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Abatzis-Papadopoulos M, Tigkiropoulos K, Nikas S, Sidiropoulou K, Alexou C, Stavridis K, Karamanos D, Kotsis V, Lazaridis I, Saratzis N. Study Protocol of a Prospective, Monocentric, Single-Arm Study Investigating the Correlation of Endograft Properties with Aortic Stiffness in Abdominal Aortic Aneurysm Patients Subjected to Endovascular Aortic Repair. J Clin Med 2024; 13:2205. [PMID: 38673477 PMCID: PMC11050864 DOI: 10.3390/jcm13082205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
The number of endovascular aortic repairs (EVARs) has surpassed the number of open surgical repairs of abdominal aortic aneurysms (AAAs) worldwide. The available commercial endoprostheses are composed of materials that are stiffer than the native aortic wall. As a consequence, the implantation of stent-graft endoprostheses during EVAR increases aortic rigidity and thus aortic stiffness, resulting in a decrease in abdominal aorta compliance. EVAR has been found to have a possibly harmful effect not only on heart functions but also on other vascular beds, including kidney function, due to the decrease in aortic compliance that it causes. Aortic stiffness is measured by various hemodynamic indices like the pulse wave velocity (PWV), the central aortic pressure (CAP), and the augmentation index (AIx). In the literature, there are increasing numbers of studies investigating the properties of endografts, which are strongly related to increases in aortic stiffness. However, there is a lack of data on whether there is a correlation between the length of various endografts implanted during EVAR and the increase in the PWV, CAP, and AIx postoperatively compared to the preoperative values. The aim of this prospective, observational, monocentric, single-arm study is to investigate the correlation between endograft length and the postoperative increase in the PWV, CAP, and AIx in patients subjected to EVAR. Additionally, this study intends to identify other endograft properties related to increases in the PWV, CAP, and AIx. Other endpoints to be studied are the existence of immediate postoperative myocardial and kidney injury after EVAR. The prediction of cardiovascular events caused by endograft-related increased aortic stiffness could contribute to the improvement of various endograft properties so that the impact of endografts on the native aortic wall can be minimized.
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Affiliation(s)
- Manolis Abatzis-Papadopoulos
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Konstantinos Tigkiropoulos
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Spyridon Nikas
- Radiology Department, Papageorgiou General Hospital, 56403 Thessaloniki, Greece;
| | - Katerina Sidiropoulou
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Christina Alexou
- Cardiothoracic Surgery Department, Papanikolaou General Hospital, 57010 Thessaloniki, Greece;
| | - Kyriakos Stavridis
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Dimitrios Karamanos
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Vasilios Kotsis
- 3rd University Department of Internal Medicine, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece;
| | - Ioannis Lazaridis
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
| | - Nikolaos Saratzis
- Vascular Unit, 1st University Surgical Department, Papageorgiou General Hospital, Aristotle University of Thessaloniki, 56403 Thessaloniki, Greece; (K.T.); (K.S.); (K.S.); (D.K.); (I.L.); (N.S.)
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Mulligan LJ, Thrash J, Mitrev L, Folk D, Exarchakis A, Ewert D, Hill JC. Evaluation of vascular aging on measures of cardiac function and mechanical efficiency: insights from in-silico modeling. Front Cardiovasc Med 2024; 11:1351484. [PMID: 38601041 PMCID: PMC11004371 DOI: 10.3389/fcvm.2024.1351484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/23/2024] [Indexed: 04/12/2024] Open
Abstract
Introduction This study evaluated the hypothesis that vascular aging (VA) reduces ventricular contractile function and mechanical efficiency (ME) using the left ventricular pressure-volume (PV) construct. Methods A previously published in-silico computational model (CM) was modified to evaluate the hypothesis in two phases. In phase I, the CM included five settings of aortic compliance (CA) from normal to stiff, studied at a heart rate of 80 bpm, and phase II included the normal to stiff CA settings evaluated at 60, 100, and 140 bpm. The PV construct provided steady-state and transient data through a simulated vena caval occlusion (VCO). The steady-state data included left ventricular volumes (EDV and ESV), stroke work (SW), and VCO provided the PV area (PVA) data in addition to the three measures of contractile state (CS): end-systolic pressure-volume relationship (ESPVR), dP/dtmax-EDV and preload recruitable stroke work (PRSW). Finally, ME was calculated with the SW/PVA parameter. Results In phase I, EDV and ESV increased, as did SW and PVA. The impact on the CS parameters demonstrated a small decrease in ESPVR, no change in dP/dtmax-EDV, and a large increase in PRSW. ME decreased from 71.5 to 60.8%, respectively. In phase II, at the normal and stiff CA settings, across the heart rates studied, EDV and ESV decreased, ESPVR and dP/dtmax-EDV increased and PRSW decreased. ME decreased from 76.4 to 62.6% at the normal CA and 65.8 to 53.2% at the stiff CA. Discussion The CM generated new insights regarding how the VA process impacts the contractile state of the myocardium and ME.
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Affiliation(s)
- Lawrence J. Mulligan
- Department of Anesthesiology, Cooper University Hospital, Camden, NJ, United States
- Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Julian Thrash
- Department of Electrical and Computer Engineering, North Dakota State University, Fargo, ND, United States
| | - Ludmil Mitrev
- Department of Anesthesiology, Cooper University Hospital, Camden, NJ, United States
- Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Douglas Folk
- Department of Integrated Engineering, Minnesota State UniversityMankato, MN, United States
| | - Alyssa Exarchakis
- Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Daniel Ewert
- Department of Biomedical Engineering, University of North Dakota, Grand Forks, ND, United States
| | - Jeffrey C. Hill
- Department of Diagnostic Medical Sonography, School of Medical Imaging and Therapeutics, Massachusetts College of Pharmacy and Health Sciences University, Worcester, MA, United States
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Mulligan LJ, Ungerleider J, Friedman A, Sanders B, Thrash J, Ewert D, Mitrev L, Hill JC. Evaluation of ventricular-vascular coupling with critical care metrics: An in silico approach. Physiol Rep 2024; 12:e15920. [PMID: 38296348 PMCID: PMC10830386 DOI: 10.14814/phy2.15920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 01/03/2024] [Accepted: 01/03/2024] [Indexed: 02/05/2024] Open
Abstract
Mean arterial pressure and cardiac output provide insufficient guidance for the management of intraoperative hypotension (IOH). In silico models offer additional insights into acute changes in hemodynamic parameters that may be encountered during IOH. A computational model (CM) generated parameters quantifying ventricular-vascular coupling, and pressure-volume construct across levels of aortic compliance (CA ). We studied how a loss from normal-to-stiff CA impacts critical care metrics of hemodynamics during vascular occlusion. Pulse pressure (PP), end-systolic pressure (Pes ), arterial compliance (Art-ca), arterial elastance (Art-ea), and dynamic arterial elastance (Eadyn), along mechanical efficiency (ME) were measured at five levels of CA . A loss in CA impacted all variables. During steady-state conditions, PP, Pes , and stroke work increased significantly as CA decreased. Art-ca decreased and Art-ea increased similarly; Eadyn increased and ME decreased. During a decrease in preload across all CA levels, arterial dynamics measures remained linear. The CM demonstrated that a loss in CA impacts measures of arterial dynamics during steady-state and transient conditions and the model demonstrates that critical care metrics are sensitive to changes in CA . While Art-ca and Art-ea were sensitive to changes in preload, Eadyn did not change.
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Affiliation(s)
- Lawrence J. Mulligan
- Department of AnesthesiologyCooper University HospitalCamdenNew JerseyUSA
- Cooper Medical School of Rowan UniversityCamdenNew JerseyUSA
| | | | - Adam Friedman
- Cooper Medical School of Rowan UniversityCamdenNew JerseyUSA
| | | | | | - Daniel Ewert
- University of North DakotaGrand ForksNorth DakotaUSA
| | - Ludmil Mitrev
- Department of AnesthesiologyCooper University HospitalCamdenNew JerseyUSA
- Cooper Medical School of Rowan UniversityCamdenNew JerseyUSA
| | - Jeffrey C. Hill
- School of Medical Imaging and TherapeuticsMassachusetts College of Pharmacy and Health Sciences UniversityWorcesterMassachusettsUSA
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Papaioannou V, Papaioannou T. Rethinking Fluid Responsiveness during Septic Shock: Ameliorate Accuracy of Noninvasive Cardiac Output Measurements through Evaluation of Arterial Biomechanical Properties. J Pers Med 2024; 14:70. [PMID: 38248770 PMCID: PMC10817669 DOI: 10.3390/jpm14010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/28/2023] [Accepted: 01/04/2024] [Indexed: 01/23/2024] Open
Abstract
Beat-to-beat estimates of cardiac output from the direct measure of peripheral arterial blood pressure rely on the assumption that changes in the waveform morphology are related to changes in blood flow and vasomotor tone. However, in septic shock patients, profound changes in vascular tone occur that are not uniform across the entire arterial bed. In such cases, cardiac output estimates might be inaccurate, leading to unreliable evaluation of fluid responsiveness. Pulse wave velocity is the gold-standard method for assessing different arterial biomechanical properties. Such methods might be able to guide, personalize and optimize the management of septic patients.
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Affiliation(s)
- Vasileios Papaioannou
- Intensive Care Unit, Alexandroupolis University Hospital, Democritus University of Thrace, Dragana, 68100 Alexandroupolis, Greece
| | - Theodoros Papaioannou
- Biomedical Engineering and Cardiovascular Mechanics Unit, 1st Department of Cardiology, Hippokration University Hospital, Medical School of the National and Kapodistrian University of Athens, 11527 Athens, Greece;
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Vander Linden K, Vanderveken E, Van Hoof L, Maes L, Fehervary H, Dreesen S, Hendrickx A, Verbrugghe P, Rega F, Meuris B, Famaey N. Stiffness matters: Improved failure risk assessment of ascending thoracic aortic aneurysms. JTCVS Open 2023; 16:66-83. [PMID: 38204617 PMCID: PMC10775041 DOI: 10.1016/j.xjon.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 01/12/2024]
Abstract
Objectives Rupture and dissection are feared complications of ascending thoracic aortic aneurysms caused by mechanical failure of the wall. The current method of using the aortic diameter to predict the risk of wall failure and to determine the need for surgical resection lacks accuracy. Therefore, this study aims to identify reliable and clinically measurable predictors for aneurysm rupture or dissection by performing a personalized failure risk analysis, including clinical, geometrical, histologic, and mechanical data. Methods The study cohort consisted of 33 patients diagnosed with ascending aortic aneurysms without genetic syndromes. Uniaxial tensile tests until failure were performed to determine the wall strength. Material parameters were fitted against ex vivo planar biaxial data and in vivo pressure-diameter relationships at diastole and systole, which were derived from multiphasic computed tomography (CT) scans. Using the resulting material properties and in vivo data, the maximal in vivo stress at systole was calculated, assuming a thin-walled axisymmetric geometry. The retrospective failure risk was calculated by comparing the peak wall stress at suprasystolic pressure with the wall strength. Results The distensibility coefficient, reflecting aortic compliance and derived from blood pressure measurements and multiphasic CT scans, outperformed predictors solely based on geometrical features in assessing the risk of aneurysm failure. Conclusions In a clinical setting, multiphasic CT scans followed by the calculation of the distensibility coefficient are of added benefit in patient-specific, clinical decision-making. The distensibility derived from the aneurysm volume change has the best predictive power, as it also takes the axial stretch into account.
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Affiliation(s)
| | - Emma Vanderveken
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Lucas Van Hoof
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Lauranne Maes
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Heleen Fehervary
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- FIBEr, KU Leuven Core Facility for Biomechanical Experimentation, Leuven, Belgium
| | - Silke Dreesen
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Amber Hendrickx
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Peter Verbrugghe
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Filip Rega
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Bart Meuris
- Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Nele Famaey
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- FIBEr, KU Leuven Core Facility for Biomechanical Experimentation, Leuven, Belgium
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May-Newman K. Dynamic pressure-flow curve analysis of the native heart and left ventricular assist device for full and partial bypass conditions. Artif Organs 2021; 46:1077-1085. [PMID: 34932239 DOI: 10.1111/aor.14157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 10/14/2021] [Accepted: 11/18/2021] [Indexed: 12/01/2022]
Abstract
BACKGROUND During left ventricular assist device (LVAD) support, the external work performed by the native heart combines with the work performed by the rotary LVAD to provide cyclic flow through the LVAD and, in some conditions, through the aortic valve. In this study, a balance of external work was developed and validated for both full and partial bypass conditions that includes valve opening and aortic compliance. METHODS The theory assumes a steady-state contribution of external work from the rotary LVAD and a dynamic portion from the heart. Cyclic flow may be ejected through either the LVAD or ascending aorta, and an energy absorption term accounts for aortic compliance. Mock loop studies were performed for LV ejection fractions of 10%-28% combined with HeartMate II LVAD support at 8 and 11 krpm to produce a range of full and partial bypass conditions. The external work of the LVAD and native heart was computed from the experimental pressure-flow (H-Q) relations and compared to the theory. RESULTS Native heart contraction produces a counterclockwise loop in the pressure-flow relation of the LVAD which increased with ejection fraction, and during full bypass conditions the external work was preserved in the total systemic flow. During partial bypass conditions, forward flow through the ascending aorta was accompanied by a reversal during aortic valve closure resulting in a reduction in energy in the downstream flow. CONCLUSIONS The study presents a balance of external work during full and partial bypass LVAD support. Experimental data validated the additional terms corresponding to forward flow and aortic compliance that contribute to the system balance. This expanded theory can be applied to LVAD design and control to improve pulsatility and aortic valve biomechanics.
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Affiliation(s)
- Karen May-Newman
- Bioengineering Program, San Diego State University, San Diego, California, USA
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Mileva NB, Vassilev DI. Intravascular ultrasound imaging in evaluation of aortic stiffness: A proof-of-concept study. Cardiol J 2021; 30:221-227. [PMID: 33438178 PMCID: PMC10129260 DOI: 10.5603/cj.a2021.0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 08/29/2020] [Accepted: 10/13/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Aortic stiffness is a well-known cardio-vascular risk factor. For years, different methods have been studied in the assessment of aortic elastic properties and large arterial stiffness for risk stratification. Herein is an assessment of the role of intravascular ultrasound (IVUS) imaging for the evaluation of aortic elastic properties. METHODS Intravascular ultrasound imaging of the aorta was performed in 12 patients with transthoracic echocardiography (TTE) and computed tomography (CT) evidence for enlargement of the ascending aorta - diameter ≥ 40.0 mm. Mechanical properties of the aorta were derived from the measured diameters and intra-aortic pressure. Paired samples T-test analyses were performed to determine differences between measurements derived by TTE, CT and IVUS. RESULTS Mean values of the calculated elastic properties via IVUS of the ascending aorta were as follows: compliance 0.021 ± 0.02; strain 205 ± 4.3; aortic stiffness index 4.3 ± 0.75; elastic modulus 0.31 ± 0.05. On paired T-test analysis maximum ascending aortic diameter measured by CT aortography and IVUS did not differ significantly (t = -0.19, p = 0.985), but a significant difference between IVUS measurements and TTE derived diameters was found (t = 13.118, p = 0.034). On average, IVUS diameters were 2.3 mm larger than the results acquired by TTE (95% confidence interval: 14.21-17.13). CONCLUSIONS Intravascular ultrasound examination of the ascending aorta provided larger diameters than the ones collected by means of TTE. However, IVUS measurements did not differ significantly from diameters derived by CT aortography.
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Affiliation(s)
- Niya Boykova Mileva
- Cardiology Clinic, "Alexandrovska" University Hospital, Medical University of Sofia.
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Tomoto T, Imai T, Ogoh S, Maeda S, Sugawara J. Relationship between Aortic Compliance and Impact of Cerebral Blood Flow Fluctuation to Dynamic Orthostatic Challenge in Endurance Athletes. Front Physiol 2018; 9:25. [PMID: 29422868 PMCID: PMC5788908 DOI: 10.3389/fphys.2018.00025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 01/09/2018] [Indexed: 12/29/2022] Open
Abstract
Aorta effectively buffers cardiac pulsatile fluctuation generated from the left ventricular (LV) which could be a mechanical force to high blood flow and low-resistance end-organs such as the brain. A dynamic orthostatic challenge may evoke substantial cardiac pulsatile fluctuation via the transient increases in venous return and stroke volume (SV). Particularly, this response may be greater in endurance-trained athletes (ET) who exhibit LV eccentric remodeling. The aim of this study was to determine the contribution of aortic compliance to the response of cerebral blood flow fluctuation to dynamic orthostatic challenge in ET and age-matched sedentary (SED) young healthy men. ET (n = 10) and SED (n = 10) underwent lower body negative pressure (LBNP) (-30 mmHg for 4 min) stimulation and release the pressure that initiates a rapid regain of limited venous return and consequent increase in SV. The recovery responses of central and middle cerebral arterial (MCA) hemodynamics from the release of LBNP (~15 s) were evaluated. SV (via Modeflow method) and pulsatile and systolic MCA (via transcranial Doppler) normalized by mean MCA velocity (MCAv) significantly increased after the cessation of LBNP in both groups. ET exhibited the higher ratio of SV to aortic pulse pressure (SV/AoPP), an index of aortic compliance, at the baseline compared with SED (P < 0.01). Following the LBNP release, SV was significantly increased in SED by 14 ± 7% (mean ± SD) and more in ET by 30 ± 15%; nevertheless, normalized pulsatile, systolic, and diastolic MCAv remained constant in both groups. These results might be attributed to the concomitant with the increase in aortic compliance assessed by SV/AoPP. Importantly, the increase in SV/AoPP following the LBNP release was greater in ET than in SED (P < 0.01), and significantly correlated with the baseline SV/AoPP (r = 0.636, P < 0.01). These results suggest that the aortic compliance in the endurance athletes is able to accommodate the additional SV and buffer the potential increase in pulsatility at end-organs such as the brain.
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Affiliation(s)
- Tsubasa Tomoto
- Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan
| | - Tomoko Imai
- Center for General Education, Aichi Institute of Technology, Toyota, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan
| | - Seiji Maeda
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Jun Sugawara
- Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan
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Hughson RL, Peterson SD, Yee NJ, Greaves DK. Cardiac output by pulse contour analysis does not match the increase measured by rebreathing during human spaceflight. J Appl Physiol (1985) 2017; 123:1145-1149. [PMID: 28798205 DOI: 10.1152/japplphysiol.00651.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/03/2017] [Accepted: 08/04/2017] [Indexed: 11/22/2022] Open
Abstract
Pulse contour analysis of the noninvasive finger arterial pressure waveform provides a convenient means to estimate cardiac output (Q̇). The method has been compared with standard methods under a range of conditions but never before during spaceflight. We compared pulse contour analysis with the Modelflow algorithm to estimates of Q̇ obtained by rebreathing during preflight baseline testing and during the final month of long-duration spaceflight in nine healthy male astronauts. By Modelflow analysis, stroke volume was greater in supine baseline than seated baseline or inflight. Heart rate was reduced in supine baseline so that there were no differences in Q̇ by Modelflow estimate between the supine (7.02 ± 1.31 l/min, means ± SD), seated (6.60 ± 1.95 l/min), or inflight (5.91 ± 1.15 l/min) conditions. In contrast, rebreathing estimates of Q̇ increased from seated baseline (4.76 ± 0.67 l/min) to inflight (7.00 ± 1.39 l/min, significant interaction effect of method and spaceflight, P < 0.001). Pulse contour analysis utilizes a three-element Windkessel model that incorporates parameters dependent on aortic pressure-area relationships that are assumed to represent the entire circulation. We propose that a large increase in vascular compliance in the splanchnic circulation invalidates the model under conditions of spaceflight. Future spaceflight research measuring cardiac function needs to consider this important limitation for assessing absolute values of Q̇ and stroke volume.NEW & NOTEWORTHY Noninvasive assessment of cardiac function during human spaceflight is an important tool to monitor astronaut health. This study demonstrated that pulse contour analysis of finger arterial blood pressure to estimate cardiac output failed to track the 46% increase measured by a rebreathing method. These results strongly suggest that alternative methods not dependent on pulse contour analysis are required to track cardiac function in spaceflight.
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Affiliation(s)
- Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario Canada; and
| | - Sean D Peterson
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Nicholas J Yee
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario Canada; and
| | - Danielle K Greaves
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario Canada; and
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Abstract
The aorta is a blood vessel that provides a low-resistance path for blood flow directed from the heart to peripheral organs and tissues. However, the aorta has another central hemodynamic function, whereby the elastic nature of the aortic wall provides a significant biomechanical buffering capacity complementing the pulsatile cardiac blood flow, and this is often referred to as Windkessel function. Stiffening of the arterial wall leads to fundamental alterations in central hemodynamics, with widespread detrimental implications for organ function. In this Recent Highlights article, we describe recent contributions in ATVB that have highlighted the novel mechanisms and consequences of arterial stiffness and the clinical conditions in which arterial stiffness occurs, with a focus on advancements in the field.
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Affiliation(s)
- Alicia N Lyle
- From the Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (A.N.L.); and Molecular and Translational Vascular Medicine, Department of Cardiology and Pneumology, Heart Center at the University Medical Center Göttingen, Germany (U.R.).
| | - Uwe Raaz
- From the Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (A.N.L.); and Molecular and Translational Vascular Medicine, Department of Cardiology and Pneumology, Heart Center at the University Medical Center Göttingen, Germany (U.R.)
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Taketazu M, Sugimoto M, Saiki H, Ishido H, Masutani S, Senzaki H. Developmental Changes in Aortic Mechanical Properties in Normal Fetuses and Fetuses with Cardiovascular Disease. Pediatr Neonatol 2017; 58:245-250. [PMID: 27816335 DOI: 10.1016/j.pedneo.2016.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/22/2016] [Accepted: 05/26/2016] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND We hypothesized that fetal aortic mechanical properties assessed by aortic diameter (AoD) and flow show maturational changes during the gestational period, and that these properties are different in fetuses with congenital heart diseases and fetuses with normal development. METHODS Phasic changes in ascending AoD along with Doppler flow profile were measured in 84 consecutive normal fetuses (gestational age, 18-36 weeks) and in 30 consecutive fetuses with cardiovascular diseases (gestational age, 22-39 weeks). RESULTS AoD and cardiac output significantly increased with gestational age. Fetal aortic compliance (AC), assessed as (maximum AoD - minimum AoD)/stroke volume, significantly decreased with gestational age in normal fetuses, indicating maturational changes in aortic wall properties. Importantly, fetuses with Marfan syndrome and tetralogy of Fallot that exhibit "aortopathy" showed significantly lower AC than normal fetuses of the same gestational age, suggesting intrinsic abnormalities in aortic wall properties in these diseases. Fetuses with trisomy 18 and Noonan syndrome also had AC values below the normal ranges. CONCLUSION Measurements of phasic changes in fetal AoD and flow measurements can provide useful information about aortic mechanical properties and may help clarify abnormal arterial hemodynamics in pathologic conditions.
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Affiliation(s)
- Mio Taketazu
- Department of Pediatric Cardiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan; Department of Pediatrics, Asahikawa Kosei General Hospital, Asahikawa, Hokkaido, Japan
| | - Masaya Sugimoto
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Hirofumi Saiki
- Department of Pediatric Cardiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Hirotaka Ishido
- Department of Pediatric Cardiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Satoshi Masutani
- Department of Pediatric Cardiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Hideaki Senzaki
- Department of Pediatric Cardiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan.
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Rabkin SW, Chan KK, Chow B, Janusz MT. Pulse wave velocity involving proximal portions of the aorta correlates with the degree of aortic dilatation at the sinuses of valsalva in ascending thoracic aortic aneurysms. Ann Vasc Dis 2015; 7:404-9. [PMID: 25593626 DOI: 10.3400/avd.oa.14-00063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 10/06/2014] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE To determine the relationship between arterial stiffness measured in different aortic segments and the presence and extent of ascending thoracic aortic aneurysm (ATAA). METHODS Patients at a Thoracic Aortic Diseases clinic at a University teaching hospital were compared to patients attending a Cardiology outpatient Clinic at the same institution. A non-invasive measure of vascular stiffness was performed using pulse wave velocity (PWV) measurement of several vascular segments-carotid-femoral pulse wave velocity (cfPWV), heart-femoral pulse wave velocity (hfPWV) and brachial-ankle pulse wave velocity (baPWV). Aortic dimensions were measured on echocardiogram. RESULTS Patients with ATAA (N = 32) were 66 years and the same age as those without ATAA (N = 46). There was no significant difference between those with or without aortic aneurysm with respect to cfPWV, hfPWV or baPWV. In ATAA, there was a significant (p <0.05) inverse correlation between aortic diameter at the sinuses of Valsalva and cfPWV, as well as hfPWV, but not with baPWV. This relationship was not evident in persons without ATAA. CONCLUSION Reduced aortic stiffness (increased compliance), assessed by cfPWV or hfPWV, correlates with larger aortic size of ATAA at the level of the sinuses of Valsalva but not at the ascending aorta, suggesting cfPWV may be a useful method to assess the size of ATAA at the level of the sinuses of Valsalva. Overall aortic stiffness assessed by PWV did not differentiate persons with or without an ATAA, in individuals who do not have a genetic or inheritable cause of their ATAA.
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Affiliation(s)
- Simon W Rabkin
- Department of Medicine, University of British Columbia , Vancouver, Canada
| | - Kenneth K Chan
- Department of Medicine, University of British Columbia , Vancouver, Canada
| | - Bryan Chow
- Department of Medicine, University of British Columbia , Vancouver, Canada
| | - Michael T Janusz
- Department of Surgery, University of British Columbia , Vancouver, Canada
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Abstract
The performance of a one-dimensional MR technique for the estimation of pulse-wave velocity in the aorta was evaluated. An expression for the error in this estimate was formulated and verified both by simulation and by experiment. On the basis of this formulation, guidelines for increasing the efficiency of the acquisition were established. The technique was further validated by comparison with pulse-wave velocity measurements made with a pressure catheter. All data were acquired from a latex tube driven by a pulsatile flow system. MR measurements of pulse-wave velocity in the tube were found to be very reproducible in the presence of white noise. Measurements by other techniques were in good agreement, falling within 2 SD of the mean. Because of its sensitivity and spatial resolution, this technique shows promise for making spatially resolved estimates of vessel distensibility. This would allow assessment of diseases, such as atherosclerosis, that cause local changes in the material properties of the vasculature.
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Affiliation(s)
- B D Bolster
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Ferguson JJ, Momomura S, Sahagian P, Miller MJ, McKay RG. The use of nitroprusside to characterize aortic pressure-diameter relationships. Tex Heart Inst J 1989; 16:5-10. [PMID: 15227229 PMCID: PMC324835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
The viscoelastic properties of the wall of the ascending aorta can be determined by calculating the relationship between pressure and diameter of the vessel. Because of potential nonlinearities in aortic pressure-diameter relationships, however, pressure-diameter curves are more accurate than compliance expressed as a single value in measuring aortic viscoelastic properties. To determine whether nitroprusside could be used to obtain aortic pressure-diameter curves over a wide range, we measured simultaneous aortic pressure and diameter in anesthetized dogs. The inferior vena cava (IVC) of each animal was briefly occluded to generate a baseline series of pressure-diameter points over a wide range of pressure and diameter. We found that moderate lowering of systolic arterial pressure (30 mmHg) with nitroprusside did not significantly affect the aortic pressure-diameter relationship in comparison with control measurements during brief IVC occlusions at similar pressures and diameters. Prolonged inferior vena caval occlusion and a more profound lowering of arterial pressure with nitroprusside or IVC occlusion resulted in a leftward and upward shift of the aortic pressure-diameter relationship, with higher pressures at comparable diameters and lower diameters at comparable pressures. However, with more profound changes in arterial pressure, possible reflex-mediated mechanisms that alter the baseline aortic pressure-diameter relationship may be activated. We conclude that nitroprusside can be used to obtain aortic pressure-diameter data over a wider range than that possible from a single cardiac cycle.
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Affiliation(s)
- J J Ferguson
- The Charles A. Dana Research Institute and the Harvard-Thorndike Laboratory of Beth Israel Hospital, Department of Medicine (Cardiovascular Division), Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, USA
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