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Open Heart Nov 2023Peak oxygen pulse (Opulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in...
BACKGROUND
Peak oxygen pulse (Opulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in patients with a Fontan circulation. However, in the Fontan population, it may be a poor marker of SV. We propose that the slope of the O pulse curve may be more reflective of SV during exercise.
METHODS
We analysed cardiopulmonary exercise test data in 22 subjects with a Fontan circulation (cohort A) and examined the association between peak SV during exercise (aortic flow measured on exercise cardiac MRI), and O pulse parameters (absolute O pulse and O pulse slopes up to anaerobic threshold (AT) and peak exercise). In a separate Fontan cohort (cohort B, n=131), associations between clinical characteristics and O pulse kinetics were examined.
RESULTS
In cohort A, peak aortic flow was moderately and significantly associated with Opulseslope (r=0.47, p=0.02). However, neither absolute Opulse nor Opulse was significantly associated with peak aortic flow. In cohort B, Opulseslope and Opulseslope were not significantly associated with clinical parameters, apart from a weak association with forced vital capacity.
CONCLUSION
The slope of the O pulse curve to peak exercise may be more reflective of peak SV in the Fontan population than a single peak O pulse value.
Topics: Humans; Fontan Procedure; Stroke Volume; Heart Rate; Exercise Test; Oxygen
PubMed: 37935560
DOI: 10.1136/openhrt-2023-002324 -
Magnetic Resonance in Medicine Sep 2023The Vespa package (Versatile Simulation, Pulses, and Analysis) is described and demonstrated. It provides workflows for developing and optimizing linear combination...
PURPOSE
The Vespa package (Versatile Simulation, Pulses, and Analysis) is described and demonstrated. It provides workflows for developing and optimizing linear combination modeling (LCM) fitting for H MRS data using intuitive graphical user interface interfaces for RF pulse design, spectral simulation, and MRS data analysis. Command line interfaces for embedding workflows in MR manufacturer platforms and utilities for synthetic dataset creation are included. Complete provenance is maintained for all steps in workflows.
THEORY AND METHODS
Vespa is written in Python for compatibility across operating systems. It embeds the PyGAMMA spectral simulation library for spectral simulation. Multiprocessing methods accelerate processing and visualization. Applications use the Vespa database for results storage and cross-application access. Three projects demonstrate pulse, sequence, simulation, and data analysis workflows: (1) short TE semi-LASER single-voxel spectroscopy (SVS) LCM fitting, (2) optimizing MEGA-PRESS (MEscher-GArwood Point RESolved Spectroscopy) flip angle and LCM fitting, and (3) creating a synthetic short TE dataset.
RESULTS
The LCM workflows for in vivo basis set creation and spectral analysis showed reasonable results for both the short TE semi-LASER and MEGA-PRESS. Examples of pulses, simulations, and data fitting are shown in Vespa application interfaces for various steps to demonstrate the interactive workflow.
CONCLUSION
Vespa provides an efficient and extensible platform for characterizing RF pulses, pulse design, spectral simulation optimization, and automated LCM fitting via an interactive platform. Modular design and command line interface make it easy to embed in other platforms. As open source, it is free to the MRS community for use and extension. Vespa source code and documentation are available through GitHub.
Topics: Magnetic Resonance Spectroscopy; Computer Simulation; Software; Databases, Factual; Heart Rate
PubMed: 37183778
DOI: 10.1002/mrm.29686 -
Medicine Nov 2023To explore the feasibility of using micro-bolus pulse injection method to reduce the dilution effect of pipeline on high concentration injection, and to understand low...
To explore the feasibility of using micro-bolus pulse injection method to reduce the dilution effect of pipeline on high concentration injection, and to understand low liquid volume bolus injection based on low injection speed. Using a programmable pulse injection pump, a 25-cm - long pipeline containing water-soluble fluorescent agent was flushed using different volumes of bolus, and the time spent for the complete disappearance of the fluorescent agent was recorded to evaluate the flushing efficiency. The finite element simulation of 2-phase flow was carried out using computational fluid dynamics (CFD) technology, and the difference of shear rate and pressure distribution in the vein of pulse injection and direct injection of bolus under hemostasis was compared and simulated. Micro-bolus pulse flushing has advantages in completing perfusion imaging applications, such as small volume imaging agent injection. Compared with non-pulse injection, the effective flushing volume decreases by 49.7%, the average injection speed decreases by 56%, and the maintenance time of high shear rate is shorter when using micro-bolus pulse injection. The impact of micro-bolus pulse injection on the vein can achieve the same or even lower negative effects as other injection methods after increasing the hemostatic distance to 100 mm. In the case of bolus injection requiring high concentration and small volume, such as for radiopharmaceutical dynamic imaging, the application of micro-bolus pulse injection is an effective way to overcome the dilution phenomenon of the imaging agent in the pipeline. During hemostasis, the micro-bolus pulse injection needs to control a longer hemostasis distance to reduce the potential impact on peripheral veins.
Topics: Humans; Injections; Veins; Computer Simulation; Heart Rate; Hemostasis
PubMed: 37933034
DOI: 10.1097/MD.0000000000035607 -
Vox Sanguinis Dec 2023Blood donation can be a potentially stressful event, leading to the activation of an acute stress response. Knowing and identifying potential stressors could help in...
BACKGROUND AND OBJECTIVES
Blood donation can be a potentially stressful event, leading to the activation of an acute stress response. Knowing and identifying potential stressors could help in optimizing the donation experience. The present study aimed to measure the physiological and psychological stress changes before, during and after blood donation.
MATERIALS AND METHODS
Physiological and psychological stress response was assessed in 70 blood donors. To evaluate physiological stress response, pulse rate, respiratory rate, blood pressure (BP), beat-to-beat BP and lead II electrocardiogram were recorded. Baroreflex sensitivity was calculated using the available software. Psychological stress response was assessed using the State-Trait Anxiety Inventory scale.
RESULTS
A significant increase in systolic blood pressure, diastolic blood pressure and mean arterial pressure was observed in the pre-donation period (p < 0.001). Among the time-domain parameters, SDSD (standard deviation of differences between adjacent respiratory rate intervals) and RMSSD (root mean square of the successive differences) were significantly lower during the post-donation period (p < 0.005, p < 0.007, respectively). Among the frequency-domain parameters, LF nu (relative power of the low-frequency band in normalized units), HF nu (relative power of the high-frequency band in normalized units) and LF% (relative power of the low-frequency band in percentage) were significantly lower before donation compared to during donation (p < 0.001, p < 0.001 and p < 0.012, respectively). LF nu, LF% and LF/HF ratio were also significantly lower during donation compared to after donation (p < 0.05, p < 0.016 and p < 0.042, respectively). Baroreflex sensitivity was also statistically higher during the pre-donation period. State score was significantly higher among the blood donors during the pre-donation period.
CONCLUSION
Physiological and psychological stress is experienced by blood donors during the pre-donation period. A pre-donation informative conversation should be carried out with each blood donor and potential stressors should be identified in each.
Topics: Humans; Blood Donors; Blood Donation; Blood Pressure; Heart Rate; Stress, Psychological
PubMed: 37830384
DOI: 10.1111/vox.13541 -
Journal of the American Heart... Dec 2023
Topics: Humans; Adult; Cardiovascular Diseases; Cohort Studies; Heart Rate; Risk Factors; Kidney Failure, Chronic; Kidney Diseases
PubMed: 38038191
DOI: 10.1161/JAHA.123.032580 -
Experimental Physiology Mar 2024The dive response, or the 'master switch of life', is probably the most studied physiological trait in marine mammals and is thought to conserve the available O for the... (Review)
Review
The dive response, or the 'master switch of life', is probably the most studied physiological trait in marine mammals and is thought to conserve the available O for the heart and brain. Although generally thought to be an autonomic reflex, several studies indicate that the cardiovascular changes during diving are anticipatory and can be conditioned. The respiratory adaptations, where the aquatic breathing pattern resembles intermittent breathing in land mammals, with expiratory flow exceeding 160 litres s has been measured in cetaceans, and where exposure to extreme pressures results in alveolar collapse (atelectasis) and recruitment upon ascent. Cardiorespiratory coupling, where breathing results in changes in heart rate, has been proposed to improve gas exchange. Cardiorespiratory coupling has also been reported in marine mammals, and in the bottlenose dolphin, where it alters both heart rate and stroke volume. When accounting for this respiratory dependence on cardiac function, several studies have reported an absence of a diving-related bradycardia except during dives that exceed the duration that is fuelled by aerobic metabolism. This review summarizes what is known about the respiratory physiology in marine mammals, with a special focus on cetaceans. The cardiorespiratory coupling is reviewed, and the selective gas exchange hypothesis is summarized, which provides a testable mechanism for how breath-hold diving vertebrates may actively prevent uptake of N during routine dives, and how stress results in failure of this mechanism, which results in diving-related gas emboli.
Topics: Animals; Diving; Mammals; Bradycardia; Heart Rate; Respiration
PubMed: 37968859
DOI: 10.1113/EP091095 -
Journal of Neural Engineering Apr 2024There is a high variability in the physiological effects of transcranial magnetic brain stimulation, resulting in limited generalizability of measurements. The cause of...
There is a high variability in the physiological effects of transcranial magnetic brain stimulation, resulting in limited generalizability of measurements. The cause of the variability is assumed to be primarily based on differences in brain function and structure of the stimulated individuals, while the variability of the physical properties of the magnetic stimulus has so far been largely neglected. Thus, this study is dedicated to the systematic investigation of variability in the pulse width of different TMS pulse sources at different stimulation intensities.The pulse widths of seven MagVenture® pulse sources were measured at the output of 10%-100% stimulation intensity in 10% increments via Near Field Probe and oscilloscope. The same C-B60 coil was used to deliver biphasic pulses. Pulse widths were compared between pulse sources and stimulation intensities.The mean sample pulse width was 288.11 ± 0.37s, which deviates from the value of 280s specified by the manufacturer. The pulse sources and stimulation intensities differ in their average pulse width (< .001). However, the coefficient of variation within the groups (pulse source; stimulation intensity) were moderately low (CV = 0.13%-0.67%).The technical parameter of pulse width shows deviations from the proposed manufacturer value. According to our data, within a pulse source of the same manufacturer, the pulse width variability is minimal, but varies between pulse sources of the same and other pulse source models. Whether the observed variability in pulse width has potential physiological relevance was tested in a pilot experiment on a single healthy subject, showing no significant difference in motor evoked potential amplitude and significant difference in latencies. Future research should systematically investigate the physiological effects of different pulse lengths. Furthermore, potential hardware ageing effects and pulse amplitude should be investigated.
Topics: Humans; Transcranial Magnetic Stimulation; Brain; Evoked Potentials, Motor; Heart Rate
PubMed: 38513287
DOI: 10.1088/1741-2552/ad367a -
Sensors (Basel, Switzerland) Dec 2023Today, cardiovascular diseases threaten human health worldwide. In clinical practice, it has been concluded that analyzing the pulse waveform can provide clinically... (Review)
Review
Today, cardiovascular diseases threaten human health worldwide. In clinical practice, it has been concluded that analyzing the pulse waveform can provide clinically valuable information for the diagnosis of cardiovascular diseases. Accordingly, continuous and accurate monitoring of the pulse wave is essential for the prevention and detection of cardiovascular diseases. Wearable triboelectric nanogenerators (TENGs) are emerging as a pulse wave monitoring biotechnology due to their compelling characteristics, including being self-powered, light-weight, and wear-resistant, as well as featuring user-friendliness and superior sensitivity. Herein, a comprehensive review is conducted on the progress of wearable TENGs for pulse wave monitoring. Firstly, the four modes of operation of TENG are briefly described. Secondly, TENGs for pulse wave monitoring are classified into two categories, namely wearable flexible film-based TENG sensors and textile-based TENG sensors. Next, the materials, fabrication methods, working mechanisms, and experimental performance of various TENG-based sensors are summarized. It concludes by comparing the characteristics of the two types of TENGs and discussing the potential development and challenges of TENG-based sensors in the diagnosis of cardiovascular diseases and personalized healthcare.
Topics: Humans; Cardiovascular Diseases; Heart Rate; Biotechnology; Monitoring, Physiologic; Wearable Electronic Devices
PubMed: 38202897
DOI: 10.3390/s24010036 -
Journal of Sleep Research Apr 2024Napping during night shifts effectively reduces disease risk and improves work performance, but few studies have investigated the association between napping and...
Napping during night shifts effectively reduces disease risk and improves work performance, but few studies have investigated the association between napping and physiological changes, particularly in off-duty daily lives. Changes in the autonomic nervous system precede diseases like cardiovascular disease, diabetes, and obesity. Heart rate variability is a good indicator of autonomic nervous system. This study aimed to investigate the link between night shift nap durations and heart rate variability indices in the daily lives of medical workers. As indicators of chronic and long-term alterations, the circadian patterns of heart rate variability indices were evaluated. We recruited 146 medical workers with regular night shifts and divided them into four groups based on their self-reported nap durations. Heart rate variability circadian parameters (midline-estimating statistic of rhythm, amplitude, and acrophase) were obtained by obtaining 24-h electrocardiogram on a day without night shifts, plotting the data of the heart rate variability indices as a function of time, and fitting them into periodic cosine curves. Using clinical scales, depression, anxiety, stress, fatigue, and sleepiness were assessed. Linear regression analysis revealed a positive relationship between 61-120-min naps and 24-h, daytime, and night-time heart rate variability indices, and the parasympathetic activity oscillation amplitude (indexed by high-frequency power, the square root of the mean of the sum of squares of differences between adjacent normal intervals, standard deviation of short-term R-R-interval variability) within one circadian cycle. This study indicated that napping for 61-120 min during night shifts could benefit medical workers' health, providing physiological evidence to promote nap management.
Topics: Humans; Circadian Rhythm; Work Schedule Tolerance; Heart Rate; Wakefulness; Autonomic Nervous System; Sleep
PubMed: 37226542
DOI: 10.1111/jsr.13935 -
Neuroscience Bulletin Oct 2023Respiration protocols have been developed to manipulate mental states, including their use for therapeutic purposes. In this systematic review, we discuss evidence that... (Review)
Review
Respiration protocols have been developed to manipulate mental states, including their use for therapeutic purposes. In this systematic review, we discuss evidence that respiration may play a fundamental role in coordinating neural activity, behavior, and emotion. The main findings are: (1) respiration affects the neural activity of a wide variety of regions in the brain; (2) respiration modulates different frequency ranges in the brain's dynamics; (3) different respiration protocols (spontaneous, hyperventilation, slow or resonance respiration) yield different neural and mental effects; and (4) the effects of respiration on the brain are related to concurrent modulation of biochemical (oxygen delivery, pH) and physiological (cerebral blood flow, heart rate variability) variables. We conclude that respiration may be an integral rhythm of the brain's neural activity. This provides an intimate connection of respiration with neuro-mental features like emotion. A respiratory-neuro-mental connection holds the promise for a brain-based therapeutic usage of respiration in mental disorders.
Topics: Humans; Respiration; Brain; Hyperventilation; Heart Rate; Lung
PubMed: 37285017
DOI: 10.1007/s12264-023-01070-5