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Rose W, Throckmorton AL, Heintzelman B, Tchantchaleishvili V. Impact of continuous-flow mechanical circulatory support on cerebrospinal fluid motility. Artif Organs 2023; 47:1567-1580. [PMID: 37602714 DOI: 10.1111/aor.14624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/26/2023] [Accepted: 07/22/2023] [Indexed: 08/22/2023]
Abstract
BACKGROUND Mechanical circulatory support (MCS), including ventricular assist devices (VADs), have emerged as promising therapeutic alternatives for end-stage congestive heart failure (CHF). The latest generation of these devices are continuous flow (CF) blood pumps. While there have been demonstrated benefits to patient outcomes due to CF-MCS, there continue to be significant clinical challenges. Research to-date has concentrated on mitigating thromboembolic risk (stroke), while the downstream impact of CF-MCS on the cerebrospinal fluid (CSF) flow has not been well investigated. Disturbances in the CSF pressure and flow patterns are known to be associated with neurologic impairment and diseased states. Thus, here we seek to develop an understanding of the pathophysiologic consequences of CF-MCS on CSF dynamics. METHODS We built and validated a computational framework using lumped parameter modeling of cardiovascular, cerebrovascular physics, CSF dynamics, and autoregulation. A sensitivity analysis was performed to confirm robustness of the modeling framework. Then, we characterized the impact of CF-MCS on the CSF and investigated cardiovascular conditions of healthy and end-stage heart failure. RESULTS Modeling results demonstrated appropriate hemodynamics and indicated that CSF pressure depends on blood flow pulsatility more than CSF flow. An acute equilibrium between CSF production and absorption was observed in the CF-MCS case, characterized by CSF pressure remaining elevated, and CSF flow rates remaining below healthy, but higher than CHF states. CONCLUSION This research has advanced our understanding of the impact of CF-MCS on CSF dynamics and cerebral hemodynamics.
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Affiliation(s)
- William Rose
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, USA
| | - Amy L Throckmorton
- BioCirc Research Laboratory, School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Briana Heintzelman
- BioCirc Research Laboratory, School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Vakhtang Tchantchaleishvili
- Division of Cardiac Surgery, Department of Surgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA
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Zhang Q, Turner KL, Gheres KW, Hossain MS, Drew PJ. Behavioral and physiological monitoring for awake neurovascular coupling experiments: a how-to guide. NEUROPHOTONICS 2022; 9:021905. [PMID: 35639834 PMCID: PMC8802326 DOI: 10.1117/1.nph.9.2.021905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/28/2021] [Indexed: 06/15/2023]
Abstract
Significance: Functional brain imaging in awake animal models is a popular and powerful technique that allows the investigation of neurovascular coupling (NVC) under physiological conditions. However, ubiquitous facial and body motions (fidgeting) are prime drivers of spontaneous fluctuations in neural and hemodynamic signals. During periods without movement, animals can rapidly transition into sleep, and the hemodynamic signals tied to arousal state changes can be several times larger than sensory-evoked responses. Given the outsized influence of facial and body motions and arousal signals in neural and hemodynamic signals, it is imperative to detect and monitor these events in experiments with un-anesthetized animals. Aim: To cover the importance of monitoring behavioral state in imaging experiments using un-anesthetized rodents, and describe how to incorporate detailed behavioral and physiological measurements in imaging experiments. Approach: We review the effects of movements and sleep-related signals (heart rate, respiration rate, electromyography, intracranial pressure, whisking, and other body movements) on brain hemodynamics and electrophysiological signals, with a focus on head-fixed experimental setup. We summarize the measurement methods currently used in animal models for detection of those behaviors and arousal changes. We then provide a guide on how to incorporate this measurements with functional brain imaging and electrophysiology measurements. Results: We provide a how-to guide on monitoring and interpreting a variety of physiological signals and their applications to NVC experiments in awake behaving mice. Conclusion: This guide facilitates the application of neuroimaging in awake animal models and provides neuroscientists with a standard approach for monitoring behavior and other associated physiological parameters in head-fixed animals.
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Affiliation(s)
- Qingguang Zhang
- The Pennsylvania State University, Center for Neural Engineering, Department of Engineering Science and Mechanics, University Park, Pennsylvania, United States
| | - Kevin L. Turner
- The Pennsylvania State University, Department of Biomedical Engineering, University Park, Pennsylvania, United States
| | - Kyle W. Gheres
- The Pennsylvania State University, Graduate Program in Molecular Cellular and Integrative Biosciences, University Park, Pennsylvania, United States
| | - Md Shakhawat Hossain
- The Pennsylvania State University, Department of Biomedical Engineering, University Park, Pennsylvania, United States
| | - Patrick J. Drew
- The Pennsylvania State University, Center for Neural Engineering, Department of Engineering Science and Mechanics, University Park, Pennsylvania, United States
- The Pennsylvania State University, Department of Biomedical Engineering, University Park, Pennsylvania, United States
- The Pennsylvania State University, Department of Neurosurgery, University Park, Pennsylvania, United States
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Napoli NJ, Rodrigues VR, Davenport PW. Characterizing and Modeling Breathing Dynamics: Flow Rate, Rhythm, Period, and Frequency. Front Physiol 2022; 12:772295. [PMID: 35264974 PMCID: PMC8899297 DOI: 10.3389/fphys.2021.772295] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/25/2021] [Indexed: 11/13/2022] Open
Abstract
The characterization of breathing dynamics provides researchers and clinicians the ability to differentiate respiratory compensation, impairment, disease progression, ventilator assistance, and the onset of respiratory failure. However, within many sub-fields of respiratory physiology, we still have challenges identifying changes within the breathing dynamics and critical respiratory states. We discuss one fundamental modeling of breathing and how modeling imprecise assumptions decades ago regarding breathing are still propagating into our quantitative analysis today, limiting our characterization and modeling of breathing. The assumption that breathing is a continuous sinusoidal wave that can consist of a single frequency which is composed of a stationary time-invariant process has limited our expanded discussion of breathing dynamics, modeling, functional testings, and metrics. Therefore, we address major misnomers regarding breathing dynamics, specifically rate, rhythm, frequency, and period. We demonstrate how these misnomers impact the characterization and modeling through the force equations that are linked to the Work of Breathing (WoB) and our interpretation of breathing dynamics through the fundamental models and create possible erroneous evaluations of work of breathing. This discussion and simplified non-periodic WoB models ultimately sets the foundation for improved quantitative approaches needed to further our understanding of breathing dynamics, compensation, and adaptation.
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Affiliation(s)
- Nicholas J Napoli
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, United States.,Human Informatics and Predictive Performance Optimization (HIPPO) Lab, University of Florida, Gainesville, FL, United States.,Breathing Research and Therapeutics (BREATHE) Center, University of Florida, Gainesville, FL, United States
| | - Victoria R Rodrigues
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, United States.,Human Informatics and Predictive Performance Optimization (HIPPO) Lab, University of Florida, Gainesville, FL, United States.,Breathing Research and Therapeutics (BREATHE) Center, University of Florida, Gainesville, FL, United States
| | - Paul W Davenport
- Breathing Research and Therapeutics (BREATHE) Center, University of Florida, Gainesville, FL, United States.,Department of Physiological Sciences, University of Florida, Gainesville, FL, United States
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Ludwig HC, Bock HC, Gärtner J, Schiller S, Frahm J, Dreha-Kulaczewski S. Hydrocephalus Revisited: New Insights into Dynamics of Neurofluids on Macro- and Microscales. Neuropediatrics 2021; 52:233-241. [PMID: 34192788 DOI: 10.1055/s-0041-1731981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time magnetic resonance imaging (MRI) evaluation of cerebrospinal fluid (CSF) flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids: (1) inspiration is a major driving force; (2) adequate filling of brain ventricles by balanced CSF upsurge is sensed by cilia; and (3) the perivascular glial network connects the ependymal surface to the pericapillary Virchow-Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework, improving knowledge and therapy for severe disorders of normal-pressure and posthemorrhagic hydrocephalus, spontaneous intracranial hypotension, and spaceflight disease.
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Affiliation(s)
- Hans C Ludwig
- Division of Pediatric Neurosurgery, Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Hans C Bock
- Division of Pediatric Neurosurgery, Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Jutta Gärtner
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Stina Schiller
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Jens Frahm
- Biomedical NMR, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Steffi Dreha-Kulaczewski
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
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Thomale UW. Integrated understanding of hydrocephalus - a practical approach for a complex disease. Childs Nerv Syst 2021; 37:3313-3324. [PMID: 34114082 PMCID: PMC8578093 DOI: 10.1007/s00381-021-05243-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/01/2021] [Indexed: 12/20/2022]
Abstract
Most of childhood hydrocephalus are originating during infancy. It is considered to be a complex disease since it is developed on the basis of heterogeneous pathophysiological mechanisms and different pathological conditions as well as during different age groups. Hence, it is of relevant importance to have a practical concept in mind, how to categorize hydrocephalus to surgically better approach this disease. The current review should offer further basis of discussion on a disease still most frequently seen in Pediatric Neurosurgery. Current literature on pathophysiology and classification of pediatric hydrocephalus has been reviewed to integrate the different published concepts of hydrocephalus for pediatric neurosurgeons. The current understanding of infant and childhood hydrocephalus pathophysiology is summarized. A simplified concept based on seven factors of CSF dynamics is elaborated and discussed in the context of recent discussions. The seven factors such as pulsatility, CSF production, major CSF pathways, minor CSF pathways, CSF absorption, venous outflow, and respiration may have different relevance and may also overlap for the individual hydrocephalic condition. The surgical options available for pediatric neurosurgeons to approach hydrocephalus must be adapted to the individual condition. The heterogeneity of hydrocephalus causes mostly developing during infancy warrant a simplified overview and understanding for an everyday approach. The proposed guide may be a basis for further discussion and may serve for a more or less simple categorization to better approach hydrocephalus as a pathophysiological complex disease.
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Affiliation(s)
- U. W. Thomale
- grid.6363.00000 0001 2218 4662Pediatric Neurosurgery, Charité Universitätsmedizin, Berlin, Germany
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Reply to Ludwig et al.: A potential mechanism for intracranial cerebrospinal fluid accumulation during long-duration spaceflight. Proc Natl Acad Sci U S A 2019; 116:20265-20266. [PMID: 31530727 PMCID: PMC6789921 DOI: 10.1073/pnas.1913041116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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