricular mass index (LVMI) was measured by two-dimensional-echocardiography. Central AP and AIx were higher with negative stiffness mismatch vs. negligible or positive stiffness mismatch (11 ± 6 vs. 10 ± 6 vs. 8 ± 6 mmHg, P < 0.001 and 24 ± 10 vs. 24 ± 11 vs. 21 ± 13%, P = 0.042). Stiffness mismatch (bPWV-aPWV) was negatively associated with AP (r = -0.18, P = 0.001) but not AIx (r = -0.06, P = 0.27). Aortic reservoir pressure strongly correlated to AP (r = 0.81, P < 0.001) and AIx (r = 0.62, P < 0.001) independent of age, sex, heart rate, mean arterial pressure, and height (standardized β = 0.61 and 0.12, P ≤ 0.001). Aortic reservoir pressure independently predicted abnormal LVMI (β = 0.13, P = 0.024). Positive aortic-brachial stiffness mismatch does not result in higher AP or AIx. Aortic reservoir function, rather than discrete wave reflection from proximal arterial stiffness mismatching, provides a better model description of AP and AIx and also has clinical relevance as evidenced by an independent association of aortic reservoir pressure with LVMI.
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Affiliation(s)
- Martin G Schultz
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Alun D Hughes
- Institute for Cardiovascular Science, University College London, London, United Kingdom; and
| | - Justin E Davies
- International Centre for Circulatory Health, Imperial College London, London, United Kingdom
| | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia;
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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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Westerhof N, Segers P, Westerhof BE. Wave Separation, Wave Intensity, the Reservoir-Wave Concept, and the Instantaneous Wave-Free Ratio. Hypertension 2015; 66:93-8. [DOI: 10.1161/hypertensionaha.115.05567] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 04/28/2015] [Indexed: 01/10/2023]
Abstract
Wave separation analysis and wave intensity analysis (WIA) use (aortic) pressure and flow to separate them in their forward and backward (reflected) waves. While wave separation analysis uses measured pressure and flow, WIA uses their derivatives. Because differentiation emphasizes rapid changes, WIA suppresses slow (diastolic) fluctuations of the waves and renders diastole a seemingly wave-free period. However, integration of the WIA-obtained forward and backward waves is equal to the wave separation analysis–obtained waves. Both the methods thus give similar results including backward waves spanning systole and diastole. Nevertheless, this seemingly wave-free period in diastole formed the basis of both the reservoir-wave concept and the Instantaneous wave-Free Ratio of (iFR) pressure and flow. The reservoir-wave concept introduces a reservoir pressure,
P
res
, (Frank Windkessel) as a wave-less phenomenon. Because this Windkessel model falls short in systole an excess pressure,
P
exc
, is introduced, which is assumed to have wave properties. The reservoir-wave concept, however, is internally inconsistent. The presumed wave-less
P
res
equals twice the backward pressure wave and travels, arriving later in the distal aorta. Hence, in contrast,
P
exc
is minimally affected by wave reflections. Taken together,
P
res
seems to behave as a wave, rather than
P
exc
. The iFR is also not without flaws, as easily demonstrated when applied to the aorta. The ratio of diastolic aortic pressure and flow implies division by zero giving nonsensical results. In conclusion, presumptions based on WIA have led to misconceptions that violate physical principles, and reservoir-wave concept and iFR should be abandoned.
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Affiliation(s)
- Nico Westerhof
- From the Departments Physiology and Pulmonary Diseases, ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands (N.W.); IBiTech-bioMMeda, Department of Electronics and Information Systems, iMinds Medical IT, Ghent University, Gent, Belgium (P.S.); Edwards Lifesciences BMEYE, Critical Care Noninvasive, Amsterdam, The Netherlands (B.E.W.); and Heart Failure Research Center, Laboratory for Clinical Cardiovascular Physiology, Academic Medical Center, Amsterdam, The Netherlands (B.E.W.)
| | - Patrick Segers
- From the Departments Physiology and Pulmonary Diseases, ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands (N.W.); IBiTech-bioMMeda, Department of Electronics and Information Systems, iMinds Medical IT, Ghent University, Gent, Belgium (P.S.); Edwards Lifesciences BMEYE, Critical Care Noninvasive, Amsterdam, The Netherlands (B.E.W.); and Heart Failure Research Center, Laboratory for Clinical Cardiovascular Physiology, Academic Medical Center, Amsterdam, The Netherlands (B.E.W.)
| | - Berend E. Westerhof
- From the Departments Physiology and Pulmonary Diseases, ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands (N.W.); IBiTech-bioMMeda, Department of Electronics and Information Systems, iMinds Medical IT, Ghent University, Gent, Belgium (P.S.); Edwards Lifesciences BMEYE, Critical Care Noninvasive, Amsterdam, The Netherlands (B.E.W.); and Heart Failure Research Center, Laboratory for Clinical Cardiovascular Physiology, Academic Medical Center, Amsterdam, The Netherlands (B.E.W.)
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Tyberg JV, Bouwmeester JC, Burrowes LM, Parker KH, Shrive NG, Wang JJ. A new teaching model of the systemic circulation that incorporates reservoir characteristics. Artery Res 2015. [DOI: 10.1016/j.artres.2015.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Abstract
The endothelium plays a crucial role in the regulation of vascular homeostasis. Our understanding of its role in health and disease has increased dramatically since the pivotal discovery of nitric oxide more than 30 years ago. Clinical researchers utilized emerging technologies to study the vasodilator properties of the endothelium in both the coronary and peripheral circulation. Early studies established the methodologies and were able to demonstrate attenuated endothelium-dependent vasodilation in response to atherosclerosis and its risk factors. A variety of interventions can modulate endothelial function. More recent studies have established that some of these measures are independent predictors of cardiovascular outcomes. As such, peripheral measures of endothelial function are now established surrogate markers of vascular risk and have become important markers for clinical research. In this review, we will discuss a variety of measures of peripheral artery function to assess both conduit and resistance vessel function in humans.
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Affiliation(s)
- Todd J Anderson
- Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary AB Canada.
| | - Shane A Phillips
- Department of Physical Therapy, Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
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Jahren SE, Amacher R, Weber A, Most H, Flammer SA, Traupe T, Stoller M, de Marchi S, Vandenberghe S. Effects of Thoratec pulsatile ventricular assist device timing on the abdominal aortic wave intensity pattern. Am J Physiol Heart Circ Physiol 2014; 307:H1243-51. [PMID: 25320334 DOI: 10.1152/ajpheart.00085.2014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arterial waves are seen as possible independent mediators of cardiovascular risks, and the wave intensity analysis (WIA) has therefore been proposed as a method for patient selection for ventricular assist device (VAD) implantation. Interpreting measured wave intensity (WI) is challenging, and complexity is increased by the implantation of a VAD. The waves generated by the VAD interact with the waves generated by the native heart, and this interaction varies with changing VAD settings. Eight sheep were implanted with a pulsatile VAD (PVAD) through ventriculoaortic cannulation. The start of PVAD ejection was synchronized to the native R wave and delayed between 0 and 90% of the cardiac cycle in 10% steps or phase shifts (PS). Pressure and velocity signals were registered, with the use of a combined Doppler and pressure wire positioned in the abdominal aorta, and used to calculate the WI. Depending on the PS, different wave interference phenomena occurred. Maximum unloading of the left ventricle (LV) coincided with constructive interference and maximum blood flow pulsatility, and maximum loading of the LV coincided with destructive interference and minimum blood flow pulsatility. We believe that noninvasive WIA could potentially be used clinically to assess the mechanical load of the LV and to monitor the peripheral hemodynamics such as blood flow pulsatility and risk of intestinal bleeding.
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Affiliation(s)
| | - Raffael Amacher
- Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland
| | - Alberto Weber
- Department of Cardiology, University Hospital Bern, Bern, Switzerland
| | - Henriette Most
- Department of Cardiology, University Hospital Bern, Bern, Switzerland
| | - Shannon Axiak Flammer
- Department of Clinical Veterinary Medicine, University of Bern, Bern, Switzerland; and
| | - Tobias Traupe
- Department of Cardiology, University Hospital Bern, Bern, Switzerland
| | - Michael Stoller
- Department of Cardiology, University Hospital Bern, Bern, Switzerland
| | - Stefano de Marchi
- Department of Cardiology, University Hospital Bern, Bern, Switzerland
| | - Stijn Vandenberghe
- Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland; ARTORG Center for Biomedical Research, University of Bern, Bern, Switzerland
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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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Mynard JP, Smolich JJ. The case against the reservoir-wave approach. Int J Cardiol 2014; 176:1009-12. [PMID: 25109888 DOI: 10.1016/j.ijcard.2014.07.070] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/22/2014] [Indexed: 01/09/2023]
Affiliation(s)
- Jonathan P Mynard
- Heart Research, Clinical Sciences, Murdoch Childrens Research Institute, Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
| | - Joseph J Smolich
- Heart Research, Clinical Sciences, Murdoch Childrens Research Institute, Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
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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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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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